U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 170507 
Storm Prediction Center ac 170505 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1105 PM CST Sat Nov 16 2019 

Valid 171200z - 181200z 

..no severe thunderstorm areas forecast... 

the risk for severe thunderstorms appears negligible across the 
U.S., Today through tonight. 

A lower/mid tropospheric cyclone continues to evolve and deepen to 
the east of the South Atlantic coast. After a gradual eastward, 
then northeastward, migration through this morning, models suggest 
that there will be a more rapid northeastward acceleration across 
the western Atlantic later today into tonight, as a vigorous 
upstream short wave trough digs within the main belt of westerlies, 
across and east of the Mississippi Valley. 

It appears that the triple Point of the occluding cyclone may 
progress into and linger near or just east of the North Carolina 
Outer Banks vicinity beyond 12z this morning, providing a continuing 
focus for convection and embedded thunderstorms. This probably will 
continue to be aided by forcing for ascent to the northeast of the 
mid-level cyclone center, and inflow of potentially unstable warm 
sector air could persist into midday before gradually shifting 
eastward away from coastal areas. 

Otherwise, generally dry and/or stable conditions appear likely to 
prevail across much of the remainder of the nation today through 
tonight, with generally negligible risk for thunderstorms. 

.Kerr/Cook.. 11/17/2019 


Mesoscale Discussion

acus11 kwns 151935 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 151934 

Mesoscale discussion 2149 
National Weather Service Storm Prediction Center Norman OK 
0134 PM CST Fri Nov 15 2019 

Areas affected...northern and western ME to the Champlain Valley 

Concerning...heavy snow 

Valid 151934z - 152300z 

Summary...snow squalls should push east-southeast from the Saint 
Lawrence valley, most likely across portions of northern and western 
ME between 4 to 7 PM EST. A brief period of heavy snow with 0.5-1.0" 
in 30 min is likely. 

Discussion...19z surface analysis placed a cold front across the 
Saint Lawrence valley. Canadian radars in Montreal and Quebec city 
have sampled a snow squall along the front. Somewhat enhanced 
reflectivity was noted along the eastern portion of the squall near 
Quebec city, which is consistent with a recent increase of 
low-topped convective development/colder cloud tops in visible and 
infrared satellite imagery. Recent amdar data near Montreal sampled 
inversion heights to 750 mb and near Quebec city to 700 mb. Latest 
rap/NAM guidance both are consistent with inversion heights further 
deepening as the shortwave trough and attendant cooling aloft 
approaches from southwest Quebec. Lack of stronger convergence along 
the front, in addition to a modest surface rise/fall couplet 
behind/ahead of the front, does suggest that squalls which progress 
across the international border will probably subside within a 
couple hours after sunset. 

.Grams.. 11/15/2019 

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


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