U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 181927 
Storm Prediction Center ac 181926 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0126 PM CST Mon Nov 18 2019 

Valid 182000z - 191200z 

..no severe thunderstorm areas forecast... 

no severe thunderstorms are expected. 

No change was made to the previous outlook. 

.Smith.. 11/18/2019 

Previous discussion... /issued 0955 am CST Mon Nov 18 2019/ 

Water vapor imagery shows a strong and progressive shortwave trough 
about 400nm off the coast of WA/OR. This feature will approach the 
Pacific northwest coast later today, with the potential for 
scattered showers and a few thunderstorms - mainly after dark. Weak 
instability should minimize the risk of severe storms. 

Elsewhere, dry and stable conditions will preclude thunderstorms 
over the remainder of the Continental U.S.. 


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... 


Latitude...Lon 45347358 45757143 47606922 47386776 47036763 45686894 
44617101 44057257 43947341 44197411 44847428 45347358