 DISCUSSION: When most people think of severe weather, tornadoes, hurricanes, and other dramatic phenomena typically come to mind. However, other less dramatic weather events can be far more deadly (e.g., heat waves). Heat waves generally occur over a longer time and a larger area than impacted by a tornado, for example, which helps to explain why they can be so deadly. High heat exerts a cumulative stress on the body. Thus, one hot day is generally not going to be much of an issue. But, a string of hot days coupled with warm nights (i.e., no relief at night) can start to lead to fatalities. As an extreme example of how deadly heat waves can be, an event in August 2003 in Europe killed an estimated 70,000 people.
In terms of weather conditions, this year has been similar to 2003 in Europe with periods of a few days to a week having above normal temperatures followed by a period of normal temperatures that repeats over and over throughout the summer. In addition, drought conditions can make heat waves worse and more persistent. There is less water to evaporate resulting in more incoming solar energy going toward an increase in temperatures instead of toward evaporation. Large portions of Europe were in a drought in 2003 and are again this summer. On 25 July, the high temperature in Paris was 109°F, and the high in London was 98°F, both of which were records. The picture above (credit: BBC) shows people crowding a beach in northern Germany to try to beat the heat that same day. Fortunately, it is relatively simple to prevent deaths from heat waves. In addition to getting enough to drink, just a few hours of air conditioning per day can relieve the accumulated stress that heat places on the body. Part of the reason for the enormous death toll in 2003 in Europe was that most people do not have air conditioning. After the 2003 heat wave, the French government took steps to prevent such a tragedy from occurring again. For example, they instituted a nationwide alert system to provide heat warnings and recommended mitigation actions and built cooling centers. Nevertheless, fatalities from excessive heat continue to occur in France perhaps because some people don’t receive the alerts nor are able to get to cooling centers (e.g., the homeless population). Thus, more work remains to be done in order to get the death toll from heat waves in Europe and elsewhere down to zero. As the summer wears on, the main takeaway message here is to not get complacent and take that heat lightly. Be sure to take necessary precautions to protect yourself and check in with people who may be more vulnerable to the heat. To learn more about European weather patterns/events and more, click here! ©2019 Meteorologist Dr. Ken Leppert II
0 Comments
 Discussion: As the US has dealt with copious amounts of severe weather over the past several months, across the pond Europe severe weather season continues as well. There will be a localized region of possible severe convection across far northwestern France this afternoon/evening (Tuesday July 22, 2019) and across portions of south to southwestern UK into the overnight. This region will be the focus of this article. Rapid destabilization will develop across extreme northwest France during the afternoon hours Tuesday. A moist air mass with dewpoint temperatures in the mid and upper 60s Fahrenheit lead to moderate CAPE across this region. In the mid and upper levels of the atmosphere, a short-wave trough approaches by the late afternoon and evening hours just to the northwest of France. This system along with potential surface boundaries may generate enough lift to allow for isolated surface thunderstorm development. Some model guidance point to convection staying just to the north mainly in the English Channel perhaps in due part to the short wave being just slightly off to the northwest. A cap in the lower portions of the atmosphere (a lid of warmer air that limits rising air and hence lowers storm chances if this feature cannot be overcome) will be another possible limiting factor to convective development. Real-time observations and trends in satellite data will likely be needed to determine convective likelihood in this region. Regardless, if storms do initiate during this time, even if isolated, there will be the potential for a few strong to severe cells with frequent lightning, strong gusty outflow winds, and large hail as the parameters used to forecast deep moist convection are rather robust in this scenario.  The image above is a forecast sounding from the GFS for far northwest France during the late afternoon hours. A couple of key features are present in this vertical profile of the atmosphere. Abundant CAPE and moisture (high low-level dewpoint temperature values) is present and hence a very unstable environment has developed in this forecast scenario. The bulk wind shear (Sfc-6km) is modest in the lower to mid-30 knot range, good enough in theory for multi-cells or possible/transient supercells. Another important factor is present, the cap (numerically represented by the negative CINH values in the sounding, graphically as the bulge or relatively warmer temperatures near 850 mb). The question is whether air can push through this feature to generate robust surface-based storms. The amount of daytime heating as well as if any surface boundaries/convergence can develop and how strong will determine if this can happen. Otherwise either elevated storms will develop with slightly less severe tendencies or very little develops at all. While uncertainty may exist regarding convective initiation and coverage across far northwest France, this is not the case across portions of the UK. Storms will either initiate during the late afternoon hours (which looks less likely and would be less widespread) or hold off and push into the region during the evening to overnight hours and as a result will be elevated. In addition to anonymously moist air and elevated CAPE, the robust shortwave will impact portions of western and southwestern UK creating the necessary lift for strong to severe convection. Frequent lightning, strong gusty winds, and even large hail will remain a possibility across southern perhaps into the central portions of the UK. Regardless of the widespread nature of the strong winds and hail, areas of heavy rainfall may be an issue given the high moisture content and the possibility for storms to congeal over the UK. The images above represent the four major ingredients for deep moist convection: moisture, instability, lift, and wind shear. The diagrams (courtesy of pivotal weather) via the GFS model are timed out to be either during the late afternoon hours or the overnight. One thing is for certain and that is the moisture present across W/NW France and the UK as this system approaches is anonymously high. The instability or convective available potential energy (CAPE) is modest along with the wind shear which is mainly limited to coastal northwest France and into S/SW United Kingdom. Notice as the shortwave approaches it appears to remain to the northwest and in closer proximity to the southern and western portions of the UK with stronger lift and therefore more widespread storm coverage. The high wind shear and CAPE values will allow for the potential for large hail and gusty outflow winds where storms do develop, especially across far southwest UK and far northwest France. The broad picture of this discussion was guided via the European Storm Forecast Experiment or “ESTOFEX”. The maps included in this discussion are mainly from model websites and not affiliated with the organization.
