277
FXUS63 KIWX 202359
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
659 PM EST SAT DEC 20 2025
KEY MESSAGES
- BREEZY CONDITIONS PERSIST THROUGH THE OVERNIGHT HOURS.
- SHARPLY COLDER OVERNIGHT THROUGH SUNDAY WITH MORNING LOWS NEAR
20 AND WIND CHILLS IN THE TEENS TO SINGLE DIGITS.
- 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 /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 651 PM EST SAT DEC 20 2025
PREVAILING VFR WITH INCREASING WESTERLY POST-FRONTAL WINDS,
BECOMING WEST-NORTHWESTWARD OVERNIGHT. SUSTAINED 15KT WITH GUSTS
TO 20-25KT THROUGH AROUND 12Z BEFORE BEGINNING TO SUBSIDE TO
10KT OR LESS THROUGH THE REMAINDER OF THE DAY. SOME LAKE EFFECT
LOW-LEVEL CLOUDS AROUND H010-015 WILL ENCROACH ON SBN AND
PERHAPS AS FAR SOUTH AS FWA IN THE MORNING, BUT CONFIDENCE IS
NOT HIGH ENOUGH TO INTRODUCE CIG-RELATED RESTRICTIONS AT THIS
TIME. BY THE AFTERNOON, CLEARING SKIES WILL PREVAIL AS HIGH
PRESSURE BUILDS INTO THE REGION.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST SUNDAY FOR LMZ043-046.
DISCUSSION...BROWN
AVIATION...NORMAN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page