DISCUSSION: When it comes to the global observation of extratropical cyclone formation and evolution thereof, there is no question that cyclone structure can be one of the more interesting marvels of modern atmospheric science dynamical observations. During the heart of a given Northern Hemispheric Winter season, there can often be situations wherein low, mid, and upper level atmospheric support comes into place for the successful development of more intense extratropical cyclones. One of the premiere factors involved with the development of such intense Pacific low-pressure systems has to do with the presence of upper-level features most commonly referred to as an upper-level trough. An upper-level trough is an atmospheric feature which helps to amplify the degree of mid- and/or upper-level instability by way of increasing the mid- to upper-level temperature contrast.
A mid- to upper-level temperature contrast is the primary catalyst which leads to a mid- to upper-level pressure contrast which leads to a more dynamically unstable mid- to upper-level atmospheric environment. As a result of these changes which sometimes occur at times over larger oceanic basins such as the Pacific and the Atlantic Ocean basins, there can also sometimes be the development of larger-scale low-pressure systems. When such low-pressure systems develop, you can sometimes observe more rapid development of such systems as is captured in the satellite imagery gif which is attached above (courtesy of The Weather Channel).
In this water vapor satellite imagery gif attached above (courtesy of the Himawari-8 satellite imager), you can clearly see how rapidly such systems can develop when all the necessary factors come into place. From going to the adolescent phase of this system to the mature phase of this extratropical cyclone, you can see how quickly the structure of a developing oceanic cyclone can change. Moreover, you can also see how quickly the well-defined center of this low-pressure system formed and the corresponding convection which wrapped right around the immediate center of this system’s circulation. Currently, this system has deepened (i.e., has further intensified) all the way down to an estimated 937 mb low. Thus, there is no debate that this is a very powerful low-pressure system to say the least. It goes without saying that it is incredible to observe the gradual as well as real-time development of such low-pressure systems as they are truly a perfect case and point for how the atmosphere can sometimes perform at an incredibly high level.
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© 2019 Meteorologist Jordan Rabinowitz
DISCUSSION: Earth's atmosphere can be divided into four layers based on how temperature changes with height. In the lowest layer of the atmosphere (troposphere), temperature generally decreases with height. Above that is the stratosphere where temperature increases with height. Then above the stratosphere is the mesosphere and thermosphere where temperature decreases and increases with height, respectively. In order for clouds to form, there must be water vapor in the air. Since the source of water vapor is the surface, most of the water in the atmosphere and associated clouds occur in the troposphere. However, on rare occasions, the small amounts of vapor in higher layers of the atmosphere can lead to cloud development. In particular, noctilucent clouds are thin clouds that occur in the mesosphere (~50 miles above the ground). When these clouds form, they tend to occur near the poles where the extremely low temperatures help them to develop. In addition, these clouds are extremely thin due to the extremely low amounts of vapor in the mesosphere. Hence, they can't be seen when the sun is high in the sky. Instead they are illuminated when the sun is low in the sky or below the horizon, which occurs a lot in polar regions.
While noctilucent clouds almost exclusively appear in polar regions, certain conditions may allow them to form at lower latitudes. For example, the picture above shows a noctilucent cloud near San Francisco, CA. In this case, as a meteor burned up high in Earth's atmosphere, it created the right conditions for a noctilucent cloud to form at an unusually low latitude. Rocket launches can also help to generate these clouds in places where you wouldn't normally expect them to form. The picture below from spaceweather.com shows such a noctilucent cloud formation over Orlando, FL as a result of a rocket launch from Cape Canaveral.
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© 2019 Meteorologist Dr. Ken Leppert II
DISCUSSION: November 13th, 2018 became an important date for the remote sensing community. The National Oceanic and Atmospheric Administration (NOAA) launched Geostationary Operational Environmental Satellite (GOES) 17 on March 1st, 2018, November 13th marked the date that GOES-17 reached its final orbit. It is expected that GOES-17 will be the operational GOES West satellite beginning December 10th, 2018.
This exciting occasion is expected to mark a time where high-definition images will now be relayed to earth of the Pacific region. Previous satellites marked heavy limitations on coverage for OCONUS (Outside Continental United States Overseas-often Alaska, Hawaii and U.S. territories), wherein GOES-17 comes to play.
GOES-17 will provide a notable improvement in the ability for meteorologists to forecast weather. The satellite offers similar remote sensing tools to that of GOES-16, considered the eastern position of satellite orbit for the Americas. The ABI or Advanced Baseline Imager is expected to, “offer the same high-resolution visible and infrared imagery in GeoColor and 16 different channels, allowing us to track and monitor cloud formation, atmospheric motion, convection, land surface temperatures, fire and smoke, volcanic ash, sea ice and more, according to NESDIS (National Environmental Satellite, Data and Information Service).
