Severe Thunderstorm Warning 104, NWS Northern Indiana

Area Forecast Discussion
National Weather Service Northern Indiana
615 PM EDT Wed Jul 16 2025

.KEY MESSAGES...

- A line of thunderstorms will track east into areas mainly
  along and west of Interstate 69 this evening. Isolated strong
  to severe storms with damaging winds and torrential downpours
  the primary threats.

- Brief return of less humid conditions Thursday/Friday behind a
  cold front.

- A Beach Hazards Statement is in effect for southern Michigan
  beaches on Thursday. Waves of 4 to 6 feet will create
  dangerous currents.

&&

.UPDATE...
Issued at 613 PM EDT Wed Jul 16 2025

SVR Watch 520 has been issued for areas mainly west of I-69 this
evening given sporadic upstream reports of severe wind gusts
associated with a primarily outflow dominant linear segment now
entering our far west. DCAPE and associated muggy air mass the
driver for this activity in spite of meager shear profiles and
better forcing lagging near a MCV and sfc reflection in
Wisconsin. No changes to the forecast otherwise as convection
tends to diminish in coverage and intensity once reaching the
I-69 corridor and east.

&&

.DISCUSSION...
Issued at 113 PM EDT Wed Jul 16 2025

With a very humid and hot airmass over the area today, scattered
pop up showers and thunderstorms have developed. Main threats
with these storms is brief heavy downpours, gusty outflow winds,
and of course lightning. Even with PWATs around 2", the fairly
quick northeasterly movement of the storms has minimized any
localized flooding or ponding issues.

Outside of these pop up storms this afternoon the focus then
becomes the development of convection along a north to south
orientated cold front over western IL/WI that will move
eastward this evening. The time of arrival for this boundary
into our western and northeastern parts of the CWA is around 6PM
CDT/7PM EDT. This is early enough in the diurnal period that
any storms forming over IL could certainly maintain their
strength into our western and northwestern areas of the CWA.
Also, the latest guidance suggests bulk shear values of 25-40
kts for mainly over southern Lake Michigan and southwestern MI
with the frontal boundary which will allow for some continued
organization. The main threats with any of the strong to severe
storms would be the associated winds. An isolated tornado would
not be out of the question with these storms along the boundary
as SR Helicity values of 50-100 m2/s2 will also be available.

This frontal boundary will continue to move eastward through
the rest of the CWA through about 06z Thursday morning keeping
increased chances of showers and thunderstorms along and ahead
of the front, however with the loss of the diurnal heating
storms should remain on the weaker side.

In the wake of the cool front, drier and cooler airmass will
advect into the area for Thursday and Friday. There will still
be the potential each afternoon for pop up thunderstorms with
the increased vertical instability. Surface dew points will go
from low to mid 70s today to the low 60s to upper 50s by
Thursday evening. And highs for Thursday and Friday will only be
in the upper 70s to low 80s. This will make for much more
comfortable conditions. Unfortunately, this relief will be
somewhat short- lived as a southeastern ridge squeezes some
moisture and warmer temperatures northward against a zonal flow
that will be centered over our heads. This will allow for
surface dew points to jump into the low to mid 70s by Saturday
afternoon. High temperatures will luckily be somewhat restrained
by the fact that the thermal gradient will mainly remain stable
due to the flat zonal flow present over the area. The bad news
is that this broad southeastern CONUS ridging does ultimately
push northward by Tuesday. This will allow for much hotter
temperatures along with the humid airmass to stream northward
over the region with highs on Tuesday in the upper 80s to lower
90s and warmer yet on Wednesday and beyond with high
temperatures in the low to mid 90s.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 613 PM EDT Wed Jul 16 2025

Line of convection will move through KSBN at the start of the
period (23-00z), with a period of LIFR/IFR and strong wind
gusts. This activity will likely begin to weaken a bit once
reaching KFWA around 01-02z, but still could create some brief
restrictions and gusty winds. VFR otherwise before a post-
frontal MVFR cloud deck wraps in overnight at KSBN, and toward
daybreak at KFWA with northwest winds near 10 knots into the day
on Thursday.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Air Quality Alert until 4 AM CDT Thursday for INZ103-203.
     Beach Hazards Statement from 4 AM CDT Thursday through late
     Thursday night for INZ103.
OH...None.
MI...Air Quality Alert until 5 AM EDT Thursday for MIZ078-177-277.
     Beach Hazards Statement from 5 AM EDT Thursday through late
     Thursday night for MIZ177-277.
MARINE...Small Craft Advisory from 5 AM Thursday to 2 AM EDT Friday for
     LMZ043-046.