This organization is similar to the Storm Prediction Center in that it forecasts for convective storms across Europe however they do not issue the watches, warnings, etc. The forecasters are volunteer with the purpose being to education and provide awareness. The ESTOFEX does issue convective outlooks, forecast discussions, mesoscale discussions, etc. If you want to check out the website the direct link is below where you can explore European convective forecasts daily among a few other neat sections of the site. http://www.estofex.org/ To learn more about European convective storms, weather patterns, and more, click here! ©2019 Meteorologist Joe DeLizio  It has been an active few days and is setting up to continue for portions of far western Europe. The general pattern has been and will continue to feature upper level troughs diving in from the west and northwest increasing moisture levels. These upper level features induce surface low pressure systems which linger around the region. The vorticity (measure of the spin in the atmosphere) and divergence aloft accompanied with surface convergence from low-pressure systems and associated fronts will result in rising motion in the atmosphere. The saturated air mass in place along with this vertical motion will produce periods of rain and heavier showers at times into Spain (mainly southeastern portions through the weekend) and Portugal (has already received showers mid-week; gets the brunt of a few weather fronts early next week as well). The reasoning for this type of active pattern resides in the upper portions of the atmosphere.  Expansive upper level ridging has built in across northern and central Europe. This forces a block in the flow, slowing down the system pushing into Portugal and Spain leading to times of rain and moderate showers (mainly in southeastern Spain) through the weekend (image above shows the first system delivering rains represented in the green colors to Spain and Portugal Friday) with the next of possibly a few systems on its heels diving into the region early next week (image below). The block looks to hold in place during this time as more rain breaks out across Spain, Portugal and France lingering into the middle portions of next week.  More details and the exact placement of the system for the middle part of next week may shift over the coming days, however agreement between the all of the major global models and ensembles at this time shows the potential for a long-lasting meridional pattern across Europe with the main impacts felt across western sections. ECMWF model output valid Friday at 12Z, Monday at 00Z, and Wednesday at 00Z. Notice how the pattern overall does not change all that much. This is courtesy of the omega block in the upper portions of the atmosphere outlined in black. As a note, the system for Friday through the weekend kicks out of the region early next week. The image for 00Z Wednesday is the next system diving in from the northwest. The upper level setup that will produce this active pattern for western regions of the European continent is known as an omega block. Omega blocking patterns like the one shown above in the slideshow can last for several days and sometimes more (as model guidance through next week is indicating for this region). The upper level ridge in central and northern Europe (orange coloring) forces troughs (blue coloring) on both sides of the high pressure. Because of this setup, the trough in western Europe remains stagnant as the high pressure “blocks” the system from moving all that much. All the while on the other side of the ridge across the Middle East a trough remains stagnant until mid to late week. The black outline in each image traces the upper level flow from west to east. The resulting image takes the shape of the Greek letter Omega hence the term Omega block. There are other blocking patterns in the atmosphere that develop and potentially lead to instances of inclement or anomalously warm/cold weather across portions of the world and the US. Other examples include a Rex Block, along with various teleconnections including the North Atlantic Oscillation, Arctic Oscillation, Pacific North American oscillation, among others. All of these patterns have significant impacts on global regions in their own respect, which will be covered in another article.  Courtesy of the GFS, stormy weather and perhaps some snow in the higher elevations of the Zagros mountains in western Iran early next week.
To close out this discussion, portions of the eastern Mediterranean into the Middle East will feel the impacts of this omega block as troughs swing into the region. These troughs will produce times of showers and thunderstorms across the desert while perhaps a bit of snowfall across the higher elevations of the Zagros mountains through early next week. To learn more about European weather be sure to click here! ©2019 Meteorologist Joe DeLizio How Hot was it Really this Summer Across the UK? (Photo Credit: UK Met Office and Climate.gov)12/5/2018   With winter having made it’s presence across most of the United States last week, it is hard to remember the heat of summer. However, what many across the USA do not realize is that this past summer, 2018, was one of the hottest on record for the United Kingdom (UK), which encompasses England, Wales, Scotland, and Northern Ireland. More accurately, the summer of 2018 is tied for the hottest summer on record in the UK with the summers of 1976, 2003, and 2006 according to the UK Met Office. To give more perspective on this, records have been kept since 1910.
