WW 582 SEVERE TSTM IL IN 131730Z - 140000Z
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 582
NWS Storm Prediction Center Norman OK
1230 PM CDT Thu Aug 13 2026
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
East Central and Northeast Illinois
Western Indiana
* Effective this Thursday afternoon and evening from 1230 PM
until 700 PM CDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Isolated large hail events to 1 inch in diameter possible
A tornado or two possible
SUMMARY...A cluster of storms may continue to intensify and organize
as it progresses east-southeastward across the region this
afternoon, with damaging winds as the primary hazard.
The severe thunderstorm watch area is approximately along and 55
statute miles north and south of a line from 20 miles west of
Bloomington IL to 25 miles east northeast of Danville IL. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU2).
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.
&&
AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few
cumulonimbi with maximum tops to 600. Mean storm motion vector
28025.
...Guyer
WW 0582 Status Updates
STATUS REPORT ON WW 582
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 S DEC TO
10 SSW CMI TO 15 NNE CMI TO 15 NE LAF.
..JEWELL..08/13/26
ATTN...WFO...ILX...LOT...IND...
STATUS REPORT FOR WS 582
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
ILC019-029-041-045-139-183-132040-
IL
. ILLINOIS COUNTIES INCLUDED ARE
CHAMPAIGN COLES DOUGLAS
EDGAR MOULTRIE VERMILION
INC011-021-023-045-063-107-119-121-133-157-165-167-171-132040-
IN
. INDIANA COUNTIES INCLUDED ARE
BOONE CLAY CLINTON
FOUNTAIN HENDRICKS MONTGOMERY
OWEN PARKE PUTNAM
TIPPECANOE VERMILLION VIGO
WARREN
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 1971 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF THE CENTRAL HIGH PLAINS
Mesoscale Discussion 1971
NWS Storm Prediction Center Norman OK
0341 PM CDT Thu Aug 13 2026
Areas affected...portions of the central High Plains
Concerning...Severe potential...Watch unlikely
Valid 132041Z - 132245Z
Probability of Watch Issuance...20 percent
SUMMARY...Thunderstorms developing along the Front Range will evolve
eastward through this evening, bringing a risk for isolated severe
wind gusts and large hail.
DISCUSSION...Latest surface analysis depicts a cold front
approaching the Front Range across portions of the central High
Plains. Easterly, upslope flow within the post-frontal air mass is
aiding in the westerly advection of richer low-level moisture
(low-to-mid 60s F surface dewpoints). As thunderstorms developing
along the Front Range evolve eastward and encounter this greater
moisture and buoyancy, at least some increase in the severe risk is
expected. Modest effective shear of 20-30 kts (indicated by recent
mesoanalysis) and cold pool consolidation should primarily favor a
multicellular/cluster storm mode, with damaging/severe wind gusts
the primary hazard owing to steep low-level lapse rates. Isolated
large hail may also accompany any more robust updrafts given the
presence of steeper mid-level lapse rates. Watch issuance appears
unlikely at this time owing to the expectation for the severe risk
to remain generally limited in coverage and magnitude.
..Chalmers/Guyer.. 08/13/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LBF...DDC...GLD...PUB...BOU...CYS...
LAT...LON 37210193 37050220 37040264 37050416 37240444 38040490
39920551 40680555 41220549 41690514 41960480 42040402
41890328 41510255 40390190 38780177 37770183 37210193
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Thu Aug 13 2026
Valid 132000Z - 141200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE MIDWEST INTO THE OHIO VALLEY...
...SUMMARY...
Isolated to scattered severe thunderstorms remain possible today
from parts of the southern/central High Plains to the Midwest.
Severe wind gusts should be the main threat, but some hail may also
occur.
...20Z Update...
The main change made to the 20Z Day 1 Convective Outlook Update was
to add 5 percent hail probabilities across portions of central NV
given modestly cold temperatures aloft and accompanying 7.5-8 C/km
mid-level lapse rates. There were considerations to trim or remove
the Slight Risk across portions of the Midwest behind the ongoing
cluster of thunderstorms. However, recovery along a residual
baroclinic boundary, overspread by 2000+ J/kg MLCAPE and 40+ kts of
effective bulks shear, may support additional storm development
later this evening when the LLJ intensifies. Otherwise, the previous
forecast remains on track, with only minor changes made to ongoing
thunder and severe probabilities to account for the latest guidance
consensus.
