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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

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O'Hare International Airport KORD (Arlington Heights South)
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Tuesday, May 12, 2026

SPC May 12, 2026 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0659 AM CDT Tue May 12 2026

Valid 121300Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
FLORIDA...AND FROM THE UPPER MISSISSIPPI VALLEY INTO KANSAS....

...SUMMARY...
Severe storms will be possible at least on an isolated basis across
parts of the Florida Peninsula today, and potentially from southeast
Kansas into parts of the Great Lakes late this afternoon and early
evening.

...KS to WI...
A progressive shortwave trough is evident on morning water vapor
imagery over MN. This feature will track across the Great Lakes
region through the forecast period, with the associated surface cold
front sagging into parts of the upper MS Valley. The air mass ahead
of the front from WI into IL/MO/KS is initially quite dry with
dewpoints only in the 30s/40s. However, strong southwesterly
low-level winds will lead to slow moistening/destabilization of the
pre-frontal air mass with a narrow corridor of MUCAPE around 500
J/kg expected by late afternoon. Thunderstorm coverage will likely
be sparse and high-based. However, a few strong/severe storms may
form - capable of hail and gusty winds into early evening.

...FL...
A moist and moderately unstable air mass remains in place over the
FL Peninsula today. A well-defined shortwave trough over southern
AL will track eastward today, resulting in sufficient large scale
forcing for scattered afternoon thunderstorms. Low-level winds are
veered, suggesting the most intense cells will be in vicinity of the
east-coast sea-breeze. A few organized multicell or supercell
storms are possible, posing a risk of damaging wind gusts and hail.

..Hart/Wendt.. 05/12/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TSVYjX

SPC May 12, 2026 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1251 AM CDT Tue May 12 2026

Valid 121200Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
FLORIDA PENINSULA AND PARTS OF THE MIDWEST/GREAT LAKES...

...SUMMARY...
Severe storms will be possible at least on an isolated basis across
parts of the Florida Peninsula today, and potentially parts of the
Great Lakes to Lower Missouri Valley and south-central Plains late
this afternoon and early evening.

...Florida Peninsula...
A front will settle southward today in advance of a low-latitude
shortwave trough crossing the northeast Gulf. A moist and
potentially unstable environment will exist during the afternoon,
especially across the central Peninsula where MLCAPE could exceed
1500 J/kg, although early day clouds and convection near/south of
the front leads to some uncertainty regarding destabilization
details. Regardless, storms should steadily increase in coverage and
intensity through late morning into the afternoon, initially across
the north-central Peninsula, maximizing toward the east coast,
although additional storms may move inland from the Gulf.
Strengthening mid/high-level winds will support upwards of 30-40 kt
effective shear and fairly long/semi-straight hodographs, which
could yield some transient supercell structures pending sufficient
destabilization. Damaging winds and hail will be possible at least
on an isolated basis, and a tornado could occur as well,
particularly near the effective front. A greater confidence in
destabilization and the possibility of more sustained
storms/supercells could warrant a Slight Risk upgrade.

...Wisconsin/Lake Michigan to south-central Plains...
A shortwave trough over the Canadian Prairies will dig southeastward
and amplify toward the Upper Great Lakes through this evening, with
a cold front moving southeastward across these regions. Low-level
moisture will be limited near/ahead of the front, but advection may
be sufficient to counteract mixing to allow surface dewpoints to
reach the 50s F by late afternoon/early evening.

In tandem with the strongest forcing for ascent, and in vicinity of
the surface low/front, isolated to widely scattered development is
initially expected, and most probable, late in the afternoon/early
evening across eastern Wisconsin, with additional storms possible
farther southwest near the front across Illinois/Missouri and
potentially into southeast Kansas/northeast Oklahoma. Where storms
develop/sustain, steep lapse rates and strong west-northwesterly
flow aloft could yield some severe storms capable of hail/damaging
wind.

...Western Oregon/southern Washington...
A few stronger storms with gusty winds and/or sub-severe hail could
develop late in the afternoon and evening regionally in advance an
upper-level trough approaching the coastal Pacific Northwest.
Strengthening deep-layer winds and steepening lapse rates could
plausibly yield some stronger storms, although the potential for
sustained/organized severe storms is currently expected to remain
low.

..Guyer/Weinman.. 05/12/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TSVFbs

Monday, May 11, 2026

SPC May 12, 2026 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 PM CDT Mon May 11 2026

Valid 120100Z - 121200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms are not expected tonight.