The UK Met Office reports that the average summer temperature for 1976, 2003, 2006, and 2018 were within 0.03˚C of one another. The average summer temperature for 2018 was 15.80˚C, while the average recorded temperature for the other three years were as follows: 1976 - 15.77˚C, 2003 - 15.77˚C, and 2006 - 15.78˚C. This is too small of a difference to declare that one of the four summers was actually warmer than any of the others due to error. Therefore, all four summers officially share the record for the hottest summer at 15.8˚C. Even though the UK summer as a whole only tied for the hottest on record, England itself saw the hottest summer on record at 17.2˚C. This beat the previous record set in 1976 at 17.0˚C. One reason this past summer was so hot in the UK was due to the heatwaves seen across Europe beginning in late June. The definition of a heatwaves varies across the globe but in general a heatwave is defined as ``a period of abnormally and uncomfortably hot and unusually humid weather. Typically, a heat wave lasts two or more days” (NOAA NWS Glossary 2018). The UK, broadly speaking, uses 30˚C or higher for two or more days as their criteria for a heatwave. The initial heatwave began, roughly, on June 23, 2018. After this, additional heatwaves occurred on and off until August, when temperatures dropped back closer to average. When all was said and done there were nine consecutive days in which the temperature topped 30˚C somewhere in the UK. During this time, the jet stream was consistently located further north than normal, allowing a nearly stationary high pressure system to set up over Europe. This drove hot, dry air northward into the region. Shockingly, although the heatwave that hit this passed summer was intense, the summer of 1976 saw 18 consecutive days with temperatures above 30˚C somewhere in the UK. However, despite the longer duration of consecutive days above 30˚C, 1976 was not as dry as 2018. In fact, the first half of summer in 2018 was the driest in 50 years across the UK. For a more in-depth comparison of the two summers see https://www.bbc.com/news/uk-44943672. To learn more about other high-impact weather events occurring across Europe, be sure to click here! © 2018 Meteorologist Sarah Trojniak, Ph.D. 
DISCUSSION: When one thinks of tropical cyclones, the initial thought directs to the tropical waters of the Pacific, Atlantic, and Indian oceans. In recent days, however, a tropical-like cyclone known informally over social media as a “medicane” (a connotation of Meditteranean hurricane) formed in the Meditteranean Sea and made landfall over southern Greece. This tropical-like cyclone delivered strong winds greater than 55 mph (80 kph) and significant precipitation to areas of southern Greece and Turkey over the weekend. While not necessarily rare, it is still an unusual event given the fact that the Meditteranean Sea is relatively drier compared to the more conducive tropical belt and waters are fairly shallow with various landmasses impeding significant development. So how did this cyclone form in an otherwise unusual region?
The development of this cyclone began from an anticyclonic wave-breaking event that occurred over northwestern Europe. As the upper-level trough over Europe began to break down, a potential vorticity (PV) streamer along the eastern flank of the trough moved south towards the Meditteranean Sea while a moisture plume was advected northward. The combination of these two features set a favorable environment for development. Enhanced PV interacted with the incoming moisture and existing convection induced baroclinic instability that led to the creation of a surface cyclone that was cut-off from the main PV streamer to the north. Sea surface temperatures around the cyclone ranged between 25-26 C which is consistent with maintaining tropical convection. However, the air aloft is much colder than what is observed with typical tropical systems, so the system has to rely on near-surface heat fluxes to help maintain convection surrounding the cyclone’s vortex. Data on September 28th from the SCATSAT-1 satellite revealed estimated surface winds of 30-40 kts (~35-45 mph), and satellite imagery indicated banding features that would resemble that of true tropical cyclones despite the fact that it is a different environment than that of the typical tropical cyclone. As the system completed its tropical transition, the system was advected eastward towards Greece under weak but present zonal (east-to-west) flow. The end result was localized flash flooding particularly in the Peloponnese islands and elevated wave heights leading to beach erosion, while the city of Kalamata experienced tropical-storm-force winds during landfall. While “medicanes” are indeed unusual, research conducted into understanding the processes involved with their formation is quite extensive. Several case studies have shown that other “medicanes” of the past were even more impressive in both strength and overall organization compared to this most recent case. In particular, a “medicane” from January 1995 serves as a reference for both researchers and forecasters alike in understanding the evolution of such a storm. While these “medicanes” can form once or twice in a year, it is their infrequent occurrence that does not warrant official tracking by any weather organization such as the National Hurricane Center. Still, witnessing a system like this develop only warrants more interests by both researchers and forecasters especially when the threat for landfall exists. To learn more about other high-impact weather events occurring across Europe, be sure to click here! © 2018 Meteorologist Brian Matilla 
DISCUSSION: Earlier on during the first half of August here in the Summer of 2018, parts of France felt the full force of several noteworthy severe weather events. During a couple of these rounds of severe weather, some locals got the opportunity to catch the full fury of some of these storms on camera. Therefore, in doing so, there is now an opportunity to break down and explain a good portion of what they physically witnessed. In looking at the footage attached above (which was provided courtesy of the Weer and Radar Facebook group), you can see how during the earlier part of the video clip there were particularly strong winds reaching the ground near the city of Forbach, France (which is located in far northern France and is practically located right on the border Germany and France).
