Severe Storm Outlook Narrative (AC)
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000
ACUS03 KWNS 030729
SWODY3
SPC AC 030728

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0228 AM CDT Wed Jun 03 2020

Valid 051200Z - 061200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHWEST INTO CENTRAL MT AND PORTIONS OF THE LOWER MO VALLEY...

...SUMMARY...
Strong to severe storms are possible on Friday across eastern
portions of the central Plains and lower Missouri Valley vicinity,
as well as across parts of southwest and central Montana. Hail and
strong wind gusts will be the main hazards with these storms.

...Eastern NE/KS into northwest MO/southwest IA...

There is still quite a bit of uncertainty regarding severe potential
on Friday. Some convection could be ongoing across parts of IA/MO
Friday morning as the decaying remains of a potential MCS in the Day
2 period. Additionally, an upper ridge will amplify across the
Plains during the Day 3/Fri period. Nevertheless, most guidance
indicates a shortwave impulse migrating across the mid/lower MO
Valley vicinity on Friday. A vast reservoir of mid 60s to low 70s F
surface dewpoints will exist across eastern portions of the
central/southern Plains toward the mid-MS Valley. Strong heating
will support MLCAPE values greater than 2500 J/kg beneath a plume of
very steep midlevel lapse rates. However, weak low level wind
profiles indicate effective shear may be rather marginal.
Uncertainty regarding the building upper ridge and associated
influence on capping and convective coverage will preclude higher
severe probabilities at this time. However, at least a conditional
threat for large hail and damaging gusts appears likely, and a
Marginal risk has been included.

...Southwest into Central MT...

An upper trough is expected to move inland across the western U.S.
This will shift the northern Rockies upper ridge eastward toward the
Plains and strong deep-layer southwesterly flow will overspread the
region as a surface low develops over the northern Great Basin.
Modest boundary-layer moisture will spread westward across MT on
east/southeasterly low-level upslope flow. Forecast soundings
indicate up to 1000 J/kg MLCAPE amid strong vertical shear and steep
lapse rates. As a result, a few high-based strong-to-severe storms
capable of hail and locally strong gusts are possible late Friday
afternoon into the evening.

..Leitman.. 06/03/2020

$$


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