U.S. Severe Weather Forecast (Convective Outlook)

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acus01 kwns 190447 
swody1 
Storm Prediction Center ac 190446 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1046 PM CST sun Nov 18 2018 


Valid 191200z - 201200z 


..no severe thunderstorm areas forecast... 


... 
only general thunderstorms are possible across parts of East Texas 
and Louisiana today. 


..synopsis and discussion... 
With an upper low over Hudson Bay, an expansive area of cyclonic 
flow aloft will remain over the eastern states with a weak upper 
ridge over the west. A dry air mass due to high pressure will exist 
over the vast majority of the Continental U.S. With a cold front just off the 
Texas coast during the day. A low-amplitude upper disturbance will 
develop east across the Gulf Coast states, with weak southerly 850 
mb winds aiding warm advection atop the relatively stable surface 
air mass over Texas and la. Here, weak elevated instability will 
support showers and a few thunderstorms mainly early in the day, 
with activity shifting offshore by evening. 


.Jewell/Bentley.. 11/19/2018 


$$ 

Mesoscale Discussion


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acus11 kwns 160857 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 160856 
mez000-nhz000-maz000-vtz000-ctz000-nyz000-njz000-paz000-161500- 


Mesoscale discussion 1652 
National Weather Service Storm Prediction Center Norman OK 
0256 am CST Fri Nov 16 2018 


Areas affected...portions of the mid-Atlantic and New England 


Concerning...heavy snow 


Valid 160856z - 161500z 


Summary...one area of heavy snow with rates in excess of 1 inch per 
hour will develop northeastward across northern New England this 
morning. Another area of moderate to locally heavy snow, with rates 
up to 1 inch per hour, will move across eastern PA into southern New 
England. 


Discussion...within large-scale upper troughing encompassing much of 
the central and eastern conus, a compact shortwave trough will 
continue moving quickly northeastward over the mid-Atlantic and New 
England regions this morning. A deepening surface low associated 
with this shortwave trough will likewise develop northeastward along 
the coast of southern New England. A band of moderate to heavy snow 
is occurring over western/northern NY, attendant to strong forcing 
for ascent and a mid-level deformation zone immediately ahead of the 
shortwave trough. Snowfall rates in excess of 1 inch per hour will 
likely continue for at least the next several hours as this band 
develops into northern New England. 


Across parts of central/eastern PA, northern NJ, southern NY, and 
southern New England, a mix of snow, sleet, and freezing rain have 
all been observed recently as strong low-level warm air advection 
has allowed for at least some melting of hydrometeors. However, a 
quick transition back to mainly snow is likely from west to east 
this morning as cold mid/upper-level temperatures embedded within 
the core of the shortwave trough overspread these areas. Forecast 
soundings from the NAM and rap both suggest that there will be 
sufficient wrap-around moisture remaining within the dendritic 
growth zone and steepening mid-level lapse rates to support moderate 
to locally heavy snow for a couple of hours. Snowfall rates up to 1 
inch per hour may occur. This scenario is well supported by recent 
high-resolution guidance, including most href members. A rapid 
decrease in snowfall intensity/coverage will likely be noted from 
west to east through the morning, as strong subsidence and mid-level 
drying behind the shortwave trough passage suppress precipitation 
potential. 


.Gleason.. 11/16/2018 


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


Attention...WFO...car...gyx...box...btv...okx...aly...phi...bgm... 
buf...ctp... 


Latitude...Lon 43667018 42917138 42457230 41937334 40907478 40407593 
40217652 40257704 41037762 41687752 43387669 44457594 
45047489 45087164 45387140 45447091 45837051 46087035 
46257028 46417018 46566969 46536828 46286771 45706771 
45216802 44626873 43996958 43667018