U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 230532 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1232 am CDT Wed may 23 2018 

Valid 231200z - 241200z 

..there is a slight risk of severe thunderstorms for the Nebraska 
Panhandle and Black Hills... 

Isolated severe thunderstorms are possible this afternoon and 
evening across the High Plains and eastern portions of 
Virginia/North Carolina. 

..High Plains... 
Southerly low-level flow across the Great Plains will maintain a 
fetch of modest moisture in the High Plains as a Lee trough moves 
little. A belt of stronger southwesterly mid-level flow will extend 
from the Desert Southwest northeastward into the Central High plains 
and Black Hills to the southeast of a weakening mid-level low. 
Steep 700-500 mb lapse rates and strong heating through mid 
afternoon will yield moderate buoyancy (1000-2000 j/kg mlcape). The 
local erosion of a capping inversion will result in isolated to 
scattered thunderstorms developing in the vicinity of the Lee trough 
by late afternoon. The potential for organized storms appears 
greatest over parts of the Central High plains where vertical shear 
is forecast to be strongest. Models suggest higher storm coverage 
and severe potential from far eastern Wyoming northeastward into western 
NE/Black Hills. Large hail and severe gusts will be the primary 
threats before storms grow upscale as a low level jet strengthens during the 
evening and the wind threat persists while the hail risk gradually 
lessens as storms move into western South Dakota. Farther south, isolated 
strong to severe thunderstorms will pose an attendant hail/wind 
threat with the stronger cores. This activity will likely weaken 
during the evening coincident with a cooling boundary layer. 

A cold front extending southwestward from southern New Jersey across central 
Virginia to middle Tennessee is expected to shift southeastward throughout the 
day. Temperatures ahead of the front will likely reach the mid-80s 
amidst dewpoints in the upper 60s, which is supportive of airmass 
destabilization and modest instability. Deep-layer shear is 
forecast to favor multicells with some upscale growth into small 
segments capable of isolated damaging wind with the strongest 
water-loaded downdrafts. 

.Smith/Cook.. 05/23/2018 


Mesoscale Discussion

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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 222324 

Mesoscale discussion 0496 
National Weather Service Storm Prediction Center Norman OK 
0624 PM CDT Tue may 22 2018 

Areas affected...southern Maryland and southeast Virginia 

Concerning...Severe Thunderstorm Watch 116... 

Valid 222324z - 230100z 

The severe weather threat for Severe Thunderstorm Watch 116 

Summary...locally strong wind gusts cannot be ruled out, though the 
overall severe-weather threat across the remainder of ww 116 is 
expected to undergo a further diminishing trend. 

Discussion...at 2315z, mosaic radar imagery showed a line of storms 
extending from Dorchester County, Maryland into far southern Maryland (st. 
Mary's county) and far southeast Virginia (james city county), with this 
line moving east at 25 kt. The environment immediately downstream 
is gradually stabilizing per objective analyses, while stronger 
shear that would support organized storms is located north of these 
storms in northern Maryland to Delaware. Given the slow storm motion, 
unfavorable thermodynamics and kinematics, and the onset of diabatic 
cooling stabilizing the boundary layer, parts or most of the 
remainder of ww 116 could be canceled early. 

.Peters.. 05/22/2018 

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


Latitude...Lon 37287795 37927705 38717661 38637609 37887599 37307627 
37177671 37227740 37287795