563
FXUS63 KIWX 110740
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
340 AM EDT THU JUN 11 2026
KEY MESSAGES
- HIGH TEMPERATURES AROUND 90 DEGREES COUPLED WITH HUMID
CONDITIONS ARE EXPECTED AGAIN TODAY SO A HEAT ADVISORY HAS
BEEN ISSUED FOR THE AREA. IF VENTURING OUTSIDE, BE SURE TO
TAKE BREAKS AND STAY HYDRATED.
- CHANCES FOR SEVERE WEATHER EXIST AGAIN TONIGHT. DAMAGING WIND,
HAIL, HEAVY RAIN, AND A FEW TORNADOES ARE POSSIBLE WITH THIS
SEVERE WEATHER THREAT.
- NEXT CHANCES FOR SHOWERS AND STORMS RETURN SATURDAY NIGHT WITH
ANOTHER COOL FRONTAL PASSAGE, BRINGING COOLER TEMPERATURES
INTO LOW/MID 70S TO LOWER 80S ALONG WITH DECREASED HUMIDITY
ACROSS THE AREA SUNDAY AND MONDAY.
- A MODERATE SWIM RISK EXISTS ALONG THE SOUTHEAST LAKE MICHIGAN
SHORELINE TODAY AND FRIDAY AS WAVES REACH 2 TO 4 FEET.
BREAKING WAVES AND CURRENTS ARE EXPECTED. STAY AWAY FROM
DANGEROUS AREAS LIKE PIERS, BREAKWALLS, AND RIVER OUTLETS.
ALWAYS HAVE A FLOTATION DEVICE WITH YOU IN THE WATER.
DISCUSSION
ISSUED AT 337 AM EDT THU JUN 11 2026
A SHORTWAVE ROUNDS THE BASE OF THE MID LEVEL TROUGH IN THE WEST AND
APPROACHES THE AREA THIS AFTERNOON AND TONIGHT. AS IT DOES SO, THE
OUTFLOW BOUNDARY FROM YESTERDAY'S STORMS SITUATED ACROSS OUR AREAS
SERVES AS A DIVIDING LINE BETWEEN HIGHER AND LOWER DEW POINTS THAN
70 DEGREES. THE GFS EVEN KEEPS THE BETTER 850 MB AIRMASS SOUTH OF
THAT BOUNDARY. THE DAYTIME APPEARS TO BE ENOUGH TO PUSH THE BOUNDARY
FARTHER NORTH TO ALLOW FOR ANOTHER WARM AND HUMID AIRMASS THAT DOES
TWO THINGS:
#1, IT MAKES FOR ANOTHER DAY WHERE A HEAT ADVISORY COULD BE
NECESSARY AS HEAT INDICES EXCEED 100 DEGREES EAST OF I-69 AND OTHER
AREAS HAVE HEAT INDICES SURPASS THE MID 90S. THERE'S SOME QUESTION
HOW HIGH DEW POINTS GET WEST OF IN-15 (THE HRRR/RAP/NAM GET TO 75
DEGREES) AND THERE'S ALSO SOME QUESTION ABOUT WHEN THAT BOUNDARY
LIFTS NORTHWARD TO ALLOW WARMER TEMPS INTO THE AREA. GIVEN THIS IS
NOW THE SECOND DAY OF SUCH HEAT INDICES AS WELL AS THE INFORMATION
ABOVE, THOUGHT IT PRUDENT TO ISSUE ANOTHER HEAT ADVISORY ACROSS THE
AREA.
#2 IS THAT WE HAVE A VERY UNSTABLE AIRMASS ACROSS THE AREA WITH THE
NAM SHOWING GREATER THAN 4000 J/KG OF SBCAPE SO THE ATMOSPHERE IS
EXPECTED TO HAVE PLENTY OF INSTABILITY IN THE WARM SECTOR. THE ONE
INTERESTING THING IS THAT THE NAM STILL SHOWS THE OUTFLOW BOUNDARY
ACROSS THE AREA AS LATE AS LATE AFTERNOON. THIS COULD BE INTERESTING
FOR SURFACE BASED CELLS IF THAT REMAINS THE CASE AS THIS TENDS TO BE
MORE CONDUCIVE TO ROTATING CELLS IF THEY CAN BECOME ROOTED TO THE
BOUNDARY. THERE IS SOME QUESTION ABOUT IF CELLS CAN ERUPT OUT IN
FRONT OF THE MAIN SQUALL LINE AND IF THAT DOES HAPPEN PERHAPS THAT
COULD EAT AWAY AT THE HEAT AND INSTABILITY FOR STORMS AS WELL AS FOR
THE HEAT ADVISORY. NAM AND HRRR BUFKIT SOUNDINGS INDICATE WE'RE
CAPPED IN THE MORNING. WE FINALLY GET THE WARMER 700 MB AIRMASS (AND
BETTER 7+ C/KM MID LEVEL LAPSE RATES) AFTER 18Z AND THIS COULD HELP
WITH HAIL AND DAMAGING WIND POTENTIAL. THAT THERMAL BOUNDARY IS
NORTH INTO MI BY THE TIME THE COLD FRONT ARRIVES ACCORDING TO THE
NAM. 30+ KTS OF EFFECTIVE SHEAR ARRIVE WITH THE COLD FRONT, BUT 200
TO 400 UNITS OF EFFECTIVE HELICITY ARRIVE IN AREAS WEST OF IN-15 BY
LATE AFTERNOON. THIS WOULD HELP WITH EMBEDDED CIRCULATIONS WITHIN
THE SQUALL LINE AND MAKE THIS MORE OF A QLCS. GIVEN THE LACK OF PRE-
FRONTAL CELLS FORECAST AS WELL AS THE PROGRESSIVE NATURE OF THE
SQUALL LINE, WOULD THINK THERE WOULD BE A LOWER CHANCE FOR FLOODING,
BUT THE ATMOSPHERE IS SO MOIST WITH THE 70 DEGREE DEW POINTS AND 850
MB DEW POINTS ABOVE 10C THAT IT CANNOT BE COMPLETELY TAKEN OFF THE
TABLE WITH THIS CONVECTIVE ENVIRONMENT. THE SQUALL LINE LOOKS LIKE
IT SHOULD BE THROUGH THE AREA BY 3 TO 4 AM.
