338
FXUS63 KLOT 230517
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1117 PM CST MON DEC 22 2025
KEY MESSAGES
- ABOVE NORMAL TEMPS ARE EXPECTED THROUGH SATURDAY AND THEN MUCH
COLDER TEMPERATURES ARE POSSIBLE EARLY NEXT WEEK.
- A PERIOD OF SOMEWHAT DREARY CONDITIONS IS SHAPING UP WEDNESDAY
AND THURSDAY WITH PERIODS OF DRIZZLE AND SHOWERS, LOW CLOUDS,
FOG.
UPDATE
ISSUED AT 914 PM CST MON DEC 22 2025
NO BIG CHANGES TO THE FORECAST THIS EVENING. CLEARING LINE IS
GRADUALLY WORKING ITS WAY EAST ACROSS NORTHERN IL AND THIS TREND
IS EXPECTED TO CONTINUE TONIGHT. OPTED TO INTRODUCE SOME PATCHY
FOG INTO THE GRIDS WEST OF THE FOX RIVER VALLEY AS WELL AS SOUTH
OF THE KANKAKEE RIVER VALLEY. AS SKIES CLEAR OUT IN THE WESTERN
CWA, WINDS COULD DECOUPLE ENOUGH TO ALLOW FOR SOME PATCHY
GROUND FOG TO FORM, PARTICULARLY IN THE TYPICAL COLD AIR
DRAINAGE AND WIND PROTECTED AREAS. ACROSS THE SOUTHERN CWA, LOW
LEVEL MOISTURE WILL CONTINUE TO ADVECT NORTHWARD AND ONCE SKIES
CLEAR THE INCREASE IN BOUNDARY LAYER MOISTURE COULD BE ENOUGH
FOR A WINDOW OF SOME PATCHY DENSE GROUND FOG TOWARD SUNRISE. NOT
TERRIBLY CONFIDENT IN FOG THREAT IN EITHER LOCATION, BUT SEEMED
TO BE ENOUGH OF A THREAT GIVEN IT'S ONE OF THE LONGEST NIGHTS
OF THE YEAR TO WARRANT AT LEAST A MENTION OF PATCHY FOG.
- IZZI
DISCUSSION
ISSUED AT 217 PM CST MON DEC 22 2025
MAIN CONCERN IN THE SHORT TERM, TONIGHT, IS THE POTENTIAL FOR
SOME LIGHT SHOWERS OR POSSIBLE DRIZZLE. THE CAMS CONTINUE TO
SHOW VERY LIGHT PRECIP THROUGH THIS EVENING BUT THERE ARE TWO
FACTORS WORKING AGAINST THE PRECIP, RATHER LOW DEWPOINTS AT THE
SURFACE AND A SOMEWHAT SHALLOW CLOUD LAYER. THAT SAID, HAVE
INCLUDED SLIGHT CHANCE POPS THROUGH THIS EVENING. CURRENT CLOUD
BASES IN THE 2KFT-4KFT RANGE WOULD NOT SUPPORT TRUE DRIZZLE BUT
IF CLOUD BASES LOWER LATER THIS EVENING, THEN SOME DRIZZLE WOULD
BE POSSIBLE. THERE IS ALSO THE POTENTIAL FOR SHOWERS ACROSS
NORTHWEST IN LATER THIS EVENING BUT THE BULK OF ANYTHING THAT
DEVELOPS HERE, LOOKS TO REMAIN MAINLY EAST OF THE LOCAL AREA.
TEMPS WILL BE SLOW TO FALL THIS EVENING AND LOW TEMPS BY MORNING
WILL LIKELY BE DEPENDENT ON WHEN/IF THE LOW CLOUDS CLEAR OUT,
WITH A SHARP CUT OFF CURRENTLY ACROSS CENTRAL IA AND MO. IF THE
LOW CLOUDS CLEAR OUT OVERNIGHT, LOW TEMPS MAY DIP LOWER THAN
CURRENTLY EXPECTED, WHICH IS MID 30S NORTH TO UPPER 30S
SOUTHEAST. WITH SOME AMOUNT OF SUNSHINE EXPECTED ON TUESDAY,
BETWEEN POSSIBLE DEPARTING LOW CLOUDS IN THE MORNING AND
INCREASING MID/HIGH CLOUDS DURING THE DAY, HIGH TEMPS IN THE
MID/UPPER 40S LOOK ON TRACK WITH PERHAPS A FEW AREAS REACHING 50.
