U.S. Severe Weather Forecast (Previsión convectiva)

día tres

acus01 kwns 131246 
Storm Prediction Center ac 131245 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0645 am CST Wed Dec 13 2017 

Valid 131300z - 141200z 

..no thunderstorm areas forecast... 

thunderstorms are not forecast across the contiguous states through 

A highly amplified pattern will continue aloft, with ridging over 
the West Coast. Broadly cyclonic flow covering most of the eastern 
2/3 of the nation, punctuated by a series of shortwaves of varying 
amplitudes. One perturbations -- initially located over southern mb 
-- should traverse the cyclonic flow, reaching the coastal mid- 
Atlantic by 12z. A foregoing trough over South Dakota/NE meanwhile will 
weaken considerably as it crosses the mid Mississippi Valley and 
south-central Appalachians. Another -- now evident in moisture- 
channel imagery over Washington -- will dig southeastward across the Great 
Basin this period, before phasing with what now is a weak/cut-off 
cyclone over northwestern mx on day 2. 

At the surface, the series of frontal passages from the past few 
days through today will combine to render the inland air mass east 
of The Rockies too dry and/or stable for thunderstorms. Meanwhile, 
dry/stable air will persist over the west near the mean mid/upper- 
level ridge. 

.Edwards.. 12/13/2017 


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... 


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