763
FXUS63 KIWX 211843
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
143 PM EST SUN DEC 21 2025
KEY MESSAGES
- COLD TONIGHT WITH LOWS IN THE 20S FOLLOWED BY WARMING
TEMPERATURES THE REST OF THE WEEK.
- THERE ARE A FEW CHANCES FOR LIGHT RAIN THIS WEEK, STARTING
WITH A 20-30% CHANCE MONDAY NIGHT.
DISCUSSION
ISSUED AT 140 PM EST SUN DEC 21 2025
HIGH PRESSURE CENTERED OVER ILLINOIS HAS BROUGHT MOSTLY CLEAR SKIES
AND BELOW NORMAL TEMPERATURES TODAY. LOOK FOR ANOTHER COLD NIGHT
BEFORE HIGH PRESSURE TRACKS EAST AND WARM AIR ADVECTION TAKES SHAPE.
EMERGING FROM THE NORTHERN ROCKIES IS A SHORTWAVE ALOFT THAT TRACKS
THROUGH WISCONSIN AND MICHIGAN MONDAY NIGHT. TO SOUTH OF THIS, IN
THE WARM SECTOR, MODEST MOISTURE ADVECTION FROM THE GULF WILL HAVE
BEEN UNDERWAY MUNCH OF MONDAY AND FORECAST SOUNDINGS DEPICT A CHANCE
FOR DRIZZLE TRANSITIONING TO A PERIOD OF LIGHT RAIN MONDAY NIGHT.
SOUNDINGS ARE GENERALLY MILD AND SUPPORTIVE OF RAIN WITH AN ELEVATED
AND POORLY SATURATED DGZ ALONG WITH WEAK FORCING THROUGH THE COLUMN
(BEST FORCING IS DISPLACED ACROSS CENTRAL MI). AS A RESULT, I ONCE
AGAIN STAYED CLOSE TO THE EXISTING FORECAST OF 30-40% CHANCE OF RAIN
MONDAY NIGHT.
UPPER-LEVEL RIDGING, CENTERED OVER THE SOUTH-CENTRAL US AMPLIFIES
THROUGH THE WEEK BUT IS HAMPERED BRIEFLY BY HIGH PRESSURE MOVING
INTO THE UPPER GREAT LAKES WEDNESDAY. THIS IS RESULTING IN A 15-
DEGREE SPREAD IN HIGH TEMPERATURES FORECASTS ACROSS MODEL MEMBERS AS
DISCREPANCIES SHINE WITH THE PLACEMENT AND MAGNITUDE OF AN IMPENDING
WARM FRONT. THE IN-HOUSE BLEND WAS THE WARMEST OF ALL MODEL GUIDANCE
BY A LONG SHOT. A REDUCTION IN TEMPERATURES WAS REQUIRED. A
LATE- DAY PUSH OF WARM AIR ADVECTION AS HIGH PRESSURE BECOMES
DISPLACED TO THE EAST MAY ALLOW FOR SITES SOUTH OF US 24 TO
CRACK 50 DEGREES. ONCE AGAIN, THIS WAA REGIME INVITES THE CHANCE
FOR DRIZZLE OR LIGHT RIGHT WEDNESDAY NIGHT INTO THURSDAY.
DESPITE A TEMPERATURE ADJUSTMENT, TEMPERATURES WILL STILL BE
WELL-ABOVE NORMAL TUESDAY THROUGH FRIDAY; NORMAL HIGHS ARE ONLY
NEAR 35 THIS TIME OF YEAR. A STORM SYSTEM NEXT WEEKEND LOOKS TO
BRING TEMPERATURES BACK TOWARD NORMAL ALONG WITH RAIN, PERHAPS
CHANGING TO SNOW AS COLD AIR SETS IN.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1223 PM EST SUN DEC 21 2025
SURFACE HIGH PRESSURE TRANSITING ACROSS THE AREA KEEPS VFR
CONDITIONS CONTINUING. AS WE HEAD OVERNIGHT, MID LEVEL CLOUD
DECKS COME IN AS WARM ADVECTION BEGINS TO TAKE SHAPE. PLENTY OF
LOW LEVEL DRY AIR AND EVAPORATION LIMITS RAINFALL ATTEMPTS TO
REACH THE GROUND DURING MUCH OF MONDAY. NORTHWEST WINDS BACK
MORE SOUTHERLY THIS EVENING WHILE STAYING BELOW 10 KTS SUSTAINED
THROUGH THE PERIOD.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...BROWN
AVIATION...ROLLER
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page