U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 171940 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0140 PM CST Wed Jan 17 2018 

Valid 172000z - 181200z 

..no thunderstorm areas forecast... 

no thunderstorm areas are expected today or tonight. 

No change was made to the previous outlook. 

.Smith.. 01/17/2018 

Previous discussion... /issued 1005 am CST Wed Jan 17 2018/ 

..Pacific northwest... 
Water vapor loop shows an upper trough rotating toward the coast of 
WA/OR. The primary band of frontal precipitation is expected to 
move inland late this afternoon and early evening, with a low risk 
of a lightning strike or two along the coastal ranges of northwest 
Washington. Given the weak thermodynamic profiles, the coverage of 
thunderstorms should remain below 10%. 

Elsewhere, dry and stable conditions will preclude thunderstorms 


Mesoscale Discussion

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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 171221 

Mesoscale discussion 0030 
National Weather Service Storm Prediction Center Norman OK 
0621 am CST Wed Jan 17 2018 

Areas affected...northern South Carolina through central North 
Carolina and south central Virginia 

Concerning...heavy snow 

Valid 171221z - 171715z 

Summary...snowfall rates locally up to 1 inch per hour are possible 
through the morning from a portion of northern SC, central NC and 
south-central Virginia. 

Discussion...the freezing line from east-central NC through western 
SC continues slowly east due to progression of deeper baroclinic 
zone and also evaporative cooling within the near-surface melting 
layer. Bands of mostly light snow persist from western SC through 
western and central NC into southern Virginia. However, water vapor and infrared 
imagery indicates upper trough taking on a more neutral tilt across 
the Tennessee Valley with general cloud-top cooling noted within the last 
couple of hours. Model data have been consistent with strengthening 
a mid-upper jet within base of this trough. The resulting forcing in 
the exit region of this feature may enhance snowfall rates within 
evolving bands through the morning, especially from central NC into 
south central Virginia where rates could approach 1 inch per hour at 

.Dial.. 01/17/2018 

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


Latitude...Lon 35058154 36907968 36547770 34927981 35058154