Mesoscale Discussion 2193
NWS Storm Prediction Center Norman OK
1156 PM CDT Tue Sep 01 2026

Areas affected...portions of southern MN into western WI

Concerning...Severe Thunderstorm Watch 640...

Valid 020456Z - 020700Z

The severe weather threat for Severe Thunderstorm Watch 640
continues.

SUMMARY...Thunderstorm clusters could continue to produce strong to
severe wind gusts and hail into the overnight hours. A downstream
watch into parts of southeast Minnesota and western Wisconsin is
uncertain, but a small downstream watch may be needed depending on
storm trends.

DISCUSSION...A cluster of storms over southern MN has weakened some
over the past 30-60 minutes as it has continued to lift northeast.
With this storm motion, convection has shifted further away from the
modest low-level jet oriented across IA, and northward into more
modest instability and midlevel lapse rates. Most recent observed
wind gusts have generally been in the 40-55 mph range, with 1.75
inch hail reported nearly an hour ago. Overall convective
organization has become more messy with time. Given overall
environment, sporadic severe wind gusts or hail could persist into
the overnight hours across southeast MN and perhaps west-central WI.
Damaging wind potential could increase if the cluster can track more
easterly near a surface boundary across southern MN. Depending on
short term trends, a small downstream watch could become necessary,
but remains uncertain.

..Leitman.. 09/02/2026

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MKX...ARX...MPX...DMX...FSD...

LAT...LON   43919524 44239508 44469362 44479226 44349118 44139021
            43858990 43638982 43449035 43379137 43379330 43319483
            43489522 43919524 

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN

Mesoscale Discussion 2193
NWS Storm Prediction Center Norman OK
1156 PM CDT Tue Sep 01 2026

Areas affected...portions of southern MN into western WI

Concerning...Severe Thunderstorm Watch 640...

Valid 020456Z - 020700Z

The severe weather threat for Severe Thunderstorm Watch 640
continues.

SUMMARY...Thunderstorm clusters could continue to produce strong to
severe wind gusts and hail into the overnight hours. A downstream
watch into parts of southeast Minnesota and western Wisconsin is
uncertain, but a small downstream watch may be needed depending on
storm trends.

DISCUSSION...A cluster of storms over southern MN has weakened some
over the past 30-60 minutes as it has continued to lift northeast.
With this storm motion, convection has shifted further away from the
modest low-level jet oriented across IA, and northward into more
modest instability and midlevel lapse rates. Most recent observed
wind gusts have generally been in the 40-55 mph range, with 1.75
inch hail reported nearly an hour ago. Overall convective
organization has become more messy with time. Given overall
environment, sporadic severe wind gusts or hail could persist into
the overnight hours across southeast MN and perhaps west-central WI.
Damaging wind potential could increase if the cluster can track more
easterly near a surface boundary across southern MN. Depending on
short term trends, a small downstream watch could become necessary,
but remains uncertain.

..Leitman.. 09/02/2026

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MKX...ARX...MPX...DMX...FSD...

LAT...LON   43919524 44239508 44469362 44479226 44349118 44139021
            43858990 43638982 43449035 43379137 43379330 43319483
            43489522 43919524 

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN

STATUS REPORT ON WW 639

SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 5 SSW BUB TO
25 ESE 9V9.

..LEITMAN..09/02/26

ATTN...WFO...FSD...OAX...LBF...


STATUS REPORT FOR WS 639 

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS 

MNC117-133-020440-

MN 
.    MINNESOTA COUNTIES INCLUDED ARE

PIPESTONE            ROCK                


NEC003-015-027-071-089-107-139-179-183-020440-

NE 
.    NEBRASKA COUNTIES INCLUDED ARE

ANTELOPE             BOYD                CEDAR               
GARFIELD             HOLT                KNOX                
PIERCE               WAYNE               WHEELER             


SDC003-009-023-027-035-043-053-061-067-079-083-087-097-099-101-
111-125-135-020440-

SD 
.    SOUTH DAKOTA COUNTIES INCLUDED ARE

AURORA               BON HOMME           CHARLES MIX         

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

STATUS REPORT ON WW 639

SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 5 SSW BUB TO
25 ESE 9V9.

..LEITMAN..09/02/26

ATTN...WFO...FSD...OAX...LBF...


STATUS REPORT FOR WS 639 

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS 

MNC117-133-020440-

MN 
.    MINNESOTA COUNTIES INCLUDED ARE

PIPESTONE            ROCK                


NEC003-015-027-071-089-107-139-179-183-020440-

NE 
.    NEBRASKA COUNTIES INCLUDED ARE

ANTELOPE             BOYD                CEDAR               
GARFIELD             HOLT                KNOX                
PIERCE               WAYNE               WHEELER             


SDC003-009-023-027-035-043-053-061-067-079-083-087-097-099-101-
111-125-135-020440-

SD 
.    SOUTH DAKOTA COUNTIES INCLUDED ARE

AURORA               BON HOMME           CHARLES MIX         

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

STATUS FOR WATCH 0640 HAS NOT BEEN ISSUED YET

STATUS FOR WATCH 0640 HAS NOT BEEN ISSUED YET

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 640
NWS Storm Prediction Center Norman OK
945 PM CDT Tue Sep 1 2026

The NWS Storm Prediction Center has issued a

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

* Effective this Tuesday night and Wednesday morning from 945 PM
  until 500 AM CDT.

* Primary threats include...
  Scattered damaging winds likely with isolated significant gusts
    to 75 mph possible
  Scattered large hail and isolated very large hail events to 2
    inches in diameter possible
  A tornado or two possible

SUMMARY...Severe thunderstorm currently moving through extreme
southeast South Dakota is expected to continue northeastward
tonight, tracking through southwest Minnesota and northwest Iowa.
Strong wind gusts from 65 to 75 mph are possible with this storm.
Additional thunderstorms are development across south-central
Minnesota. Some large hail is possible with these storms over the
next hour or two. A lone supercell is also progressing northeastward
across far northeast Nebraska, with an attendant threat for damaging
gust and large hail it is gradually moves northeastward.

The severe thunderstorm watch area is approximately along and 45
statute miles north and south of a line from 40 miles north
northwest of Sioux City IA to 35 miles north northeast of Mason City
IA. For a complete depiction of the watch see the associated watch
outline update (WOUS64 KWNS WOU0).

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...WW 639...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 65 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
24035.

...Mosier

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 640
NWS Storm Prediction Center Norman OK
945 PM CDT Tue Sep 1 2026

The NWS Storm Prediction Center has issued a

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

* Effective this Tuesday night and Wednesday morning from 945 PM
  until 500 AM CDT.

* Primary threats include...
  Scattered damaging winds likely with isolated significant gusts
    to 75 mph possible
  Scattered large hail and isolated very large hail events to 2
    inches in diameter possible
  A tornado or two possible

SUMMARY...Severe thunderstorm currently moving through extreme
southeast South Dakota is expected to continue northeastward
tonight, tracking through southwest Minnesota and northwest Iowa.
Strong wind gusts from 65 to 75 mph are possible with this storm.
Additional thunderstorms are development across south-central
Minnesota. Some large hail is possible with these storms over the
next hour or two. A lone supercell is also progressing northeastward
across far northeast Nebraska, with an attendant threat for damaging
gust and large hail it is gradually moves northeastward.

The severe thunderstorm watch area is approximately along and 45
statute miles north and south of a line from 40 miles north
northwest of Sioux City IA to 35 miles north northeast of Mason City
IA. For a complete depiction of the watch see the associated watch
outline update (WOUS64 KWNS WOU0).

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...WW 639...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 65 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
24035.

...Mosier