...Northern Plains into the Upper Midwest...
Along the northern periphery of an expansive upper ridge over the
West, a midlevel trough will continue eastward from the northern
Plains into the upper MS Valley tonight. Ahead of this feature,
isolated to widely scattered high-based thunderstorms are evolving
eastward across northern ND -- in the vicinity of an eastward-moving
surface trough/front. Despite limited buoyancy, a deeply mixed
boundary layer could favor a couple strong wind gusts before the
boundary layer nocturnally cools/stabilizes. See MCD #707 for more
details. Farther east, a strong low-level jet and related warm
advection preceding the midlevel trough will promote isolated
elevated thunderstorms across the upper MS Valley into the upper
Midwest overnight. Weak instability will preclude severe storms.

...Central Gulf Coast and Southeast...
Isolated thunderstorms will spread/develop eastward along an
west/east-oriented diffuse cold front extending from the central
Gulf Coast into northern FL tonight. This activity will remain north
of the moderately unstable air mass over the Gulf. Across parts of
the eastern and southern FL Peninsula, a few thunderstorms will
continue through around 03Z along lingering outflow boundaries.
While locally strong gusts and small hail are possible, the overall
severe threat appears low.

..Weinman/Worster.. 05/12/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TSV5N1

SPC May 11, 2026 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1131 AM CDT Mon May 11 2026

Valid 111630Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE COASTAL
CAROLINAS ITO THE EASTERN FLORIDA PENINSULA...AND ACROSS THE CENTRAL
GULF COAST...

...SUMMARY...
Isolated severe storms with locally damaging wind gusts and hail are
possible this afternoon from the coastal Carolinas into the Florida
Peninsula, and along the central Gulf Coast.

...Synopsis...
Upper pattern across the CONUS this morning consists of western
ridging and eastern troughing. A pair of shortwave troughs are
embedded within the parent trough, one moving through the middle OH
Valley and the other farther south across TX. A convectively
generated vorticity maximum moving across the western Gulf precedes
the TX shortwave. Farther west, a shortwave trough is moving through
the northern periphery of the upper ridging over northern MT and
adjacent southern Saskatchewan.

Recent surface analysis places a low over the eastern NC/SC border
vicinity, with a cold front extending southwestward through the
Southeast and southern AL through the far western Gulf into Deep
South TX. Another low exists farther northwest over southern
Saskatchewan, with a cold front extending south-southwestward from
this low across eastern into south-central MT.

...Eastern SC/Far Southern NC...
Regional radar imagery shows isolated thunderstorms currently
ongoing near the surface low over the eastern NC/SC border vicinity.
A modest increase in buoyancy is anticipated ahead of these storms
over the next few hours. This buoyancy coupled with strong shear
could result in a few bowing segments capable of damaging gusts.
Additional isolated thunderstorm development is anticipated late
this afternoon as the weak cold front moves eastward across SC.
Moderate buoyancy and shear will support the potential for a few
more robust/organized updrafts capable of isolated hail and/or
damaging gusts.

...Eastern FL...
Warm/moist conditions are expected today over the FL Peninsula, with
temperatures over the interior warming into the 90s. Deep westerly
flow will focus convergence along the east-coast sea-breeze, leading
to scattered afternoon thunderstorms. Sufficient deep-layer vertical
shear may result in isolated strong-severe storms producing
gusty/damaging winds and hail.

...Northern/eastern ND into eastern SD...
Despite limited low-level moisture, modest buoyancy may develop late
this afternoon/early this evening amid cooling mid-level
temperatures and increasing mid-level moisture. This buoyancy will
develop atop a deeply mixed boundary layer, supporting the potential
for strong gusts if any updrafts can deepen/mature. Given the weak
and elevated nature of the buoyancy, developing a mature updraft
capable of lightning will be difficult and the current expectation
is for most of this activity to be shallow and non-lightning
producing. That being said, gusty surface winds are possible with
any convection does develop atop the deeply mixed boundary layer.

...Coastal LA/MS/AL...
The convectively generated shortwave trough over the western Gulf
mentioned in the synopsis (and associated surface low) are expected
to progress eastward throughout the day, while the stronger
shortwave trough back across TX also progress east-southeastward.
Easterly/southeasterly low-level flow will be maintained north of
the Gulf low, increasing low-level convergence along the slow-moving
frontal zone. This convergence will be augmented by ascent attendant
to the TX shortwave, with numerous showers and thunderstorms likely.
Poor lapse rates will limit buoyancy, although moderate deep-layer
shear could support a few deeper, more organized updrafts. Primary
risk over this area is heavy rain (as noted in the WPC Day 1
Excessive Rainfall Outlook), but a few water-loaded downbursts
capable of wind damage are possible as well.

..Mosier/Chalmers.. 05/11/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TSTw1b
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