Hail in Indiana, February 19, 2026

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1053 PM CST Wed Feb 18 2026

.KEY MESSAGES...

- There is a 20 to 30% chance for isolated thunderstorms south
  of a Gibson City to Rensselaer line late tonight. IF a storm
  forms it would be capable of producing hail.

- There is a low (5 to 15%) chance for severe thunderstorms on
  Thursday, primarily during the afternoon and early evening
  hours.

- Temperatures will tumble tomorrow night into Friday. A
  rain/snow mix may graze the Illinois and Wisconsin state line.

- Another period of strong winds is expected on Friday, with
  southwesterly wind gusts in excess of 40 mph.

&&

.UPDATE...
Issued at 1008 PM CST Wed Feb 18 2026

Hi-res model guidance over the past several runs continue to
develop isolated thunderstorms overnight tonight near and south
of a Gibson City to Rensselaer line during the ~2-5 AM CST
timeframe coincident with an axis of elevated instability that
lifts into those areas. Given the persistent signal, opted to
introduce 20-30% shower and thunderstorm chances to the
forecast. Confidence in storms initiating remains on the lower
side given rather subtle forcing mechanisms for ascent.
However, if storms do manage to develop they would be capable
of producing hail in addition to lightning.

Looking ahead to tomorrow there has been a noted southward trend
with the track of the surface low compared to previous model
runs. This could support a southward shift in the greater severe
weather threat farther south as well, closer to central IL/IN.
In fact, shower and isolated embedded thunderstorm development
could hold off until late afternoon/early evening for areas
north of I-80. Confidence is not high enough to make big
messaging changes with that just yet though and will let the
overnight shift get one final look at things in case things
trend back north.

Petr

&&

.DISCUSSION...
Issued at 245 PM CST Wed Feb 18 2026

Through Friday:

A stout 990 mb surface low continues to traverse across MN and
the northern Great Lakes which has been generating gusty west-
southwest winds over northern IL and northwest IN. As the core
of the low moves into WI over the next couple of hours winds
should peak with gusts around 45-50 mph especially for areas
along and north of I-88 where a Wind Advisory remains in effect
through 6 PM this evening. In addition to the gusty winds, dew
points have continued to tank behind a dry-line resulting in
15-25% RHs across the area. These conditions are making
conditions very favorable for rapid grass and brush fire spread
which is why the Red Flag Warning has once again been expanded
to include all of northern and northeast IL counties through 8
PM this evening. Regardless if your area is under a Red Flag
Warning any burning should be postponed and extreme caution
should be used when discarding any burning materials until
conditions improve.

Heading into this evening, the gusty winds will subside after
sunset and become light and variable as a lull in the pressure
gradient moves overhead. With the lack of cloud cover,
temperatures will cool rather quickly and dip into mid 30s to
lower 40s which will further improve RHs for tonight. That said,
our attention will turn towards the shortwave trough that is
ejecting out of the Four Corners and into the Central Plains.
The shortwave is expected to be lifting into the mid-Mississippi
Valley by Thursday morning with another surface low forecast to
develop over northern MO that will then lift across eastern IA
and northern IL Thursday afternoon. As the shortwave begins to
enter the Mississippi Valley a couple of subtle impulses look to
break off the wave and drift across IL and IN early Thursday
morning. While moisture locally continues to look limited, a
rather stout EML is forecast to be overhead as these impulses
move through which could be sufficient to kick off some isolated
to widely scattered showers and thunderstorms Thursday morning.
Given that confidence on any shower and/or storm developing in
the morning is low, have opted to largely maintain a dry
forecast for this period aside from some 15-20% POPs east of
I-55 where a plume of slightly better moisture is forecast.
However, if any storms due materialize the 40-50 kts of deep
layer shear and 7-8C/km lapse rates could result in a strong
storm or two capable of hail and maybe some gusty winds.

The better coverage of showers and thunderstorms on Thursday
are expected to develop in the afternoon and evening as the
aforementioned surface low pivots overhead and allows a surge of
moisture to spread into the area. Though exactly how far north
this moisture will get remains a point of uncertainty and
therefore the coverage of storms with northward extent also
remains uncertain. Regardless, an arc of scattered showers and
storms should develop and lift across the southern half to
2/3rds of the area Thursday afternoon. With deep layer shear
still expected to be around 40-50 kts, a few of these storms
could become strong to severe especially south of the US-24. Any
severe storms will be capable of damaging winds and hail with
some possibly even being able to produce tornadoes if sufficient
low-level instability is realized. As a result the Storm
Prediction Center has expanded their marginal (level 1 of 5)
risk across most of northern IL and northwest IN with a sliver
of the slight (level 2 of 5 risk) along US-24.

Showers and storms will quickly move east of the area Thursday
evening as the system's dry slot moves into the region. However,
some precipitation associated with the deformation band on the
backside of the low is forecast to drift across portions of
northern and northwest IL late Thursday night into Friday
morning. With temperatures expected to be quickly cooling behind
the cold front precipitation should transition to snow by
Friday morning. That said, surface temperatures are forecast to
be generally in the lower to mid-30s which should limit overall
snow accumulations to maybe a half inch with the highest amounts
forecast to occur near the IL-WI line. Outside of the
precipitation, winds will also become gusty as the low lifts
into MI with west-northwest gusts around 30-40+ mph expected.
Since the NBM gusts were only around 20-25 mph did opt to
increase them into the 30-35 mph range for now, but suspect our
current forecast is still too low and will need to be adjusted
up closer to the 40-45 mph range with time.

