784
FXUS63 KIND 170521
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
121 AM EDT SAT OCT 17 2026
KEY MESSAGES
- PATCHY FROST POSSIBLE LATE TONIGHT IN SHELTERED LOCATIONS NORTH
OF INDIANAPOLIS
- WIDESPREAD FROST SATURDAY NIGHT WITH SUB-FREEZING TEMPS POSSIBLE
- **FREEZE WATCH** NORTH AND EAST/SOUTHEAST OF INDIANAPOLIS
SATURDAY NIGHT INTO EARLY SUNDAY MORNING
FORECAST UPDATE
ISSUED AT 1006 PM EDT FRI OCT 16 2026
GLOOMY, AT TIMES WINDY, TRANSITION INTO AUTUMN WILL BE WANING THROUGH
THE OVERNIGHT...AS STRONG, BROAD, AND AMPLIFIED POLAR SURFACE HIGH
PRESSURE SETTLES OVER MOST OF THE CONUS...WITH ITS POSITIVELY-TILTED
AXIS FROM THE SOUTHERN HIGH PLAINS TO CHICAGOLAND, ADVANCING CLOSE
ENOUGH TO CENTRAL INDIANA TO DROP SUSTAINED WINDS UNDER 10 MPH BY
DAWN. AT LEAST PARTIAL CLEARING HAS ALREADY BEGUN OVER THE
NORTHWESTERN HALF OF THE CWA, WITH SCT/BKN DECKS EXPECTED TO CONTINUE
WEST OF LAFAYETTE/CRAWFORDSVILLE FROM FETCH OFF OF LAKE MICHIGAN THAT
MAY ALLOW A STRAY RW OVER THESE FEW WESTERN COUNTIES.
CARROLL COUNTY AND VICINITY MAY BE IN A SMALL AREA EAST OF THESE LAKE
CLOUDS, YET NEAR THE PRE-DAWN WANING WINDS...TO ALLOW PATCHY FROST IN
THE FEW MOST PROTECTED AREAS, ALTHOUGH CHANCES/CONFIDENCE TOO LOW FOR
ANY CORRESPONDING HEADLINE. DEWPOINTS CONTINUING TO DROP INTO THE
MID- TO UPPER 30S BY 12Z WILL GUIDE OVERNIGHT MINIMUM TEMPERATURES,
EXPECTED TO RANGE FROM MID-30S NORTH/EAST OF MARION COUNTY...TO AROUND
40F ACROSS THE REGION'S SOUTHERN-THIRD AND IN DOWNTOWN INDIANAPOLIS.
FREEZE WATCH CONTINUES FOR ZONES NORTH/EAST/SOUTHEAST OF INDIANAPOLIS
SATURDAY NIGHT.
DISCUSSION (THIS EVENING THROUGH FRIDAY)
ISSUED AT 301 PM EDT FRI OCT 16 2026
COLD AIR ADVECTION IS ONGOING FOLLOWING A COLD FRONTAL PASSAGE LAST
NIGHT. TEMPERATURES HAVE BEEN FALLING THROUGH THE DAYLIGHT HOURS AS
NORTHWESTERLY WINDS GUST TO BETWEEN 20-30 MPH. LITTLE ADDITIONAL
TEMPERATURE RECOVERY IS ANTICIPATED AND OUR HIGHS FOR THE DAY ARE
LIKELY TO HAVE ALREADY OCCURRED. PERSISTENT LOW CLOUD COVER WILL
HELP TODAY FEEL QUITE MISERABLE AFTER THE PROLONGED STRETCH OF WARM
WEATHER WE HAVE SEEN.
ALOFT, A POTENT BUT POSITIVELY-TILTED TROUGH IS DIVING IN FROM THE
NORTH. THIS FEATURE WILL STEEPEN LAPSE RATES WHILE PROPELLING A
SECONDARY FRONT SOUTHWARD. LAPSE RATES COULD STEEPEN EVEN MORE
IMMEDIATELY DOWN WIND OF LAKE MICHIGAN AS FLOW PASSES OVER THE
WARMER WATER, INCREASING BOUNDARY LAYER TEMPS BY A FEW DEGREES. A
BAND OF SCATTERED SHOWERS IS LIKELY THIS EVENING IN CONJUNCTION WITH
THESE FEATURES. BEST TIMING BRINGS SHOWERS TO THE LAFAYETTE AREA
AROUND 5-6PM WITH ACTIVITY REACHING INDY BY 7-8PM, AND EVENTUALLY
BLOOMINGTON BY 9-10PM. SHOWER ACTIVITY COULD BE BRIEFLY HEAVY, BUT
OVERALL RAINFALL AMOUNTS WILL BE UNDER A TENTH OF AN INCH.
WINDS ARE EXPECTED TO BECOME NORTHERLY BEHIND THE SECONDARY FRONT.
