U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 201216 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0716 am CDT Wed Mar 20 2019 

Valid 201300z - 211200z 

..no severe thunderstorm areas forecast... 

isolated thunderstorms are expected over portions of California into 
the southwestern U.S. Today and tonight, and near the North Carolina 
coast overnight. 

An upper-level trough will slowly approach the coast of California 
today. Strong large-scale ascent and steep lapse rates associated 
with the trough will make isolated thunderstorm development possible 
across parts of California and Nevada today. As surface heating 
takes place in the Desert Southwest, additional thunderstorms may 
develop across parts of the Arizona this afternoon. The chance of 
thunderstorms from California into the Desert Southwest will 
continue this evening. 

Further east, an upper-level trough will approach the lower to mid 
Mississippi Valley as west southwesterly mid-level flow remains over 
the eastern Seaboard. A few thunderstorms will be possible today 
into tonight along a corridor of maximized low-level moisture in far 
eastern North Carolina. 

No severe weather is expected across the Continental U.S. Today or tonight 
mainly due to weak instability. 

.Broyles.. 03/20/2019 


Mesoscale Discussion

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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 152340 

Mesoscale discussion 0222 
National Weather Service Storm Prediction Center Norman OK 
0640 PM CDT Fri Mar 15 2019 

Areas affected...parts of central Maryland....southeastern 
Pennsylvania...northern New Jersey...southeastern New York 

Concerning...severe potential...watch unlikely 

Valid 152340z - 160145z 

Probability of watch issuance...5 percent 

Summary...a narrow line of storms may be accompanied by some risk 
for potentially damaging wind gusts through about 8-9 PM EDT across 
the northern mid Atlantic coast region, mainly west and northwest of 
the greater Philadelphia and New York City metropolitan areas. 

Discussion...an evolving narrow line of generally low-topped 
thunderstorm activity appears to have formed within Lee surface 
troughing, in response to an area of enhanced mid/upper forcing for 
ascent and and lower/mid tropospheric cooling spreading to the east 
of the Allegheny Mountains. The latest rapid refresh suggests that 
a secondary surface low may be in the process of forming across the 
northern mid Atlantic coast region into southern New England by this 

Peak boundary layer cape appears limited to around 500 j/kg or so, 
and should begin waning with the onset of radiational surface 
cooling during the next couple of hours. So current vigorous 
convective intensities are not anticipated to be particularly 
long-lived. However, strongly sheared, 40-50 kt mean southwesterly 
flow in the convective layer could still support some increase in 
potential for damaging convective gusts through 00-01z, before 
storms begin to weaken. 

.Kerr/Hart.. 03/15/2019 

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


Latitude...Lon 40457579 41477391 41337356 40917368 40207481 39467617 
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