U.S. Severe Weather Forecast (Convective Outlook)

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Storm Prediction Center ac 211928 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0128 PM CST Wed Nov 21 2018 


Valid 212000z - 221200z 


..no severe thunderstorm areas forecast... 


... 
isolated thunderstorms are possible today from coastal into central 
California, and across parts of southeast Texas. 


..20z update... 


No changes to 1630z outlook are warranted. Earlier thoughts 
regarding convection continue. 


.Darrow.. 11/21/2018 


Previous discussion... /issued 1029 am CST Wed Nov 21 2018/ 


... 
A weak southern-stream shortwave trough will move eastward to the 
northwest Gulf Coast by tonight, in advance of a larger-scale trough 
that will progress eastward and inland over California. Steepening 
low/mid-level lapse rates with the California trough will support a threat 
for isolated thunderstorms this afternoon into tonight. Along the Texas 
coast, a modifying low-level air mass and a low-level warm advection 
regime will contribute to weak destabilization atop a coastal front. 
A few elevated thunderstorms will be possible from this afternoon 
into tonight. Elsewhere, a stray lightning strike or two cannot be 
entirely ruled out across northern New York into New England in 
association with shallow convection related to fast-moving bands of 
snow. 


$$ 




Mesoscale Discussion


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Storm Prediction Center mesoscale discussion 211409 
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Mesoscale discussion 1653 
National Weather Service Storm Prediction Center Norman OK 
0809 am CST Wed Nov 21 2018 


Areas affected...northern New York into northern Vermont 


Concerning...heavy snow 


Valid 211409z - 211815z 


Summary...the potential exists for snow squalls, producing reduced 
visibilities and snowfall rates approaching 1 inch per hour, to 
develop this morning across northern New York as a cold front 
advances eastward, reaching northern Vermont toward 18z. 


Discussion...a deep, cold closed low will move across southern 
Quebec today, while an accompanying cyclonic flow regime persists 
through the northeast states. Strong 100-110+ kt mid-upper low jets 
will spread into central New York this morning and central/southern Vermont/New Hampshire 
by early afternoon. The discussion area favorable for snow squalls 
will remain on the cyclonic shear side of the 500-mb jet, while 
linear forcing along the cold front should also support an 
environment favorable for snow squalls as this boundary advances 
east. Reduced visibilities and higher snowfall rates will tend to 
be short-lived, limiting overall snow accumulation. 


.Peters.. 11/21/2018 


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


Attention...WFO...btv...aly...bgm...buf... 


Latitude...Lon 45137287 44977236 44977236 44697222 44467220 44137260 
43787321 42867451 42607559 42677675 42937709 43597638 
43927613 44347595 44867538 45127482 45367388 45137287