The strong, gusty winds were which recorded towards the beginning of the footage were more than likely a product of a severe thunderstorm's main downdraft reaching the ground. A strong downdraft can often appear very much like those winds associated with a tropical cyclone at the point of landfall. This is due to the fact that rain-cooled air will often out from underneath the base of the thunderstorm and reaches the ground with substantial force. As a result of strong downdraft reaching and impacting the surface of the Earth, there are quite often found to be consequences such as downed trees, downed power lines, damaged homes and/or commercial businesses as a result flying debris or broken trees/tree limbs. Hence, regardless of the situation it is always imperative to respect the natural power associated with approaching severe thunderstorms when they do occur. Later on this severe thunderstorm footage, you also get a chance to see the periods of large hail and flash flooding which occurred in this same region with this round of severe weather. In starting off with hail stones, it is worth noting that once hail stones reach a critical size and weight, they are often quite damaging to nearly anything come into contact with during their descent towards the surface of the Earth. When larger hail stones are combined with periods of persistent, heavier rainfall this more often than not leads to major safety issues at the ground. This can often be further exacerbated by people trying to to risk travelling in the vicinity or even directly through flooded roadways which can lead to a further risk of unnecessary fatalities due to people and/or automotive vehicles being swept away in minutes or less. Thus, if you are ever faced with such a situation, always be sure to respect the natural power of severe thunderstorms and the natural hazards they are capable of producing. To learn more about other high-impact weather events occurring across Europe, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz DISCUSSION: While an average of over 1000 tornadoes are reported each year in America, our friends in Europe receive an average of 300 tornadoes per year though much fewer are reported. If Europe was one country, it would knock Canada out of second place for tornado production each year. An article highlighted the European part of Russia as the leading countries for tornadoes due to Russia’s large size. Coming in second place with more than 30 tornadoes per year is the U.K. The strongest tornadoes tend to span between Germany and northeast France towards Poland. The formal study of European tornadoes began in the 17th-century when Italian astronomer and mathematician Geminiano Montanari analyzed a tornado that occurred in the Veneto region of Italy in July 1686.Digging deeper into European tornado history revealed that before the end of World War II, European scientists and meteorologists were the leading tornado researchers. One reason for this was that the word tornadowas banned by the Weather Bureau and the government didn’t want to cause panic.One AMS study stated that after 1950, the interest in European tornadoes declined when the majority of tornado reports were collected outside the national meteorological services.  Figure: The AMS study stated “(a) The spatial distribution of tornado reports (tornadoes per 10,000 km2) in Europe in between 1950 and 2015 on a 50 km × 50 km grid, shaded according to the scale. (b) The population density (inhabitants per km2) estimated for 2015, shaded according to the scale. The population density was obtained from SEDAC (2015). The four main regions of Europe are also indicated (dashed lines).” The study further explained how the European Severe Weather Database (ESWD), of the European Severe Storms Laboratory, obtained 5,478 tornado reports from 1950 – 2015 (seen in the figure). ESWD records indicated that the tornado season for most of Europe occurs between May to August with a peak in July. Eastern Europe sees most of their tornadoes during the spring and early summer months. Northern Europe’s tornado season is from mid to late summer. Finally, southern Europe most frequently receives tornadoes and waterspouts in the Mediterranean Sea during the fall and early winter.
During that 1950 – 2015 timeframe, European tornadoes resulted in 4,462 injuries, 316 fatalities and damages estimated at more than €1 billion. A recent study explained that the Enhanced Fujita (EF) scale is the leading scale for ranking European tornados, though the Fujita scale and Torro scale are also used. The Torro scale was first developed in and is still used by the U.K.; it is a pure wind speed scale. The paper further expressed that to be most effective in Europe, the EF-scale damage indicators should be modified to represent European construction techniques. Looking ahead, tornadoes will continue to impact European countries. Additionally, there are many active areas of European tornado research including the best scale for classifying tornado damage. So, even though it isn’t tornado season here in the U.S., keep your eye out for tornadoes and related research in Europe throughout the year! To learn more about European weather, click here. © 2018 Meteorologist Amber Liggett   DISCUSSION: To the first order, the temperate oceanic and continental climate that governs the conditions across much of Europe can be characterized by relatively cool temperatures during the summer months. Over the course of the last few days, however, most of Europe has been under the influence of a significant summer heat wave where many long-standing temperature records have already been challenged. Recently, daily maximum temperatures have risen well above 30°C (~86°F) in southern England, 35°C (~95°F) in most of western Europe, and over 38°C (~100°F) over southern and central Spain. The heat is creating noticeable strain on transportation operations (by virtue of cancellations and delays) in order to maintain safety, and multiple forest fires have ignited, including the recent Greek wildfire that has claimed 92 lives.