Previously, lower resolution images of Hawaii, and Alaska were being transmitted providing little clarity for forecasters. GOES-17 will contribute a critical mend to the issue of resolution, providing clearer imagery of our OCONUS states. The importance in this is the difference in atmospheric and environmental conditions in those locations that prove to be difficult to analyze. Hawaii being home to 11 of 13 climate zones, volcanoes, and its sheer location in the Pacific, makes understanding the Hawaiian environment a difficult one for atmospheric scientists. Alaska posing some similar forecasting issues with volcanoes (ash), sunlight, sea ice extent, a variety of conditions that GOES-17 is hoping to resolve especially given its capabilities regarding monitoring volcanic ash, sea ice and land surface temperatures. These high-resolution images will allow forecasters to properly determine orographic issues that may not have been previously seen on imagery.
Current images being transmitted from GOES-17 are considered non-operational. December 10th, 2018 will mark the date for GOES-17 operational use, another landmark date for atmospheric scientists as data can be officially transmitted for practical use.
For more information on remote-sensing products visit the Global Weather and Climate Center!
© 2018 Meteorologist Jessica Olsen
“NESDIS News & Articles.” NESDIS NOAA, 15 Nov. 2018, www.nesdis.noaa.gov/content/noaa-goes-17-shares-first-images-alaska-hawaii-and-pacific.
DISCUSSION: There is no debate whatsoever that the past 48 to 72 hours or so have been some of the worst for the state of California in recorded history in the context of state-wide wildfire impacts. Having said that, there are some impressive images and things can still be taken away from this absolutely horrifying and down-right terrible situation across various parts of both northern, central, and even southern California. Attached above is a brief video briefing which helps to capture and discuss a few of these points for everyone's insights and knowledge base.
To learn more about this fire weather situation as it evolves, be sure to monitor our Twitter account as well as our website for updates!
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© 2018 Meteorologist Jordan Rabinowitz
A Unique Radar Perspective on the Landfall of Hurricane Florence (Imagery Credit: Meteorologist William Churchill)
DISCUSSION: There is no doubt that #Florence has been firing up to no end on social media over the past several days, but there is more to this story "than meets the eye." What many people will often not consider when it comes to a given tropical cyclone landfall are some of the neater things which an individual can learn by simply observing air stream flow in the vicinity of a National Weather Service radar site. One such detail is how a dual-polarization radar system can identify key features associated with the approach and forward movement of a landfalling tropical cyclone. Attached above is a classic example in which a very clear and concise video briefing goes over one such topic to provide clearer insights into how Hurricane Florence could be seen and tracked via radar imagery as it slowly began to make its way across the state of North Carolina.
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© 2018 Meteorologist Jordan Rabinowitz
How is GOES-16 Impacting Weather Forecasting and Research? (credit: Meteorologist Jordan Rabinowitz)
DISCUSSION: With the GOES-16 (or also known as the GOES-East) satellite imager fast-approaching the 2-year mark of its existence as an orbiting highly-advanced weather and observational satellite imager, it certainly has already earned plenty of tremendous of respect and appreciation. Here, you will be taken through some of what this state-of-the-art satellite imager has already accomplished in a relatively short period of time since its launch in late November of 2016. It goes without saying that since the onset of the advanced remote sensing era, there has been a substantial increase in both the prevalence and the confidence invested into the integration of high-resolution satellite imagery into the both weather research and weather forecast process.
As operational National Weather Service meteorologists and other atmospheric research scientists continue to adapt to revolutionary changes in the ways by which we are now able to study the atmosphere, so will the level of detail we find in corresponding results of such work. Thus, it goes without saying that the impacts of the GOES-16 satellite imager have transformed weather forecasting and applied research in a number of profound ways. For example, before the introduction of GOES-16, we could never visualize the initiation of severe thunderstorms to the level of detail which we now can. Whether it is understanding the rate of change with time in terms of how fast the updraft columns are growing horizontally and vertically within a strengthening convective storm or understanding how fast the cloud-top temperatures are evolving on a minute-to-minute basis, GOES-16 is forever changing atmospheric science.
Moreover, when it has come to forecasting both short-term and longer-term changes in association with Tropical Atlantic and Tropical Eastern Pacific hurricanes, GOES-16 has allowed atmospheric scientists who study tropical cyclones in sparkling details and learn even more than we already know and understand about the dynamics and inner core structure associated with both developing and mature tropical cyclones. Whether it has been getting a close-up view of eye wall formation, eye wall replacement cycles, deep convective generation within the inner core of more intense hurricanes (e.g., Hurricane Harvey, Hurricane Irma, and Hurricane Maria from 2017), or even having a more clear understanding for how various tropical storms have interacted with islands or coastal as well as more inland regions of the United States, GOES-16 has not failed to disappoint. Another example of this phenomenal ability is shown in the animated visible satellite imagery of Hurricane Aletta attached above (courtesy of Meteorologist Dan Lindsey who is currently a Senior Scientific Adviser from the National Oceanic and Atmospheric Administration's National Environmental Satellite, Data, and Information Service program). It is worth noting that Hurricane Aletta was one of the first tropical cyclones which was captured in real-time by GOES-16 and the level of detail you can see within the inner core of Aletta in this animated satellite imagery effectively speaks for itself.
