SPC Severe Thunderstorm Watch 639
WW 639 SEVERE TSTM IA MN NE SD 012050Z - 020400Z



URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 639
NWS Storm Prediction Center Norman OK
350 PM CDT Tue Sep 1 2026

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of
Far Northwest Iowa
Far Southwest Minnesota
North-Central and Northeast Nebraska
Southeast South Dakota

* Effective this Tuesday afternoon and evening from 350 PM until
1100 PM CDT.

* Primary threats include...
Scattered damaging winds likely with isolated significant gusts
to 80 mph possible
Scattered large hail likely with isolated very large hail events
to 2 inches in diameter possible
A tornado or two possible

SUMMARY...Initial supercells will likely pose a threat for large
hail up to 2 inches in diameter. A tornado or two may also occur
with any sustained supercell, especially if thunderstorms can remain
at least semi-discrete through early evening as low-level shear
increases. Otherwise, a bowing cluster is expected to eventually
develop and pose a greater threat for severe/damaging winds up to
70-80 mph as it tracks generally eastward across southeast South
Dakota/northeast Nebraska and vicinity.

The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 60 miles northwest of
Burwell NE to 35 miles east southeast of Sioux Falls SD. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU9).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 638...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 70 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
25030.

...Gleason


Read more
https://www.spc.noaa.gov/products/watch/ww0639.html