U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 231627 
Storm Prediction Center ac 231625 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1125 am CDT Fri Aug 23 2019 

Valid 231630z - 241200z 

..there is a slight risk of severe thunderstorms this afternoon 
into early tonight across parts of Virginia/NC and the High Plains... 

Severe thunderstorms appear most probable this afternoon into early 
tonight for portions of North Carolina and Virginia, as well as the 
Central High plains. 

..VA/NC this afternoon/evening... 
A surface cold front will continue to move slowly southward across 
Virginia this afternoon into NC overnight, in the wake of a midlevel 
trough crossing New England. The southern fringe of the westerlies 
extends south to near the Virginia/NC border, where a series of subtle 
speed maxima/embedded mcvs will translate eastward this afternoon. 
Low-level convergence/ascent along the front and an accompanying 
differential heating zone should support thunderstorm development by 
early afternoon across central VA, and storms will spread 
east-southeastward through the remainder of the afternoon/evening. 
Though midlevel lapse rates will be rather modest, surface heating 
will steepen low-level lapse rates and boost afternoon MLCAPE to 
near 1500 j/kg. Given effective bulk shear in the 25-35 kt range, 
and mix of organized multicell clusters and some low-end supercells 
can be expected in a broken band along the front this afternoon. 
Damaging winds should be the main severe threat. 

..Central High plains this afternoon into tonight... 
A midlevel shortwave trough is moving slowly eastward over the 
northern rockies, as other subtle embedded waves progress eastward 
over the central rockies. Steep midlevel lapse rates, daytime 
heating, and low-level upslope flow will promote an environment 
favorable for afternoon thunderstorm development east of the Front 
Range from northeast nm northward into eastern Wyoming. Deep-layer 
vertical shear will not be particularly strong over most of the High 
Plains. The corridors of the somewhat stronger vertical shear will 
be immediately east of the midlevel trough in WY, and in the 
vicinity of southeast Colorado where low-level east-southeast flow will 
reside beneath the more westerly flow aloft, contributing to 
effective bulk shear of 30-35 kt. Thus, expect a mix of multicell 
clusters and some low-end supercells capable of producing damaging 
winds and large hail. A few clusters will likely persist into 
tonight in association with warm advection and a modest low-level 

.Thompson/Cook.. 08/23/2019 


Mesoscale Discussion

acus11 kwns 230839 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 230838 

Mesoscale discussion 1837 
National Weather Service Storm Prediction Center Norman OK 
0338 am CDT Fri Aug 23 2019 

Areas affected...portions of south-central NE into north-central Kansas 

Concerning...severe potential...watch unlikely 

Valid 230838z - 231045z 

Probability of watch issuance...5 percent 

Summary...a long-lived supercell thunderstorm may continue to 
produce severe wind gusts and large hail through the early morning 
hours. This threat is expected to remain too isolated to justify 
watch issuance. 

Discussion...a measured severe wind gust to 66 kt (76 mph) was 
recorded at 0759z at Hastings NE (ksi) with a supercell thunderstorm 
moving slowly southward across south-central NE. This storm may be 
related to an mesoscale convective vortex from convection yesterday across the Central 
Plains, and it is located along a moisture/instability gradient 
evident on latest 850 mb and MUCAPE mesoanalysis fields. The vwp 
from kuex has shown only a modest increase in a 15-20 kt 
south-southeasterly low-level jet over the past couple of hours, 
with mid-level westerly flow increasing to only about 30-35 kt. 
Regardless, this is apparently sufficient to support a persistent 
supercell, as observed by kuex radar imagery. Given the ongoing 
storm organization and modestly steepened mid-level lapse rates 
across this region, isolated large hail may occur with this 
supercell in addition to severe wind gusts. It is uncertain how long 
this storm will persist, but it is moving slowly southward into a 
region with a relative minimum in convective inhibition owing to 
upper 60s to low 70s surface dewpoints. A severe risk may continue 
for the next couple of hours into part of north-central KS, but 
watch issuance is not currently expected given the very isolated 
nature of the threat. 

.Gleason/Edwards.. 08/23/2019 

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


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