163
FXUS63 KIWX 071736
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
136 PM EDT TUE JUL 7 2026
KEY MESSAGES
- SEASONABLE TEMPERATURES ARE EXPECTED THROUGH THE REMAINDER OF
THE WEEK. TEMPERATURES AND HUMIDITY LEVELS MAY CREEP UPWARD
LATE THIS WEEKEND INTO EARLY NEXT WEEK.
- DRY CONDITIONS ARE EXPECTED THROUGH EARLY THURSDAY. CHANCES
OF SHOWERS AND STORMS WILL INCREASE LATER THURSDAY INTO
FRIDAY.
DISCUSSION
ISSUED AT 134 PM EDT TUE JUL 7 2026
NO SIGNIFICANT CHANGES WERE MADE TO THE INHERITED FORECAST FOR THIS
CYCLE. QUIET CONDITIONS PREVAIL TODAY COURTESY OF BROAD SUBSIDENCE
ASSOCIATED W/ THE BUILDING UPPER-LEVEL RIDGE. WEAK FLOW ALOFT WILL
PERSIST THROUGH MID-WEEK AS THE BULK OF THE MID & UPPER LEVEL JET
ENERGY REMAINS WELL TO THE NORTH. CHANCES FOR PRECIPITATION SHOULD
INCREASE BY LATER THURSDAY AS THE RIDGE FLATTENS IN RESPONSE TO A
LOW-AMPLITUDE SHORT WAVE TRAVERSING THE FLOW ACROSS THE LOWER GREAT
LAKES. INCREASING FLOW ALOFT SHOULD CONTRIBUTE TO SHEAR PROFILES
SUPPORTIVE OF ORGANIZED CONVECTION, THOUGH IT IS DIFFICULT TO TELL
AT THIS POINT WHETHER SUFFICIENT INSTABILITY WILL EXIST FOR A MORE
SUBSTANTIAL FORWARD-PROPGATING SEVERE MCS OR MORE OF A HEAVY RAIN
THREAT WITH EXPECTED PWATS APPROACHING OR EXCEEDING 2 INCHES. STILL,
HIGH CONFIDENCE EXISTS IN A LARGE PORTION OF THE AREA RECEIVING
MEASURABLE RAINFALL FROM THURSDAY NIGHT THROUGH FRIDAY. /HAMMER
PREVIOUS DISCUSSION (ISSUED AT 335 AM EDT TUE JUL 7 2026):
THE VERY SLOW MOVING MID/UPPER LEVEL TROUGH THAT HAS PRODUCED
MULTIPLE DAYS OF SCATTERED SHOWERS AND STORMS IS NOW SLOWLY PUSHING
ACROSS THE EASTERN GREAT LAKES REGION THIS MORNING. A BROAD UPPER
VORT FILAMENT EXTENDS TO THE SOUTHWEST ACROSS CENTRAL INDIANA,
TRAILING BACK TO A CLOSED LOW FEATURE ACROSS NORTHEAST ARKANSAS.
MID/UPPER LEVEL RIDGING WILL BEGIN TO BUILD BACK INTO THE SOUTHERN
GREAT LAKES REGION IN THE WAKE OF THIS BROAD NEGATIVE UPPER HEIGHT
ANOMALY WITH AN ASSOCIATED BROAD LOW LEVEL ANTICYCLONE BUILDING IN
FROM THE NORTHWEST THROUGH WEDNESDAY. THE PROGRESSION OF THIS WAVE
PATTERN AND NORTHERLY LOW LEVEL FLOW EAST OF THE RIDGE AXIS WILL
ALLOW FOR A DRIER AIRMASS ACROSS CENTRAL/NORTHERN LOWER MI (~0.60
PWATS IN 00Z APX RAOB) TO ADVECT SOUTHWARD ACROSS THE LOCAL AREA.
THIS DRIER AIRMASS COMBINED WITH BROAD SYNOPTIC SCALE SUBSIDENCE
WILL PROVIDE PLEASANT CONDITIONS TODAY. HIGHS SHOULD BE 2 TO 5
DEGREES WARMER THAN YESTERDAY BASED MOSTLY ON INCREASED INSOLATION.
LIGHT/CALM WINDS AND MAINLY CLEAR SKIES ARE EXPECTED TONIGHT AS
ANTICYCLONE BUILDS EAST. MAY NEED TO WATCH FOR SOME PATCHY FOG
POTENTIAL ACROSS FAR NE IN/NW OH EARLY WEDNESDAY ON EASTERN
PERIPHERY OF THE HIGH BUILDING EASTWARD. SOME HIGH CLOUDS MAY ALSO
CLIP SOUTHERN/SOUTHEAST PORTION OF THE FORECAST AREA IN ASSOCIATION
WITH EASTWARD MIGRATION OF THE LOWER MS VALLEY CUT-OFF LOW WHICH
COULD ALSO HELP LIMIT FOG FORMATION.
WEDNESDAY SHOULD LARGELY FEATURE SIMILAR CONDITIONS TO THAT OF
TUESDAY WITH PERHAPS ANOTHER DEGREE OR TWO OF WARMING WITH
MODIFICATION OF LOW LEVEL AIRMASS IN SUBSIDENCE REGIME. DEW POINTS
WILL REMAIN IN CHECK IN LOW-MID 60S HOWEVER.
