WW 574 SEVERE TSTM IA IL IN 121140Z - 121800Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 574
NWS Storm Prediction Center Norman OK
640 AM CDT Wed Aug 12 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Eastern Iowa
Northern and Central Illinois
Northwest Indiana
* Effective this Wednesday morning and afternoon from 640 AM
until 100 PM CDT.
* Primary threats include...
Scattered damaging winds likely with isolated significant gusts
to 75 mph possible
Isolated large hail events to 1 inch in diameter possible
SUMMARY...A cluster of intensifying thunderstorms will move into
Watch and pose a risk for scattered severe gusts (60 to 75 mph).
Isolated large hail may accompany the more intense thunderstorm
cores. This activity will likely shift to the east and southeast
through the morning and into the midday.
The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 45 miles north
northwest of Burlington IA to 30 miles north northeast of Danville
IL. For a complete depiction of the watch see the associated watch
outline update (WOUS64 KWNS WOU4).
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 573...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 65 knots. A few
cumulonimbi with maximum tops to 550. Mean storm motion vector
29035.
...Smith
WW 573 SEVERE TSTM IA NE 120720Z - 121500Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 573
NWS Storm Prediction Center Norman OK
220 AM CDT Wed Aug 12 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Western into Central Iowa
Central into Eastern Nebraska
* Effective this Wednesday morning from 220 AM until 1000 AM CDT.
* Primary threats include...
Scattered damaging winds likely with isolated significant gusts
to 80 mph possible
Isolated large hail events to 1 inch in diameter possible
SUMMARY...A long-lived and compact squall line will continue to the
east-southeast into the Watch during the overnight and morning.
Scattered severe gusts 60 to 80 mph will be the primary hazard.
The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 40 miles south
southwest of Oneill NE to 15 miles south southeast of Des Moines IA.
For a complete depiction of the watch see the associated watch
outline update (WOUS64 KWNS WOU3).
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 572...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 70 knots. A few
cumulonimbi with maximum tops to 500. Mean storm motion vector
29040.
...Smith
WW 0574 Status Updates
STATUS REPORT ON WW 574
THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.
FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1949
..MEAD..08/12/26
ATTN...WFO...DVN...ILX...LOT...
STATUS REPORT FOR WS 574
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
ILC011-019-031-037-039-043-053-057-063-067-071-073-075-089-091-
093-095-099-103-105-107-109-113-123-125-131-143-147-155-161-175-
179-183-187-195-197-203-121540-
IL
. ILLINOIS COUNTIES INCLUDED ARE
BUREAU CHAMPAIGN COOK
DE KALB DE WITT DUPAGE
FORD FULTON GRUNDY
HANCOCK HENDERSON HENRY
IROQUOIS KANE KANKAKEE
KENDALL KNOX LA SALLE
LEE LIVINGSTON LOGAN
MCDONOUGH MCLEAN MARSHALL
MASON MERCER PEORIA
PIATT PUTNAM ROCK ISLAND
STARK TAZEWELL VERMILION
WARREN WHITESIDE WILL
WOODFORD
INC007-073-089-111-127-121540-
WW 0573 Status Updates
STATUS REPORT ON WW 573
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 W LWD TO
15 S FOD.
..MEAD..08/12/26
ATTN...WFO...DMX...OAX...FSD...LBF...GID...
STATUS REPORT FOR WS 573
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
IAC015-039-049-053-079-091-121-153-159-169-175-181-187-197-
121540-
IA
. IOWA COUNTIES INCLUDED ARE
BOONE CLARKE DALLAS
DECATUR HAMILTON HUMBOLDT
MADISON POLK RINGGOLD
STORY UNION WARREN
WEBSTER WRIGHT
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
MD 1949 CONCERNING SEVERE THUNDERSTORM WATCH 574... FOR NORTHERN AND CENTRAL ILLINOIS INTO WESTERN INDIANA
Mesoscale Discussion 1949
NWS Storm Prediction Center Norman OK
0904 AM CDT Wed Aug 12 2026
Areas affected...northern and central Illinois into western Indiana
Concerning...Severe Thunderstorm Watch 574...
Valid 121404Z - 121600Z
The severe weather threat for Severe Thunderstorm Watch 574
continues.
