U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 160049 
Storm Prediction Center ac 160048 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0648 PM CST Fri Dec 15 2017 

Valid 160100z - 161200z 

..no thunderstorm areas forecast... 

thunderstorms are not forecast tonight. 


00z soundings across south Texas exhibit poor mid-level lapse rates 
north of a strong frontal zone. Despite the possibility for weak 
elevated convection along a corridor from northeast Mexico into the 
northwest Gulf basin, updrafts will remain too shallow and warm to 
generate lightning. 

.Darrow.. 12/16/2017 


Mesoscale Discussion

acus11 kwns 152243 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 152242 

Mesoscale discussion 1797 
National Weather Service Storm Prediction Center Norman OK 
0442 PM CST Fri Dec 15 2017 

Areas affected...portions of western New York and far northwestern 

Concerning...heavy snow 

Valid 152242z - 160245z 

Summary...a squall of heavy snow will continue to move ashore areas 
near Eastern Lake Erie this evening. Thereafter, lake effect snow 
bands will develop through the overnight. Snowfall rates upwards of 
two inches per hour will be possible. 

Discussion...along the cyclonic flank of a mid-level jet, broad 
ascent has fostered the development of a lake-enhanced snow squall 
over Eastern Lake Erie. This band should gradually move ashore over 
the next hour or so, aided by sufficient low-level instability and 
convergence. Kbuf dual-pol data suggest some enhancement of Crystal 
growth around -12 to -18 c, with subtle increases in kdp (upwards of 
0.4-0.6 deg/km) noted around 5000-6000 ft above radar level. 
Therefore, heavy snow is likely as the band continues to move 
onshore, and snowfall rates upwards of 2 inches per hour appear 
possible. Following the squall, lake-effect bands will likely 
organize later this evening, with continued localized heavy snow 

.Picca.. 12/15/2017 

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


Latitude...Lon 42118055 42997924 43347900 43417838 43297826 42687842 
42067905 41907963 41838010 41868039 41918050 42118055