In other respects, GOES-16 has also helped meteorologists to better understand how various atmospheric phenomena work even more which include (but are certainly not limited to) sea-breezes (and convection thereof), cold front progression, squall line formation and/or evolution, fog formation and/or dissipation, wildfire forecasting (and critical monitoring thereof), etc. Thus, these are just more examples which help to strengthen the net argument for how the GOES-16 satellite imager is forever changing the ways in which we are now able to look at and study the Earth's atmosphere and all the remarkable forces of nature which it generates year in and year out.
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© 2018 Meteorologist Jordan Rabinowitz
Back in early July, a strong heat wave impacted the Northeast United States, creating heat indices above 100 degrees Fahrenheit for many areas. Places like Albany, New York, saw above-average temperatures for this time of year. For Albany, NY, average temperatures for the first week of July are in the low 80’s. Although there were above-average temperatures, it is not uncommon for New Yorkers as it occurred the first week of July. However, it was unusual due to the fact that it lasted for a total of six days. The last time maximum temperatures were greater than or equal to 90 degrees Fahrenheit for six days straight in Albany, NY, was in July of 2013, and before that, August of 2002. The heat wave did max out at six days, as average temperatures arrived when needed.
This began on Friday, June 29th, as a high-pressure system moved into the Northeast United States, creating a strong ridge over much of the Eastern seaboard. This set up the heat wave for many areas in New York State, especially in the Hudson and Mohawk Valleys. In this, I will focus on the Capital Region Area (Albany, NY).
The Capital Region was under a heat advisory from the morning of Saturday June 30th to the evening of Thursday July 5th. Then on Sunday July 1st and Monday July 2nd, an excessive heat warning was issued for the Capital Region. The National Weather Service defines a heat advisory as heat indices exceeding 105 degrees Fahrenheit but can be lowered if it is a multi-day heat wave or if it’s early in the season. Being that this was a multi-day heat wave, the National Weather Service in Albany, NY, lowered the criteria for a heat advisory to heat indices above 95 degrees Fahrenheit. In addition, the National Weather Service also lowered the criteria for an excessive heat warning of heat indices from 110 to 105 degrees Fahrenheit.
The peak of the heat wave was on July 1st and July 2nd, as there was an excessive heat warning issued on Sunday and Monday for much of the Hudson and Mohawk River Valleys. Over the heat wave period, temperatures in Albany, NY reached as high as 97 degrees Fahrenheit with heat indices near 110 degrees Fahrenheit. Although this heat wave brought some very hot temperatures to the area, only two records were broken, and one record was tied for Albany, NY over the five-day period:
Luckily a cold front pushed south from Canada and was able to break through the ridge. This cold front brought some rain to the area that ended this strong heat wave and finally brought relief to the region.
Credit: National Weather Service
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DISCUSSION: When observing the radar at night, large circles of reflectivity usually surround the radar scan area. It is likely that this reflected feedback from the radar is ground clutter, although in other cases you might see something else. When there isn’t any active weather within a radar coverage area, the local radar is set to a slower antenna rotation which causes the radar to have a finer resolution and heightened sensitivity. This setting is called “clear air mode”. During this mode of operation, the radar will pick up reflected ground clutter from mountains, buildings and tall objects as well as clear air echoes such as dust particles, light drizzle, air mass boundaries and fronts. Clear air mode is also used by scientists to pick up on certain echoes that many wouldn’t think of being a possibility. These specific clear air echoes are birds and insects. This has been beneficial to scientists who have used clear air mode to study bird and insect migrations for years.
When the radar is in clear air mode, it has an advantage of picking up on small objects such as insects and birds. This is because of its increased sensitivity and resolution. When birds or insects cluster together in larger groups, they become increasingly visible by the radar. The more birds and insects in one area, a higher reflectivity is shown in the radar image. Scientists can determine the difference between bird and insect reflectivity in a multitude of ways. For birds, it depends on the time of day. Most species of migrating birds continue their travel at sunset and fly through most of the night before landing at sunrise. Using radar velocity imagery, scientists can also decipher between birds or insects by comparing their movement to the prevailing winds. If the reflectivity moves against or faster than the wind, it could be birds. It is challenging to determine if the reflectivity is caused by insects because they fly with the wind rather than against it. For insects, it depends on the time of year and location more so than the time of day and speed. Many insects in the spring and summer tend to swarm near rivers, lakes, fields and ocean shores where they hatch, use up resources and gather to reproduce.
