159
FXUS63 KILX 041754
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
1154 AM CST SUN JAN 4 2026
KEY MESSAGES
- MILD CONDITIONS ARE FORECAST DURING THE WORK WEEK WITH DAILY
HIGHS GENERALLY IN THE 50S.
- AMIDST PERSISTENT DROUGHT CONDITIONS, THE BEST OPPORTUNITY FOR
BENEFICIAL RAIN WILL BE THURSDAY INTO FRIDAY. CHANCES FOR MORE
THAN A HALF INCH OF RAINFALL RANGE FROM 40-50% SOUTH OF I-70 TO
20-30% IN WEST-CENTRAL IL.
DISCUSSION
ISSUED AT 135 AM CST SUN JAN 4 2026
***** SEASONABLY COOL TODAY *****
SURFACE HIGH PRESSURE SPRAWLED OVER THE MIDWEST CONTINUES TO
MAINTAIN TRANQUIL CONDITIONS OVER THE FORECAST AREA THIS MORNING,
WHILE SUBSIDENCE ASSOCIATED WITH UPSTREAM RIDGING HAS COMPRESSED
BOUNDARY LAYER MOISTURE AND RESULTED IN WIDESPREAD LOW CLOUDS. THE
NBM AND NAM, WHICH ARE HANDLING THIS STRATUS BEST, SUGGEST IT'LL
RETREAT NORTHWARD AS LOW LEVEL WARM ADVECTION DEVELOPS ACROSS THE
AREA THIS AFTERNOON. THOUGH MID-HIGH CLOUDS WILL PERSIST, EVEN THE
FILTERED SUNSHINE SHOULD BE SUFFICIENT TO WARM AREAS SOUTH OF A
ROUGHLY MACOMB TO ROBINSON LINE TO 40+, WHILE TEMPERATURES TOP OUT
IN THE MID 30S NORTH OF I-74. WE'LL HAVE TO WATCH OUT FOR SOME FOG
DEVELOPING IN WEST-CENTRAL IL BY EARLY TOMORROW MORNING AS TEMPS
DROP WITH DEPARTING MID-HIGH CLOUDS AND MOISTURE ADVECTION
PERSISTS; HREF SUGGESTS 15-30% CHANCES FOR VISIBILITIES LESS THAN
1/2 MILE WEST OF THE IL RIVER BY 6AM TOMORROW.
***** CLOUDY BUT MILD MONDAY INTO TUESDAY *****
WHEREVER THIS FOG AND/OR LOW STRATUS LINGERS (MOST LIKELY WEST OF
THE IL RIVER), TEMPERATURES ON MONDAY MAY RUN A LITTLE COOLER THAN
GUIDANCE, BUT FURTHER SOUTH EXPECT HIGHS TO CLIMB INTO THE 50S.
WARM, MOIST ADVECTION WILL CONTINUE TOMORROW NIGHT, AND AS A RESULT
ANOTHER ROUND OF, PERHAPS MORE WIDESPREAD, LOW CLOUDS, FOG, AND/OR
DRIZZLE SEEM PLAUSIBLE. BOTH THE NAM AND GFS ADVERTISE NEGLIGIBLE
PROBABILITIES OF CLOUD ICE, NEGATIVE OMEGA (UPWARD MOTION) AND NEAR
SATURATION (RH > 85%) IN THE LOWEST 1KM, WITH THE NAM ALSO
ADVERTISING DIMINISHED VISIBILITY (< 1 MILE) AND LIGHT QPF (T -
0.03") NORTH OF ROUGHLY I-72. TEMPS SHOULD BE TOO WARM FOR ANY
DRIZZLE TO FREEZE, SO WHILE THERE COULD BE IMPACTS IF FOG BECOMES
DENSE, CONFIDENCE WAS TOO LOW TO MAKE THOSE CHANGES TO THE
FORECAST AT THIS TIME.
