LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0103 AM CDT Fri Sep 08 2023
Valid 081200Z - 091200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHERN
VIRGINIA INTO SOUTHWEST MAINE...AND FROM THE RED RIVER VALLEY ACROSS
THE ARKLATEX AND SABINE VALLEY...
...SUMMARY...
Thunderstorms producing both hail and damaging winds are possible
from parts of the Mid Atlantic into the Northeast today, and from
the Red River Valley and Arklatex southward across the Sabine
Valley. Other isolated strong storms are expected over Montana.
...Synopsis...
An upper ridge will remain over NM today, with anticyclonic flow
aloft from CA into the northern Rockies and southeastward into the
lower MS Valley. Meanwhile, a weak upper trough/low heights will
remain over much of the East, resulting in cool profiles aloft.
Various speed maxes will round the upper ridge, and possibly enhance
thunderstorm potential. A low amplitude feature will affect MT with
30-40 kt westerly winds at 500 mb. To the southeast, relatively
strong midlevel flow with around 50 kt will spread south out of the
Ozarks and across AR, LA and northern MS. Meanwhile, modest 35 kt
southwesterlies at 500 mb will remain over New England.
At the surface, high pressure will extend from the upper Great Lakes
southward across the middle and lower MS Valley, with weak northerly
surface winds. A surface trough/wind shift will stretch from New
England to the FL Panhandle, with 70s F dewpoints common ahead of
it.
Farther west, low pressure will exist over northwest TX and
southwest OK with hot temperatures. Easterly winds over much of OK
and eastern TX will maintain a narrow moist plume, east of the hot
air and west of the surface ridge. A favorable area of instability
and shear may thus develop due to the aforementioned enhanced flow
aloft.
...Northeast and Mid Atlantic...
A substantial plume of low-level moisture will remain over the
region today, with models suggesting as much as 3000 J/kg MUCAPE
from southeast NY across MA, southern VT, NH and southwest ME.
Modest midlevel flow around 30 kt and front-parallel winds aloft
should result in a corridor of enhanced thunderstorm probabilities,
and water-loaded downdrafts may produce wind damage. In addition,
the cool profiles aloft will favor brief periods of hail in the
strongest storms.
Farther south, another concentrated area of storms is likely from
eastern WV across northern VA and into central MD, with storms
moving northeastward across an unstable air mass. Although shear
will be weak, forward-propagation is likely in the moist, uncapped
air mass, with strong to severe winds expected through early
evening.
...Southeast OK, Arklatex, eastern TX, LA...
Storms are likely to be ongoing from eastern OK into western AR this
morning, aided by weak theta-e advection at 850 mb with 25 kt
westerlies. Cooling aloft will gradually occur throughout the period
as a midlevel disturbance drops south out of MO. Some of this
activity could contain marginal hail as temperatures aloft will be
relatively cool with effective shear around 40 kt.
As heating occurs downstream into LA, a narrow zone of 2500-3000
J/kg MUCAPE may develop, with a thunderstorm revival possible as the
remnants of the early day activity proceeds southeastward. Damaging
winds appear most likely, and storms may favor westward propagation
as the low level lapse rates will be steeper to the west.
Farther west, isolated storms are also expected near peak heating
across the Red River Valley, and hot temperatures/deep mixing layers
as well as steep midlevel lapse rates may favor damaging downbursts
or even brief periods of marginal hail with the strongest storms.
...MT...
Destabilization will occur during the afternoon due to strong
heating, with mixed-layer CAPE around 500-1000 J/kg during the
afternoon. As a midlevel short-wave trough moves eastward across the
area, isolated to widely scattered thunderstorms are expected, over
central MT, with peak convective coverage from late afternoon
through mid evening. Given a belt of 30 to 40 kt mid-level
westerlies and inverted-v type profiles, a few strong/longer-lived
storms may produce locally damaging winds. Hail cannot be ruled out
given cool temperatures aloft and 50 kt flow above 500 mb.
..Jewell/Squitieri.. 09/08/2023
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/Svnxj7
