U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 120537 
Storm Prediction Center ac 120536 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1136 PM CST Mon Dec 11 2017 

Valid 121200z - 131200z 

..no thunderstorm areas forecast... 

thunderstorms are not forecast across the Continental U.S. Today. 

..southern New England... 

A surface low will deepen over New England this morning in response 
to forcing for ascent accompanying a vigorous shortwave trough 
embedded within an increasingly negative-tilted synoptic trough. 
Trailing cold front will continue east and off the Atlantic Seaboard 
later today. Preceding the front, limited moisture will advect north 
along the warm conveyor belt and beneath steepening mid-level lapse 
rates, contributing to very weak instability with MLCAPE below 200 
j/kg over southern New England. While weak, shallow convection will 
likely develop in this regime, especially over southeast MA, 
instability and equilibrium temperatures are not expected to become 
sufficient to support any thunderstorm activity. 


Offshore flow will maintain stable conditions inland. 

.Dial.. 12/12/2017 


Mesoscale Discussion

acus11 kwns 120330 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 120330 

Mesoscale discussion 1795 
National Weather Service Storm Prediction Center Norman OK 
0930 PM CST Mon Dec 11 2017 

Areas affected...central New York 

Concerning...heavy snow 

Valid 120330z - 120930z 

Summary...snowfall rates will increase gradually through 06-09z, 
with peak rates likely to exceed 1 inch per hour from about 07-12z. 

Discussion...in association with a midlevel shortwave trough 
approaching the upper Ohio Valley, a deformation snow band has been 
developing eastward over Lake Erie. Low-midlevel warm 
advection/ascent in advance of the trough, as well as weak 
frontogenesis, will support additional eastward expansion of the 
snow band across central New York through the early morning hours. 
Top-down saturation of the column is just beginning across western 
into central NY, and snowfall rates will increase as column 
saturation develops eastward and forcing for ascent increases 
through the early morning hours. Peak snowfall rates should 
approach or exceed 1 inch per hour, and may persist for 3-6 hours at 
locations within the expected corridor of the snow band. 

.Thompson.. 12/12/2017 

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


Latitude...Lon 43217361 43007412 42747497 42497608 42457687 42517744 
42667771 43037760 43837544 44037419 43947361 43617347