074
FXUS63 KILX 061151
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
551 AM CST TUE JAN 6 2026
KEY MESSAGES
- MILD CONDITIONS ARE FORECAST DURING THE WORK WEEK WITH DAILY
HIGHS GENERALLY IN THE 50S. SEASONABLY COOL WEATHER WILL RETURN
THIS WEEKEND, WITH A 70-80% CHANCE OF HIGH TEMPERATURES BELOW
40 BY SUNDAY.
- THERE IS HIGH CONFIDENCE (90% CHANCE) IN BENEFICIAL RAIN
THURSDAY INTO FRIDAY. THERE IS AROUND A 30% CHANCE FOR MORE
THAN AN INCH OF RAINFALL IN ANY GIVEN LOCATION, WHICH MAY HELP
THE ONGOING DROUGHT.
DISCUSSION
ISSUED AT 309 AM CST TUE JAN 6 2026
***** CLOUDY INTO WEDNESDAY MORNING *****
AT 3AM, A SURFACE LOW WAS LOCATED BENEATH A SHORTWAVE TROUGH OVER
SOUTHEAST IOWA. AHEAD OF THIS FEATURE, SOUTHERLY FLOW WAS KEEPING
TEMPERATURES IN THE MID TO UPPER 40S IN CENTRAL AND SOUTHEAST IL,
WITH DEWPOINTS ONLY A FEW DEGREES LOWER. THIS NEARLY SATURATED
LOW LEVEL AIRMASS WILL BARE WATCHING FOR FOG THIS MORNING AS THE
SURFACE LOW PASSES TO OUR NORTH, THOUGH GUIDANCE IS GENERALLY
SUGGESTING JUST ENOUGH MIXING OVER OUR AREA THAT LOW STRATUS WILL
BE MORE COMMON. THE BEST CHANCE OF PATCHY FOG AND DRIZZLE WOULD BE
NEAR AND NORTHEAST OF A ROUGHLY PEORIA TO ROBINSON LINE WHERE
HREF CHANCES FOR VISIBILITIES LESS THAN 1/2 MILE ARE HIGHEST AT
15-30% AND WHERE THE NAM PAINTS LIGHT QPF IN A NEARLY SATURATED
(RH > 90%) LOW LEVEL (0-1KM) AIRMASS; HOWEVER GIVEN THE (NEAR)
SATURATION EVIDENT IN FORECAST SOUNDINGS IT'S CERTAINLY PLAUSIBLE
ELSEWHERE, AND IN ANY CASE IT WILL BE A DREARY AND RELATIVELY
HUMID MORNING. NBM AND HREF SUGGEST HIGH (60-90%) PROBABILITIES
THE LOW CLOUDS WILL LINGER THROUGH THE DAY AND EVEN THE OVERNIGHT
TONIGHT. THIS, TOGETHER WITH A PUSH OF COOL ADVECTION, WILL KEEP
TEMPERATURES A LITTLE COOLER THAN INITIALLY FORECAST FOR TODAY,
ESPECIALLY NORTH OF A JACKSONVILLE TO PARIS LINE WHERE AFTERNOON
TEMPERATURES WILL STRUGGLE TO REACH 50, ACCORDING TO THE 06Z HRRR
AND RRFS.
