845
FXUS63 KIWX 150522
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1222 AM EST MON DEC 15 2025
KEY MESSAGES
- WIND CHILLS OF -5 TO -15 TONIGHT INTO MONDAY MORNING.
- WARMING TREND TUESDAY THROUGH THURSDAY WITH HIGHS UP NEAR 50 BY
THURSDAY.
- PERIODS OF RAIN ON THURSDAY, FOLLOWED BY WINDY CONDITIONS AND
BRIEFLY COOLER TEMPERATURES INTO THURSDAY NIGHT AND FRIDAY.
DISCUSSION
ISSUED AT 129 PM EST SUN DEC 14 2025
~1042 HPA ARCTIC HIGH PRESSURE CENTER OVER FAR WEST-CENTRAL IL WILL
WEAKEN SOUTHEAST THROUGH THE LOWER OH VALLEY AND CENTRAL
APPALACHIANS TONIGHT INTO MONDAY UNDER BUILDING HEIGHTS ALOFT. THIS
WILL ALLOW LOW LEVEL FLOW TRAJECTORIES TO BACK WEST INTO THIS
EVENING, AND TO THE SOUTHWEST LATER TONIGHT AND MONDAY. LINGERING
LAKE EFFECT SNOW SHOWERS/FLURRIES WILL TAPER OFF AS A RESULT THIS
AFTERNOON AND EVENING WITH LITTLE ADDITIONAL ACCUM/IMPACT NEAR LAKE
MI. LIGHTER WINDS ON THE EDGE OF THE SFC HIGH AND EVENTUAL NORTHWARD
LIFT AND EROSION OF LAKE CLOUDS SHOULD ALLOW FOR DECENT
RADIATIONAL COOLING OVER FRESH SNOW, WITH LOWS NEAR ZERO IN MANY
LOCATIONS. TEMPS THEN LIKELY LEVEL OUT INTO EARLY MONDAY AS
LIGHT SOUTHWEST FLOW DEVELOPS. WHETHER WIND CHILLS CAN SETTLE
SOLIDLY INTO ADVISORY CRITERIA (-15 TO -24F) FOR A TIME LATER
TONIGHT INTO MONDAY MORNING REMAINS HIGHLY UNCERTAIN. A MODEL
CONSENSUS AND HREF PROBS GENERALLY FAVOR WIND CHILLS IN THE -5
TO -15F RANGE FOR MOST. HAVE OPTED TO HOLD OFF ON A CW.Y AS A
RESULT, BUT WILL CONTINUE TO MESSAGE THE COLD IN OTHER PRODUCTS.
A 40-50 KT LLJ DEVELOPS LATE TONIGHT INTO MONDAY IN RESPONSE TO
A TIGHTENING LOW LEVEL HEIGHT GRADIENT BEHIND THE DEPARTING
HIGH AND A WEAK SFC TROUGH TRACKING EAST INTO THE NORTHERN GREAT
LAKES. SOUTHWESTERLY GUSTS REACHING 25-30 MPH WITHIN THIS
FEATURE DURING THE DAY ON MONDAY COULD RESULT IN PATCHY
BLOWING/DRIFTING IN RURAL AREAS, ESPECIALLY NEAR LAKE MI AND
OVER THE SOUTHERN HALF OF THE FORECAST AREA WHERE SEVERAL INCHES
OF SNOW FELL YESTERDAY.
A MORE ZONAL FLOW REGIME WILL BRING RELATIVELY QUIET WEATHER AND
WARMING TEMPERATURES TUESDAY INTO WEDNESDAY. A BUCKLE IN THIS MORE
PROGRESSIVE, FLATTENED, FLOW DOES SEND A STRONGER COLD FRONT THROUGH
AROUND THURSDAY WITH PERIODS OF RAIN LIKELY. WINDY AND BRIEFLY
COLDER BEHIND THIS SYSTEM THEN INTO THURSDAY NIGHT AND FRIDAY.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1222 AM EST MON DEC 15 2025
LAKE EFFECT STRATUS DECK WILL FINALLY ERODE IN THE NEXT FEW
HOURS AS SOUTHWESTERLY FLOW INCREASES AHEAD OF THE NEXT
SHORTWAVE. THIS WAVE IS WEAK AND WILL PASS NORTH OF THE AREA SO
NO PRECIP OR LOW CLOUDS ARE EXPECTED. HOWEVER, TIGHTENING
GRADIENT WILL SUPPORT SW WIND GUSTS AROUND 25 KTS DURING THE
DAY. THIS COULD LEAD TO SOME PATCHY BLOWING AND DRIFTING SNOW
BUT CONFIDENCE IN VIS REDUCTION IS LOW GIVEN MARGINAL WIND
SPEEDS. ELEVATED WARM/MOIST AIR ADVECTION WILL ALSO BRING A FAIR
AMOUNT OF MIDDLE AND HIGH CLOUDS. SOME MODELS SUGGEST ENOUGH
LOW LEVEL MOISTURE TO SUPPORT SOME 3-5 KFT CLOUDS TODAY BUT MOST
GUIDANCE KEEPS THE LOWER LEVELS DRY AND WILL THEREFORE HOLD
WITH JUST A SCT MENTION.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...GALE WARNING FROM 5 AM EARLY THIS MORNING TO 1 PM EST THIS
AFTERNOON FOR LMZ043-046.
DISCUSSION...STEINWEDEL
AVIATION...AGD
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