 Flash Flooding Seen Across Algeria 9/25/16 DISCUSSION: A persistent cut-off upper-level low dumped copious amounts of rain over the Italian island of Sicily early this morning (local time). Heavy rains also impacted coastal communities in Algeria where cars were seen floating down roadways completely submerged under several feet of fast moving water. This recent rainfall comes on top of an already wet September across the Mediterranean. Videos posted to Facebook convey the destructive damage as the flash floods swept through Algeria earlier today. The pattern across much of Europe has remain consistent over the past month which has set the stage for flooding to occur across these rain soaked regions. Weather forecasters, looking at the important weather models, are warning that up to 50mm (about 2 inches) of additional rain are expected in some of the same areas in the upcoming week. Sicily typically sees around 42mm of rainfall each September, according to local climatological averages. However, this month has been unusually wet due to a persistent upper-level low hanging out over the Mediterranean for the majority of the month. Official numbers for Algeria are harder to come by as weather observations are virtually nonexistent across the country. To learn more about other high-impact weather events from across Europe, be sure to click here! ~ Meteorologist Jake Keiser
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DISCUSSION: As of earlier today (local time), there was a weak low-pressure system centered over far northern sections of Italy. This is depicted quite well in the lower graphic found above (courtesy of the University of Wyoming's Upper-Air Data Archive) by way of the 1470 decameter height contour which covered northern/central Italy and the Northern Adriatic Sea. The presence of this weak low-pressure system helping to facilitate southerly flow in the direction of northeast Italy as well as far western portions of Croatia. The combination of the southerly flow closer to the surface coupled with increasingly stronger southwesterly/westerly flow aloft helped to generate environmental conditions conducive for thunderstorms capable of producing tornadoes and/or waterspouts as shown in the footage below (courtesy of IstraMet). Though this particular waterspout spinning over the northern Adriatic Seas appeared to be fairly far from the shoreline, this certainly was of great concern to mariners and other shipping interests in that region. Therefore, when there are forecasts for possible waterspout occurrence it is always prudent to "Keep your eye to the skies."
To learn more about other high-impact weather events from across Europe, be sure to click here! ~Weather Forecaster Christine Clements DISCUSSION: Heavy rainfall led to flooding and a landslide in the United Kingdom earlier today, which brought travel disruptions to the morning commute in the capital. Local news reported that a train traveling south to London hit a landslide, then derailed and hit another train traveling in the opposite direction. Both trains remained upright during the stressful four-hour ordeal, but passengers praised the staff onboard the trains for remaining calm. During the time of the incident, heavy rain was falling across the area which forecasters believe led to the landslide and the eventual derailment. As of noon local time, officials said that both trains were emptied and that several people were brought to local hospitals for observation, but it appeared that none were severely injured and no deaths were reported as well. Several delays and cancellations were caused by this incident; however, engineers were hopeful in having the tunnel cleared for the evening rush. Train travel wasn’t the only form of transportation affected by the storm, parts of several highways and local roads had to be temporarily closed due to flooding. Nearly 40mm (1.5 inches) of rain fell in about an hour in and around the London area as an impressive storm system made its way across the British Isles. London’s Heathrow Airport officially recorded 20mm (slightly less than 1 inch) of rain from the storm. Thunderstorms developed over the region late Thursday night, and then slowly trekked to the east during the early morning hours on Friday. When thunderstorms sit over the same place for an extended period of time, they become known as training thunderstorms as they continue to dump copious amounts of rainfall over the same region. Training thunderstorms often last for several hours before finally weakening or moving on. These thunderstorms formed along a powerful but slow moving cold front which has brought some much needed heat-relief along with it. Sunny skies are in the forecast for the rest of the week and into early next week with temperatures right around average for this time of year. To learn more about other high-impact weather events from across Europe, be sure to click here! DISCUSSION: As discussed last week, a very stable omega block has setup shop over Central Europe which has led to unusually warm weather for this time of year. Places in Germany, France, and Spain have all shattered numerous daytime highs over the last several days. On the other hand, a persistent cut-off low pressure system swirling over the Mediterranean (between Greece and Italy) has led to deadly flash flooding. Several days of rain brought traffic to a standstill on one major interstate in Southern Italy, and videos posted to Facebook conveyed the impressive power of moving water. Trees, cars, and even several buildings in Greece were destroyed by the heavy rainfall and the ensuing flash floods. Thankfully, a pattern change is on the way for Europe. Later this week, the cut-off low pressure system will eventually spin down, effectively losing strength and falling apart. While that occurs across Southeastern Europe, the presence of an impressively deep trough will ultimately bring much needed relief to many areas across Europe. A