443
FXUS63 KIWX 060543
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
143 AM EDT SUN JUL 6 2025
KEY MESSAGES
- REMAINING HOT AND MUGGY THROUGH SUNDAY, THEN SLIGHTLY COOLER
AND LESS MUGGY MONDAY INTO TUESDAY.
- SCATTERED SHOWERS AND STORMS SUNDAY AFTERNOON-EVENING,
ESPECIALLY ALONG AND NORTH OF US 24. LOCALLY HEAVY RAINFALL,
WIND GUSTS TO 40 MPH AND LIGHTNING THE PRIMARY THREATS.
- CHANCES (20-60%) FOR SHOWERS LINGERING INTO MONDAY, MAINLY
ALONG AND SOUTHEAST OF US 24. SHOWER/STORM CHANCES (30-40%)
RETURN ON WEDNESDAY, BEST CHANCES DURING THE AFTERNOON HOURS.
DISCUSSION
ISSUED AT 222 PM EDT SAT JUL 5 2025
UPPER RIDGE PROVIDING THE SUNSHINE AND HOT CONDITIONS TODAY WILL
BREAK DOWN TONIGHT INTO SUNDAY AS A DAMPENING, POSITIVELY TILTED,
MID LEVEL TROUGH TRACKS EAST INTO THE WESTERN/CENTRAL GREAT LAKES ON
SUNDAY, EVENTUALLY WASHING OUT OVERHEAD SUNDAY NIGHT. THIS FEATURE
WILL FORCE A MOISTURE-LADEN COLD FRONT SLOWLY SOUTHEAST INTO THE
LOCAL AREA SUNDAY INTO MONDAY. POOLED PRECIPITABLE WATER VALUES NEAR
2", LITTLE IN THE WAY OF CAPPING, AND EXPECTATIONS FOR A 1000-2000
J/KG OF SKINNY SBCAPE SHOULD ALLOW AT LEAST SCATTERED CONVECTION TO
DEVELOP ALONG THE COLD FRONT AND/OR ANY LEADING PRE-FRONTAL FEATURES
DESPITE THE LACKING FLOW/FORCING LATER SUNDAY MORNING INTO SUNDAY
AFTERNOON, BEST CHANCES ALONG AND NORTH OF THE US 24 CORRIDOR.
LIGHTNING AND LOCALIZED TORRENTIAL DOWNPOURS WILL BE THE PRIMARY
HAZARDS GIVEN PROGGED 15-17C 850 MB DEWPOINTS, A DEEP WARM CLOUD
LAYER AND SLOW CELL MOTIONS WITH ONLY ~15 KNOTS OF SOUTHWESTERLY
FLOW IN THE 850-700 MB LAYER PARALLEL TO THE FRONT.
COVERAGE/INTENSITY OF THE CONVECTION SHOULD DIMINISH INTO SUNDAY
NIGHT AND MONDAY MORNING AS THE BOUNDARY LAYER STABILIZES AND THE
FRONT BECOMES INCREASINGLY DIFFUSE. A MODEL CONSENSUS STALLS THIS
WEAK FRONT AND INSTABILITY/MOISTURE AXIS NEAR OR JUST SOUTH OF THE
US 24 CORRIDOR BY PEAK HEATING MONDAY WHICH COULD SUPPORT RENEWED,
WIDELY-SCATTERED, CONVECTION HERE. DRIER, LESS HUMID AIR ACROSS
NORTHERN PORTIONS OF THE FORECAST FILTERS SOUTH THEREAFTER INTO
MONDAY NIGHT AND TUESDAY WITH SEASONABLY WARM AND DRY CONDITIONS
ANTICIPATED.
AVAILABLE MODEL GUIDANCE CONTINUES TO SHOW BROAD, LOW AMPLITUDE WEST-
NORTHWEST FLOW ALOFT TUESDAY NIGHT AND BEYOND. THIS WEAK, QUASI-
ZONAL, FLOW REGIME WILL SET THE STAGE FOR SLOW MOVING, CONVECTIVELY-
AUGMENTED, SHORTWAVES TO MOVE THROUGH THE MIDWEST AND GREAT LAKES
WITH EPISODES OF SHOWERS AND STORMS. WHEN AND IF ANY OF THESE
CONVECTIVELY INDUCED WAVES IMPACT US LOCALLY REMAINS OF VERY LOW
CONFIDENCE. THE RESULT WAS HOLDING TO NBM'S DAILY 20-40% POPS,
HIGHEST DURING PEAK HEATING. OF HIGHER CONFIDENCE IS THE TEMPERATURE
FORECAST, GENERALLY AVERAGING OUT NEAR TO SLIGHTLY ABOVE NORMAL FOR
JULY STANDARDS.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 130 AM EDT SUN JUL 6 2025
VFR CONDITIONS EXPECTED AT LEAST THROUGH AROUND 16Z SUN WHEN
CHANCES FOR THUNDERSTORMS INCREASE ALONG AND AHEAD OF A COLD
FRONTAL PASSAGE WHICH WILL BRING MVFR CIGS AND MVFR/IFR VSBYS
IN THUNDERSTORM RAINS WHICH MAY BECOME MODERATE TO HEAVY AT
TIMES. AT THIS TIME KEPT MVFR CONDITIONS IN THE TAFS AS
CONFIDENCE ON THE EXACT PLACEMENT AND TIMING/OCCURRENCE OF THE
HEAVIER DOWNPOURS IS LOW. GUSTY WINDS AND LIGHTNING WILL BE THE
PRIMARY THREATS WITH ANY STORMS THAT DEVELOP. CONTINUED TO USE
THE PROB 30 GROUPS TO HIGHLIGHT THE MOST PROBABLE TIME FRAMES.
SOUTH-SOUTHWEST WINDS THROUGH MOST OF THE PERIOD, SHIFTING WEST
AS THE FRONT NEARS. AFTER 04Z MON, VSBYS FOR KSBN LOOK TO DROP
INTO THE IFR/LIFR CATEGORIES IN MIST DUE TO THE POTENTIAL FOR
STILL VERY MOIST LOWER LEVELS AND SOME COOLING THAT WILL LOWER
DEW POINT DEPRESSIONS. WILL NEED TO MONITOR FOR THIS POTENTIAL
AND EXTENT EASTWARD.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...STEINWEDEL
AVIATION...ANDERSEN
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