So what is the culprit for the development of this heat wave? It all begins with a robust ridge of high pressure that is situated between the middle and upper-levels of the atmosphere. Geopotential height, a measure of the height of a constant pressure surface above the mean sea level, is a useful diagnostic tool and proxy for determining the strength of a ridge or trough affecting a region, and higher (lower) heights usually correspond to warmer (cooler) surface temperatures. During this heat wave, most of Europe has been faced with 500 hPa (~5,500 meters above sea level) geopotential heights that are 2-3 standard deviations above normal for this time of year, which equates to anywhere from 5,800-5,900 m. Specifically, most of western Europe At the surface, maximum temperatures have been 6-10°C above normal. Furthermore, the positioning of the jet stream also favors south-to-north advection of warmer air in the upper levels. The excessive warmth is expected to continue once again by the end of this week as current Global Forecast System (GFS) model runs indicate the development of another high pressure system and upper-level ridge. Southwesterly winds will once again facilitate robust warm air advection over much of Europe and keep temperatures several degrees above normal as the air above the surface warms considerably. In addition, moisture over western France and the UK will likely yield heat indices that exceed 38°C (~100°F) there while much warmer temperatures are forecast over Spain. Under this level of warmth, it is imperative to stay hydrated and cool to escape potentially harmful heat-related illnesses, especially in regions that are not adapted to very warm conditions. To learn more about other high-impact weather events across Europe, be sure to click here! © 2018 Meteorologist Brian Matilla  DISCUSSION: Over the past week, a series of wildfires have been burning across the Attica region of Greece. The first of these fires began in Kineta, a beach town around 30 miles west of Athens, and the second major fire started northeast of Athens in the Penteli and Rafina areas, primarily centered in the coastal village of Mati. As of Sunday, the death toll from these fires rose to 91, making these Greece’s worst fires in over a decade.
These fires, which drove swarms of people to the sea seeking refuge from the flames, are suspected to have been the result of arsonists looking to loot homes abandoned during the fires. Although the fire was likely initially human-caused, the climate and weather in the region provided an environment conducive to exacerbating the flames. The Attica region of Greece typically experiences dry summers and shorter wet periods in the winter; however, this region saw a drier winter this year, leading to drier forests that are more vulnerable to fires. Fires in this region are common during the hot, dry summers, and while the drier than normal winter may have been a factor in how extreme these fires have become, it is likely that high winds played a bigger role. Dry conditions and hot temperatures can provide an environment likely to burn when a spark is introduced, however, it is strong winds that can cause fires to spread across more area very quickly. Wind gusts reaching record speeds of up to 120 km per hour (around 75 miles per hour) and average wind speeds of 65 km per hour (around 40 miles per hour), were recorded in the Attica region last week when the fires began. Winds provide oxygen to help fuel the fires while also working to push the fires across more land area. Stronger winds can speed up the spread of the fires, making it more difficult for them to be contained. To learn more about other high-impact weather events occurring across Europe, be sure to click here! ©2018 Meteorologist Stephanie Edwards  DISCUSSION: As very cold air began to make its way into parts of central and eastern Europe over the past several days, there was a major uptick in the threat for accumulating snowfall across many different sections of central and southern Europe. Once such region which received some accumulating snowfall was in and around the city of Rome, Italy. As a particularly cold air mass made its way across central and southern Europe, this facilitated a noticeable clash of warmer and colder air masses. Thus, this helped to set the stage for more cyclonic flow in the vicinity of the boundary created between the colder air mass to the north and the warmer (Mediterranean-based) air mass to the south.
This aforementioned cyclonic flow is due to the fact that in the Northern Hemisphere, winds associated with a extra-tropical low-pressure systems rotate counter-clockwise as a consequence of the impacts of the Coriolis effect. Thus, with a low-pressure system delivering accumulating snowfall across an area such as central/southern Italy, this would mean that there would a reasonably strong influx of warmer air into the colder air mass located to the north courtesy of warm-air advection. Warm-air advection is best defined as a surge of warmer air which heads in a poleward direction most often in association with a Winter-time extra-tropical low-pressure system which helps to generate the precipitation shields on the eastern, northeastern, northern, and northwestern flanks of extra-tropical cyclones. Hence, warm-air advection acts as a key in-storm mechanism to continue pumping critical warm, moist air into the precipitation shield which fuels winter storms such as the one which recently impacted central and southern Italy as reflected by the graphic above with a great shot of a snow-covered Rome, Italy. It is also worth noting that the particularly (and unusually) cold air which made it this far south across portions of central eastern Europe had far-reaching impacts which reached far beyond just Italy. For example attached below is an excerpt from the ABC News which details some other impacts which were inflicted on the region. "Elsewhere in Europe, the storm set dangerously low temperatures: Lithuanian officials said temperatures that plunged to as low as minus 24 degrees Celsius (minus 11 Fahrenheit) in some places were to blame for the deaths of at least three people over the weekend. Hospitals in Lithuania and Latvia have reported an uptick in people being treated for hypothermia and frostbite. Scientists say the big chill in Europe is partly caused by the fact that strong winds which normally keep cold air 'locked' over the Arctic have weakened, releasing icy blasts across the northern hemisphere. Similar sudden drops in temperature have occurred over North America in recent years and climate researchers say they could become more frequent as global warming further saps strength from the air currents around the pole." To learn more about this particular story, feel free to click here! To learn more about other high-impact weather events occurring across Europe, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz  DISCUSSION: Along most coastlines, the ocean has a very large influence for much of the atmospheric phenomena and temperatures that occur in these locations. With everything else being equal, continental air masses will be more extreme than maritime ones (meaning the land heats up and cools down quicker creating larger temperature departures whereas maritime air masses modify the temperature). We see this come into play across the entire west coast of the U.S., where the coldest air during the winter comes straight from the North American continent as opposed to the milder Pacific Ocean air. This concept is very much related to portions of western Europe. Typically, a westerly wind advects mild Atlantic air keeping portions of the countries such as Portugal and Spain relatively mild. Over the next week or so, high-pressure systems migrating north and east from the Azores will produce a more north to northeasterly wind over these regions shown above (notice 850mb winds from the north and northeast). This allows for cooler continental air masses to advect chiller temperatures as shown below (2-meter temperature anomaly chart with blues and purples meaning well below average).  