880
FXUS63 KIWX 181715
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
115 PM EDT SUN OCT 18 2026
KEY MESSAGES
- ANOTHER COOL NIGHT WITH LOWS IN THE MID 30S AND AREAS OF FROST
EXPECTED.
- A FROST ADVISORY IS IN EFFECT FOR OUR INDIANA AND OHIO
COUNTIES LATE TONIGHT INTO EARLY MONDAY MORNING. THE GROWING
SEASON HAS ENDED FOR THE STATE OF MICHIGAN.
- DRY AND PLEASANT WEATHER PERSISTS THROUGH THE ENTIRE WEEK WITH
HIGHS AROUND 70, LOWS IN THE 40S, AND NO RAIN IN SIGHT.
DISCUSSION
ISSUED AT 115 PM EDT SUN OCT 18 2026
MAIN FORECAST CONCERN FOR THIS PACKAGE IS OVERNIGHT LOWS AND
SUBSEQUENT FROST HEADLINES. SURFACE GRADIENT TIGHTENED A BIT TODAY
AS LOW PRESSURE AND A WEAK FRONT CROSSED NORTHERN ONTARIO. HOWEVER,
THE GRADIENT RELAXES SUBSTANTIALLY OVERNIGHT AS FRONT EXITS AND HIGH
PRESSURE REBUILDS OVER THE GREAT LAKES. CALM WINDS AND CLEAR SKIES
SET THE STAGE FOR IDEAL RADIATIONAL COOLING. MOST 12Z GUIDANCE HAS
UPPER 30S FOR LOWS TONIGHT BUT ROUGHLY 25% HAS MID 30S AND THERE ARE
A FEW MEMBERS (10%) SUGGESTING 33-34F POSSIBLE. GIVEN IDEAL
RADIATIONAL COOLING AND RECENT PERFORMANCE, DECIDED TO LEAN TOWARD
THE 25TH PERCENTILE WITH 35-37F FOR MOST LOCATIONS. SURFACE
DEWPOINTS ARE A LITTLE LOW FOR A WIDESPREAD/HEAVY FROST BUT AREAS OF
FROST WILL CERTAINLY BE POSSIBLE. MUCH OF OUR CWA (ESPECIALLY OUR
SOUTHERN HALF) DID NOT EXPERIENCE A WIDESPREAD, KILLING FREEZE THE
PAST TWO NIGHTS. THEREFORE, THE GROWING SEASON WILL CONTINUE FOR IN
AND OH AND A FROST ADVISORY HAS BEEN ISSUED FOR TONIGHT/EARLY MON.
COLDER TEMPS AND CLIMATOLOGY SUPPORTED AN END TO THE GROWING SEASON
FOR THE STATE OF MICHIGAN SO NO HEADLINES WILL BE ISSUED THERE.
A GRADUAL MODERATING TREND IS STILL EXPECTED THIS WEEK AS HIGH
PRESSURE SLOWLY DRIFTS EAST. HIGHS ON MON CLIMB INTO THE UPPER 60S
AND HOVER AROUND 70F THROUGH THE WEEKEND. THE GRADIENT REMAINS WEAK
MONDAY NIGHT BUT THERE ARE INDICATIONS OF SOME PASSING HIGH CLOUDS
AND A SLIGHTLY WARMER AFTERNOON SHOULD KEEP OVERNIGHT LOWS IN THE
UPPER 30S/NEAR 40F FOR MOST. AFTER MONDAY NIGHT, LOWS REMAINS SAFELY
IN THE 40S THE REST OF THE WEEK. DON'T ANTICIPATE NEEDING ANOTHER
FROST ADVISORY AT THIS TIME. AFTERNOON RH VALUES NEAR 30 PERCENT ARE
POSSIBLE EACH DAY BUT WINDS REMAIN LIGHT AND WILL MINIMIZE FIRE WX
CONCERNS. THERE IS VIRTUALLY NO RAIN IN SIGHT FOR THE NEXT 10 DAYS.
WEAK FRONTS PASS TO THE NORTH WED AND SUN BUT STRONG RIDGING REMAINS
LOCKED OVER THE OHIO VALLEY.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 115 PM EDT SUN OCT 18 2026
HIGH PRESSURE CONTINUES TODAY BUT IS SQUEEZED SOMEWHAT BY A DEEPENING
LOW OVER INTERIOR MANITOBA. THIS PRESSURE GRADIENT EASES OVERNIGHT
THROUGH MONDAY.
IWX WATCHES/WARNINGS/ADVISORIES
IN...FROST ADVISORY FROM 1 AM EDT /MIDNIGHT CDT/ TO 9 AM EDT /8 AM
CDT/ MONDAY FOR INZ005>009-012>015-017-018-020-022>027-
032>034-103-104-116-203-204-216.
OH...FROST ADVISORY FROM 1 AM TO 9 AM EDT MONDAY FOR OHZ001-002-004-
005-015-016-024-025.
MI...NONE.
MARINE...NONE.
DISCUSSION...AGD
AVIATION...BROWN
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