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acus01 kwns 231627
swody1
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
jet.
.Thompson/Cook.. 08/23/2019
$$
Mesoscale Discussion
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acus11 kwns 230839
sels mesoscale discussion
Storm Prediction Center mesoscale discussion 230838
ksz000-nez000-231045-
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...
Attention...WFO...top...Gid...
Latitude...Lon 40689863 40679819 40179778 39669763 39529814 39609863
40349878 40689863