While this colder air is in place, these regions, especially in the northern mountains of Spain, have a chance to see snow based on the latest GFS model guidance below (colors and numbers correspond to accumulations in centimeters). The GFS even hints at some light snow making its way all the way down to the northern regions of Portugal. This is uncommon for this region, but not unheard of. In any event, an interesting pattern ahead for southwestern portions of Europe is on the way!  Stay tuned to GWCC and click here for more on Europe weather! ©2018 Weather Forecaster Joseph DeLizio 
DISCUSSION: During the course of a given Winter season, there are often a collection of particularly strong low-pressure systems which impact many parts of western and/or northwestern Europe with strong winds as well as heavy rain and/or snow. During such events, strong winds have the opportunity to travel over relatively large bodies of water such as (but certainly not limited to) the North Sea. Thus, with these strong winds traveling over large expanses of open water, this helps to facilitate the generation of especially large waves and swells. Such large wave action can often be a major threat to both smaller and larger ocean-going vessels. In particular, this can be quite a costly economic problem when various shipping interests unsuccessfully attempt to complete the delivery of a given product aboard a given shipping vessel. As shown in the footage above (courtesy of Scandinavian Nature), such large swells can make for quite a rough ride to say the least and reinforces the point that the power of water should always be treated with dignity and respect.
To learn more about other high-impact weather events occurring across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz Waterspout Impacts Coastal Sections of Northern Italy (credit: Meteo Europe via Weer and Radar)12/2/2017 
DISCUSSION: Within the last 24 to 36 hours, a fairly potent low-pressure system deepened over part of the eastern Mediterranean Sea. As a result of this deepening low-pressure system, there was subsequently increased southerly to southwesterly flow at the lowest-levels of the atmosphere (i.e., within the lowest 0.25 to 0.50 miles above the surface. Further up in the atmosphere, there was found to be more west-southwesterly to westerly flow which facilitated increased deep-layer rotation in any convective storms which developed within the warm sector of this deepening low-pressure system. Thus, as shown above, one such storm which developed just offshore from coastal sections of northwestern Italy flared up into a deeper convective storm which ultimately went on to produce a nasty waterspout (as captured on film in the footage attached above).
It goes without saying that even though, waterspouts such as the one captured above can be small and brief with respect to both intensity and duration, they can still often represent a substantial threat to both small boats, beach-goers, and coastal infrastructure/businesses. Thus, even though, winter is setting in across many areas in this region of the world, there is still a residual threat for various forms of severe weather even across parts of south-central Europe even in early December. To learn more about other high-impact weather events occurring across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz 
DISCUSSION: Over the course of the past 24 hours, parts of south-central Europe were slammed by a classic winter storm. In particular, some parts of northern Italy received well over 1.5 feet of fresh snowfall which put many people's lives at a complete standstill. These types of winter weather events are more common in this part of Italy based on the fact that such elevated parts of Italy and other surrounding nations are prone to heavier snowfall events at higher elevations. This is chiefly due to the fact that at higher elevations, air parcels are essentially "squeezed" even more and this allows for more moisture to be extracted from a given column of air. Therefore, at higher elevations, this facilitates a greater potential for heavier localized snowfall totals during any given event in a particular winter season. Thus, the stage was perfectly set for a heavier snowfall event with the increased moisture, colder air in place, and the region being positioned at a higher elevation.
To learn more about other high-impact weather events across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz 
DISCUSSION: Over the course of the past few days, a weak area of low-pressure organized across a large portion of the eastern Mediterranean Sea. As this occurred, there was consequently a notable increase in the magnitude of the larger-scale southerly flow. As a result of this stronger southerly flow increasing on the eastern flank of this strengthening low-pressure system, this allowed for a more efficient transport of warm, moist air northward. As this warm, moist air traveled further and further northward, this set the stage for increasing amounts of convectively unstable air parcels due to the increasingly more elevated terrain across many parts of Italy and many surrounding nations.
Hence, the air parcels are naturally forced to rise up and over this higher terrain which leads to more rapid condensation of water droplets, to then form clouds and create the threat for showers and storms. It is also worth noting that some of the stronger and more persistent convection which fired up over parts of Italy has induced some fairly prolific flooding and even some flash flooding in some locations across central/northern Italy. Attached above is nice animated graphic which depicts the recent evolution of this low-pressure system as of earlier in the day on Monday (11/06/2017). To learn more about other high-impact weather events occurring across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz
 In midst of some of the worst California fires in recent memories, our friends from across the Atlantic have been dealing with similar conditions recently and throughout the summer. Portugal has a very similar climate to California, they are both coastal landmasses, influenced by large oceans, and typically have a wet and dry season. The problem this summer in Portugal has been the extreme heat and the aridity accompanied with high winds which create the fire conditions we so often see and hear about along the western United States.