SUMMARY...Damaging winds with gusts up to 75 mph are expected to
continue with an ongoing bow echo. The severe weather threat may
develop east of the watch area by 1530Z, likely requiring a new
severe thunderstorm watch.
DISCUSSION...The northern extension of an MCS has sustained a bowing
structure over northern IL with an eastward system motion of around
40 kt. An outflow boundary associated with an area of thunderstorms
farther east extends from the vicinity of the bow echo
south-southeast through eastern IL into southwest IN. The presence
of that boundary may result in the MCS turning more to the southeast
over the next hour to two, fueled by a strongly unstable
environment, per the 12Z DVN sounding.
The current DVN VWP is sampling 35-50 kt west-northwesterly winds in
the 1-6 km layer, which are oriented largely perpendicular to the
bow, likely maintaining a robust rear-inflow jet. As such, damaging
winds are expected to continue with gusts up to 75 mph possible as
the system advances toward northwest and west-central IN.
Extrapolation of the current motion takes it to the eastern edge of
the watch by 1530Z, likely requiring an additional watch.
..Mead.. 08/12/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...IWX...IND...LOT...ILX...DVN...
LAT...LON 41909007 41758803 41268700 40498663 40088648 39578665
39578722 39588774 39848855 40268968 40819028 41499046
41909007
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0736 AM CDT Wed Aug 12 2026
Valid 121300Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE
NORTHERN/CENTRAL PLAINS TO THE LOWER OHIO VALLEY...
...SUMMARY...
Scattered severe thunderstorms are possible today through this
evening from parts of the mid Mississippi Valley and lower Ohio
Valley into portions of the central and northern High Plains.
Severe gusts and large hail are the primary hazards.
...IA to OH Valley...
Radar/satellite imagery this morning show several thunderstorm
clusters ongoing from IA into the OH Valley. The most notable
thunderstorm cluster is over far eastern IA and is moving into
central and northern IL this morning. The airmass downstream of
this activity is very moist and extremely unstable [reference the 12
UTC Davenport, IA raob (4300 J/kg MLCAPE)], and it is located near
the terminus of a 35-kt west-southwesterly LLJ over northern MO.
Expecting a gradual intensification of storms this morning across IL
with a risk for scattered severe gusts and associated wind damage.
Considerable uncertainty remains regarding the eventual evolution of
additional storm clusters over parts of the Midwest through this
afternoon. Outflow from morning showers/storms over eastern IN into
central KY will likely inhibit appreciable severe risk farther east
across parts of the OH Valley. Nonetheless, a moist and
destabilizing boundary layer will lend a risk for scattered wind
damage and isolated large hail with the stronger storms through the
late afternoon and evening.
...Northern/Central Plains...
East/southeasterly low-level flow will maintain modest moisture
across the Dakotas, increasing with southward extent across NE into
northern KS. Near-60 F dewpoints will likely spread westward into
eastern CO/WY/MT beneath steep lapse rates. Ample heating will
result in moderate buoyancy and 30+ kt effective shear---supporting
some organization to the scattered thunderstorms forecast to develop
later this afternoon/evening. Initial cells will pose a threat for
large hail and severe gusts. Some clustering may occur during the
evening but confidence remains low regarding specific corridors
where the severe threat will focus.
...Lower MI into NY/PA/NJ...
A belt of stronger northwesterly flow aloft will extend from Lower
MI into NY/PA today. A seasonally moist/unstable airmass will be in
place. Vertically veering wind profiles will foster 35+ kt
effective shear magnitudes, while hodographs are fairly elongated.
Midlevel lapse rates will remain modest, with MLCAPE around
1000-1500 J/kg expected. Isolated to widely scattered storms will
pose a risk for damaging gusts and marginally severe hail.
...TN Valley/Southeast...
Thunderstorms are expected to develop by midday within a very moist
and strongly unstable airmass. Deep-layer northwesterly flow will
remain weak, but steepened 0-2 km lapse rates and high PW (near 2
inches) will support an isolated risk for some stronger water-loaded
downdrafts capable of wind damage.
...Lower CO River Valley...
Model guidance shows widely scattered storms developing this
afternoon near a weak upper trough analyzed this morning via
water-vapor imagery. Some of the stronger thunderstorm downdrafts
may be capable of isolated severe gusts.
..Smith/Kerr.. 08/12/2026
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