&&

UPDATE...Steinwedel
DISCUSSION...Andersen
AVIATION...Steinwedel

Hazardous Weather Outlook
National Weather Service Northern Indiana
342 PM EDT Wed Jul 16 2025

INZ005>009-012>015-017-018-020-022>027-032>034-104-116-203-204-216-
MIZ078>081-OHZ001-002-004-005-015-016-024-025-171945-
Elkhart-Lagrange-Steuben-Noble-De Kalb-Starke-Pulaski-Marshall-
Fulton IN-Whitley-Allen IN-White-Cass IN-Miami-Wabash-Huntington-
Wells-Adams-Grant-Blackford-Jay-Eastern St. Joseph IN-
Northern Kosciusko-Southern La Porte-Western St. Joseph IN-
Southern Kosciusko-Cass MI-St. Joseph MI-Branch-Hillsdale-Williams-
Fulton OH-Defiance-Henry-Paulding-Putnam-Van Wert-Allen OH-
342 PM EDT Wed Jul 16 2025 /242 PM CDT Wed Jul 16 2025/

This Hazardous Weather Outlook is for northern Indiana, southwest
Michigan and northwest Ohio.

.DAY ONE...This afternoon and tonight.

Scattered thunderstorms are expected through this evening. A few
storms may produce damaging winds this evening, best chances north of
US 24 in Indiana and Michigan.

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

Periodic chances of thunderstorms are anticipated for Saturday into
the early parts of next week. A few periods of stronger storms are
possible, but confidence in the details of timing and the extent of
any severe weather threat is low at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this evening.

INZ103-MIZ177-277-171945-
Northern La Porte-Northern Berrien-Southern Berrien-
342 PM EDT Wed Jul 16 2025 /242 PM CDT Wed Jul 16 2025/

...BEACH HAZARDS STATEMENT IN EFFECT FROM LATE TONIGHT THROUGH LATE
THURSDAY NIGHT...

This Hazardous Weather Outlook is for northern Indiana and
southwest Michigan.

.DAY ONE...This afternoon and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Beach Hazards Statement.

Scattered thunderstorms are expected through this evening. A few
storms may produce damaging winds this evening.

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

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Beach Hazards Statement.

Periodic chances of thunderstorms are anticipated for Saturday into
the early parts of next week. A few periods of stronger storms are
possible, but confidence in the details of timing and the extent of
any severe weather threat is low at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this evening.

LMZ043-046-171945-
New Buffalo MI to St Joseph MI-Michigan City IN to New Buffalo MI-
342 PM EDT Wed Jul 16 2025

...SMALL CRAFT ADVISORY IN EFFECT FROM 5 AM THURSDAY TO 2 AM EDT
FRIDAY...

This Hazardous Weather Outlook is for the nearshore waters of
southeastern Lake Michigan.

.DAY ONE...This afternoon and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Small Craft Advisory.

Thunderstorms this evening will be capable of producing wind gusts in
excess of 35 knots.

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

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Small Craft Advisory.

There are periodic chances of thunderstorms for Saturday through the
early parts of next week.

Special Weather Statement
National Weather Service Northern Indiana
636 PM EDT Wed Jul 16 2025

INZ014-162315-
Marshall IN-
636 PM EDT Wed Jul 16 2025

...A STRONG THUNDERSTORM WILL IMPACT MARSHALL COUNTY THROUGH 715 PM
EDT...

At 635 PM EDT, Doppler radar was tracking a strong thunderstorm near
Hamlet, or near Knox, moving east at 30 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Plymouth, Bremen, Bourbon, Argos, Culver, Koontz Lake, La Paz, Twin
Lakes, Inwood, Rutland, Burr Oak, Maxinkuckee, Tyner, Hibbard, Old
Tip Town, Donaldson, Linkville, and Lake Of The Woods.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until midnight EDT for
north central and northwestern Indiana.

&&

LAT...LON 4144 8647 4148 8606 4122 8606 4118 8647
TIME...MOT...LOC 2235Z 270DEG 24KT 4131 8650

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

NWS

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