trough is indicative of cooler temperatures, but troughs are also associated with unsettled weather which may not necessarily be a bad thing for parts of Europe currently struggling from drought conditions. As a result of the warm temperatures and increased humidity ahead of the cold front coupled with strong upper-level winds, there will be an increase potential for the development of strong to severe thunderstorms. Following the cold front’s passage, the trough will dig in and provide showery but cooler weather. For example, temperatures across parts of Germany have surpassed 30°C (86°F) over the past several weeks and will fail to rise above 15°C (60°F) on Sunday. Next week appears to be very similar to the conditions Europeans have been experiencing since late August, with another cut-off low forming over the Eastern Mediterranean and high pressure dominating the rest of the continent. After a brief reprieve from the heat, cities and towns in Spain and Portugal will very likely surpass 30°C again. September is shaping up to be one of the hottest on record for Spain and Portugal. Remember to stay hydrated and keep cool during the warmest part of the day, typically between 10am-2pm. To learn more about other high-impact weather events from across Europe, be sure to click here! @ Meteorologist Jake Keiser  The animated GIF linked above depicts the Global Forecast System (GFS) Model's Prediction for Temperature Anomalies Over The Course of the Next 5 Days. (Blue-colored regions indicate cooler-than-average temperatures; while red-colored regions denote warmer-than-average temperatures). This animated graphic is courtesy of Tropical Tidbits. DISCUSSION: An area of low pressure and an associated cold front situated near the heel of Italy coupled with the warm waters of the Mediterranean Sea provided all the necessary ingredients for the creation of robust storms that left Greece drenched with rain and more! Last night and into this morning (local time), parts of Greece and surrounding areas faced incredibly heavy rain, with some local reports of 200 millimeters (about 7.9 inches) of rain in southern coastal Greece. With so much precipitation in such a short amount of time, flooding has occurred, damaging roads, buildings, and washing away cars (see pictures above, courtesy of Meteo Europe), as well as leading to a few fatalities and missing persons.
These thunderstorms didn’t just slam Greece with rain though; off the shore of Southwestern Greece, in Katakolon, twin waterspouts were spotted this morning. No reports of damage or fatalities have been reported from these waterspouts, thankfully. Accompanying the rain and waterspouts was an incredible light show as well. Captured in the image above, courtesy of Meteo Europe, is a map of the intense lighting storm that produced an estimated 30,000 strikes in the past 36 hours over Greece. While this system continues to move North/Northeast into mainland Greece and Europe over the next day or two, residents should continue to be vigilant for severe weather in the region. To learn more about other high-impact weather events from across Europe, click here! @Meteorologist Katie McCracken Intense Heat Persists Over The Majority of Europe!!! (Sources: MeteoEurope and Tropicaltidbits.com)9/5/2016 DISCUSSION: Hot and humid weather has been the main story for much of Europe this past month thanks in part to a strong area of high pressure parked over the region. Temperatures have been several degrees above average these past few months, and there is no relief in sight. Many of the primary global weather models which meteorologists use are indicating that the heat will last until at least the middle of September. Towards the end of the month, stronger bursts of cooler air from the Arctic are expected to cool down the majority of the continent. Places in Spain and Portugal have surpassed 40°C (104°F) on several occasions this past week, which is much above normal even in the heart of summer. Cities and towns in France, Germany, and Austria broke several daily high temperature records this week as well. The one place that has remained rather cool recently is Southeastern Europe, where a cutoff upper-level low pressure system has stalled above the area. Southern Italy and much of Greece have experienced below average temperatures these past few days. Since the low pressure system is separated from the jet stream, or the upper-level winds that guide the majority of weather systems across the globe, it has nowhere to go until it catches up with the jet stream again. This could take anywhere from a couple of days to sometimes a week or more. Looking at the weather models it appears that the cut-off low pressure system will persist for the next week, bringing cool air, clouds, and showery weather. As for the rest of Europe, it appears that the heatwave will finally break over the weekend as a powerful cold front makes its way across the continent. However, the cool air will be short lived as it appears summer air is bound to make a comeback shortly following the fronts passage. The unusually warm air for this time of year is being caused by what is known as an Omega block. In an Omega block, an area of high pressure located in the upper layers of the atmosphere is wedged between two areas of low pressure. Inside an area of high pressure, the air sinks, compresses, and warm which is why the temperatures have been well above average. Omega blocks are typically responsible for intense heatwaves; such as that which unfolded during the deadly European heatwave in 2003. To learn more about other high-impact weather events from across Europe, be sure to click here!  Here Is An Example of an Omega Block, which is currently parked over the region. Note how the lines form the Omega symbol shape over central Europe. Also note the area of low pressure over Italy and near the British Isles. (Credit: TropicalTidbits) |
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