SPC Jun 30, 2020 0100 UTC Day 1 Convective Outlook

SPC 0100Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0751 PM CDT Mon Jun 29 2020

Valid 300100Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN HIGH PLAINS...

...SUMMARY...
A few severe thunderstorms with large hail and wind damage are
possible this evening across parts of the northern High Plains.

...Northern High Plains...
Water imagery current shows an upper-level low in the northwestern
U.S. with south to south-southwest mid-level flow over the northern
High Plains. A subtle shortwave trough appears to be moving through
eastern Montana. At the surface, a 997 mb low is analyzed over
southwestern North Dakota with a trough extending southward into
western South Dakota. Scattered strong to severe thunderstorms are
ongoing just to the north of the surface low and just to the west of
the surface trough. The storms are located along the western edge of
a very moist airmass with surface dewpoints from the mid 60s to the
mid 70s F. This is contributing to very strong instability with
MLCAPE in the western Dakotas estimated to be in the 2000 to 4000
J/kg range. In addition, regional WSR-88D VWPs show wind profiles
with substantial directional shear in the lowest 3 km above ground
level. This combined with speed shear in the mid-levels is resulting
in 50 to 60 kt of 0-6 km shear which will be favorable for
supercells this evening. The more dominant supercells in western
North Dakota could produce hailstones of greater than 2 inches in
diameter and could also have a tornado threat. Wind damage will also
be possible with supercells and organized multicell line
segments...see MCD 1054. The severe threat should persist into the
late evening and perhaps into the early overnight period as
low-level flow strengthens across the region.

...West-central Texas...
The latest surface analysis shows a surface trough across west Texas
with south-southeasterly flow located across much of west-central
Texas. A very moist airmass exists to the east of the surface trough
with surface dewpoints mostly in the upper 60s and lower 70s F.
Thunderstorms are ongoing along the western edge of the moist
airmass where the RAP is analyzing MLCAPE in the 2500 to 3500 J/kg
range. This combined with steep mid-level lapse rates will be enough
for hail and marginally severe wind gusts with the stronger
cells...see MCD 1053. The threat should persist for a couple more
hours before instability begins to weaken across the region.

..Broyles.. 06/30/2020

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from SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_0100.html