..Squitieri.. 08/13/2026
.PREV DISCUSSION... /ISSUED 1132 AM CDT Thu Aug 13 2026/
...Midwest including parts of eastern Iowa and Illinois/Indiana...
Supported by an MCV, a long-lived MCS continues to move
east-southeastward into west-central/northwest Illinois late this
morning. Greater stability initially precedes the MCS across
northern Illinois, but the remnant cluster and additional
redevelopment will likely tend to favor a more southeastward
progression in closer proximity to the front/instability gradient
that extends across Illinois/Indiana, with additional/renewed
development and intensification possible into the afternoon and
evening. Damaging wind gusts will be the primary severe hazard,
although a brief tornado and marginally severe hail are also
possible into this evening. While not certain, additional severe
redevelopment may also occur tonight farther west/northeastward
across areas potentially including eastern Iowa and northern/central
Illinois as a low-level jet nocturnally increases.
...Southern/Central High Plains...
High-based thunderstorms are expected to initially develop over the
higher terrain of the central Rockies/Front Range this afternoon,
with post-frontal low-level upslope flow persisting across the
central High Plains. Storm motions into slightly richer moisture
will favor some aggregation of outflow within a hot boundary layer
featuring steep lapse rates. Isolated to widely scattered severe
wind gusts 60-75 mph are possible, along with occasional hail with a
few of the stronger cores.
...Great Basin...
Modestly enhanced southwesterly mid-level flow will persist today
across the Great Basin downstream of a weak mid-level trough over
California. Weak to locally moderate instability is forecast via
diurnal heating. Scattered to numerous thunderstorms are expected
and some of the stronger evaporatively cooled downdrafts will be
capable of 60-75 mph gusts.
...Northeast...
Seasonably cool mid-level temperatures are forecast today across
parts of the Northeast, with a mid-level trough expected to move
east-southeastward from Quebec into New England. While instability
is forecast to remain fairly limited, strong west-northwesterly flow
aloft may support a risk for isolated damaging winds (50-65 mph)
with thunderstorms that develop and spread southeastward through the
afternoon. Isolated hail may also occur with the stronger cells.
SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0237 PM CDT Thu Aug 13 2026
Valid 151200Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
HIGH PLAINS INTO THE MIDWEST...PARTS OF THE OHIO VALLEY...AND
SOUTHERN APPALACHIANS...
...SUMMARY...
Strong to locally severe storms are possible on Saturday from the
central High Plains eastward into parts of the Midwest, Ohio Valley,
southern/central Appalachians, and Carolinas.
...Central High Plains eastward into parts of the Midwest/Ohio
Valley...
Two MCV features are forecast with one within the central Plains and
another near southern Lake Michigan early on Saturday. These MCVs
will interact with a moist airmass north of surface boundary. While
the MCV moving into the Mid-Missouri Valley be moving into areas
that will have been affected by the lead MCV. Destabilization during
the afternoon in Iowa/Illinois is not certain, but a few strong to
marginally severe storms could develop.
Depending on the evolution/track of the lead MCV, destabilization
within parts of the Ohio Valley appear more probable. The main
questions continue to be early precipitation/cloud cover and where
the MCV will track relative to the greater buoyancy. A corridor of
greater severe potential could develop in parts of eastern Indiana
into Ohio, though confidence is still low at this time.
...Colorado Front Range...
A moist airmass will remain near the higher terrain. Scattered
convection is again possible from the Front Range into parts of the
adjacent Plains. Deep-layer shear will still not be very strong.
While convection may be somewhat disorganized, the strongest storms
could produce hail and isolated severe winds.
...Southern Appalachians...
Given the moist airmass, scattered storm development within the
higher terrain is possible. Modest northwesterly flow aloft may
allow a few strong to marginally severe storms to move off of the
terrain and pose a threat of wind damage.
..Wendt.. 08/13/2026
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0225 PM CDT Thu Aug 13 2026
Valid 141200Z - 151200Z
No changes were made to the drawn areas. Consideration was given to
extending the Isolated Dry Thunder area further north along the
eastern side of the Cascades. However, given the slightly more moist
environment, slower storm motions, and resultant likelihood for
storms to remain anchored over high terrain, an expansion was
decided against. Over the southern Plains, model consensus is
trending the driest conditions slightly farther north/east. If this
trend continues, a slight reduction in the southwestern extent of
the current Elevated area may be necessary. The limiting factor is
whether or not RHs will drop low enough during peak heating, which
is contingent, at least in part, upon if, how widespread, and how
much rainfall could occur on Day 1/Thursday over the eastern TX
Panhandle.