***** RAIN CHANCES (40-60%) CLOSE THE WORK WEEK *****
CONDITIONS ARE FORECAST TO REMAIN MILD THROUGH AT LEAST THURSDAY,
AFTER WHICH TIME RIDGING WILL BEGIN TO SHIFT EAST AS A MORE POTENT
UPPER LEVEL TROUGH APPROACHES. GLOBAL MODELS AND THEIR RESPECTIVE
ENSEMBLES CONTINUE TO DIFFER DRAMATICALLY IN THE EVOLUTION AND TRACK
OF A SURFACE LOW DEVELOPING IN THE LEFT EXIT REGION OF A 100+ KT
500MB JET STREAK. FOR EXAMPLE, THE CURRENT GFS HAS THE SURFACE LOW
TRACKING ALONG THE OHIO RIVER TO KEEP OUR AREA COOL AND DRY, WHILE
THE ECMWF HAS THE LOW LIFTING NORTH ALONG THE MISSISSIPPI RIVER INTO
THE IA/IL/WI TRISTATE AREA - WHICH WOULD BRING OUR AREA SUFFICIENT
MOISTURE AND WARMTH FOR A BENEFICIAL RAINFALL AND PERHAPS SOME
THUNDERSTORMS LATE THURSDAY INTO FRIDAY. FOR WHAT IT'S WORTH, RAW
ENSEMBLE GUIDANCE (LREF) GIVES 40-50% CHANCES FOR MORE THAN A HALF
INCH OF RAINFALL OVER SOUTHEAST IL, WITH THOSE PROBABILITIES
TAPERING TO 20-30% WEST OF THE IL RIVER IN WEST-CENTRAL IL. BEHIND
THIS SYSTEM, CONDITIONS WILL TURN SEASONABLY COLD AND BREEZY ONCE
AGAIN.
BUMGARDNER
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1154 AM CST SUN JAN 4 2026
MVFR CEILINGS FROM EARLIER THIS MORNING HAVE SCATTERED AS A THICK
BLANKET OF HIGH CLOUDS AOA 15,000FT STREAMS ACROSS THE SKY FOR THE
BALANCE OF THE AFTERNOON INTO THE EARLY EVENING. 1730Z/1130AM
SATELLITE IMAGERY SHOWS THE BACK EDGE OF THE CLOUD COVER ACROSS
FAR EASTERN NEBRASKA/KANSAS...AND TIMING TOOLS SUGGEST THE
CLEARING WILL SPREAD INTO THE ILLINOIS RIVER VALLEY SHORTLY AFTER
SUNSET. SKIES WILL THEN REMAIN MOSTLY CLEAR OVERNIGHT INTO MONDAY
MORNING. THE POSSIBLE EXCEPTION WILL BE KPIA/KBMI AS THE HRRR
CONTINUES TO SUGGEST THE RE-DEVELOPMENT OF MVFR CEILINGS AFTER
13Z MON. THINK THE BULK OF THE LOWER CLOUDS WILL FORM FURTHER
NORTH ALONG/NORTH OF THE I-80 CORRIDOR, SO HAVE ONLY MENTIONED SCT
MVFR AT THOSE SITES FOR THE TIME BEING. WINDS WILL INITIALLY BE
SE AT 5-10KT THIS AFTERNOON, THEN WILL VEER TO S AND INCREASE INTO
THE 10-15KT RANGE THIS EVENING. MEANWHILE A 40-45KT 925MB JET IS
PROGGED TO DEVELOP WEST OF THE MISSISSIPPI RIVER, THEN TRANSLATE
EASTWARD ACROSS CENTRAL ILLINOIS OVERNIGHT. HAVE THEREFORE ADDED
WIND SHEAR AT ALL SITES. ONCE THE JET PUSHES FURTHER EAST AND
WEAKENS AFTER SUNRISE MONDAY, HAVE DROPPED THE WIND SHEAR AND GONE
WITH SW WINDS OF 5-10KT.
BARNES
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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