787
FXUS63 KIWX 131939
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
339 PM EDT SAT JUN 13 2026
KEY MESSAGES
- A MARGINAL RISK FOR SEVERE WEATHER REMAINS INTACT FOR TONIGHT,
MAINLY TO THE WEST OF INTERSTATE 69. THE PRIMARY RISK IS FOR
ISOLATED DAMAGING WIND GUSTS AND SOME BRIEF HEAVY DOWNPOURS,
BUT ISOLATED LARGE HAIL IS POSSIBLE. THE MAIN TIMEFRAME OF
THIS ISOLATED SEVERE WEATHER RISK IS ROUGHLY FROM 10 PM EDT
TO 4AM EDT.
- DRY AND COOLER CONDITIONS TO BEGIN NEXT WEEK, TEMPERATURES
MODERATE SOME INTO THE MIDDLE OF THE WEEK BUT THERE WILL BE
INCREASED CHANCES OF SHOWERS AND STORMS FOR THE TUESDAY
THROUGH THURSDAY PERIOD.
- THERE IS A HIGH SWIM RISK FOR SOUTHEAST LAKE MICHIGAN BEACHES SUNDAY
INTO SUNDAY EVENING. LIFE THREATENING WAVES AND CURRENTS ARE
EXPECTED.
DISCUSSION
ISSUED AT 334 PM EDT SAT JUN 13 2026
THE POTENTIAL OF ISOLATED SEVERE STORMS CONTINUES TO BE THE MAIN
SHORT TERM FORECAST CONCERN.
ISOLATED TO SCATTERED SHOWERS AND STORMS HAVE FORMED THIS AFTERNOON
FROM CENTRAL IL INTO PORTIONS OF NORTHEAST ILLINOIS. THESE
SHOWERS HAVE DEVELOPED ALONG THE LEADING EDGE OF AN AMPLIFYING
LOW LEVEL THETA-E RIDGE NOSING TO THE SOUTHERN LAKE MICHIGAN
VICINITY THIS AFTERNOON. CONVECTIVE COVERAGE APPEARS TO BE
ENHANCED ACROSS CENTRAL IL DUE TO SOME CONTRIBUTION OF A
CONVECTIVELY ENHANCED VORT MAX MOVING ACROSS THESE LOCATIONS.
DOWNSTREAM AIRMASS LOCALLY IS MORE STABLE AT THIS TIME, BUT
GRADUAL EASTWARD ADVECTION OF THIS LOW LEVEL HIGHER THETA-E AIR
SHOULD LEAD TO SOME DESTABILIZATION FROM WEST TO EAST. SOME PRE-
FRONTAL CONFLUENCE SHOULD PROVIDE BEST MOISTURE POOLING INTO
THIS EVENING FROM NORTHEAST ILLINOIS INTO SOUTHWEST LOWER
MICHIGAN WHERE AN MLCAPE AXIS OF 1500 J/KG IS EXPECTED TO REACH.
WHILE DIURNAL TIMING OF STORMS IS SOMEWHAT UNFAVORABLE FOR
SEVERE WEATHER, THE SOUTHERN GREAT LAKES DO APPEAR TO BE
SITUATED AT SOUTHERN EXTENT OF STRONGER WESTERLIES WITH RAP
SHORT TERM PROGS SUGGESTING 30 TO 35 KNOTS OF EFFECTIVE SHEAR
EARLY THIS EVENING ACROSS FAR N IN/S LOWER MI. THE POTENTIAL
EXISTS FOR ISOLATED CONVECTION ACROSS THE WEST AS EARLY AS 22
OR 23Z, BUT SHOWERS AND STORMS SHOULD BECOME MORE NUMEROUS LATE
EVENING INTO THE OVERNIGHT, PARTICULARLY ALONG THE PRE-FRONTAL
CONFLUENT AXIS ACROSS THE NORTHWEST WHERE INSTABILITY SHOULD BE
MAXIMIZED. SOME MODEST MID LEVEL LAPSE RATES OF AROUND 7 DEG
C/KM ALSO SHOULD ADVECT INTO THE REGION AND SHOULD ALSO HELP
SUSTAIN SOME MODEST MLCAPE PAST PEAK DIURNAL TIMING. OVERALL
SETUP STILL APPEARS MARGINAL FOR SEVERE STORMS WITH AREAS WEST
OF I-69 STILL APPEARING TO BE IN BEST JUXTAPOSITION OF
SHEAR/INSTABILITY FOR ISOLATED SEVERE THREAT. ISOLATED WIND
APPEARS TO BE PRIMARY THREAT BUT CANNOT RULE OUT A NARROW WINDOW
OF ISOLATED MARGINALLY SEVERE HAIL IN THE 03Z-06Z TIMEFRAME AT
THE LEADING EDGE OF SLIGHTLY STEEPER PLUME OF MID LEVEL LAPSE
RATES. SCATTERED SHOWERS/EMBEDDED STORMS SHOULD CONTINUE INTO
SUNDAY MORNING AS LAGGING MID/UPPER LEVEL TROUGH INTERACTS WITH
LOW/MID LEVEL BAROCLINIC. THE GREATER POTENTIAL OF SEVERE
WEATHER ON SUNDAY STILL APPEARS TO REMAIN FOCUSED EAST OF THE
LOCAL AREA GIVEN FRONTAL PROGRESSION EAST OF THE AREA BY PEAK
DIURNAL TIMING. OTHERWISE, IT WILL BE MUCH COOLER ON SUNDAY WITH
BREEZY CONDITIONS.
