893
FXUS63 KIWX 191104
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
704 AM EDT SAT JUL 19 2025
KEY MESSAGES
- SHOWERS AND THUNDERSTORM CHANCES WILL INCREASE THIS AFTERNOON
AND EVENING (MAINLY BETWEEN 1 AND 7 PM EDT). SOME OF THE
STORMS MAY BE STRONG TO SEVERE, WITH THE PRIMARY THREATS
DAMAGING WINDS, HEAVY RAIN AND LOCALIZED FLOODING.
- ADDITIONAL SHOWER AND THUNDERSTORM CHANCES EXIST LATER TONIGHT
INTO SUNDAY EVENING, BUT CONFIDENCE IN AREAS MOST LIKELY TO BE
IMPACTED IS LOW AS INFLUENCE OF TODAY'S STORMS AND FINAL
FRONTAL POSITION WILL BE KEY.
- A SIGNIFICANT PERIOD OF DANGEROUS HEAT AND HUMIDITY IS
EXPECTED TO BUILD IN FROM THE MIDDLE TO THE END OF NEXT WEEK,
WITH HEAT INDICES IN EXCESS OF 100 DEGREES ANTICIPATED.
DISCUSSION
ISSUED AT 355 AM EDT SAT JUL 19 2025
SHOWERS AND STORMS HAVE BEEN IMPACTING SOUTHERN MN INTO N WI THE
PAST SEVERAL HOURS. THE MOST ORGANIZED AREA HAS REMAINED FOCUSED
IN SOUTHERN MN WHERE LOW 70 DEWPOINTS ARE FEEDING INTO THE
CLUSTER OF STORMS. MODELS HAVE STRUGGLED TO HANDLE THE OVERALL
EVOLUTION OF THE UPSTREAM CONVECTION, WITH HRRR FINALLY SEEMING
TO HAVE CAUGHT ON TO THE OVERALL SCENARIO. THIS AREA OF STORMS
IS LIKELY TO DRIFT ESE ALONG THE CAPE/THETA-E GRADIENT. THUS
FAR THESE HAVE BEEN SUB-SEVERE, WITH SOME POTENTIAL FOR UPSCALE
GROWTH WITH TIME AS IT MOVES ACROSS NE IOWA THROUGH 12Z AS NOTED
IN THE MOST RECENT SWOMCD. HAVE TRIMMED POPS CONSIDERABLY
THROUGH 15Z. CURRENT ALIGNMENT OF LIKELY POPS IS ORIENTED MORE
SW TO NE AND PROGRESSIVE ACROSS THE CWA, BUT ANTICIPATED
LOCATION OF THE INSTABILITY GRADIENT AND TRENDS IN HRRR SUGGEST
SW THIRD TO HALF OF THE AREA (ROUGHLY US-30 SOUTH AND EAST) MAY
HAVE THE BEST CHANCE FOR A LINE OF STRONG TO SEVERE STORMS AS IT
ARRIVES DURING PEAK HEATING. SLIGHT RISK WAS MAINTAINED BY SPC
FOR THE ENTIRE AREA, BUT COULD SEE SOME CHANGES IN LATER
OUTLOOKS TO FOCUS THE GREATEST THREAT TO THE AREA NOTED ABOVE.
LOCALLY HEAVY RAIN WILL REMAIN A CONCERN, BUT PROGRESSIVE NATURE
SHOULD LIMIT OVERALL FLOODING POTENTIAL. A WEAK FRONT WILL
DROP SOUTH INTO THE AREA TONIGHT INTO SUNDAY WITH YET ANOTHER
GRADIENT IN MOISTURE SETTING UP. INHERITED LIKELY POPS IN THE
SOUTH HAVE BEEN CAPPED AT UPPER CHANCE GIVEN AN INCREASING
LIKIHOOD THAT THE FURTHER SW TRACK OF STORMS THIS AFTERNOON WILL
EFFECTIVELY LIMIT CHANCES OVERNIGHT.
EFFECTIVE BOUNDARY WILL LIKELY REMAIN ACROSS PORTIONS OF CENTRAL
IL AND IN SUNDAY, WITH THE BULK OF NEW STORM DEVELOPMENT LIKELY
TO RESIDE IN THESE AREAS. FAR SOUTHERN COUNTIES REMAIN CLIPPED
BY A MARGINAL RISK FOR SEVERE ON DY2 WITH AXIS OF EXCESSIVE
RAINFALL ALSO SOUTH OF THE AREA. WHILE SKEPTICAL ON INHERITED
LIKELY POPS THROUGH THE DAY, WILL LEAVE THEM ALONE TO SEE WHAT
TRANSPIRES OVER THE NEXT 24 HOURS WRT TO THE BEST AXIS FOR
STORMS.
UPPER LEVEL FLOW BEGINS TO FLATTEN, BRIEFLY FOR MONDAY AND
TUESDAY WITH SEASONABLE TEMPERATURES AND MOST LIKELY DRY
CONDITIONS. EXPANSIVE UPPER LEVEL RIDGE WILL THEN BEGIN ITS PUSH
NORTH, INTRODUCING A PERIOD OF INCREASINGLY HOT AND HUMID
CONDITIONS FOR MAINLY WED AND THUR WITH HIGHS NEAR OR ABOVE 90
AND HEAT INDICES OF 100 DEGREES OR HIGHER. CAN'T RULE OUT A
STRAY STORM OR 2 IN WHAT WILL BE A VERY UNSTABLE, BUT LIKELY
CAPPED ENVIRONMENT. MODELS DISAGREE ON HOW SOON THE RIDGE WILL
FLATTEN IN THE FRI TO SAT TIME FRAME.
AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 647 AM EDT SAT JUL 19 2025
COMPLICATED FORECAST THIS PERIOD, WITH BOTH FOG/BR TO CONTEND
WITH AND THEN CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
SUNDAY MORNING. KSBN MAY SEE SOME BRIEF BR (5-6SM) THIS MORNING
BEFORE RETURNING TO VFR UNTIL SHOWERS AND STORMS MOVE IN THIS
AFTERNOON. SIMILARLY, KFWA WILL LINGER AROUND VLIFR/LIFR THROUGH
EARLY THIS MORNING (1/4SM AS OF THIS OB) FOR FOG.
LATER IN THE AFTERNOON INTO THE EVENING HOURS EXPECT MVFR TO IFR
CONDITIONS (ESPECIALLY WITHIN STORM ACTIVITY). SOME STORMS MAY
BE STRONG TO SEVERE, WITH DAMAGING WIND GUSTS POSSIBLE. MODELS
VARY QUITE A BIT WITH REGARDS TO TIMING, AND IT'S POSSIBLE THIS
AFTERNOON THAT STORMS GO SOUTH OF KSBN--MAINTAINING VFR FOR A
LONGER PERIOD. BEHIND THE COMPLEX OF STORMS MVFR/IFR CEILINGS
AND VISIBILITIES ARE POSSIBLE WITH LIGHT WESTERLY/CALM WINDS.
HOWEVER, SOME OF THE GUIDANCE BRINGS IN ANOTHER ROUND OF STORMS
LATE TONIGHT TO BOTH TERMINALS AROUND THE 3-6Z TIME FRAME
(SLIGHTLY LATER AT KFWA). UNCERTAINTY IS HIGH IN THIS PERIOD,
BUT USED TEMPOS/PROB30S TO TRY AND NARROW DOWN A BEST GUESS FOR
PLANNING PURPOSES.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...FISHER
AVIATION...MCD
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page