Severe Weather 2019

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701
Location
Harvest, Alabama
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Storm Mapping User
#64
Verbatim GFS instability is not impressive, probably would be a modest event similar to yesterday-today with those values.
GFS instability isn't something to really take at face value during the cool season. It struggles MIGHTILY with thermodynamics in general, much less in February. When using the GFS, I look for the synoptic pattern and then ask myself if the smaller details like instability it's showing makes sense. Oftentimes, it doesn't.
 
#65
BMX thoughts on Tuesday (Matt Grantham):

A significant trough will begin to take shape across the Plains on
Monday, and the ejection of one or more lead waves may encourage the
warm front to move northward Monday night into Tuesday. Run-to-run
consistency with this system remains poor, but a quality warm sector
may become established across Alabama by Tuesday morning. While
instability could become sufficient for thunderstorms, currently the
strongest dynamics and height falls appear to remain to our
northwest as the trough becomes negatively tilted on Tuesday. If
that trend continues, any potential for severe storms would be
rather limited. At this time, confidence is too low for any mention
in the HWO. A cold frontal passage is expected on Tuesday into
Tuesday night with widespread rainfall and cooler and drier
conditions for Wednesday.

87/Grantham
 

ghost

Member
PerryW Project Supporter
Messages
369
Location
NW AL
#66
Hard to believe in N AL with temps in the upper 70s DPs in the 60s with a strong cold front approaching there isn’t a threat for severe today
 

Taylor Campbell

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Messages
485
Location
Wedowee, AL
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SKYWARN® Volunteer
#67
The amount of jet energy the globals show traversing the United States over the next two weeks is pretty wild! How significant, and exactly where these severe weather events occur appear to be highly uncertain at this point, but I suspect there will be many threats with a lot of potential for them to be bad. I would not write with much confidence about Tuesday's threat yet. Some model indications have been more significant than others.
 
Messages
33
Location
Alabama
#68
The GFS/Euro shows a pretty dynamic storm system on Tuesday that looks mildly suspicious as I think we all can see. One of the limiting factors I see now is the models are speeding up the timing to pre-dawn hours Tuesday instead of late Tuesday afternoon in Dixie Alley. This may be contributing to very low instability values. The GFS ensemble only shows very low probabilities of convective parameters being sufficient for a significant threat of severe weather, such as CAPE exceeding 500J only about a 10% chance near the Alabama Gulf Coast, 5% chance of exceeding 1000J. EHI probabilitie exceeding 1 unit is a whooping 1% chance on Tuesday 18z. I currently don't see much evidence of anything more than a classic HSLC event near the Gulf Coast, and pretty much just heavy rain everywhere else in Dixie Alley.
 
Messages
701
Location
Harvest, Alabama
Special Affiliations
Storm Mapping User
#73
On that note, the weaker the early week system is, the better chance of the late week one being a high-impact event.. if its weak and sheared out, it has a lesser chance of driving a front into the gulf and killing the moisture return... That's going to be a big thing to watch..
 

Taylor Campbell

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PerryW Project Supporter
Messages
485
Location
Wedowee, AL
Special Affiliations
SKYWARN® Volunteer
#75
The amount of jet energy the globals show traversing the United States over the next two weeks is pretty wild! How significant, and exactly where these severe weather events occur appear to be highly uncertain at this point, but I suspect there will be many threats with a lot of potential for them to be bad. I would not write with much confidence about Tuesday's threat yet. Some model indications have been more significant than others.
It looks like we are going to get through this week without a significant severe weather threat, but the potential for one next week is growing legs. The EURO model has been consistent on developing several thunderstorms in a large, and sheared warm sector early next week. Although the operational GFS isn’t as enthusiastic, more and more of its ensembles are starting to support the EURO.
 
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684
Location
Silver Spring, MD
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SKYWARN® Volunteer
#77
The 12z GFS certainly supports the idea of some severe threat Tuesday and Wednesday of next week although the instability is relatively confined along the Gulf Coast south of I-20. Still a ways out though.
 
Messages
86
Location
North Prattville, Al
#78
MattW is on the money today. Tornado warning for Atlanta area:

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 200 PM EST FOR WEST
CENTRAL ROCKDALE...SOUTHWESTERN DEKALB...NORTHWESTERN HENRY AND
NORTHEASTERN CLAYTON COUNTIES...

At 143 PM EST, a severe squall line capable of producing both
tornadoes and extensive straight line wind damage was located over
Ellenwood, or 8 miles northeast of Jonesboro, moving east at 40 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.
 

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