248
FXUS63 KIWX 130412
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1212 AM EDT MON JUL 13 2026
KEY MESSAGES
- DRY AND TRENDING WARMER THROUGH THE MIDDLE OF THE WEEK.
- HIGHS IN THE UPPER 80S TO MID 90S BY TUESDAY AND WEDNESDAY,
WITH PEAK AFTERNOON HEAT INDICES UP NEAR 100 DEGREES.
- LOW CHANCES (20-30%) FOR SHOWERS AND STORMS RETURN LATE THIS
WEEK INTO NEXT WEEKEND.
DISCUSSION
ISSUED AT 131 PM EDT SUN JUL 12 2026
THE BOUNDARY BETWEEN MORE AND LESS MOIST AIR IS SOUTH OF THE AREA
MEANING WE'RE IN THE DRIER AIR NOW. THIS PERIOD OF DRIER AIR IS
EXPECTED TO CONTINUE THROUGH AT LEAST TUESDAY. BY WEDNESDAY, THE
CENTER OF THE RIDGE SHIFTS WESTWARD AND THE TROUGH ON THE EAST COAST
BUILDS WESTWARD. THE SAME ENERGY THAT'S BEEN AROUND THE REGION THE
LAST FEW DAYS ATTEMPTS COME BACK NORTHWARD LATER WEDNESDAY OR
PERHAPS THURSDAY AS THE GFS SHOWS. IF THE ECMWF IS RIGHT AND WE END
UP DRY DURING THIS PERIOD, IT COULD BE THAT THE NEXT CHANCE FOR RAIN
DOESN'T COME UNTIL THE PATTERN TURNS INTO MORE OF A RIDGE RIDER/MCS
PATTERN BY FRIDAY AND NEXT WEEK END AS THE ECMWF SHOWS AND
EVENTUALLY THE GFS SHOWS. OF COURSE, PINNING DOWN EXACT TIMING OF
POP UP STORMS IS MUCH EASIER IN THE SHORT TO NEAR TERM WHEN
BOUNDARIES (LIKE LAKE BREEZES AND OUTFLOW BOUNDARIES) CAN BE
REALIZED.
HEAT IS THE OTHER QUESTION DURING THIS PERIOD. A LOW LEVEL THETA-E
PLUME ARRIVES MONDAY TO MONDAY NIGHT PROVIDING 850 MB TEMPS THAT ARE
USUALLY CONDUCIVE TO 90 DEGREE HIGH TEMPS. THE MAIN ISSUE WITH
SEEING IF THIS PERIOD IS CONDUCIVE TO HEAT HEADLINES IS TRYING TO
GET MODELS TO REALIZE WHAT MAGNITUDE HUMIDITY WE GET. BECAUSE THIS
AIRMASS IS BEING ADVECTED IN FROM THE NORTHWEST, MOISTURE WILL HAVE
TIME TO MIX WITH DRIER AIR. AT THE SAME TIME, CROP
EVAPOTRANSPIRATION MAY ADD HUMIDITY THAT MODELS MAY BE HAVING A HARD
TIME CAPTURING. IT IS POSSIBLE THAT WE END UP WITH 70F SFC DEW
POINTS AS EARLY AS TUESDAY. THE OTHER QUESTION IS HOW LONG THIS HIGH
HEAT AND HUMIDITY CONTINUES. THERE'S SIGNS OF A BACKDOOR FRONT
PUSHING IN WEDNESDAY NIGHT TO EARLY THURSDAY ALLOWING FOR SOME
COOLING AT THE SURFACE. THE ECMWF BRINGS THIS BACK NORTHWARD AS A
WARM FRONT 48 HOURS EARLIER THAN THE GFS ON EITHER FRIDAY AS OPPOSED
TO SUNDAY. GIVEN THESE UNCERTAINTIES HAVE DECIDED TO HOLD OFF ON
HEAT HEADLINES FOR TUESDAY YET.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1212 AM EDT MON JUL 13 2026
HIGH PRESSURE REMAINS IN CONTROL OVER THE NEXT SEVERAL DAYS WITH
VFR CONDITIONS, LITTLE IN THE WAY OF CLOUD COVER, AND LIGHT
WINDS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...ROLLER
AVIATION...STEINWEDEL
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