SPEEDS AND GUSTS ARE ALSO EXPECTED TO INCREASE, WITH GUSTS THIS
EVENING BETWEEN 25 TO 35 MPH POSSIBLE. THE UPPER TROUGH DEPARTS
OVERNIGHT AND A QUICK REDUCTION IN WINDS APPEARS LIKELY TONIGHT.
GUIDANCE IS IN GOOD AGREEMENT SHOWING SPEEDS DROPPING TO UNDER 15
MPH BY SUNRISE.
COMBINED WITH CLEARING SKIES, WINDS MAY BECOME CALM ENOUGH TO ALLOW
FOR PATCHY FROST NORTH OF INDY OVERNIGHT MAINLY IN SHELTERED AREAS.
OVERALL, OUR CURRENT THINKING IS WINDS REMAIN ELEVATED JUST ENOUGH
TO PREVENT WIDESPREAD FROST. AS SUCH, A FROST ADVISORY WAS NOT
ISSUED FOR TONIGHT. NEVERTHELESS, WE INTRODUCED THE MENTION OF
PATCHY FROST IN RURAL AREAS OVER THE NORTHERN PARTS OF OUR CWA.
AS SURFACE HIGH PRESSURE BUILDS IN ON SATURDAY, THE CLEARING TREND
CONTINUES WITH WINDS BECOMING CALM BY SUNSET. TEMPERATURES LIKELY
REMAIN SUPPRESSED SOMEWHAT DUE TO WANING COLD AIR ADVECTION. HIGHS
ONLY IN THE 50S ARE PROBABLE DESPITE A RETURN TO SUNSHINE. BY
SATURDAY NIGHT, IDEAL RADIATIVE COOLING CONDITIONS WILL BE IN PLACE.
TEMPERATURES IN THE 30S ARE VERY LIKELY WITH WIDESPREAD FROST.
NORTHEASTERN PORTIONS OF OUR CWA MAY EVEN DIP INTO THE LOW 30S OR
UPPER 20S. WE HAVE ISSUED A FREEZE WATCH FOR THESE NORTHEASTERN
AREAS SATURDAY NIGHT INTO SUNDAY MORNING. DEPENDING ON HOW THE
SURFACE HIGH SETS UP, THE FREEZE WATCH MAY NEED TO BE EXPANDED IN
FURTHER UPDATES.
SIMILAR CONDITIONS ARE LIKELY SUNDAY NIGHT WITH AREAS OF FROST
LIKELY, ESPECIALLY IN RURAL LOCATIONS.
NEXT WEEK
ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT SHOWING SURFACE HIGH PRESSURE
REMAINING IN PLACE THROUGH AT LEAST MID NEXT WEEK...POSSIBLY EVEN
THE ENTIRE WEEK. ALOFT, TROUGHING IS REPLACED BY RIDGING. THESE TWO
FACTORS POINT TOWARDS A WARMING TREND THROUGH NEXT WEEK. THE WARMING
SHOULD BE GRADUAL, AS THE ADVECTIVE COMPONENT IS NOT THERE. HIGHS
REBOUND INTO THE 70S WHICH IS A FAR CRY FROM THE NEAR 90 READINGS WE
SAW A FEW DAYS AGO.
AVIATION (06Z TAF ISSUANCE)
ISSUED AT 121 AM EDT SAT OCT 17 2026
IMPACTS:
- RAIN SHOWERS POSSIBLE THROUGH 09Z AT KLAF WITH MINIMAL VIS IMPACTS
DISCUSSION:
NORTHERLY WINDS OFF OF LAKE MICHGAN WILL CONTINUE LOW CHANCES FOR
RAIN AND CELINGS AROUND 4000FT AT KLAF. THIS COULD REACH KHUF, BUT
CONFIDENCE IS TOO LOW TO INCLUDE AT THIS TIME.
THE LOW LEVEL AIRMASS WILL SLOWLY DRY THROUGHOUT THE DAY, LEADING TO
MOSTLY CLEAR SKIES FROM 15Z ONWARD. WHILE GUSTS WILL NOT BE ABUNDANT
A FEW ISOLATED GUSTS TO 20MPH WILL BE POSSIBLE THIS AFTERNOON OUT OF
THE NNE. THIS HAS NOT BEEN INCLUDED IN THIS ISSUANCE DUE TO LOW
CONFIDENCE, BUT IS SOMETHING THAT MAY BE ADDED IS LATER UPDATES.
AS HIGH PRESSURE INCREASES THIS EVENING, WINDS WILL SLOWLY CALM,
WITH A PREDOMINANT DIRECTION OUT OF THE ENE AT 2-4MPH OVERNIGHT.
IND WATCHES/WARNINGS/ADVISORIES
FREEZE WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR INZ030-
031-037>042-048-049-056-057-065.
UPDATE...AGM
AVIATION...UPDIKE
DISCUSSION...ECKHOFF
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