648
FXUS63 KIWX 262328
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
728 PM EDT SUN JUL 26 2026
KEY MESSAGES
- LOW CONFIDENCE ON ANY SEVERE THUNDERSTORMS TONIGHT INTO
SUNRISE MONDAY. IF STORMS MAINTAIN STRENGTH INTO OUR AREA,
DAMAGING WIND GUSTS ARE THE PRIMARY HAZARD.
- IMPROVED CONFIDENCE IN SEVERE THUNDERSTORMS MONDAY AFTERNOON
AND EVENING. DAMAGING WIND GUSTS ARE THE PRIMARY HAZARD.
TORNADOES CANNOT BE RULED OUT.
- HOT ON MONDAY WITH HIGHS NEAR 90S AND AN AFTERNOON HEAT INDEX
APPROACH 100 FOR WESTERN NORTHERN INDIANA.
- DANGEROUS WAVES AND CURRENTS EXPECTED ON TUESDAY AT SOUTHEAST
LAKE MICHIGAN BEACHES.
DISCUSSION
ISSUED AT 235 PM EDT SUN JUL 26 2026
FILTERED SUNSHINE THIS AFTERNOON NOW THAT MORNING STRATUS HAS MIXED
OUT; MORE HUMID AS WELL WITH DEW POINTS IN THE LOW-70S. ALL EYES ON
THE UPPER GREAT LAKES THIS AFTERNOON WHERE THUNDERSTORMS ARE
UNDERWAY IN EXTREME NORTHWEST MINNESOTA. AS TO BE EXPECTED, CAMS
THIS MORNING HAVE VARIED WILDLY RUN-TO-RUN REGARDING THE EVOLUTION
OF UPSTREAM STORMS THESE NEXT 24 HOURS. THE GENERAL CONCENSUS
IS THAT EMBEDDED MID-AND-UPPER LEVEL DISTURBANCES PASSING
THROUGH ENERGETIC NORTHWESTERLY FLOW WILL SPARK AFTERNOON AND
EVENING THUNDERSTORMS OVER THE UPPER MIDWEST TODAY. STORMS THEN SPILL
SSE ATOP A STRONG RIDGE IN THE LEE OF THE ROCKIES. THIS TRACK
GENERALLY KEEPS THE MOST ROBUST THUNDERSTORMS OVER WISCONSIN AND
ILLINOIS TONIGHT, BUT THERE ARE INTERMITTENT RUNS THAT SEND A
DECAYING COMPLEX OF STORMS THROUGH WEST-CENTRAL MICHIGAN.
WITH FADING INSTABILITY TONIGHT, WANING BULK SHEAR VALUES, LAGGING
UPPER-LEVEL SUPPORT, AND A WEAKENING RISE/FALL COUPLET ON PRESSURE-
CHANGE PLOTS, THERE IS MEDIUM-HIGH CONFIDENCE THAT UPSTREAM ACTIVITY
WEAKENS AS IT PERHAPS LIMPS INTO TO THE WESTERN- THIRD OF THE
FORECAST AREA AFTER MIDNIGHT. ALTERNATIVELY, IT COULD BE DRY ALL
NIGHT GIVEN THE BEST FORCING IS WELL NORTH. ALSO UNCERTAIN IS
WHETHER OR NOT A SECOND COMPLEX OF STORMS CAN QUICKLY DEVELOP
TONIGHT OVER WI, DRIFTING IN LOCALLY AFTER SUNRISE MONDAY. SOME
CAMS HAVE THESE TWO COMPLEXES COMICALLY CLOSE TO ONE OTHER,
RAISING SIGNIFICANT QUESTIONS ABOUT HOW QUICKLY THE ATMOSPHERE
COULD RECOVER. WE'LL RETAIN SOME POPS MONDAY MORNING TO ACCOUNT
FOR THIS POSSIBILITY, BUT CONFIDENCE IS LOW FOR SEVERE STORMS
TONIGHT THROUGH SUNRISE MONDAY.
MONDAY AFTERNOON AND MONDAY NIGHT IS OUR BEST OPPORTUNITY FOR
SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WIND GUSTS.
AN APPROACHING 50-60 KNOT 500-MB JET DIVES IN BY LATE AFTERNOON,
LIKELY SPARKING STORMS OVER SOUTHERN WI OR CENTRAL MI WHICH
ORGANIZE AND DROP SOUTH THROUGH OUR AREA. SEVERE WEATHER
PARAMETERS REMAIN FAVORABLE, INCLUDING ENHANCED AREAS OF SRH,
INTRODUCING A CHANCE FOR EMBEDDED TORNADOES. ANY MORNING
ACTIVITY WILL DIRECTLY IMPACT HOW THE AFTERNOON EVOLVES, BUT THE
CURRENT TIMING OF 2PM TO 2AM MONDAY APPEARS ON TRACK. HOT ON
MONDAY AS WELL WITH HIGHS NEAR 90, ESPECIALLY IN THE WESTERN
HALF OF NORTHERN IN. AFTERNOON HEAT INDICIES WILL APPROACH 100
DEGREES, BUT THE POSSIBILITY OF CLOUD DEBRIS AND THUNDERSTORMS
LIMITS CONFIDENCE IN ANY HEAT- RELATED HEADLINES.
NOT AS HOT THE REST OF THE WEEK AS TROUGHING AND SURFACE HIGH
PRESSURE SETTLE OVER THE EASTERN GREAT LAKES. HIGH PRESSURE
SOFTENS TOWARD NEXT WEEKEND, INTRODUCING THE CHANCE FOR SHOWERS
AND THUNDERSTORMS.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 726 PM EDT SUN JUL 26 2026
THE AREA IS IN A SORT OF SUPPRESSED (READ: SUBSIDENCE) PATTERN AS A
STRONGER SHORTWAVE DEPARTS TO THE EAST OF THE AREA AND ONLY WEAK
SHORTWAVES ATTEMPT TO ROUND CLOSER TO THE HEIGHT MAX OF THE RIDGE.
IT IS POSSIBLE THAT CONVECTION FORMS OVER THE UPPER MISSISSIPPI
VALLEY FORMS AROUND 6Z AND APPROACHES THE AREA FROM THE
NORTH/NORTHWEST BETWEEN 12 AND 15Z MONDAY WITH AMPLE SHEAR AND
AROUND 1500 J/KG OF MUCAPE. ON THE OTHER HAND, THERE APPEARS TO
BE A LOW PRESSURE SYSTEM THAT APPROACHES DURING THE EARLY
AFTERNOON, MONDAY, AND THAT MAY BE ENOUGH TO SET OFF
THUNDERSTORMS DURING AFTERNOON. AS SUCH, WILL STILL KEEP A
MENTION OF THUNDERSTORMS FOR THE 12Z TIME MONDAY OUT AND THERE
IS A MODEL CAMP FOR AROUND 00Z MONDAY EVENING FOR THUNDERSTORMS,
BUT THAT'S AT THE END OF THIS TAF PERIOD SO WILL LEAVE THAT OUT
AS WELL. ADDITIONALLY, WILL KEEP VFR CONDITIONS IN PLACE WITH
SOUTHWEST WINDS PREVAILING AND SUSTAINED 10+ KTS WINDS DURING
MONDAY AFTERNOON.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...BROWN
AVIATION...ROLLER
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