U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 160525 
Storm Prediction Center ac 160524 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1124 PM CST Sat Dec 15 2018 

Valid 161200z - 171200z 

..no severe thunderstorm areas forecast... 

a few thunderstorms are expected along the Pacific coast beginning 
this afternoon through late tonight. 

A mid- to upper-level trough over the eastern Pacific is forecast to 
move into California/or by late tonight. Convective showers and a few 
thunderstorms are possible as cooling in the mid levels associated 
with the approaching disturbance yields weak instability near the 
coastal ranges of central/northern California northward along the or/Washington 
coast. Elsewhere, high pressure will encompass a large part of the 
central and eastern U.S. As a mid-level low moves off the Delmarva 
and into the western Atlantic south of Cape Cod. 

.Smith/nauslar.. 12/16/2018 


Mesoscale Discussion

acus11 kwns 142350 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 142350 

Mesoscale discussion 1711 
National Weather Service Storm Prediction Center Norman OK 
0550 PM CST Fri Dec 14 2018 

Areas affected...west-central Florida 

Concerning...Severe Thunderstorm Watch 438... 

Valid 142350z - 150145z 

The severe weather threat for Severe Thunderstorm Watch 438 

Summary...severe risk continues for locally damaging winds gusts and 
perhaps a tornado across portions of west-central Florida within 

Discussion...the line of storms west of the Florida Peninsula 
continue to move slowly eastward with most of the line still 
offshore. Shear values (effective bulk shear of 45-60 knots) and 
hodographs with 200-300 m2/s2 0-1 km storm relative helicity per 
mesoanalysis/rap soundings remain supportive of embedded supercells 
and bowing segments. However, these features have yet to materialize 
within the line of storms. Subtle height falls aloft have helped 
maintain marginal buoyancy (500-1000 j/kg of mlcape) across the area 
even with the loss of insolation. As the storms continue slowly 
moving eastward, locally damaging wind gusts and a brief tornado 
remain possible through 03z across ww438. 

.Nauslar/Edwards.. 12/14/2018 

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


Latitude...Lon 28338305 28708231 29078147 28748144 27888146 27628146 
27298219 26998279 26888308 27588309 28338305