ACUS01 KWNS 041939
SWODY1
SPC AC 041938

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0238 PM CDT Sun Aug 04 2024

Valid 042000Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR A FEW
TORNADOES OVER PART OF FLORIDA AND EXTREME SOUTHERN GEORGIA...AND
FOR DAMAGING GUSTS ACROSS SOUTHEAST MONTANA THIS EVENING...

...SUMMARY...
Tropical Storm Debby may produce a few tornadoes over parts of
Florida and extreme southern Georgia through early tomorrow morning
as it intensifies.  Scattered thunderstorms may produce damaging
wind gusts across parts of Montana this evening.

...20Z Update...
Overall forecast outlined in the previous discussion (appended
below) remains valid, with no changes needed. TS Debby continues to
strengthen off the west coast of FL, while numerous convective rain
bands progress across FL Peninsula. Brief tornadoes will remain
possible within these bands through the afternoon and evening, with
a lower, but still non-zero chances overnight. Thunderstorms capable
of strong gusts are still anticipated this evening from eastern ID
into southern MT and northern WY. Strong gusts are possible this
evening from eastern SD into southern MN and northern IA, with some
isolated hail possible as well.

Isolated severe threat across the Northeast was discussed in
recently issued MCD #1814, which mentioned that short-lived, strong
storm cores capable of marginally severe hail will be the primary
risk over the next few hours as they travel east/southeast across
the narrow instability zone.

..Mosier.. 08/04/2024

.PREV DISCUSSION... /ISSUED 1123 AM CDT Sun Aug 04 2024/

...FL/South GA...
Tropical Storm Debby continues to intensify off the west coast of
the FL.  Low-level wind fields are enlarging, resulting in
strengthening shear profiles across much of peninsula.  Dewpoints in
the mid-upper 70s and pockets of heating, combined with deep
tropical moisture, will result in scattered to widespread afternoon
thunderstorms.  Given the favorable wind fields, a few tornadoes are
possible.

...MT/WY...
Water vapor loop shows a well-defined mid-level shortwave trough
moving eastward across ID.  This feature and an associated mid-level
speed max will cross the northern Rockies and into southern
MT/northern WY this afternoon/evening.  A consensus of 12z model
guidance shows clusters of thunderstorms forming in this region,
tracking eastward across southern MT through the evening.  CAMs have
a consistent signal for a more organized damaging wind threat, so
have added a small SLGT to account for this scenario.

...SD/MN/IA...
A strengthening low-level jet will enhance warm advection and lift
over eastern SD/western MN this evening/tonight.  Isolated
thunderstorm development is possible in this regime, perhaps not
until after midnight.  This region will be beneath the southern
fringe of stronger west-northwest flow aloft, and in a region of
relatively steep mid-level lapse rates.  Elevated storms capable of
hail and perhaps gusty winds are possible.

...Northeast States...
Scattered thunderstorms are expected today across much of New
England and eastern NY/PA into NJ.  Surface conditions are
considerably cooler than recent days, which should weaken low-level
lapse rates and temper the overall severe threat.  Nevertheless, a
few strong storms are possible - capable of gusty wind and small
hail.

$$
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