THE HRRR, RAP, ARW, AND NAMNEST ARE EACH SUGGESTING THAT AS MOISTURE
ADVECTION RETURNS FROM THE SOUTHWEST TONIGHT, A PORTION OF THE AREA
WILL SEE SOME (ADVECTION) FOG. WHILE THEY DON'T COMPLETELY AGREE ON
THE LOCATION AND TIMING, OVERLAP IS GREATEST NORTHWEST OF A
SPRINGFIELD TO RANTOUL LINE FROM 1-9AM WEDNESDAY WHEN NBM AND HREF
ADVERTISE A 20-40% PROBABILITY OF VISIBILITIES LESS 1 MILE; WE ADDED
A MENTION OF PATCHY FOG TO ACCOUNT FOR THIS. MID TO LATE MORNING,
ANY FOG SHOULD LIFT, BUT LOW STRATUS WILL TAKE ITS TIME RETREATING
NORTHWARD ON SOUTHERLY BREEZES. HREF PROBS FOR CLOUD COVER DROPS
SHARPLY FROM 50-70% TO 15-30% BETWEEN NOON AND 3PM, BUT GIVEN ITS
TENDENCY TO GET RID OF CLOUDS TOO QUICKLY THIS TIME OF YEAR ONE
SHOULDN'T BE SURPRISED IF IT TAKES EVEN LONGER (ESPECIALLY NORTH OF
I-74). THIS COULD KEEP TEMPERATURES A BIT COOLER MAINLY ACROSS OUR
NORTH TOMORROW WITH SOME SPOTS NOT REACHING 50 ONCE AGAIN; WHERE
STRATUS CLEARS BEFORE NOON (MOST LIKELY SOUTHWEST OF A MACOMB TO
ROBINSON LINE), TEMPERATURES WILL LIKELY CLIMB INTO THE LOW-MID 50S.
***** RAIN LIKELY (90% CHANCE) THURDSAY-FRIDAY *****
GLOBAL MODELS AGREE THAT A CUT OFF LOW CURRENTLY OFF THE COAST OF
SOUTHERN/CENTRAL CALIFORNIA WILL GET SWEPT UP BY THE JET STREAM OVER
THE SOUTHERN PLAINS AND LIFT INTO THE MS RIVER VALLEY/MIDWEST
THURSDAY INTO THURSDAY NIGHT. STRONG DIVERGENCE IN THE LEFT EXIT
REGION OF A 150+ KT 250MB JET STREAK WILL FOSTER CYCLOGENESIS AT THE
SURFACE OVER MISSOURI, WITH THE LOW SUBSEQUENTLY SHIFTING THROUGH
NORTHWEST IL OR FAR EASTERN IOWA THURSDAY EVENING INTO THURSDAY
NIGHT. RICH DEEP LAYER MOISTURE BROUGHT NORTHWARD FROM THE GULF WILL
BRING PWATS INTO THE 1.1-1.3" (ABOVE THE DAILY RECORD FROM ILX
RAOBS) RANGE ACCORDING TO THE GEFS AND EPS ENSEMBLE MEANS, SO WITH A
WARM CLOUD LAYER DEPTH OF 8-10KFT SHOWERS SHOULD BE SEASONABLY
EFFICIENT RAINFALL PRODUCERS. WE MAY EVEN WIND UP WITH A FEW
THUNDERSTORMS, WITH THE HIGHEST CHANCES (10-20%) IN SOUTHEAST IL
WHERE INSTABILITY IS LIKELY TO BE HIGHEST. LREF SUGGEST A 20-30%
CHANCE FOR RAINFALL TOTALS OVER 1 INCH, AND GIVEN GLOBAL MODELS'
(COMPRISING THE LREF) INABILITY TO RESOLVE THE CONVECTIVE PROCESSES
DRIVING HEAVIER TOTALS WE SUSPECT THIS MAY EVEN BE A LITTLE
UNDERDONE WITH THE TRUE CHANCE BEING A TAD HIGHER - GOOD NEWS FOR
THE ONGOING DROUGHT.