..Stearns.. 08/13/2026
.PREV DISCUSSION... /ISSUED 1251 AM CDT Thu Aug 13 2026/
...Synopsis...
Troughing will remain along the West Coast while upper ridging will
continue to edge eastward into the Upper Midwest and Deep South for
D2/Friday. This troughing along with monsoon moisture across much of
the West should bring another round of isolated afternoon showers
and thunderstorms to the northwest CA mountains into southwestern
and central OR. Persistent dry and breezy conditions south of a
surface trough and attendant frontal boundary across the central
plains will bring elevated fire weather concerns to portions of the
Southern Plains.
...Southern Plains...
Relentless heat with highs in the lower 100s will result in RH
reductions to 15-20 percent by Friday afternoon. Breezy southerly
winds of 15-20 mph south of a lingering surface trough across the
Central Plains will present an elevated fire weather threat to
portions of northwestern TX and western OK as very dry fuels remain
across the region. A corridor of thunderstorms in proximity to a
diffuse frontal boundary is expected to evolve over the TX/OK
Panhandles and northeastward into southern KS. However, the
sub-cloud boundary layer could be modified by convection on
D1/Thursday, inhibiting the overall threat of additional dry
thunderstorms.
...Northwest California and southwest/central Oregon...
An isolated dry thunderstorm threat exists for portions of
northwestern CA and OR Friday. Upper-level troughing across the West
Coast, monsoon moisture and increasing instability will likely bring
isolated convection back into the mountains of northwestern CA,
Oregon Cascades and central OR. PWATs generally below 0.90" and
faster northeastward thunderstorm trajectories bolstered by a
mid-level wave moving towards the Cascades, will promote limited
rainfall in some locations. Although monsoon moisture will generally
improve fuels over the next several days, ERC values still nearing
the 90th percentile and should promote the potential for new
ignitions Friday.
...Please see www.spc.noaa.gov/fire for graphic product...
SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0500 PM CDT Thu Aug 13 2026
Valid 151200Z - 211200Z
...Synopsis...
The extended forecast period begins with mid-level troughing in
place over the west CONUS coast and broad ridging in place over the
eastern two-thirds of the CONUS. By Day 4/Sunday, ridging builds
back westward over much of the Intermountain West. By Day 5/Monday,
models begin to diverge, though the general consensus is for a
shortwave trough to progress through the flow and impinge on the
northern CA coast that afternoon. However, differences in the
amplitude of this small disturbance will result in some uncertainty
as to the sensible surface weather as it passes overhead. By the
time Day 6/Tuesday arrives, larger uncertainties amongst forecast
guidance are presented with a mid-level trough strengthening near
the Pacific Northwest. On Day 7/Wednesday and Day 8/Thursday, a more
significant mid-level trough is expected to move onshore and
progress across the northwestern quadrant of the CONUS. However,
significant differences remain between forecast guidance as to the
amplitude and speed of this system as it moves eastward.
...Day 3/Saturday through Day 5/Monday...
The aforementioned shortwave trough will provide lift amid
sufficient instability to generate probabilities of isolated morning
and afternoon thunderstorms over portions of central OR on Day
3/Saturday. Precluding this threat are the two days of preceding
thunderstorm activity on Day 1/Thursday and Day 2/Friday. Thus,
additional probabilities may be needed in future outlook cycles if
storms trend drier and/or less-than-forecast precipitation is
received leading up to Day 3/Saturday. Additional chances for
thunderstorms are possible again on Day 4/Sunday and Day 5/Monday
over northern CA and southern/central OR. While the likelihood of
thunderstorm occurrence is currently low and uncertain due to the
nature of the aforementioned pattern evolution, so is the preceding
precipitation accumulation, particularly across portions of central
OR.
...Day 6/Tuesday through Day 7/Wednesday...
There are initial signs of coincident dry and windy conditions over
portions of western/northern Great Basin on Day 6/Tuesday and Day
7/Wednesday. Should the slower end of the forecast guidance spectrum
come to fruition regarding the progression of the aforementioned
mid-level trough early next week, the pattern would support a
tightening surface pressure gradient amid above-normal temperatures,
promoting deep-mixing and gusty southerly flow from central CA
through far southwestern MT for at least a day if not two depending
on the resilience of the ridge centered over the southern High
Plains.
..Stearns.. 08/13/2026
...Please see www.spc.noaa.gov/fire for graphic product...
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