FOR WEDNESDAY NIGHT INTO THURSDAY, AN UPPER LEVEL SHORT WAVE
CURRENTLY LIFTING ACROSS ID/WESTERN MT WILL HELP DEAMPLIFY WESTERN
CONUS UPPER RIDGE AND THIS SHORT WAVE IS EXPECTED TO DAMPEN ACROSS
THE NORTHERN GREAT LAKES WED PM. DRY CONDITIONS WILL PERSIST THROUGH
WEDNESDAY NIGHT AS BETTER LOW LEVEL MOISTURE TRANSPORT REMAINS
CONFINED TO THE PLAINS INTO THE UPPER MS VALLEY. BEST MOISTURE
CONVERGENCE ACROSS THE CENTRAL PLAINS COULD GIVE RISE TO ANOTHER
CONVECTIVELY ENHANCED VORT MAX SHIFTING EASTWARD INTO IL/IN THURSDAY
AFTERNOON INTO FRIDAY. AT THE SAME TIME, GUIDANCE IS IN GENERAL
AGREEMENT THAT UPSTREAM WESTERN CONUS RIDGE WILL START TO AMPLIFY
AGAIN WHICH RAISES SOME QUESTION AS TO HOW FAR NORTH AND EAST POCKET
OF BETTER INSTABILITY CAN REACH DURING THIS PERIOD FROM THE MID MS
VALLEY. THIS LOW AMPLITUDE FLATTENED FLOW PATTERN WILL PROVIDE SOME
BETTER WESTERLY SHEAR BY THE LATE WED/THU PERIOD, BUT INSTABILITY
MAGNITUDES IS AN ITEM OF LOWER CONFIDENCE WITH POSSIBILITY THAT
EFFECTIVE LOW LEVEL BOUNDARY AND RESERVOIR OF BETTER INSTABILITY
COULD BE CONFINED WEST AND SOUTHWEST OF THE LOCAL AREA. MORE VEERED
WESTERLY DEEP LAYER FLOW BY THURSDAY COULD YIELD SOME WEAK
PROPAGATION VECTORS, AND WITH HIGH PWAT AIRMASS IN PLACE BY THIS
TIME, CANNOT RULE OUT SOME DECENT RAINFALL AMOUNTS LATE
THURSDAY/FRIDAY. HOWEVER, SOME POSSIBILITY EXISTS THAT AREAS
WEST/SOUTHWEST OF THE LOCAL AREA MAY BE MOST FAVORED FOR HEAVIER
RAINFALL.
SOME LOW POPS WERE MAINTAINED INTO SATURDAY GIVEN UNCERTAINTY IN
EVOLUTION OF ANY CONVECTIVE ENHANCEMENT TO SHORT WAVES, ALTHOUGH BY
THIS TIME, BULK OF GUIDANCE SUGGESTS DRYING TREND AS EFFECTIVE
FRONTAL BOUNDARY MAY SLIP SOUTH OF THE AREA. MEDIUM RANGE GUIDANCE
CONTINUES TO SUGGEST MORE PRONOUNCED AMPLIFICATION OF THE CENTRAL
CONUS RIDGE BY LATE WEEKEND INTO EARLY NEXT WEEK THAT SHOULD SUPPORT
A WARMING TREND TOWARD THE END OF THE PERIOD WITH SOME INCREASE IN
HUMIDITY. IT IS POSSIBLE SOME UPWARD ADJUSTMENTS MAY BE NEEDED TO
TEMPS BY NEXT MONDAY WITH DETERMINISTIC/ENSEMBLE GUIDANCE STARTING
TO COME INTO A LITTLE BETTER AGREEMENT BY NEXT MONDAY REGARDING THIS
SCENARIO. AFTER MONDAY, CONFIDENCE BEGINS TO WANE AS ENSEMBLE
SPREADS BECOME MORE DRAMATIC IN THE HANDLING OF THE EXTENT OF
STRENGTH OF WAVES TOPPING THIS RIDGE AFFECTING THE LONGITUDINAL
PLACEMENT OF THE RIDGE AXIS BY THE MIDDLE OF NEXT WEEK. MAINLY DRY
CONDITIONS HAVE BEEN MAINTAINED FOR THE WEEKEND INTO MONDAY WHEN
GUIDANCE EXHIBITS THIS STRONGER AGREEMENT IN RIDGE PLACEMENT. /MARSILI
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 113 PM EDT TUE JUL 7 2026
DRY WEATHER IS EXPECTED THROUGH THE PERIOD WITH THE REGION UNDER
HIGH PRESSURE. VFR CONDITIONS WILL PREVAIL AT SBN WITH ONLY A
FEW FAIR WEATHER CU THIS AFTERNOON THAT WILL GIVE WAY TO CLEAR
SKIES TONIGHT. FWA WILL ALSO BE MAINLY VFR, EXCEPT THAT GROUND
FOG ON WEDNESDAY MORNING COULD CAUSE MVFR VISIBILITY. LIGHT
NORTHERLY WINDS WILL BECOME LIGHT AND VARIABLE OR CALM LATER
THIS EVENING AND OVERNIGHT.
IWX WATCHES/WARNINGS/ADVISORIES
IN...AIR QUALITY ALERT FROM MIDNIGHT TONIGHT TO MIDNIGHT CDT
WEDNESDAY NIGHT FOR INZ103-203.
OH...NONE.
MI...AIR QUALITY ALERT FROM MIDNIGHT TONIGHT TO MIDNIGHT EDT
WEDNESDAY NIGHT FOR MIZ078-177-277.
MARINE...NONE.
DISCUSSION...HAMMER/MARSILI
AVIATION...COBB
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page