FRIDAY LOOKS DRIER (50 DEGREE DEW POINTS) AND COOLER (HIGHS AROUND
80 DEGREES), BUT AS THE WAVE THAT CAUSES OUR THURSDAY NIGHT STORMS
PUSHES NORTHEASTWARD, ANOTHER WAVE DIVES SOUTHWARD FROM CANADA AND
PICKS UP SOME MOISTURE FROM OUR SOUTH AND WEST. AS THE PLUME SWINGS
THROUGH SATURDAY NIGHT, DEW POINTS IN THE UPPER 60S ALLOW FOR MUCAPE
VALUES BETWEEN 1500 AND 2000 J/KG. STORMS ARE LIKELY ELEVATED AT
THIS POINT GIVEN THE FORMATION OF A LOW LEVEL INVERSION ON NAM AND
GFS SOUNDINGS, BUT MID LEVEL LAPSE RATES COULD REACH 6.5 C/KM FOR A
PERIOD SO PERHAPS SOME HAIL COULD FORM. WE COULD PROBABLY ALSO EEK
OUT SOME HEAVY RAIN GIVEN THE MOIST PROFILES. I'M INITIALLY
SKEPTICAL OF A DAMAGING WIND THREAT WITH THIS, BUT THINGS COULD
CHANGE. SPC HAS PUT THE AREA IN A MARGINAL RISK OF SEVERE WEATHER
FOR THIS PERIOD.
THE UPPER LOW STILL REMAINS ACROSS EASTERN CANADA DURING THE NEXT
WORK WEEK AND SO WHILE WE LOOK DRIER AND A LITTLE COOLER, IT DOESN'T
LOOK LIKE ANOTHER PROLONGED DRY PERIOD. IN FACT, THERE'S SOME MODEL
CONFLUENCE ON RAIN BY TUESDAY.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 741 PM EDT WED JUN 10 2026
ANOTHER WARM AND HUMID DAY THAT STARTS WITH A THERMAL BOUNDARY
AROUND THE AREA. THERE'S SOME QUESTION ABOUT WHEN IT LIFTS NORTHWARD
AND, AS THERE WAS THIS MORNING, THAT COULD PRODUCE A BRIEF PERIOD OF
ADVERSE FLIGHT CONDITIONS AS IT DOES SO, BUT DON'T HAVE ENOUGH
CONFIDENCE TO INCLUDE IT IN THESE TAFS. OTHERWISE, WE'LL BE WAITING
UNTIL LIKELY AFTER 00Z FOR OUR CHANCE FOR THUNDERSTORMS TO ARRIVE TO
THE AREA. THESE LOOK TO BE INTENSE WITH ENOUGH MOISTURE IN THE
ATMOSPHERIC COLUMN TO PRODUCE IFR CONDITIONS OR WORSE SO WILL PUT
THAT INTO A PREVAILING GROUP AS CONFIDENCE IS AT LEAST MEDIUM
THAT IT COMES THROUGH. THIS IS EXPECTED TO HAVE DAMAGING WIND
WITH IT AND MAY HAVE EMBEDDED TORNADIC CIRCULATIONS. THIS MOVES
THROUGH THE AREA BY 7 OR 8Z. DRIER CONDITIONS FOLLOW THIS SYSTEM
FOR FRIDAY. WE'LL ALSO HAVE SOME GUSTY WINDS TO 25 KTS AHEAD OF
THE LINE THIS AFTERNOON.
IWX WATCHES/WARNINGS/ADVISORIES
IN...HEAT ADVISORY FROM NOON EDT /11 AM CDT/ TODAY TO 8 PM EDT /7
PM CDT/ THIS EVENING FOR INZ005>009-012>015-017-018-020-
022>027-032>034-103-104-116-203-204-216.
OH...HEAT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR
OHZ001-002-004-005-015-016-024-025.
MI...HEAT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR
MIZ078>081-177-277.
MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 5 AM EDT
FRIDAY FOR LMZ043-046.
DISCUSSION...ROLLER
AVIATION...ROLLER
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