259
FXUS63 KIWX 211744
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
144 PM EDT SAT MAR 21 2026
KEY MESSAGES
- THERE IS A 30-60 PERCENT CHANCE OF RAIN ON SUNDAY WITH A FEW
THUNDERSTORMS POSSIBLE SOUTH OF US-24. SEVERE WEATHER IS NOT
EXPECTED.
- HIGHS DROP INTO THE 40S FOR MONDAY BUT SLOWLY CLIMB BACK TO
THE 60S BY THURSDAY.
- DRY CONDITIONS ARE EXPECTED MONDAY THROUGH WEDNESDAY BUT
ADDITIONAL RAIN IS LIKELY ON THURSDAY.
DISCUSSION
ISSUED AT 145 PM EDT SAT MAR 21 2026
MAIN FORECAST CONCERN IS THUNDERSTORM POTENTIAL LATE TOMORROW. A
MIDLEVEL SHORTWAVE IS CURRENTLY ENTERING THE NORTHERN GREAT LAKES
BUT BECOMES INCREASINGLY SHEARED WITH TIME AS THE MID/UPPER LEVEL
FLOW BRIEFLY DAMPENS AND BECOMES MORE ZONAL LATE TONIGHT. THE MOST
NOTABLE ASPECT OF THE SYSTEM AT THIS POINT IS STRONG LOW LEVEL WAA.
LOWS TONIGHT LIKELY REMAIN IN THE 50S GIVEN STEADY SOUTHWEST
WIND/WAA. THIS STRONG W/SW FLOW ADVECTS MODEST SURFACE DEWPOINTS
(MID/UPPER 50S) INTO THE AREA ALONG WITH A NOTABLE EML (MIDLEVEL
LAPSE RATES OVER 8 C/KM). HOWEVER, THIS ALSO RESULTS IN A STRONG
CAPPING INVERSION AROUND 750MB FOR MUCH OF THE DAY. THE TRAILING
SURFACE COLD FRONT THAT CROSSES OUR CWA TOMORROW ARRIVES VERY EARLY,
REACHING THE US-24 CORRIDOR BY 15-16Z. THIS SIGNIFICANTLY LIMITS THE
POTENTIAL FOR SURFACE-BASED DIURNAL DESTABILIZATION AND, OUTSIDE
SOME BROAD LOW LEVEL CONVERGENCE, THIS FRONT DOESN'T HAVE MUCH
AVAILABLE FORCING FOR ASCENT (CERTAINLY NOT ENOUGH TO OVERCOME A
STRONG CAP, AT LEAST UNTIL A SECONDARY SHORTWAVE ARRIVES LATER
TOMORROW EVENING). IN FACT, FORECAST SOUNDINGS SHOW VIRTUALLY NO
OPPORTUNITY FOR SURFACE-BASED CONVECTION WITH A STRONG CAP AHEAD OF
THE FRONT AND SIGNIFICANT 1000-850MB CAA BEHIND THE FRONT. THERE IS
STILL SOME POSTFRONTAL MUCAPE AVAILABLE AS MIDLEVEL LAPSE RATES
REMAIN ON THE HIGH SIDE BUT DEPTH AND STRENGTH OF LOW LEVEL STABLE
LAYER SUGGESTS SMALL HAIL AS THE ONLY POTENTIAL THREAT. BY THE TIME
THE SECONDARY SHORTWAVE ARRIVES AND DIURNAL DESTABILIZATION IS
MAXIMIZED (21-03Z), THE SURFACE FRONT IS ALREADY WELL SE OF OUR AREA.
WILL MAINTAIN A THUNDERSTORM MENTION AND WON'T RULE OUT SOME SMALL
HAIL SOUTH OF US-24 BUT OVERALL THE SEVERE RISK APPEARS VERY LOW.
REST OF THE FORECAST IS RELATIVELY QUIET AS CANADIAN HIGH PRESSURE
SETTLES INTO THE REGION FOR THE MON-WED PERIOD. HIGHS MONDAY DROP
INTO THE 40S WITH 850MB TEMPS NEAR -5C. SLOW BUT STEADY MODERATION
EXPECTED ON TUE WITH WAA REALLY RAMPING UP LATE WED. THIS WILL BE
OUR NEXT CHANCE OF PRECIP, PARTICULARLY INTO THU AS ANOTHER MODEST
WAVE CROSSES THE NORTHERN GREAT LAKES AND SENDS A SHARP COLD FRONT
THROUGH OUR AREA. THIS SYSTEM LOOKS VERY SIMILAR TO SUNDAY WITH
DECENT THETA-E ADVECTION AHEAD OF THE FRONT BUT LACKLUSTER MID/UPPER
LEVEL SUPPORT FOR ASCENT IN OUR AREA. STILL PLENTY OF TIME FOR
ADJUSTMENTS HERE THOUGH.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1225 PM EDT SAT MAR 21 2026
PESKY IFR STRATUS DECK AT KFWA SHOULD MIX OUT HERE SHORTLY WITH
MAINLY VFR TO FOLLOW THIS AFTERNOON INTO SUNDAY MORNING. THERE
HAS ALSO BEEN SOME PATCHES OF MVFR HAZE ACROSS NORTHERN IN SO
FAR TODAY. EXPECTATIONS ARE FOR THIS TO LIFT NORTH BY 19/20Z AS
AS WINDS VEER TO THE SOUTH-SOUTHWEST AND PICK UP A BIT. LLWS
CONDITIONS ARE STILL ANTICIPATED IN ADVANCE OF A COLD FRONT
TONIGHT, WITH FROPA ANTICIPATED AROUND 11/12Z SUN AT KSBN, AND
TOWARD MIDDAY AT KFWA. WINDS WILL TURN NORTHERLY IN IT'S WAKE
WITH FLIGHT CONDITIONS POSSIBLY LOWERING INTO MVFR. ANAFRONTAL
FORCING THEN GENERATES INCREASING CHANCES FOR SHOWERS SUNDAY
AFTERNOON, MAINLY AT KFWA.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON SUNDAY TO 3 PM EDT MONDAY FOR
LMZ043-046.
DISCUSSION...AGD
AVIATION...STEINWEDEL
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