The beginning of October in Portugal featured above normal temperatures and dry conditions, a “loaded gun” setup for fires to develop. The only thing missing was breezy winds. Unfortunately, hurricane Ophelia decided to spin up in the Atlantic at this time and track close enough to bring stiff sustained winds to the region without the benefit of moisture, making for a worst-case scenario. A country that went through the deadliest forest fire in its history four months ago, with 64 losing their life, are mourning as around 40 more met their demise this October. Some relief developed after Ophelia’s passing, as a cold front moved through the country providing some moisture and cooler temperatures. This pattern has not lasted as the recent trend features more of the same, a summer type pattern with a ridge over head for the next few days, drier than normal conditions (PWAT anomalies), and temperatures well above average (temperature anomalies), all arranged in order chronologically above. The first image presents the 500mb height pattern on November 1st, which keeps warm dry weather in western Europe throughout this time. The next image is for the same time period, November 1st, which shows the precipitable water anomalies, a measure of how dry the air is compared to average with brown colors meaning below average. The third photo presented is the temperature anomalies, red being well above normal temperatures for this time. All of these ingredients will continue to present a forest fire risk across Portugal. This pattern will be watched by GWCC throughout the rest of October and beyond. Stay up to the date on the latest fire weather news here! ©Forecaster Joe DeLizio While the remnants of hurricanes occasionally affect the British Isles, Hurricane Ophelia is going to be much stronger than the average United Kingdom (U.K.) storm. As of early this Sunday morning, Ophelia, still a category 2 hurricane (Saffir-Simpson Hurricane Scale), was forecast to become extra-tropical before land-falling in Ireland on Monday. Still, Ophelia, with a large storm force wind field (winds 39 to 73 miles per hour)…To read the full story, click here - http://www.weatherworks.com/lifelong-learning-blog/?p=1423 © 2017 H. Michael Mogil To learn more about other aspects of high-impact tropical cyclone-based weather events, be sure to click here!  Hurricane Ophelia Threatening Northwestern Europe (credit: NWS National Hurricane Center)10/13/2017  DISCUSSION: As we continue to watch Hurricane Ophelia spin over the eastern Atlantic Ocean, there continue to be increasing concerns regarding the future of this evolving tropical cyclone. Over the next couple of days, Hurricane Ophelia will be undergoing a process known as extra-tropical transition within which Ophelia will lose many critical tropical characteristics (including but not limited to) losing the tropical cyclone's signature warm-core low and shifting towards a cold-core low. However, despite various thinking across social media, this does not necessarily mean that Ophelia will lose a substantial amount of core intensity. Rather, during a typical process of extra-tropical transition, a tropical cyclone can often maintain a relatively large percentage of its maximum intensity just prior to undergoing extra-tropical transition.
In looking to later in the weekend and on towards Monday, the latest intensity and track forecast has Hurricane Ophelia impacting Ireland by Monday morning and afternoon. In all likelihood, this storm will deliver strong/gusty winds as well as fairly heavy rainfall to much of Ireland before heading further north on towards the northern British Isles. Thus, many people living across far NW Europe will soon be at risk from incoming impacts projected from an evolving Hurricane Ophelia. To learn more about other high-impact weather events occurring across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz 
DISCUSSION: Within the past 24 to 36 hours, yet another impressive round of strong to severe thunderstorms erupted over parts of western to northwestern Germany. As has consistently been the case in recent days and weeks, the skies once again did not fail to disappoint people who were in the path of some of the particularly stronger convective storms. With strong convective instability in place both prior to and at the time of convective initiation, this greatly boosted the potential for strong to severe thunderstorm activity to be generated across several parts of Germany. As you can see in the image and raw footage attached above, one of the stronger storms exhibited fairly impressive misoscale to mesoscale features such as effective low-level lifting of developing clouds which helping to generate the shelf-like cloud feature racing out ahead of the approaching thunderstorm. This type of shelf-like cloud feature is very characteristic of strong to severe thunderstorms since features acts to often lift and destabilize air parcels out ahead of the storm which act to keep a given storm revitalized throughout the course of its lifetime.
To learn more about other high-impact weather events occurring across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz 
DISCUSSION: Within the last 24 hours, there has been a fairly impressive increase in the coverage of deeper convection across parts of western and northwestern Europe. During the last 24 hours, a weak (but slightly invigorated) piece of mid-level energy was propagating across western Europe. As it did so, the surface low pressure helped to shift the larger-scale regional wind field direction from a northeasterly to more of a southeasterly orientation. Hence, this wind direction change helped to increase the influx (i.e., the amount of incoming air from a given region) of warmer air from the greater Mediterranean Sea. As this warm air coming north increased with time, this helped to bolster the overall amount of convective instability as a result of the warmer air closer to the surface being coupled with much cooler air aloft.
