556
FXUS63 KILX 210000
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
600 PM CST FRI DEC 20 2024
KEY MESSAGES
- SEASONABLY COLD THROUGH SATURDAY, THEN TURNING MILD. THE AVERAGE
TEMPERATURE NEXT WEEK WILL RUN ABOUT 10 DEGREES WARMER THAN
WHAT IS CONSIDERED NORMAL FOR LATE DECEMBER.
- CHOPPY ATMOSPHERIC FLOW WILL BRING FORTH MULTIPLE CHANCES FOR
LIGHT RAIN THROUGHOUT NEXT WEEK.
DISCUSSION
ISSUED AT 1231 PM CST FRI DEC 20 2024
THE MAIN FORECAST CHALLENGES THIS EVENING INVOLVE CLOUD COVER AND
OVERNIGHT TEMPS. UPSTREAM OBSERVATIONS ACROSS NORTHERN IL AND
SOUTHEAST IA REVEAL QUITE A BIT OF CLEARING, AND THIS MAKES SENSE
AS A DRIER/SUBSIDENT AIRMASS MOVES IN BEHIND THE DEPARTING UPPER-
LEVEL SHORTWAVE TROUGH. WHILE MODEL GUIDANCE IS IN FAIRLY GOOD
AGREEMENT THAT LOW CLOUDS WILL CLEAR OVERNIGHT, THERE REMAINS SOME
MINOR DIFFERENCES ON EXACTLY WHEN, AS WELL AS THE EASTERN EXTENT
OF CLEARING. WITH N/NE LOW-LEVEL WINDS IN PLACE TONIGHT, THERE
COULD BE A SHALLOW PLUME OF MOISTURE/CLOUDS BENEATH THE INVERSION
THAT ADVECTS IN FROM LAKE MICHIGAN. THE LATEST HREF GUIDANCE
SUPPORTS GREATER THAN A 70% CHANCE FOR CLOUDS WITH BASES BELOW 3
KFT TO STICK AROUND THROUGH 09Z/3AM IN AREAS EAST OF A CHAMPAIGN
TO CHARLESTON LINE. THE HIGHEST PROBABILITIES WILL COME ALONG THE
IL/IN STATE LINE.
AS FAR AS TEMPERATURES GO TONIGHT, THEY WILL BE IMPACTED BY NOT
ONLY CLOUD COVER BUT ALSO SNOWPACK. MOST SHORT RANGE GUIDANCE
SUPPORTS OVERNIGHT LOWS AROUND 20 DEGF, THOUGH IT WOULD BE
REASONABLE FOR LOCATIONS WITH A FRESH SNOWPACK AND CLEAR SKIES TO
DIP DOWN INTO THE MID TEENS. AREAS NORTH OF PEORIA TO PARIS LINE
COULD FIT THIS BILL.
CONDITIONS THEN REMAIN DRY AND SEASONABLY COLD THROUGH SATURDAY
AS A RIDGE OF HIGH PRESSURE QUICKLY BUILDS ACROSS THE MIDWEST.
THE PATTERN BECOMES MORE MILD BY SUNDAY AS BREEZY SOUTHERLY WINDS
INCREASE AHEAD AN AREA OF DEVELOPING LOW PRESSURE. AFTERNOON
TEMPERATURES WILL WARM INTO UPPER 30S BY SUNDAY, AND MID-TO-UPPER
40S BY MONDAY AHEAD OF THE COLD FRONT. MOISTURE RETURN AHEAD OF
FRONTAL PASSAGE IS FAIRLY LIMITED, WITH MID-LEVEL DRY AIR KEEPING
QPF BELOW 0.10".
DESPITE COLD FRONTAL PASSAGE ON MONDAY, MILD TEMPERATURES WILL
REMAIN IN PLACE THROUGH THE REMAINDER OF NEXT WEEK AS A PAIR OF
UPPER- LEVEL SHORTWAVE TROUGHS DIG INTO THE SOUTHERN PLAINS AND
THEN LIFT/PIVOT ACROSS THE OHIO VALLEY. PLENTY OF WARM/MOIST GULF
AIR WILL BE WRAPPED INTO THESE DISTURBANCES, PROPPING TEMPERATURES
UP INTO THE 50S BY THE BACK HALF OF NEXT WEEK WHILE SUPPORTING
MULTIPLE CHANCES FOR RAIN. WITH CENTRAL ILLINOIS POSITIONED ON THE
NORTHERN FRINGE OF THESE DISTURBANCES, AT LEAST FOR NOW, QPF
AMOUNTS ARE CURRENTLY LESS THAN 0.25" THROUGH NEXT WEEK.
MJA
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 600 PM CST FRI DEC 20 2024
MVFR CIGS THAT WERE PREVALENT OVER THE AREA THIS AFTERNOON
CONTINUE TO ERODE FROM THE NORTH AND SHOULD EXIT THE AREA IN THE
NEXT FEW HOURS. REMAINING MVFR CIGS WILL LIKELY LAST THE LONGEST
AT KSPI, AND POSSIBLY KCMI IF LAKE EFFECT CLOUD COVER SHIFTS
SLIGHTLY WESTWARD. OTHERWISE, VFR CONDITIONS SHOULD CONTINUE FOR
THE NEXT 24 HOURS WITH PERIODS OF MID AND HIGH LEVEL CLOUDINESS
CONTINUING. WINDS NNW 8-12 KTS DECREASING GRADUALLY THROUGH THE
PERIOD.
37
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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