U.S. Severe Weather Forecast (Convective Outlook)

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Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0754 PM CDT Tuesday Sep 27 2016 


Valid 280100z - 281200z 


..no severe thunderstorm areas forecast... 


... 
no organized severe threat is expected across the Continental United 
States this evening through tonight. 


An upper-level low will move southward across the Great Lakes region 
through tonight as a cold front advances south-southeastward into the middle MS 
valley. A moist airmass will remain in place from the Gulf Coast 
states northeastward into the Carolinas and middle-Atlantic region where widely 
scattered thunderstorms will be possible. Clusters of thunderstorms 
will also be possible in parts of the Desert Southwest. Due to the 
weak instability...no organized severe threat is expected across the 
Continental U.S. Through tonight. 


.Broyles.. 09/28/2016 


$$ 

Mesoscale Discussion


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Mesoscale discussion 1737 
National Weather Service Storm Prediction Center Norman OK 
0316 PM CDT Tuesday Sep 27 2016 


Areas affected...portions of far northestern Georgia and the western Carolinas 


Concerning...severe potential...watch unlikely 


Valid 272016z - 272215z 


Probability of watch issuance...5 percent 


Summary...thunderstorms moving eastward from higher terrain may pose a 
strong to locally damaging wind threat along with some large hail 
risk. Ww issuance is not expected due to the marginal nature of the 
threat. 


Discussion...terrain driven circulations along with weak convergence 
along a surface cold front have fostered convective development over the 
past hour across western NC/SC. This area is displaced to the S from 
stronger flow aloft associated with an upper low over the Great 
Lakes region. But...some marginally enhanced middle-level flow around 
25-30 knots is present across the western Carolinas per recent vwps from 
area radars. The low-level airmass along/S of the cold front has 
experienced some warming and steepening of low-level lapse 
rates...even though middle-level lapse rates remain poor. Rap 
mesoanalysis estimates MLCAPE generally ranges from 500-1500 j/kg 
across the mesoscale discussion area...and effective bulk shear values are 25-30 knots. 
This will support some organization /mainly multicells/ with ongoing 
activity as it moves eastward towards the central Carolinas through the 
early evening. Isolated strong to locally damaging winds should be 
the primary threat...but marginally severe hail may occur as well. 
The lack of even stronger middle-level flow and poor middle-level lapse 
rates should temper the overall severe threat...and ww issuance is 
not expected. 


.Gleason/Hart.. 09/27/2016 


..please see www.Spc.NOAA.Gov for graphic product... 


Attention...WFO...rah...cae...gsp...ffc... 


Latitude...Lon 34978302 35948136 35978039 35498004 34618042 34108159 
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