U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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acus03 kwns 210738 
swody3 
Storm Prediction Center ac 210737 


Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0237 am CDT Tue may 21 2019 


Valid 231200z - 241200z 


..there is an enhanced risk of severe thunderstorms ... 


..There is a slight risk of severe thunderstorms over a portion of 
the southern and Central Plains as well as the Ohio Valley and 
northeast states... 


... 
Severe storms with large hail, damaging wind and tornadoes will be 
possible over a part of the central and Southern Plains Thursday. 
Other strong to severe storms with damaging wind and large hail 
might occur from a portion of the northeast states into the Ohio 
Valley. 


... 


A significant shortwave trough will rotate through the base of an 
upper low centered over the Great Basin 12z Thursday and into the 
Central High plains Thursday afternoon and evening. Farther east, a 
low-amplitude shortwave trough will crest an upper ridge anchored 
over the southeast U.S. And move through the Great Lakes before 
turning southeast into the northeast states Thursday evening. At the 
surface a warm or stationary front will likely extend from the 
middle MS valley region southwest into central or southern Kansas. A 
dryline will reside near the Texas/nm border. The warm front is 
expected to lift north into southeast NE, while the dryline mixes 
through West Texas during the day. Farther east a surface low attending 
the northern-stream shortwave trough will move through southern 
Canada while trailing cold front advances southeast through the 
Great Lakes. A warm front will advance east into a portion of the 
northeast states. 


..central and Southern Plains... 


A very moist and unstable airmass with dewpoints in the upper 60s to 
around 70 f will reside in the warm sector from Kansas to OK and Texas 
beneath 7-7.5 c/km mid-level lapse rates, contributing to moderate 
to strong instability (2500-3000 j/kg mlcape). While much of the 
warm sector across this region may remain capped, forcing for ascent 
attending the northeast-migrating upper jet will likely promote 
thunderstorm development over the central and southern High Plains. 
Models suggest early timing of this feature and initiate storms near 
and north of the warm front from the Texas Panhandle into southwest Kansas 
early in the period. Some of this activity may intensify as it 
develops northeast, and additional storms are expected to develop 
along the dryline as well as along and north of the warm front. 
Vertical wind profiles and the thermodynamic environment will 
support organized storms including supercells with all hazards 
possible. 


..northeast states through Ohio Valley... 


The warm sector will gradually moisten west of the warm front during 
the day with low 60s f dewpoints beneath 6.5 c/km lapse rates along 
with diabatic warming contributing to moderate instability during 
the day. Current indications are that storms will most likely 
develop over the Great Lakes along southeast-advancing cold front 
and spread southeast into the Ohio Valley and northeast states by late 
afternoon and evening. Winds will strengthen as the mid-level speed 
Max attending the shortwave trough approaches the region with 
effective shear supporting supercells. These storms may produce 
large hail and damaging wind as they move southeast through the 
region later Thursday afternoon into the evening. 


.Dial.. 05/21/2019 


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