QUIET WEATHER IS EXPECTED FOR SUNDAY NIGHT INTO MONDAY AS THE COOLER
AND DRIER AIRMASS SETTLES INTO THE REGION. ANOTHER UPPER LEVEL
SHORT WAVE IS EXPECTED TO DIVE SOUTH FROM SOUTH CENTRAL CANADA
MONDAY NIGHT INTO TUESDAY WITH SOME RENEWED CONVECTIVE FORCING.
HOWEVER, THE OPPORTUNITY FOR ANY SIGNIFICANT MOISTURE TRANSPORT
APPEARS TO BE LIMITED GIVEN THE OVERALL WESTERLY FLOW REGIME.
SHOWERS AND STORMS APPEAR LIKELY ON TUESDAY, ALTHOUGH WITH SOME
MOISTURE LIMITATIONS HAVE SOME CONCERN THAT BLENDED POPS MAY BE
A BIT AGGRESSIVE. BY THE MIDDLE OF THE WEEK, MORE SIGNIFICANT
PACIFIC ENERGY SHOULD TOP WESTERN CONUS RIDGE AND SET UP A
POTENTIAL OF BETTER NORTHWARD SURGE OF LOW LEVEL THETA-GRADIENT
INTO THE LOCAL AREA, WITH PERHAPS A CHANCE OF BETTER
SHOWER/STORM ORGANIZATION HEADING INTO WEDNESDAY/THURSDAY. AS
PREVIOUS FORECAST MENTIONED, STILL A GOOD DEAL OF UNCERTAINTY
HERE WITH WHERE EXACT FRONTAL/WARM FRONTAL PLACEMENT WILL BE FOR
MIDDLE OF WEEK WITH SOME CONVECTIVE MODULATION OF THIS POSITION
POSSIBLE. A BREAK IN SHOWER/STORM CHANCES APPEARS LIKELY FOR
THURSDAY AND FRIDAY, BUT THE POTENTIAL OF ADDITIONAL NW FLOW
WAVES AND LIKELY EXISTENCE OF STRONGER LOW/MID LEVEL THETA-E
SOMEWHERE IN THE VICINITY IN THIS PATTERN ARGUES FOR ADDITIONAL
PRECIP CHANCES BY LATER NEXT WEEKEND.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 200 PM EDT SAT JUN 13 2026
SEVERAL SMALL SCALE SHORT WAVES ARE RIPPLING THROUGH LOW
AMPLITUDE WESTERLY FLOW ACROSS THE MID MS VALLEY AND GREAT LAKES
REGION THIS AFTERNOON. STRONGER UPPER FORCING WILL CLIP THE
SOUTHERN GREAT LAKES TONIGHT, ALTHOUGH IT DOES APPEAR SOME MCV-
TYPE FEATURE AND THE LEADING EDGE OF A HIGHER LOW LEVEL THETA-E
AIRMASS ARE HELPING TO SUPPORT THE DEVELOPMENT OF ISOLATED-
SCATTERED SHOWERS/STORMS ACROSS CENTRAL ILLINOIS. BEST
INSTABILITY AXIS HEADED TOWARD EARLY EVENING IS EXPECTED TO
SETUP FROM EAST CENTRAL IL INTO FAR NW IN/SW LOWER MICHIGAN AS
SOME PRE-FRONTAL CONFLUENCE SETS UP ACROSS THESE AREAS. SOME
QUESTION AS TO THE EASTWARD SUSTAINABILITY OF EAST CENTRAL IL
SHOWERS/STORMS THIS EVENING AS THEY ENCOUNTER A SLIGHTLY MORE
STABLE AIRMASS WITH AN EASTWARD EXTENT BUT GIVEN ADVECTIVE
FORCING AND POSSIBLE MCV-TYPE FEATURE CANNOT COMPLETELY RULE OUT
STRAY SHOWER DEVELOPMENT AFTER 22Z ACROSS KSBN VICINITY. GREATER
CHANCES OF SHOWERS AND STORMS STILL APPEAR TO BE LATER THIS
EVENING INTO THE OVERNIGHT AS LARGER SCALE LOW LEVEL FRONTAL
RESPONSE INCREASES WITH APPROACH OF BETTER LARGER SCALE
POSITIVELY TILTED TROUGH ACROSS THE UPPER MIDWEST. DID INCLUDE
SOME PREVAILING SHOWERS GIVEN BROAD FRONTAL RESPONSE/UPPER
FORCING. IN TERMS OF THUNDER, HAVE MAINTAINED PROB30 MENTION
WITH GREATEST CHANCES IN THE 03Z-08Z WINDOW. SOME MVFR CIGS MAY
ACCOMPANY FRONT/POST-FRONT ENVIRONMENT EARLY SUNDAY WITH
IMPROVING CONDITIONS DURING THE DAY AS A DRIER LOW LEVEL AIRMASS
ADVECTS INTO THE REGION.
IWX WATCHES/WARNINGS/ADVISORIES
IN...BEACH HAZARDS STATEMENT FROM SUNDAY MORNING THROUGH SUNDAY
EVENING FOR INZ103.
OH...NONE.
MI...BEACH HAZARDS STATEMENT FROM SUNDAY MORNING THROUGH SUNDAY
EVENING FOR MIZ177-277.
MARINE...NONE.
DISCUSSION...MARSILI
AVIATION...MARSILI
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