845
FXUS63 KIWX 170542
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
142 AM EDT FRI APR 17 2026
KEY MESSAGES
- WIDELY SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON, MAINLY
ALONG AND NORTH OF US 30.
- AREAS OF FOG POSSIBLE LATE TONIGHT INTO EARLY FRIDAY, ESPECIALLY
NEAR LAKE MICHIGAN.
- UNSEASONABLY WARM ON FRIDAY WITH HIGHS NEAR 80 DEGREES.
- A ROUND OF SHOWERS AND THUNDERSTORMS TRACK THROUGH FRIDAY NIGHT
INTO SATURDAY MORNING. A FEW STORMS COULD BECOME SEVERE WITH
DAMAGING WINDS THE PRIMARY THREAT.
- COOLER AIR ARRIVES SATURDAY NIGHT INTO EARLY NEXT WEEK. THIS
MAY BRING FROST AND FREEZE CONCERNS, ESPECIALLY EARLY MONDAY
MORNING.
DISCUSSION
ISSUED AT 152 PM EDT THU APR 16 2026
COLD POCKET ALOFT WITH A DAMPENING UPPER WAVE AND NEAR 60F SFC
DEWPOINTS PROMOTING SOME WEAK LIFT/INSTABILITY THIS AFTERNOON
FOR WIDELY SCATTERED SHOWERS AND THUNDERSTORMS. A LAKE BREEZE
MAKING SLOW INLAND PENETRATION WILL LIKELY PROVIDE AN ADDITIONAL
FOCUS WITH BEST CHANCES (30-50%) FOR MEASURABLE RAIN NORTH OF
THE US 30 CORRIDOR. DEEPER MOISTURE EXITING EAST WILL LIMIT
COVERAGE A BIT WITH STRONGER CELLS POTENTIALLY CONTAINING SMALL
HAIL AND 30-50 MPH WIND GUSTS. SHORTWAVE RIDGING THEN FOLLOWS IN
TONIGHT INTO FRIDAY MORNING WITH THE POTENTIAL FOR FOG GIVEN
RESIDUAL SFC MOISTURE, LIGHT WINDS AND CLEARING SKIES.
RETURN FLOW AND AMPLE SUNSHINE IN ADVANCE OF THE NEXT SYSTEM WILL
MAKE FOR AN UNSEASONABLY WARM FRIDAY WITH HIGHS NEAR 80. ANOTHER
ROUND OF CONVECTION THEN BECOMES THE CONCERN FRIDAY NIGHT INTO
SATURDAY MORNING AS A MORE PRONOUNCED UPPER TROUGH AND STRONG COLD
FRONT TRACK THROUGH. ROBUST UPSTREAM CONVECTIVE INITIATION WILL
BE BACK TOWARD THE MID/UPPER MS VALLEYS LATE FRIDAY AFTERNOON,
LIKELY CONGEALING INTO A LINEAR SEGMENT/QLCS WITH EASTWARD
PROGRESSION FRIDAY EVENING. THE UNFAVORABLE DIURNAL TIMING AND
RESULTING LESSER CAPE SHOULD FAVOR A GRADUAL WEAKENING TREND AS
THIS MOVES WEST TO EAST THROUGH THE AREA LATE FRIDAY EVENING
INTO EARLY SATURDAY. HOWEVER, WILL STILL HAVE TO MONITOR FOR
DAMAGING WINDS GIVEN FAVORABLE SHEAR/FLOW PROFILES AND LOW 60F
SFC DEWPOINTS, ESPECIALLY WEST OF INTERSTATE 69. SHOWERS THEN
LIKELY LINGER ALONG THE FRONTAL BOUNDARY AND ASSOCIATED CORRIDOR
OF DEEPER MOISTURE SATURDAY MORNING, WITH COOLER AND DRIER
CONDITIONS LIKELY FOR THE SECOND HALF OF THE DAY THROUGH EARLY
NEXT WEEK POST-FRONTAL.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 125 AM EDT FRI APR 17 2026
VFR CONDITIONS INITIALLY THIS FORECAST PERIOD, HOWEVER WITH AN
INVERSION DEVELOPING TRAPPING MOIST LAKE MI MARINE AIR AND
THE MOIST SURFACE CONDITIONS IN PLACE FROM RECENT RAINFALL, WILL
SEE FOG DEVELOP AND GRADUALLY THICKEN OVERNIGHT AS TEMPERATURES
SLOWLY DROP FOR BOTH TAF SITES. MVFR CONDITIONS WILL BECOME
IFR/MVFR IN REDUCED CIGS/VSBYS WITH VSBYS DROPPING AFTER 05Z
FRI FOR BOTH SITES. IMPROVEMENTS IN VSBYS WILL BEGIN AROUND 12Z
FRI WITH INCREASES IN DIURNAL SOUTHERLY WINDS WHICH WILL
INCREASE MIXING. GUSTS AROUND 20 KTS EXPECTED THROUGH THE
EVENING. AN APPROACHING COLD FRONT FROM THE WEST WILL INCREASE
PRECIPITATION CHANCES IN THUNDERSTORMS IN WHICH A FEW OF THE
STORMS MAY BECOME STRONG TO SEVERE AFTER 00Z SAT AND SPREAD
EASTWARD INTO SATURDAY MORNING.
IWX WATCHES/WARNINGS/ADVISORIES
IN...DENSE FOG ADVISORY UNTIL 8 AM EDT /7 AM CDT/ THIS MORNING FOR
INZ005>009-012>015-017-018-020-022>027-032>034-103-104-
116-203-204-216.
OH...DENSE FOG ADVISORY UNTIL 8 AM EDT THIS MORNING FOR OHZ001-002-
004-005-015-016-024-025.
MI...DENSE FOG ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MIZ078>081-
177-277.
MARINE...DENSE FOG ADVISORY UNTIL 8 AM EDT THIS MORNING FOR LMZ043-046.
DISCUSSION...STEINWEDEL
AVIATION...ANDERSEN
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