052
FXUS63 KIWX 280213
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1013 PM EDT MON JUL 27 2026
KEY MESSAGES
- WIDELY SCATTERED TO SCATTERED SHOWERS MAY IMPACT AREAS LATE
THIS EVENING INTO THE OVERNIGHT HOURS THAT MISSED OUT ON
EARLIER STORMS. HEAVY RAIN WOULD BE THE MAIN CONCERN, WITH
SEVERE WEATHER NOT EXPECTED.
- HIGH SWIM RISK TUESDAY FOR SOUTHEAST LAKE MICHIGAN BEACHES.
UPDATE
ISSUED AT 1012 PM EDT MON JUL 27 2026
THE SEVERE THREAT HAS GREATLY DIMINISHED IN THE WAKE OF THE
AFTERNOON AND EARLY EVENING STORMS, ESPECIALLY SOUTHWEST OF A
BENTON HARBOR TO JAY COUNTY LINE. NE OF THIS AREA LOSS OF
DAYTIME HEATING HAS REDUCED THE OVERALL INSTABILITY AS WELL.
THAT BEING SAID, A WEAK DISTURBANCE WAS CAUSING WIDELY SCATTERED
SHOWERS AND STORMS FROM NW OF CHICAGO TO SOUTH HAVEN WITH
SOMEWHAT OF AN INCREASE FOR POINTS TO THE NE. THE STORM BY SOUTH
HAVEN IS ON THE STRONGER SIDE, BUT NOT LIKELY TO PRODUCE MUCH
MORE THAN SOME GUSTY WINDS AND MAYBE SMALL HAIL. SOME CAMS
SUGGEST AN UPTICK IN SHOWER/STORM COVERAGE OVER THE NEXT SEVERAL
HOURS MAINLY FOR NE PARTS OF THE FORECAST AREA. CONFIDENCE IS ON
THE LOWER SIDE FOR THIS TO OCCUR, BUT GIVEN THE UPSTREAM
CONVECTION IS HOLDING ITS OWN AND THE LLJ WILL RAMP UP SOMEWHAT
AT LEAST SCATTERED CONVECTION SEEMS PLAUSIBLE. HAVE CLEANED UP
POPS QUITE A BIT AND TENDED TO LIMIT CHC POPS TO THE NE AREAS
INTO THE OVERNIGHT HOURS.
DISCUSSION
ISSUED AT 255 PM EDT MON JUL 27 2026
THE MAIN FORECAST CONCERN WILL BE ON THE SEVERE WEATHER POTENTIAL
THROUGH THIS EVENING.
A COMPLICATED CONVECTIVE SCENARIO IS UNFOLDING ACROSS THE GREAT
LAKES REGION THIS AFTERNOON. PREFERRED REGION OF CONVECTIVE
DEVELOPMENT HAS BEEN ACROSS NORTHEAST ILLINOIS ALONG A CORRIDOR
OF LOW LEVEL WARM/MOIST ADVECTION. THIS FORCING IS COINCIDENT
WITH STRENGTHENING UPPER LOW LEVEL FLOW AND EFFECTIVE SHEAR
PROFILES. EXTREME INSTABILITY WITH MLCAPES 4-5K J/KG CAPES IS
SITUATED ACROSS NORTHEAST INDIANA WITH SHARP EASTWARD
DIMINISHMENT IN INSTABILITY ACROSS NORTHEAST INDIANA/NORTHWEST
OHIO. CELLS ACROSS NORTHEAST ILLINOIS ARE FAVORING STRONG COLD
POOLS WITH SIGNATURES OF VERY STRONG BASE VELOCITY SHIFTING
SOUTHEAST ACROSS FAR NORTHWEST INDIANA. THE COMBINATION OF
SHALLOW LOW LEVEL SOUTHWEST FLOW AND DEEPER NORTHWESTERLY FLOW
IN THE MID/UPPER LEVELS IS FAVOR SOME NORTH TO SOUTH PREFERENCE
IN PROPAGATION VECTORS WITH THE STORMS ACROSS NORTHEAST
ILLINOIS. AREAS WEST OF US ROUTE 31 ACROSS NORTHEAST INDIANA
SHOULD STAND GREATEST RISK OF SEEING HIGHER END THUNDERSTORM
WIND GUSTS (80+ MPH) AS THE STORMS ACROSS NE ILLINOIS DROP
SOUTHEAST. IN ADDITION TO THE RISK OF HIGHER END DAMAGING WIND
GUSTS, THE EXTREME INSTABILITY WILL SUPPORT SOME ISOLATED LARGE
HAIL OF 1 TO 2 INCHES IN DIAMETER. ALSO, THE AFOREMENTIONED
BACKGROUND SHEAR PROFILES WILL CONTINUE TO SUPPORT SOME EMBEDDED
SUPERCELL STRUCTURES WITH A RISK OF ISOLATED TORNADOES. 0-3KM
SHEAR VECTORS ORIENTED FROM THE NORTHWEST AT AROUND 30 KNOTS
COULD ALSO SUPPORT A FEW QLCS TORNADO SPINUPS WHERE ANY REAR
INFLOW JET CAN ORIENT IN A NW TO SE FASHION AND WHERE MORE
MATURE COLD POOLS DEVELOP.
