948
FXUS63 KIWX 200605
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
205 AM EDT THU AUG 20 2026
KEY MESSAGES
- CHANCES FOR RAIN SHOWERS TONIGHT INTO THURSDAY MORNING,
ESPECIALLY SOUTH OF US 30. HEAVY RAIN AND MINOR FLOODING IS
POSSIBLE IN THE FLOOD WATCH AREA.
- MOSTLY DRY THURSDAY WITH ONLY A SLIGHT CHANCE (20 PERCENT) FOR
ISOLATED SHOWERS AND STORMS IN THE LATE AFTERNOON AND EARLY
EVENING. SEVERE WEATHER IS NOT EXPECTED.
- HAZARDOUS SWIMMING CONDITIONS ARE POSSIBLE FOR LAKE MI BEACHES
ALONG BERRIEN CO, MI AND LA PORTE COUNTY, IN THIS WEEKEND,
ESPECIALLY ON SUNDAY. DANGEROUS CURRENTS AND WAVES ARE
POSSIBLE. MONITOR THE BEACH FORECAST FOR UPDATES.
UPDATE
ISSUED AT 954 PM EDT WED AUG 19 2026
A LINGERING LOW LEVEL TROUGH/BOUNDARY AND SOME MODERATE DIURNAL
INSTABILITY WAS RESPONSIBLE FOR SOME HEAVIER SHOWERS AND
THUNDERSTORMS ACROSS SOUTHERN PORTIONS OF THE AREA EARLIER TODAY
WITH A FEW POCKETS OF 1-2 INCH RAINFALL AMOUNTS. THIS EVENING,
COMPOSITE OUTFLOW HAS SHIFTED THIS FOCUS ACROSS CENTRAL INDIANA.
A MORE SIGNIFICANT SHORT WAVE IS DIVING EAST-SOUTHEAST FROM
NORTHEAST MISSOURI/WESTERN ILLINOIS WHICH HAS ALSO BEEN
ASSOCIATED WITH GREATER COVERAGE SHOWERS/EMBEDDED STORMS ACROSS
CENTRAL ILLINOIS. GIVEN SOUTHEAST TRACK OF THIS WAVE AND A
CONTRACTING/WEAKENING MLCAPE AXIS ALONG/SOUTH OF US ROUTE 24
CORRIDOR, SOME QUESTION OVERNIGHT AS TO COVERAGE OF SHOWERS AND
STORMS AS FAR NORTH AS US ROUTE 24 CORRIDOR WITH A GRADUAL
SOUTHEAST SHIFT TO THE LOW LEVEL TROUGH AXIS. LATEST TRENDS ARE
SUPPORTING EAST CENTRAL IL INTO CENTRAL IN FOR THE HEAVIEST
ADDITIONAL RAINFALL AMOUNTS. SOME CONSIDERATION GIVEN THIS
EVENING TO CANCELING THE FLOOD WATCH EARLY, BUT WITH LOW
COVERAGE ADDITIONAL SHOWERS DEVELOPING ALONG AND AXIS FROM WEST
CENTRAL IN INTO NORTHEAST IN ALONG LOW LEVEL TROUGH AXIS, HAVE
OPTED TO CONTINUE THE FLOOD WATCH FOR NOW GIVEN THE POCKETS OF
HEAVIER RAIN EARLIER TODAY. SEVERE THREAT APPEARS TO HAVE
DIMINISHED WITH ONLY CONCERN LATE EVENING/EARLY OVERNIGHT ON ANY
LOCALIZED HEAVIER SHOWERS.
DISCUSSION
ISSUED AT 127 PM EDT WED AUG 19 2026
A PRETTY WASHED OUT FRONTAL BOUNDARY HANGING AROUND OVER THE
FAR SOUTHERN PORTIONS OF OUR CWA AND ORIENTATED SLIGHTLY FROM
THE NORTHWEST TO EAST. THIS BOUNDARY WILL BE THE FOCAL POINT FOR
CONVECTION THIS AFTERNOON AND INTO THE EVENING. WITH THE FLOW
RUNNING PRETTY PARALLEL TO THAT BOUNDARY ANY STORMS THAT DO FORM
WILL BE LIKELY TO TRAIN OVER THE SAME AREAS WHICH MAY CAUSE SOME
LOCALLY HEAVY RAINFALL. WITH THE CONCERN THAT THIS WILL IMPACT
AREAS THAT HAVE RECENTLY HAD HEAVY RAINFALL AND FLOODING ISSUES
DID HOIST A FLOOD WATCH OVER THESE LOCATIONS WHICH WAS MAINLY
THE COUNTIES SOUTH OF US-30 AND THIS WILL RUN UNTIL EARLY
THURSDAY MORNING. THERE IS ALSO THE POTENTIAL FOR A FEW OF THE
STORMS ALONG THE BOUNDARY TO BECOME STRONG TO SEVERE WITH
MUCAPE VALUES AROUND 2000 J/KG, LOW LEVEL LAPSE RATES AROUND 6-7
C/KM, SR HELICITY VALUES AROUND 50 M2/S2 OR LESS, AND BULK
SHEAR VALUES AROUND 50-60 KTS. THIS LEADS TO THE MAIN THREATS
WITH THESE STORMS BEING FOR LARGE HAIL AND STRONG WIND GUSTS.
