Powerful Storm Brewing

October 17, 2011

An extremely powerful early Fall weather system is brewing and will begin developing as early as tomorrow. A strong low pressure system induced by a strong polar vortex will merge and morph with a disturbance coming out of the Gulf of Mexico. This disturbance moving North out of the Gulf of Mexico will bring an abundant amount of moisture with it. As the warm and moist tropical air moves North, the warm and moist air (latent heat release) will help strengthen the morphed weather system as it travels North along the Spine of the Appalachian Mountains.

The water vapor imagery essentially tells the story this evening. You can see the large area of disturbed weather across portions of the Gulf of Mexico. The second system that will be a factor in this eventual large and phased weather system is a developing weather system across portions of Colorado. The extremely dry air across portions of Arizona and New Mexico is associated with our third player in this developing storm system and that is a very strong jet stream.

Nearly all of our forecast guidance has locked on to a solution of a strong weather system developing and moving into portions of the Midwest and Eastern Ohio Valley.

As the weather system begins to develop along the East Coast on Tuesday, strong and severe storms will be possible across the Southeastern United States. Increasing shear and an extremely tropical and buoyant atmosphere will lead to the threat of tornadoes from Florida into Georgia and eventually South Carolina.

This strengthening weather system will bomb out across portions of the Eastern Ohio Valley, strengthening possibly to as low or near 980 mb. This type of track is rare, as most storms that develop in this manner have a coastal low that transfers off the Mid Atlantic coast and tracks up the Northeast coast verses strengthening over land.

The track of his system means that a very large area will be impacted with heavy rain occurring from Florida all the way up the Appalachians, through the Ohio Valley and into portions of the Interior Northeast.

As the system reaches it’s peak intensity over the Eastern Ohio Valley and Eastern Great Lake states Wednesday and Thursday, extremely strong winds are also possible. You can see the tight wind field noted by the extremely close isobars around the low pressure.

With extremely impressive height falls as the low pressure deepens, it is not out of the question that some light snow could fall across portions of Northern Illinois, Southern and Eastern Wisconsin, Northern and Northwestern Indiana and Western Michigan. Obviously with extremely warm ground temperatures and fairly warm lower and mid level temperatures, no accumulation would occur, but the fact that some wet snowflakes are possible is definitely impressive.

Stay tuned to our facebook page for the latest on this developing storm system over the next 24-48 hours (www.Facebook.com/SWATChasers).

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Was Florida hit by a Tropical Storm or a Non Tropical Gale Force?

October 11, 2011

If you were following SWAT’s updates on Facebook (www.Facebook.com/SWATChasers) Sunday Night, you should be well aware that a large area of disturbed weather struck the East Coast of Florida, packing heavy rain and strong winds in excess of 60-70 mph. During the day on Sunday, a weather feature began to develop over the Bahamas. This feature began to show signs of developing into a closed low pressure system within a larger, more synoptically driven weather system/pattern.  By Sunday Evening, the circulation had tightened on  radar, and velocity data was showing upwards of 70+ mph winds. A semi apparent eyewall like feature also became evident just East of Palm Bay, Florida.

There was much debate in the meteorology community as to whether this area of disturbed weather should have been classified as a Tropical Storm or not. Winds gusted to over hurricane force in several reporting stations along the Eastern Florida Coast, but the National Weather Service and National Hurricane Center remained persistent that the disturbed weather was nothing more than a Non Tropical Gale Force.

Radar data/loops clearly showed a well defined center of circulation/eyewall feature as stated above off the Eastern Florida Coast. Without knowing what you were being shown, at first glance, the radar image below looks like several prior landfalling tropical systems.

So besides the well defined center of circulation off the Florida Coast, why do I believe that this area of disturbed weather should have been classified as a tropical storm? There are several reasons, but for starters, here is what I posted Sunday Evening on the SWAT Facebook page.

“I rarely criticize the National Weather Service/National Hurricane Center, but this area of low pressure center has obviously gained tropical storm characteristics. The area of low pressure system has formed over warm sea surface temperatures, has organized convection over the center of circulation, has surface winds over 35 knots and the strongest winds are near the center. This all combined with Cape Canaveral recently reporting a 69 mph wind gusts is blatantly obvious evidence that we have at least a tropical depression if not a tropical storm off the East Florida Coast. Our viewers in Eastern Florida should be prepared for heavy rain, very strong winds and coastal flooding through the morning hours.”

Shortly after I published that update on the SWAT Facebook page, several reports of 75 mph wind gusts were received along the Eastern Florida Coast from the United States Air Force weather observing stations. The winds were strong enough that the National Weather Service was forced to not only issue High Wind Warnings but also Storm Warnings for the adjacent waters. Storm Warnings are extremely rare in the Southeast during Hurricane Season.

In addition to radar data and reports of winds gusting well over 70+ mph at several official reporting stations, the pressure also began to rapidly drop. Cape Canaveral, Florida saw pressures rapidly fall as the area of disturbed weather approached.

The center of circulation passed very close to Cape Canaveral and their pressure bottomed at 999.5 millibars, a pressure reading commonly found in tropical storms. Nearly all (if not all) of the characteristics needed for a storm to be classified as a tropical storm had been met, so why did the National Hurricane Center and National Weather Service choose not to classify or upgrade the storm to a “tropical storm”? There is still some doubt in the meteorology community whether the area of disturbed weather attained a warm core. A definition of tropical cyclones is that they must have a warm core, which means the temperature in the vertical core of the cyclone extending up through the atmosphere is higher than in the air surrounding it. With the area of disturbed weather over extremely warm sea surface temperatures, I personally believe that at the very least, a shallow warm core was likely present.

The second possible reason that the National Weather Service/National Hurricane Center did not upgrade the storm to an official “tropical storm” could be based off of the logistical nightmare surrounding a possible late evening upgrade. The following was posted by a National Weather Service Melbourne, Florida Meteorologist on an online forum.

“You probably don’t realize what a logistical nightmare this would cause our office to name this thing at such a late hour. We would have to cancel the Gale Warning, High Surf Advisory, Wind Advisory and Lake Wind Advisory that have been up now for two days and replace them with Subtropical Storm Warning. We would need to put out products cancelling the current advisories, and then issue a Subtropical Storm Local Statement, update the Zone Forecasts, Coastal Waters Forecast Hazardous Weather Outlook, our blog and Short term Forecast. Local graphics would have to be updated as well as our forecast grids.”

While I understand his point, I do not agree with the decision. If the storm truly was a tropical storm, tropical storm warnings grab the attention of the public far better than high wind warnings or storm warnings. This area of “disturbed weather/non tropical gale force” caused significant damage and as seen via multiple social media outlets, the public appeared to have had no real idea that inclement weather was likely. Granted, high wind warnings were in place, but again, tropical storm warnings have much more significance on public perception than a high wind warning does.

Needless to say, I 100% believe the area of disturbed weather off the Florida Coast Sunday Night was a tropical storm. Hopefully the system is revisited/relooked at in post season analysis. This means that the National Hurricane Center can revisit and take a second look at the storm to decide if it was actually a tropical storm and add it to the list of 2011 tropical cyclones/historical data.