Yack

Friday night Onward:

This weekend, somewhat disorganized upper-level cyclonic flow (with
an embedded orphaned ridge "bubble") will be in place across the
Great Lakes region. With all embedded shortwaves more or less far
from our area on Saturday, relatively benign weather is in store
locally with seasonable highs in the mid to upper 30s, northwesterly
winds of 10 to 15 mph, and partly cloudy skies.

On Sunday, several upper-level shortwaves will merge and dive
southeastward across the Great Lakes. Tumbling 850mb temperatures
toward the minus 10 to minus 12 range will lead to a corresponding
drop in temperatures, with highs only expected to top off near the
freezing mark. Increasing over-water instability will support lake
effect snow showers as well, with predominantly northwesterly flow
favoring northwestern Indiana. Sunday night looks like it'll be
relatively chilly with a continuation of breezy northwesterly winds
and overnight lows in the teens contributing to wind chills falling
toward the single digits.

Lake effect snow may continue into early Monday morning before the
cyclonic shear axis of the upper-level cyclonic flow slides overhead.
Ensemble guidance continues to exhibit a signal for broad quasi-
zonal flow to become reestablished next week allowing for a steady
feed of relatively mild Pacific flow to return to the area.
Accordingly, the expectation is for temperatures to warm into next
week (back into the 40s). Ensemble 24-hour meteograms from the EPS
and GEFS favor the next opportunity for widespread precipitation
materializing sometime toward the end of next week.

Borchardt

&&

.AVIATION /06Z TAFS THROUGH 12Z FRIDAY/...
Issued at 1053 PM CST Wed Feb 18 2026

Forecast concerns include...

Chance of thunderstorms Thursday afternoon/evening.
Ifr/low mvfr cigs possible Thursday.
Ifr, possible lifr cigs, Thursday night.
Chance of snow predawn hours Friday morning.

Overall, no significant changes to the previous forecast.
Scattered showers and a few thunderstorms are expected to
develop over east/central IL overnight and move northeast across
northern IN through mid/late Thursday morning, mainly southeast
of a BMI/IKK/VPZ line. There is increasing confidence with this
area and thus maintained a dry forecast for all the terminals.

Showers and isolated thunderstorms are expected to develop
Thursday afternoon and continue into Thursday evening, lifting
mainly from south to north across the area. While confidence
for prevailing showers is increasing, there remains uncertainty
for thunder coverage, especially across the terminals. Have
maintained prob thunder mention with this forecast, but further
refinement can still be expected.

Cig trends remain uncertain for Thursday and Thursday night.
There remains the potential for ifr/low mvfr cigs Thursday and
this chance appears to be increasing for areas south of the
terminals. A surface low pressure will move across the area
Thursday night and will likely produce low cigs and possibly fog
along its path, which could be near or over the terminals.
There is too much uncertainty at this time and maintained the
previous forecast for mvfr vis/cigs with scattered ifr cigs.

The track of the surface low will also have large impacts on the
wind directions. Light southerly winds will become light and
variable overnight then northeast by daybreak and remain
east/northeast Thursday. If the low passes north of the
terminals, winds will turn southeast then southwest, as is
currently expected. However, a more southern track, as a few
models now show, would maintain northeast winds. Eventually,
winds will turn westerly early Friday morning and steadily
increase mid/late Friday morning. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

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Hazardous Weather Outlook...UPDATED
National Weather Service Chicago/Romeoville IL
942 PM CST Wed Feb 18 2026

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-200345-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
942 PM CST Wed Feb 18 2026 /1042 PM EST Wed Feb 18 2026/

This Hazardous Weather Outlook is for portions of north central
Illinois...northeast Illinois and northwest Indiana.

.DAY ONE...Tonight.

Weather hazards expected...

  Limited Thunderstorm Risk.

DISCUSSION...

Isolated thunderstorms may develop near and south of a Gibson
City, Illinois to Rensselaer, Indiana line late tonight. If storms
develop they would be capable of lightning and small hail.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Thursday...
  Limited Thunderstorm Risk...with an associated:
     Level 2 of 5 Severe Thunderstorm Risk.

DISCUSSION...

Additional thunderstorms may develop during the afternoon and evening on
Thursday, some of which could be strong to severe.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation will not be necessary through tonight.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the northeast at 45 mph.

LMZ740>745-200345-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
942 PM CST Wed Feb 18 2026

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Tonight.

  No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Thursday...
  Hazardous conditions for small craft are likely.
  Limited Thunderstorm Risk...with an associated:
     Level 1 of 5 Severe Thunderstorm Risk.
Friday...
  Gale force winds and hazardous waves are possible.
Friday night through Tuesday...
  Hazardous conditions for small craft are likely.

Petr

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