This increasing unstable lower-to-upper atmospheric combination led to a regional atmospheric environment which was much more conducive for deep convective development. As shown in the footage above, one such convective storm developed into a severe thunderstorm which exhibited a classic shelf cloud. Shelf clouds often form in convective situations wherein there was effective low-level lift which helped to create the layered cloud deck which was observed as a shelf cloud out ahead of the aforementioned severe thunderstorm. To learn more about other high-impact weather events occurring across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz 
DISCUSSION: Within the last 12 to 24 hours, yet another impressive round of strong to severe thunderstorms impacted portions of northern Europe. As these strong storms impacted countries including (but certainly not limited to) Poland, there were several instances of tremendous scenic storm exhibitions for people who were positioned in or in the vicinity of the path of some of these storms. As captured in the images above (courtesy of Meteo Europe Facebook team), you can see how there was incredibly effective lifting on display out in front of this particular shelf cloud which gradually propagated across the landscape of central to eastern Poland. Note how just behind the most pronounced part of the incoming shelf cloud, you can also see how there is a seemingly small amount of deep-layer clearing which allows a person to see directly though the approaching storm. In addition, this clearing often gives the regional sky a somewhat bluish-green appearance which is always an awe-inspiring sight. It is always neat to see the natural power of Mother Nature at work!
To learn more about other high-impact weather events occurring across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz 
DISCUSSION: As a strengthening mid-level low-pressure system gradually moved across portions of northern Europe, the stage was quickly set as of earlier today for relatively strong thunderstorm activity. This set-up was largely due in part to the fact that the incoming low-pressure system helped to amplify the strength of southerly flow across this part of Europe (i.e., thereby bringing in critical warm, moist air into the region during the 24 to 36 hours leading up to this particular convective event). Due to the convective instability in place prior to the onset of the deeper convection, this allowed for very intense updrafts to form during the height of the most intense thunderstorms. As shown in the graphic above, these intense updrafts facilitated the generation of relative large hailstones in association with the blow-up of the deeper convective cluster shown in the satellite image attached above courtesy of the EUMETSAT satellite feed. In addition, note the particularly impressive lightning associated with the deeper convection which further indicated the natural ferocity associated with these deeper convective storms. In strong convective storm threats such as this one, it is important to note that safety should always be put first and foremost by being weather-ready whenever there is a threat for any type of severe weather.
To learn more about other high-impact weather events occurring across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz 
DISCUSSION: Just over four days ago, a major hailstorm impacts areas both in and around Istanbul, Turkey. Prior to the onset of this major hailstorm, there was a particularly impressive regional cloud exhibition on display as strong rising motion was evident in the raw footage attached above. In addition, right at the very beginning of the footage attached above, you can see the rising motion in action by way of the rapidly rising cloud columns towards the back-right portion of the image. This is a clear sign of what was a fairly strong core updraft. There is no debate that this was a particularly intense storm based on the many sources of large hail reports which were submitted and observed in other footage closer to the ground during the course of this recent severe weather event that slammed south-central Europe. This event reinforces the point for why it is incredibly important to always remain weather-ready during any period of time in which there is a threat for severe weather!
To learn more about other high-impact severe weather events occurring across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz 
On July 27th, a radar indicated supercell hit Istanbul, Turkey, accompanied by large hail and straight line winds produced from a severe downburst. Hail was recorded to be up to 8 – 9 cm in diameter. Widespread damage was reported to be associated with this storm system, including damage to buildings, cars and airliners.
A downburst is a phenomena where a localized area of strong wind flows rapidly downward, typically from a severe storm system such as a supercell. For the conditions to be correct to produce a downburst, the downward flow (downdraft) out of a supercell needs to be unusually high. To create the downburst effect, the system needs to be close to the ground. In combination, this creates strong winds, that when pushed out, have no where to go, and often spreads out in all directions from the point of contact on the ground. Downbursts typically only last a couple of minutes. This can sometimes lead to straightline winds, which can often cause damage similar to that of tornadoes. The difference being, tornadoes have high winds that move inward and upward. Where as a downburst winds move downward and outward. A microburst or macroburst refer to a small or large scale downburst respectively. In the video, courtesy of Meteo Europe, you can see the strong wind effects of an active downburst hitting Istanbul this past Thursday. To learn more about other severe weather events in Europe, be sure to click here! ©2017 Meteorologist Claudia Pukropski 
DISCUSSION: Over the past couple of days, there has been yet another burst of severe weather across portions of western and central Europe. During the course of this most recent severe weather event, there were increasingly more favorable conditions for a heightened potential for tornadoes. This was chiefly due to both substantially increased convective instability in the region as well as robust vertical wind shear which helped to promote rotation within the lower to middle parts of the atmosphere. Hence, there was a very conducive environment across parts of central Europe for severe thunderstorms capable of generating tornadoes (and some particularly damaging tornadoes for that matter). As it turned out, some tornadoes did occur during the course of this latest European severe weather event. As it shown in the footage attached above, there was a classic tornadic progression to this particular severe thunderstorm which was reflected by the tornado swiftly descending from the base of the wall cloud at the bottom of the severe thunderstorm. This is a relatively common characteristic among many different tornadic thunderstorm; though most cases do not evolve as quickly.
To learn more about other high-impact weather events occurring across Europe, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz |
Archives
August 2019
|
RSS Feed