913
FXUS63 KLOT 212326
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
526 PM CST SUN DEC 21 2025
KEY MESSAGES
- TEMPERATURE MODERATION WILL BE UNDERWAY MONDAY WITH ABOVE
NORMAL TEMPS EXPECTED THROUGH SATURDAY.
- LOW (LESS THAN 20%) CHANCE FOR LIGHT RAIN/SPRINKLES ACROSS
FAR NE IL MONDAY AFTERNOON.
- LIGHT RAIN/DRIZZLE/PATCHY FOG EXPECTED CHRISTMAS EVE PM INTO
CHRISTMAS AM.
DISCUSSION
ISSUED AT 125 PM CST SUN DEC 21 2025
THROUGH MONDAY NIGHT:
STRONG HIGH PRESSURE IS CRESTING THE AREA THIS AFTERNOON AND
WILL CONTINUE TO SHIFT EAST INTO THIS EVENING. A SERIES OF
WAVES RESULTING IN PUSHES OF WARM ADVECTION WILL THEN MOVE
ACROSS THE AREA THROUGH MONDAY NIGHT. THE FIRST WILL PASS LATE
TONIGHT BRINGING AN INCREASE IN MID/HIGH LEVEL CLOUD COVER WHICH
WILL COMBINE WITH MODESTLY INCREASING SOUTHERLY WINDS BEHIND
THE DEPARTING HIGH TO BRING RISING TEMPERATURES OVERNIGHT. A
SOMEWHAT BETTER ORGANIZED WAVE WILL CROSS THE AREA MONDAY
AFTERNOON, KEEPING ABUNDANT CLOUD COVER IN PLACE AND BRING A LOW
CHANCE (LESS THAN 20%) CHANCE FOR LIGHT RAIN OR EVEN JUST
SPRINKLES TO AREAS FROM ROUGHLY ROCKFORD SOUTHEAST ACROSS THE
NORTHERN CHICAGO METRO AREA. WARM ADVECTION ALOFT WILL AGAIN
INCREASE MONDAY EVENING WITH STEADY SOUTHWEST LOW LEVEL WINDS
SUPPORTING A MILDER NIGHT WITH LOWS IN THE MID TO UPPER 30S FOR
MOST AREAS.
MDB
TUESDAY THROUGH SUNDAY:
A WEAK COLD FRONT/WIND SHIFT WILL BE DISSIPATING ACROSS THE AREA
TUESDAY WITH DRY WEATHER EXPECTED. CLOUD COVER IS TRICKY FOR
TUESDAY, WITH THE POTENTIAL FOR LOW CLOUDS TAKING THEIR TIME TO
SCATTER OUT IN THE MORNING AND THEN POSSIBLE MID/HIGH LEVEL
CLOUDS. BUT TUESDAY HAS THE POTENTIAL TO BECOME MOSTLY SUNNY IN
THE AFTERNOON, WHICH WOULD HELP HIGH TEMPS REACH WELL INTO THE
40S AND POSSIBLY LOWER 50S ACROSS THE SOUTH. LIGHT WINDS AND AT
LEAST MOSTLY CLEAR SKIES WILL ALLOW LOWS TUESDAY NIGHT TO DIP
INTO THE UPPER 20S/LOWER 30S.
CLOUDS WILL BE ON THE INCREASE WEDNESDAY AS THE NEXT WEAK SYSTEM
MOVES ACROSS THE AREA WEDNESDAY NIGHT. AS HAS BEEN ADVERTISED
OVER THE PAST FEW DAYS, THERE IS QUITE A BIT OF UNCERTAINTY FOR
HOW FAR NORTH THE WARM FRONT WILL LIFT ACROSS THE LOCAL AREA AND
THUS HOW WARM TEMPS WILL RISE ON WEDNESDAY, ESPECIALLY WITH THE
INCREASING CLOUD COVER AND THE CHANCE OF LIGHT RAIN/DRIZZLE BY
MID/LATE AFTERNOON AS THE WAVE APPROACHES. MAINTAINED THE
PREVIOUS FORECAST'S TEMPS WITH HIGHS WEDNESDAY RANGING FROM THE
LOWER 40S NORTH TO THE LOWER 50S SOUTH. THE BEST CHANCE/HIGHEST
COVERAGE FOR LIGHT RAIN OR DRIZZLE APPEARS TO BE WEDNESDAY
EVENING AND MAINTAINED PREVIOUS LIKELY POPS DURING THIS TIME
PERIOD. TEMPS WILL LIKELY HOLD STEADY FROM WEDNESDAY'S HIGH
TEMPS ACROSS THE NORTH AND LIKELY RISE A FEW DEGREES INTO AT
LEAST THE MID 50S ACROSS THE SOUTH BY THURSDAY MORNING. WITH THE
BOUNDARY LIKELY STILL NEARBY OR ACROSS THE AREA, MAINTAINED A
CHANCE OF DRIZZLE INTO CHRISTMAS DAY BUT ALSO ADDED PATCHY FOG
FOR WEDNESDAY NIGHT INTO CHRISTMAS MORNING. WHILE IT MIGHT BE A
BIT EARLY TO SAY WHERE THE FOG WILL FORM, AS TRENDS LOOK NOW,
THERE WILL PROBABLY BE FOG, POSSIBLY DENSE NEAR THE BOUNDARY.
