193
FXUS63 KIWX 192357
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
757 PM EDT SUN JUL 19 2026
KEY MESSAGES
- SMOKE FROM CANADIAN WILDFIRES WILL CONTINUE TO BRING PERIODS
OF POOR AIR QUALITY AND REDUCED VISIBILITY THROUGH AT LEAST
MONDAY.
- MODERATE SWIM RISK CONDITIONS ARE EXPECTED THIS EVENING ALONG
LAKE MI BEACHES IN SOUTHERN BERRIEN COUNTY, MI AND LA PORTE
COUNTY, IN. BREAKING WAVES AND CURRENTS ARE EXPECTED.
- THERE IS A 30-60% CHANCE OF THUNDERSTORMS MONDAY NIGHT.
THUNDERSTORMS MAY BE SEVERE. CONFIDENCE IN SEVERE WEATHER
OCCURRING IS LOW. STORMS MAY REDEVELOP TUESDAY.
DISCUSSION
ISSUED AT 145 PM EDT SUN JUL 19 2026
NOT AS HOT TODAY WHICH HAS BEEN A WELCOME CHANGE OF PACE. HIGH
PRESSURE HAS CENTERED OVER EASTERN WISCONSIN BEHIND YESTERDAY'S COLD
FRONT. THE DOWNSIDE IS THE RETURN OF WILDFIRE SMOKE TODAY.
THE PRIMARY PERIOD OF INTEREST IS MONDAY NIGHT THROUGH TUESDAY
EVENING WHEN A TROUGH MOVES THROUGH THE NORTHERN PLAINS AND INTO THE
UPPER GREAT LAKES. THE FORECAST HERE REMAINS RATHER MURKY DESPITE
THE ADVERTISED SLIGHT RISK AREAS FOR SEVERE THUNDERSTORMS. UPPER
LEVEL SUPPORT VIA A 60-70 KNOT 500-MB JET FAILS TO ARRIVE UNTIL VERY
LATE TUESDAY NIGHT. THIS RESULTS IN MARGINAL SHEAR (BUT SHEAR THAT
IMPROVES THROUGH TIME) AND DIMINISHING INSTABILITY WITH THE LOSS OF
DAYTIME HEATING. IN CONTRAST, MID-LEVEL LAPSE RATES AROUND 7.5 C/KM
INDICATES SOME ABILITY TO SUSTAIN CONVECTION. HOWEVER, FORECAST
SOUNDINGS FROM A COUPLE AVAILABLE CAMS SHOW AN ELEVATED MIXED LAYER
KEEPING A LID ON THINGS MOST OF MONDAY NIGHT. ALL TOLD, THE SUM OF
PARTS SUGGESTS UPSTREAM CONVECTION WILL STRUGGLE TO SUSTAIN
SEVERITY INTO OUR FORECAST AREA MONDAY NIGHT. OF COURSE, THIS THEN
RAISES THE QUESTION OF HOW TUESDAY PLAYS OUT. WITH THE UPPER-LEVEL
JET BISECTING OUR AREA BY LATE-MORNING, THE I-69 CORRIDOR COULD BE
THE TARGET FOR SEVERE THUNDERSTORMS. ALTERNATIVELY, DECAYING
CONVECTION (STRATIFORM RAIN) TUESDAY MORNING COULD SQUELCH THE
AFTERNOON RISK OF STORMS. OVERALL, TUESDAY'S SEVERE RISK WILL BE
HIGHLY CONDITIONAL ON HOW MONDAY NIGHT PANS OUT.
COOLER STILL BY WEDNESDAY AS A REINFORCING DOSE OF COOL AIR DESCENDS
FROM CANADA. LOOK FOR HIGHS ONLY IN THE MID-70S AND LOWS IN THE 50S.
BY LATE-WEEK, HIGH PRESSURE SHIFTS EAST AND SOUTHERLY RETURN FLOW
BRINGS HIGHS BACK INTO THE 80S WITH SILENT-10% POPS FRIDAY AND INTO
NEXT WEEKEND AS A COUPLE OF DISTURBANCES PASS TO OUR WEST OR SOUTH.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 747 PM EDT SUN JUL 19 2026
PREDOMINANTLY VFR CONDITIONS AT THE TERMINALS THROUGH THE
PERIOD, WITH POTENTIAL FOR MVFR CONDITIONS THANKS TO LINGERING
WILDFIRE SMOKE. ONGOING LIGHT E-NE FLOW WILL BECOME VARIABLE FOR
TONIGHT, THEN SHIFT TOWARDS THE S-SW ON MONDAY. MOSTLY CLEAR
SKIES AND NEARLY CALM WINDS MAY ALLOW FOR ENOUGH RADIATIONAL
COOLING TO GET BR (BEST CHANCE AT KSBN PER GUIDANCE), OR TO SEE
A FURTHER REDUCTION IN VISIBILITY DUE TO HZ/FU ONCE WE ARE
BENEATH THE NIGHTTIME INVERSION. HAVE A TEMPO AT KSBN FOR 4SM FU
BETWEEN 6-10Z AS CONFIDENCE IS HIGHER THERE THAN AT KFWA (KSBN
IS STILL REPORTING 6SM/HZ AS OF THIS WRITING, AND KFWA IS 7SM).
IWX WATCHES/WARNINGS/ADVISORIES
IN...AIR QUALITY ALERT UNTIL MIDNIGHT EDT /11 PM CDT/ MONDAY NIGHT
FOR INZ005>009-012>015-017-018-020-022>027-032>034-103-
104-116-203-204-216.
OH...NONE.
MI...AIR QUALITY ALERT UNTIL MIDNIGHT EDT MONDAY NIGHT FOR
MIZ078>081-177-277.
MARINE...NONE.
DISCUSSION...BROWN
AVIATION...MCD
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