SPC DOES HAVE PORTIONS OF OUR AREA UNDER A MARGINAL SEVERE RISK.
THESE STORMS WILL CONTINUE TO PUSH SOUTHWARD TONIGHT WHICH WILL
BRING A RETURN TO DRIER WEATHER CONDITIONS OVERNIGHT TONIGHT
AND LOOKS TO CONTINUE THROUGH FRIDAY. HIGH TEMPERATURES IN THE
UPPER 70S TO LOW 80S WILL BE THEME INTO EARLY NEXT WEEK.
HOWEVER, A TROUGH DROPPING SOUTH FROM ONTARIO WILL BEGIN TO
PUSH SOUTHEASTWARD INTO THE GREAT LAKES AREA BY FRIDAY EVENING
AND PUSH AN ASSOCIATED COOL FRONT ACROSS THE AREA FROM WEST TO
EAST AND WILL SLOWLY MOVE EASTWARD INTO SATURDAY EVENING. THE
BEST POTENTIAL FOR RAIN SHOWERS AND STORMS LOOKS TO BE SATURDAY
AFTERNOON FOR MAINLY AREAS EAST OF I-69 ALONG THE FRONT. AT THIS
TIME ANY STORMS LOOK TO REMAIN SUB-SEVERE. SLIGHTLY COOLER
TEMPERATURES ARRIVE IN THE WAKE OF THIS BOUNDARY FOR SUNDAY AND
MONDAY WITH A MORE NORTHERLY FLOW (HIGHS IN THE MID TO UPPER
70S). THIS NORTHERLY FLOW WILL ALSO INCREASE CHANCES FOR
HAZARDOUS BEACH CONDITIONS ON LAKE MICHIGAN. WILL CONTINUE TO
MONITOR THAT SITUATION.
RIDGING OVER THE CENTRAL CONUS BEGINS TO BUILD INTO THE REGION
EARLY NEXT WEEK AND WILL BRING A RETURN TO SLIGHTLY WARMER
CONDITIONS WITH HIGHS BACK INTO THE 80S.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 152 AM EDT THU AUG 20 2026
PREDOMINANTLY VFR CONDITIONS AT KSBN THIS PERIOD. KFWA WILL BE
PREDOMINANTLY MVFR TONIGHT INTO EARLY AFTERNOON, WITH CEILINGS
AROUND 1500-2500 FEET MOST LIKELY. SOME OF THE GUIDANCE DROPS TO
IFR IN TERMS OF CEILINGS (700 FT), AND I CAN'T RULE THAT OUT
GIVEN KHHG JUST TO THE SOUTHWEST IS PRESENTLY REPORTING
700 FT CEILINGS. UNCERTAIN IF THAT WILL CARRY NORTHWARD, BUT DO
EXPECT TO SEE 1500 FT CEILINGS DEVELOP SOON. UNCERTAIN AS TO IF
IT WILL BE PERSISTENT SO USED A TEMPO FOR NOW. MODELS ALSO KEEP
HINTING AT 2-3SM VISIBILITY (SOME DROP TO 1/4SM LATE), BUT MOST
OF THE AREA IS CURRENTLY REPORTING GREATER THAN 6SM (ONE OR TWO
AT 4SM). UNCERTAIN AS TO HOW FAR WE'LL DROP TONIGHT WITH NEARLY
CALM WINDS AND SATURATED LOW LEVELS-IT'S POSSIBLE THE CLOUD
COVER LIMITS THE POTENTIAL. FOR NOW, KEPT VISIBILITY AT 4SM IN
THE TEMPO GROUP FROM 7-11Z WITH 1500 FT CEILINGS. IF IFR
CONDITIONS APPEAR MORE LIKELY, WILL MODIFY WITH AMENDMENT.
THE BULK OF THE RAIN SHOWERS WILL REMAIN SOUTH OF THE TERMINAL
EARLY THIS MORNING, HOWEVER THERE IS SOME UNCERTAINTY WITH
REGARDS TO THIS AFTERNOON. IT'S POSSIBLE WE GET SOME
SHOWERS/STORMS LATER THIS AFTERNOON/EARLY EVENING AT KFWA, BUT
KEPT AS A PROB30 GIVEN LOWER CONFIDENCE RE: IMPACTS TO THE
TERMINAL. THE MODELS THAT DEVELOP STORMS/SHOWERS HAVE THEM
EXTREMELY ISOLATED/WIDELY SCATTERED (IF THEY DEVELOP AT ALL).
IWX WATCHES/WARNINGS/ADVISORIES
IN...FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR INZ013-015-020-
022>027-032>034.
OH...NONE.
MI...NONE.
MARINE...NONE.
UPDATE...MARSILI
DISCUSSION...ANDERSEN
AVIATION...MCD
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