ALSO MAINTAINED PREVIOUS FORECAST TEMPS FOR THURSDAY WITH HIGHS
RANGING FROM THE UPPER 40S NORTH TO AROUND 60 SOUTH. HOWEVER,
THERE APPEARS TO BE GROWING CONSENSUS FROM THE MODELS THAT THE
WARM FRONT WILL LIFT ACROSS THE AREA THURSDAY NIGHT AS NEW LOW
PRESSURE PASSES NORTH OF THE AREA THURSDAY NIGHT INTO FRIDAY.
THIS COULD LEAD TO RISING TEMPS THURSDAY EVENING THROUGH FRIDAY
MORNING MAKING FOR A DIFFICULT DAYTIME HIGH TEMP AND NIGHTTIME
LOW TEMP. ANOTHER TRAILING WEAK COLD FRONT IS THEN EXPECTED TO
MOVE ACROSS THE AREA FRIDAY. MODELS SUGGEST A STRONGER COLD
FRONT ARRIVING NEXT WEEKEND WITH PERHAPS WELL ABOVE NORMAL TEMPS
ON SATURDAY AND NEAR/BELOW NORMAL AND FALLING TEMPS SUNDAY. CMS
AVIATION /00Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 526 PM CST SUN DEC 21 2025
KEY AVIATION MESSAGES FOR THE CURRENT TAF PERIOD:
- GUSTY SOUTHERLY WINDS ARE EXPECTED MONDAY
- A MARGINAL RISK FOR LOW LEVEL WIND SHEAR (LLWS) MONDAY
MORNING
- CHANCE FOR MVFR CIGS MONDAY EVENING.
VFR CONDITIONS ARE EXPECTED OVERNIGHT. LIGHT WINDS WILL REMAIN
OUT OF THE SOUTHWEST AS HIGH LEVEL CLOUDS SLOWLY MOVE OVER THE
AIR SPACE.
A 40 TO 50 KNOT LOW LEVEL JET WILL INCREASE MONDAY MORNING.
RECENT MODELS DEPICT THE CORE OF THE JET ABOVE 3000 FEET, SO
THERE IS LOWER CONFIDENCE IN THE STRENGTH AND DURATION OF
STRONGER WINDS ALOFT TO MERIT THE ADDITION OF LLWS AT THIS TIME.
ADDITIONALLY, THERE IS ALSO UNCERTAINTY ON HOW STRONG THE
INVERSION WILL BE TOMORROW MORNING, WHICH WOULD INHIBIT THE
AMOUNT OF MIXING FOR STRONGER SURFACE WIND GUSTS. THAT BEING
SAID, THE INVERSION SHOULD ERODE ENOUGH TO ALLOW FOR SOUTHERLY
WIND GUSTS OF 20 TO 25 KNOTS THROUGH THE LATE MORNING AND EARLY
AFTERNOON.
A WEAK BOUNDARY WILL PASS OVER THE AREA IN THE LATE AFTERNOON.
MID LEVEL SATURATION WILL INCREASE CLOUD COVER, BUT LOW LEVEL
DRY AIR LOWERS CONFIDENCE IN PRECIPITATION. WHILE THERE IS A
LESS THAN 20 PERCENT CHANCE FOR A STRAY SHOWER/SPRINKLE IN THE
AFTERNOON, THE TAFS WERE KEPT DRY. THERE IS A BETTER CHANCE FOR
MVFR CIGS BEHIND THE BOUNDARY MONDAY EVENING.
DK
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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