995
FXUS63 KIWX 210552
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1252 AM EST SUN DEC 21 2025
KEY MESSAGES
- BREEZY CONDITIONS PERSIST THROUGH THE OVERNIGHT HOURS. CHILLY,
WITH LOWS OF 18-22 DEGREES. WIND CHILLS IN THE SINGLE DIGITS
AND TEENS TONIGHT INTO SUNDAY MORNING.
- SHARPLY COLDER SUNDAY WITH PARTLY TO MOSTLY SUNNY SKIES. HIGHS
WILL BE IN THE UPPER 20S AND LOW 30S. WIND CHILLS WILL BE IN
THE TEENS AND 20S IN THE AFTERNOON.
- TRENDING WARMER MONDAY THROUGH AT LEAST FRIDAY WITH CHANCES
FOR RAIN.
DISCUSSION
ISSUED AT 140 PM EST SAT DEC 20 2025
RIDGING OVER THE EASTERN US AND ASSOCIATED WARM AIR ADVECTION HAS
PROPELLED HIGH TEMPERATURES WELL INTO THE 30S AND INTO THE 40S AS OF
THIS MIDDAY WRITING. WIND GUSTS HAVE BEEN STEADILY INCREASING BUT
LOW-LEVEL MIXING HAS BEEN LIMITED DUE TO MOSTLY CLOUDY SKIES. A COLD
FRONT IS ARRIVING OVER NORTHWEST ILLINOIS AND PRESENTS ONE MORE
OPPORTUNITY FOR BREEZY CONDITIONS AS WIND BECOME NORTHWESTERLY AFTER
SUNSET. COLD AIR ADVECTION BENEATH MOSTLY CLEAR SKIES WILL ALLOW
TEMPERATURES TO FALL INTO THE 20S OVERNIGHT. CANNOT RULE OUT A BRIEF
PERIOD OF LIGHT LAKE EFFECT SNOW FOR BERRIEN COUNTY LATE TONIGHT
AMID STIFF WESTERLY FLOW. FORECAST SOUNDINGS REVEAL POOR SATURATION
AND EQUILIBRIUM LEVELS, BOTH OF WHICH WILL LIMIT SNOWFLAKE SIZE AND
ANY ACCUMULATION POTENTIAL.
AFTER A COLD SUNDAY, A MILD WEEK LIES AHEAD WITH A PROGRESSIVE UPPER-
AIR PATTERN IN PLACE AND A STEADILY AMPLIFYING RIDGE OVER THE
SOUTHERN US. AN EMERGING SHORTWAVE FROM THE NORTHERN PLAINS
REPRESENTS ONE TARGET OF OPPORTUNITY IN THIS FORECAST PACKAGE. HIGH
PRESSURE NOW OVER THE EASTERN SEABOARD OFFERS WEAK MOISTURE
ADVECTION FROM THE GULF INTO A DEVELOPING WARM SECTOR THROUGH THE
MID-MISSISSIPPI VALLEY. ANTECEDENT COLD AIR OVER THE GREAT LAKES
REGION PRESENTS SOME PRECIPITATION-TYPE CONCERN, THOUGH DETAILS ARE
HIGHLY UNCERTAIN AT THIS DISTANCE. I'VE STAYED CLOSE TO THE EXISTING
FORECAST OF SNOW SHOWERS CHANGING TO RAIN MONDAY NIGHT INTO TUESDAY.
UPPER-LEVEL RIDGING CONTINUES TO AMPLIFY BY MIDWEEK WITH HIGHS IN THE
50S ANTICIPATED WEDNESDAY WHEN OUR NEXT CHANCE OF RAIN ARRIVES. HOW
LONG THIS WARMTH LASTS IS SOMEWHAT UNCERTAIN AS A CANADIAN LOW
PRESSURE SYSTEM LOOKS TO DROP IN AT SOME POINT NEXT WEEKEND, MARKING
A PERIOD OF RAIN PERHAPS CHANGING TO SNOW, BEFORE RIDGING
RESUMES.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1240 AM EST SUN DEC 21 2025
VFR CONDITIONS AT THE TERMINALS THROUGH THE PERIOD, WITH MAINLY
HIGH CLOUDS OR SCATTERED LAKE EFFECT CLOUDS (KSBN, 3500FT) TO
CONTEND WITH THROUGH EARLY-MID AFTERNOON. OTHERWISE, GUSTY WEST-
NORTHWEST WINDS WILL DIMINISH AND SHIFT TO THE SOUTH-SOUTHWEST
BY LATE AFTERNOON-EARLY EVENING. GUSTS THIS MORNING (AROUND
25KTS) ASSOCIATED WITH THE PASSING COLD FRONT WILL BE MORE
SPORADIC AS WE ATTEMPT TO DECOUPLE AND THE FRONT MOVES FURTHER
EAST INTO OHIO.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR LMZ043-
046.
DISCUSSION...BROWN
AVIATION...MCD
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