THE FORECAST FOR MUCH COOLER TEMPS MIDWEEK OVER THE PAST FEW
DAYS APPEARS TO BE ON TRACK AS MUCH OF THE 12Z MODEL RUNS HAVE
CONTINUED WITH A MORE SOUTHERN SOLUTION TO THE LOCATION OF A
FRONTAL BOUNDARY. THE FIRST WEAK WAVE WILL MOVE ACROSS THE AREA
WEDNESDAY AFTERNOON/NIGHT BRINGING A PERIOD OF LIGHT
RAIN/DRIZZLE TO THE AREA WITH THE FRONTAL BOUNDARY NOW LOOKING
TO PUSH SOUTH OF THE CWA AND THEN THE NEXT SYSTEM AND ITS
SURFACE LOW DEVELOPING NEAR THE LOCAL AREA AND RACING EAST LATE
THURSDAY NIGHT INTO FRIDAY MORNING. THIS WOULD KEEP THE LOCAL
AREA IN NORTHEAST FLOW. THUS HAVE MAINTAINED THE PREVIOUS
FORECAST'S HIGHS FOR WEDNESDAY, AROUND 40 NORTH TO UPPER 40S
SOUTH. THEN THE BLENDED GUIDANCE IS NOW ACTUALLY SLIGHTLY COOLER
THAN THE PREVIOUS FORECAST FOR CHRISTMAS WITH HIGHS IN THE
LOWER 40S NORTH TO LOWER 50S SOUTH AND THESE TEMPS MAY STILL BE
A FEW DEGREES TOO WARM.
ONE CHANGE TO THE FORECAST IS NOW THAT THE FRONTAL BOUNDARY IS
LOOKING TO BE FURTHER SOUTH, THIS MAY LIMIT THE DRIZZLE
POTENTIAL ACROSS MUCH OF THE AREA ON CHRISTMAS. MAINTAINED
PATCHY FOG WEDNESDAY NIGHT AREAWIDE, BUT FOR CHRISTMAS, HAVE
ONLY INCLUDED PATCHY FOG/DRIZZLE IN THE MORNING AND FOR AREAS
SOUTH OF I-80. STILL LIKELY TO BE A CLOUDY DAY, BUT MUCH LOWER
CONFIDENCE FOR DRIZZLE PERSISTING THROUGH THE DAY.
TEMPS REMAIN TRICKY FOR THURSDAY NIGHT/FRIDAY MORNING AND
DEPENDENT ON THE EXACT TRACK/TIMING OF THE SECOND LOW NOTED
ABOVE. THERE COULD BE A BRIEF PERIOD WHERE TEMPS RISE AHEAD OF
THE LOW AND THEN FALL ONCE IT PASSES BUT TOO MUCH UNCERTAINTY TO
MAKE ANY CHANGES TO THE BLENDED GUIDANCE FROM THIS DISTANCE.
PRECIP CHANCES LOOK TO RAPIDLY INCREASE THURSDAY EVENING INTO
EARLY FRIDAY MORNING WITH LIKELY POPS REASONABLE. TEMPS WILL BE
SUFFICIENTLY WARM TO SUPPORT ALL LIQUID PRECIP ACROSS THE LOCAL
AREA. THERE MAY ALSO BE A FEW THUNDERSTORMS ON THE SOUTH SIDE OF
THE SYSTEM, POTENTIALLY ACROSS THE SOUTHEAST CWA BUT CONFIDENCE
FOR THUNDER TOO LOW FOR MENTION AT THIS TIME.
BEYOND THIS TIME PERIOD, THERE STILL APPEARS TO BE GOOD SUPPORT
FOR A STRONG COLD FRONT TO MOVE ACROSS THE AREA SATURDAY NIGHT
INTO EARLY SUNDAY MORNING AND AFTER HIGHS IN THE 40S, POSSIBLY
LOWER 50S ON SATURDAY, TEMPERATURES COULD BE FALLING THROUGH THE
20S ON SUNDAY WITH NORTHWEST WINDS GUSTING 30-35 MPH. WIND
CHILLS COULD BE FALLING BELOW ZERO DURING SUNDAY AFTERNOON AS
WELL. DESPITE THE GOOD AGREEMENT CURRENTLY, THIS IS STILL
SEVERAL DAYS AWAY AND CHANGES ARE POSSIBLE. MADE NO CHANGES TO
THE BLENDED GUIDANCE, WHICH DID COME IN MUCH COLDER THAN THE
PREVIOUS BLENDED GUIDANCE. CMS
AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 1117 PM CST MON DEC 22 2025
AS THE BACK EDGE OF MVFR CIGS SLOWLY MOVE EAST, WIDESPREAD VFR
CONDITIONS ARE EXPECTED AFTER 07Z AND THROUGH THE REMAINDER OF
THE TAF PERIOD. THERE IS A CHANCE FOR PATCHY FOG FOR AREAS FAR
AWAY FROM THE CHICAGO METRO (LIKE KRFD). WHILE TRENDS WILL BE
MONITORED THROUGH THE NIGHT, THE PROBABILITY OF IT OCCURRING
(LESS THAN 25 PERCENT) WAS TOO LOW TO ADD IT TO THE TAF.
WINDS WILL SLOWLY VEER FROM THE SOUTHWEST TO THE WEST TUESDAY
MORNING, BUT REMAIN AT OR BELOW 10 KNOTS THROUGH THE DAY. AS THE
WINDS WEAKEN TUESDAY NIGHT, THEY WILL SLOWLY BECOME NORTHERLY
AND THEN OUT OF THE NORTHEAST AFTER 09Z WEDNESDAY MORNING. WILL
NEED TO MONITOR THE RISK FOR FOG ON WEDNESDAY MORNING IN LATER
TAF PACKAGES.
DK
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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