WE'LL HAVE TO MONITOR SEVERE POTENTIAL WITH THIS FEATURE THURSDAY
EVENING, AS THE LOW LEVEL HELICITY MAXIMUM WITH THE WARM FRONT LIFTS
NORTH THROUGH OUR AREA. FORECAST SOUNDINGS SUGGEST ANY INSTABILITY
SHOULD BE ELEVATED, THOUGH IT WILL BE A SOMEWHAT PRECARIOUS
SITUATION WITH 55-65KT 0-6KM BULK SHEAR AND A FAIRLY SHALLOW CAPPING
INVERSION APPARENT ON FORECAST SOUNDINGS. AT THIS TIME, INSTABILITY
SEEMS TOO LOW TO BECOME OVERLY CONCERNED, ESPECIALLY WITH NO UH
TRACKS IN THE PAST COUPLE RRFS FORECASTS, BUT OF COURSE WE'LL KEEP
AN EYE ON INCOMING CAM GUIDANCE TO REASSESS THE POTENTIAL. ALSO
BEARING WATCHING WILL BE POTENTIAL FOR GUSTY WINDS NEAR THE SURFACE
LOW, THE DEPTH OF WHICH AS IT PASSES NEARBY REMAINS A POINT OF
DIFFERENCE AMONG THE MODEL SUITE. A DEEPER SURFACE LOW, LIKE THAT
DEPICTED BY THE 00Z NAM AT 990MB, COULD RESULT IN STRONG GRADIENT
WIND GUSTS FROM THE SOUTHWEST THURSDAY EVENING-NIGHT, WHEN ITS
FORECAST SOUNDINGS SUGGESTED 40-45 KT GUSTS WOULD MIX DOWN TO THE
SURFACE. THE 06Z ITERATION, LIKE MOST OTHER GUIDANCE, IS LESS
BULLISH ON THE DEPTH OF THE LOW AND ASSOCIATED WINDS, BUT WE'LL
CONTINUE TO MONITOR. MEAN EPS GUIDANCE (WHICH OFTEN REPRESENTS THE
MOST LIKELY SCENARIO) SUGGESTS PEAK GUSTS NEARER 35 MPH, WHICH
WOULDN'T CAUSE ANY PROBLEMS.
***** TURNING SEASONABLY COOL AGAIN THIS WEEKEND *****
IT'S UNCLEAR HOW MUCH WE'LL COOL OFF BEHIND THE LOW THURSDAY NIGHT
INTO FRIDAY, AS THE GLOBAL MODELS DON'T REALLY ADVERTISE A
PARTICULARLY STRONG PUSH OF COOL AIR BEHIND IT. HOWEVER, ANOTHER LOW
IS SLATED TO DEVELOP OVER OR EAST OF US FRIDAY NIGHT OR EARLY
SATURDAY, AND THEN DEEPEN AS IT LIFTS INTO THE GREAT LAKES. THIS
WILL GIVE US A STRONGER PUSH OF COOL AIR BY SATURDAY NIGHT OR
SUNDAY, WHEN NBM ADVERTISES A 70-80% CHANCE HIGHS FALL BACK INTO
THE SEASONABLE 30S.
BUMGARDNER
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 540 AM CST TUE JAN 6 2026
LOW MVFR AND IFR CEILINGS OVER EASTERN IOWA AND NORTHERN MISSOURI
WILL OVERSPREAD CENTRAL IL THIS MORNING, RESULTING IN
DETERIORATING FLIGHT CONDITIONS AT ALL OF THE AIRFIELDS. HREF
GUIDANCE SUGGESTS A BRIEF PERIOD OF MVFR CEILINGS MAY (50-70%
CHANCE) OCCUR AT SPI, DEC, AND CMI THIS AFTERNOON AS CLOUD BASES
RISE WITH DIURNAL HEATING. HOWEVER, IFR CEILINGS ARE EXPECTED TO
BE PREDOMINANT THROUGHOUT THE FORECAST PERIOD, WITH VISIBILITY
REDUCTIONS AT PIA AND BMI TONIGHT IN PATCHY FOG. WINDS WILL VEER
TO A WESTERLY DIRECTION AND INCREASE TO 10-15 KT WITH GUSTS TO
AROUND 20 KT LATE MORNING BEHIND A COLD FRONT, THEN EASE AGAIN TO
5 TO 10 KT BY LATE AFTERNOON.
BUMGARDNER
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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