In the image above, a radar signature posted by NWS Norman, Oklahoma shows grasshoppers and beetles as they move over agricultural fields in Quanah, Texas on July of 2015. The radar shows the movement of these insects to be northeast in the direction of Oklahoma. It is typical for grasshoppers and beetles to migrate from one area to another using up resources and then moving on to find more food elsewhere. Grasshoppers are especially one of the most burdensome migratory insects to agriculture. They eat most of the grain, cereal, tomato and onion crops until there is nothing left.
Radar is used in detecting density, location, direction, and speed of birds and insects. A study done by Dr. Sid Gauthreaux and Carroll Belser was able to quantify bird migration using radar reflectivity by interpreting magnitude of bird migration in terms of radar values measured in dBZ (decibels of Z, where Z represents the energy reflected back to the radar). Their findings are used today as a guide to scientists who record and predict migrating bird patterns. The guide is established as follows:
Radar has been very beneficial to the science of studying bird and insect migration just as much as it has been for meteorologists who study and forecast the weather. One would not expect, aside from the normal radar imagery of precipitation in large and small storms, that they would have the ability to see insects and birds as well. Clear air mode allows for this and is a very useful tool in furthering scientific discoveries.
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©2018 Meteorologist Alexandria Maynard
DISCUSSION: There is no debate that the first "true round" of severe weather has now arrived across the Central United States over the past 24 to 48 hours. This multi-day severe weather event has been predominantly characterized by impressive storm structure, impressive lightning displays, and very heavy rainfall bursts anywhere in the path of the more intense convective storms. However, a very important aspect of severe weather which is quite often overlooked is the impact of how modern satellite imager observations have revolutionized the ways in which scientists study, analyze, and forecast both current and past severe weather events.
There is no debate across the atmospheric science forecasting and research communities that GOES-East satellite imagery has completely "changed the game" in terms of how meteorological forecasters and/or researchers analyze and study the atmosphere. More specifically, the GOES-East Advanced Baseline Imager (ABI) 16-channel platform facilitates incredibly high-resolution analyses of storms on very small scales. One such example can be found with the GOES-East 1-minute visible satellite imagery on 2 May 2018 as storms fired up across many parts of Kansas and also across northwest Oklahoma. In the aforementioned 1-minute visible satellite imagery attached above, you can see how there appears to be a "bubbling" phenomena occurring near the center of the cloud deck associated with the blossoming convective storm complex.
This "bubbling" effect is a visual manifestation of what are known as "overshooting tops." Overshooting tops are an indication of the fact that there is a particularly intense region of a given thunderstorm wherein the updraft is so strong that it breaks through the upper-most part of the thunderstorm. This point at which the updraft breaks through the top of the given cloud deck is what is visually observed as the "overshooting top" part of the thunderstorm. Therefore, it goes without saying that when severe thunderstorms develop these "overshooting tops" features, that is not a time that you want to be under or in the path of such a storm since it would have that much of a greater potential to develop heavier rainfall and even hail at times.
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© 2018 Meteorologist Jordan Rabinowitz
Bat Signal Caught on Radar…and no it isn’t Batman (Photo Credit: NWS Austin/San Antonio and Radarscope)
DISCUSSION: Earlier this month, the National Weather Service in Austin/San Antonio tweeted a radar image of a colony of bats outside of the cities of Concan and Knippa in Texas. Where did these bats come from and how can we see them on radar?
Texas is home to some of the largest bat colonies in world. This includes the largest known bat colony at the Bracken Cave Preserve and the largest urban bat colony at the Congress Avenue Bridge in Austin. Just a few hours away from these two colonies is the Frio Bat Cave, which is where the bat colony shown in the above radar imagery resides. In April and May, it is common to see swarms of hungry pregnant mother bats leaving their caves looking for food just after sunset with waves of bats leaving for 2-3 hours. In early June, the baby bats are born, meaning that the swarms of bats leave their caves later in the evening. In late July/early August, bat season reaches its peak and these bat swarms will continue to be seen until as late as November. How exactly can these bats be seen from weather radar?
Radar sends out signal that hits an object and is then reflected back to the radar at varying strengths depending on the size of the object. Usually, the signal received back is reflected from precipitation. However, other objects such as smoke plumes, insects, birds, and bats, can also reflect signal back to the radar. This is why you can get what looks like precipitation showing up on the radar even when there is none occurring in that area. How do we know a radar signature is bats and not actually rain or another source? A bat signature on radar will show up first as a sudden circle that quickly spreads outwards in subsequent frames of the radar until the bats have all dispersed. These signatures are also typically found in the evening when bats leave their caves to find food. If you live in an area with an active bat colony, you may just be able to spot these animals leaving their caves on radar!
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©2018 Meteorologist Stephanie Edwards