075
FXUS63 KIWX 201026
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
626 AM EDT MON JUL 20 2026
KEY MESSAGES
- SMOKE FROM CANADIAN WILDFIRES WILL CONTINUE TO BRING PERIODS
OF POOR AIR QUALITY AND REDUCED VISIBILITY THROUGH AT LEAST
TODAY.
- THERE IS A 30-60% CHANCE OF THUNDERSTORMS TONIGHT WITH A COLD
FRONT MOVING INTO THE AREA. STORMS MAY BECOME STRONG TO
SEVERE. CONFIDENCE IN SEVERE WEATHER OCCURRING IS LOW. STORMS
MAY REDEVELOP TUESDAY.
DISCUSSION
ISSUED AT 322 AM EDT MON JUL 20 2026
TODAY WILL MAINLY BE DRY WITH AN INCREASE IN SOUTHERLY FLOW
AHEAD WELL ADVERTISED SHORTWAVE DISTURBANCE PUSHING
SOUTHEASTERLY WITH THE CYCLONIC FLOW ON THE EASTERN PERIPHERY OF
THE BROAD RIDGING OVER THE CENTRAL CONUS. A COLD FRONT
ASSOCIATED WITH THIS DISTURBANCE IS STILL PROGGED TO DROP
THROUGH THE AREA LATER TONIGHT WITH STILL SOME UNCERTAINTY ON
THE EXACT TIMING AND STRENGTH OF THE STORMS AS THEY PUSH INTO
THE NORTHWESTERN PORTIONS OF THE CWA. STILL LOOKING LIKE AROUND
10 PM EDT FOR THE FRONT TO ARRIVE INTO THE AREA BUT SOME
ISOLATED STORMS COULD DEVELOP JUST AHEAD OF THE FRONT A LITTLE
EARLIER THAN THAT TIME. A FORECASTED 125 KT 200 MB JET MAX WILL
PUSH THROUGH THE REGION LATER TONIGHT HELPING BOLSTER THE
DYNAMICS WITH THE STORMS THAT DEVELOP ACROSS NORTHERN IL AND WI
LATER TODAY AND THIS COULD HELP TO KEEP STORMS A BIT STRONGER AS
THEY PUSH INTO OUR AREA. BUT, THERE WILL BE A LOSS OF MOST OF
THE AVAILABLE SURFACE INSTABILITY WITH THE ARRIVAL BEING WELL
AFTER SUNSET. MID LEVEL LAPSE RATES AROUND 7-8 DEG/KM THOUGH MAY
HELP TO KEEP CONVECTION MORE ELEVATED. BULK SHEAR VALUES OF
ONLY AROUND 25 TO 30 KTS ALSO DOES KEEP STORMS LESS ORGANIZED AT
THAT TIME. SO QUESTIONS ON HOW INTENSE STORMS WILL BE ONCE THEY
ARRIVE STILL EXIST. THE SAME TIMING DILEMMA ALSO BRINGS
CONFIDENCE LOWER FOR ANY STORMS ALONG THE FRONTAL BOUNDARY
TUESDAY LATE MORNING INTO THE AFTERNOON. THE BETTER CHANCES DO
SEEM TO BE THE FAR SOUTHEASTERN PORTIONS OF THE CWA WITH BETTER
DIURNAL WARMING AVAILABLE IN THOSE AREAS. SPC STILL DOES HAVE
PARTS OF OUR AREA WITHIN A SLIGHT RISK FOR STORMS TONIGHT AND
TUESDAY. SHOWERS AND THUNDERSTORMS SEEM LIKE A GOOD BET ACROSS
OUR AREA WITH THIS SYSTEM BUT AGAIN THE STRENGTH OF THE STORMS
WILL BE QUESTIONABLE.
IN THE WAKE OF THE COLD FRONT LATE TUESDAY A COOLER AND DRIER
AIRMASS WILL PUSH INTO THE AREA WITH A NORTHWESTERLY FLOW ALOFT
THROUGH FRIDAY. THIS KEEPS TEMPERATURES COOLER WITH HIGHS
RANGING IN THE 70S FOR WEDNESDAY THROUGH FRIDAY WITH A FEW LOWER
80S SPRINKLING IN ON FRIDAY. UPPER FLOW SMOKE INTRUSION IS
LIKELY TO RETURN WITH THE NORTHWESTERLY FLOW ALOFT AND IN THE
OVERNIGHT PERIODS MAY MAKE IT'S WAY CLOSER TO THE SURFACE SO
WILL NEED TO WATCH FOR THAT. RIDGING OVER THE CENTRAL CONUS
BEGINS TO PUSH EASTWARD INTO THE REGION SO WILL SEE A WARMING
TREND THIS WEEKEND WITH HIGHS IN THE MID TO UPPER 80S INTO THE
BEGINNING OF NEXT WEEK WHEN THE NEXT CHANCES FOR PRECIPITATION
LOOK TO INCREASE.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 617 AM EDT MON JUL 20 2026
MVFR VSBYS FOR KSBN THROUGH 14Z MON DUE TO SMOKE AND MIST.
OTHERWISE, VFR CONDITIONS ARE EXPECTED FOR BOTH SITES THROUGH
04-05Z TUE FOR KSBN AND AROUND 07-08Z TUE WHEN AFTER THESE TIME
PERIODS A COLD FRONTAL PASSAGE WILL BRING SHOWERS/THUNDERSTORMS
AND POSSIBLE MVFR VSBYS IN -TSRA AND MIST ESPECIALLY FOR KSBN.
LIGHT AND VARIABLE WINDS BECOMING SOUTHERLY AND INCREASING TO
AROUND 10 TO 12 KTS AFTER 14Z MON AHEAD OF THE COLD FRONTAL
PASSAGE. CONFIDENCE ON EXACT TIMING AND INTENSITY OF
THUNDERSTORMS IS LOW AT THIS TIME, BUT GUSTY OUTFLOW WINDS AHEAD
OF AND WITHIN THUNDERSTORMS WILL BE POSSIBLE.
IWX WATCHES/WARNINGS/ADVISORIES
IN...AIR QUALITY ALERT UNTIL MIDNIGHT EDT /11 PM CDT/ TONIGHT 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 TONIGHT FOR MIZ078>081-
177-277.
MARINE...NONE.
DISCUSSION...ANDERSEN
AVIATION...ANDERSEN
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