ADDITIONAL STORMS ARE EXPECTED TO DEVELOP ACROSS THE GREAT LAKES
REGION THIS EVENING AS LOW LEVEL FRONT PUSHES SOUTHWARD WITH AN
ADDITIONAL RISK OF SCATTERED DAMAGING WIND GUSTS THROUGH AROUND 02Z.
CONFIDENCE IN SEVERE GUSTS AFTER 00Z DOES DIMINISH SOMEWHAT HOWEVER.
BY TUESDAY MORNING, THE NOSE OF THE UPPER LEVEL JET STREAK WILL
REACH THE MID ATLANTIC STATES WITH LAGGING SFC TROUGH/COOL FRONT
EXPECTED TO EXTEND FROM WESTERN PA TO SOUTHERN ILLINOIS. PASSAGE OF
THIS FRONT WILL LEAD QUIETER WEATHER CONDITIONS THROUGH THE MIDDLE
OF THE WEEK WITH TEMPERATURES/DEW POINTS CLOSER TO SEASONABLE LEVELS.
THE NEXT SYSTEM TO WATCH WILL BE TOWARD END OF THE WORK AS THE
POTENTIAL EXISTS FOR SYNOPTIC WAVE TO BECOME CONVECTIVELY ENHANCED
ACROSS THE DAKOTAS. SOME QUESTION EXISTS AS TO INSTABILITY
MAGNITUDES AS FAR EAST AS SOUTHERN GREAT LAKES/OHIO VALLEY WITH THIS
SYSTEM WITH SOME INDICATIONS OF THIS SYSTEM BECOMING MORE VERTICALLY
STACKED IN NATURE WELL TO THE WEST.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 735 PM EDT MON JUL 27 2026
THE POTENTIAL OF THUNDERSTORMS HAS DIMINISHED ACROSS THE
TERMINALS THIS EVENING. SOME LINGERING LIGHT RAIN SHOULD CLEAR
THE TERMINAL BY 00Z. CANNOT COMPLETELY RULE OUT ISOLATED SHOWERS
LATE THIS EVENING/EARLY OVERNIGHT AS COLD FRONT APPROACHES FROM
THE NORTH, BUT THIS PROBABILITY APPEARS TOO LOW TO INCLUDE WITH
THE 00Z TAFS. SOME POST-FRONTAL STRATUS AND PERHAPS SOME FOG
COULD DEVELOP LATE TONIGHT INTO EARLY TUESDAY MORNING, WITH
GREATER CONFIDENCE IN STRATUS DEVELOPMENT OPPOSED TO FOG.
IFR/MVFR CIGS SHOULD GRADUALLY MIX OUT LATE TOMORROW MORNING
INTO EARLY AFTERNOON WITH NORTHWEST WINDS BECOMING GUSTY TO 15
TO 20 KNOTS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...BEACH HAZARDS STATEMENT THROUGH WEDNESDAY MORNING FOR INZ103.
OH...NONE.
MI...BEACH HAZARDS STATEMENT THROUGH WEDNESDAY MORNING FOR MIZ177-
277.
MARINE...SMALL CRAFT ADVISORY FROM 2 AM TUESDAY TO 2 AM EDT WEDNESDAY
FOR LMZ043-046.
UPDATE...FISHER
DISCUSSION...MARSILI
AVIATION...MARSILI
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