254
FXUS63 KILX 180521
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
1121 PM CST TUE DEC 17 2024
KEY MESSAGES
- LIGHT RAIN WILL AFFECT MUCH OF THE AREA TONIGHT, WITH A 30%
CHANCE OF LIGHT SNOW NORTH OF A GALESBURG TO LACON LINE.
- ANOTHER WEATHER SYSTEM WILL BRING SNOW TO PARTS OF THE REGION
THURSDAY NIGHT INTO FRIDAY MORNING, THOUGH CURRENT GUIDANCE
KEEPS MOST OF THE ACCUMULATIONS NORTH OF CENTRAL IL.
- SLIGHTLY ABOVE NORMAL TEMPERATURES THROUGH THURSDAY TREND A FEW
DEGREES BELOW NORMAL FRI-SUN.
DISCUSSION
ISSUED AT 200 PM CST TUE DEC 17 2024
AT 18Z A SURFACE RIDGE STRETCHED NW-SE ACROSS CENTRAL IL. FARTHER
WEST, WEAK LOW PRESSURE WAS ANALYZED OVER THE OK PANHANDLE AND
THIS IS FORECAST TO SHIFT EAST TO FAR SOUTHERN IL BY 12Z/WED.
ELEVATED WARM ADVECTION AHEAD OF IT WILL CAUSE CLOUDS TO
LOWER/THICKEN, WITH SCATTERED SHOWERS SPREADING IN FROM THE
SOUTHWEST THIS EVENING AND OVERNIGHT. HIGHEST POPS (LIKELY) AND
QPF (0.10-0.20") ARE FOCUSED SOUTH OF I-72. A SECOND BAND OF LIFT
FARTHER NORTHWEST, ASSOCIATED WITH FRONTOGENETIC LIFT CENTERED
NEAR 700 MB, FOCUSES ANOTHER AREA OF PRECIP FROM EASTERN IA INTO
NORTHERN IL OVERNIGHT. HIGH-RES GUIDANCE SHOWS THIS SCRAPING OUR
FAR NORTHERN CWA, WHERE THERMAL PROFILES ARE VERY NEAR THE
RAIN/SNOW THRESHOLD. PROBABILISTIC GUIDANCE FROM THE 12Z HREF
SHOWS A 40-60% CHANCE OF MEASURABLE SNOW NORTH OF A GALESBURG TO
BLOOMINGTON LINE, WITH PROBS OF 0.5" DROPPING BELOW 20%. SFC
TEMPS WILL BE CRITICAL TO MINOR ROAD IMPACTS FROM THIS LIGHT
FREEZING PRECIP, AND LATEST BLENDED GUIDANCE OFFERS READINGS NEAR
32F FROM GALESBURG TO LACON AROUND SUNRISE.
AFTER A QUIET STRETCH OF WEATHER INTO THURSDAY AFTERNOON, ACTIVE
NORTHWEST FLOW BRINGS A MORE ORGANIZED CLIPPER INTO THE MIDWEST
LATE THURSDAY AFTERNOON INTO FRIDAY MORNING. 12Z/TUE
DETERMINISTIC AND MUCH OF THE ENSEMBLE GUIDANCE TRACKS THE SURFACE
LOW NEAR OR JUST NORTH OF THE FAR NORTHERN CWA, KEEPING MOST OF
THE ACCUMULATING WARM ADVECTION SNOW TO OUR NORTH. WILL NEED TO
WATCH FOR TRENDS AS ANY SHIFT FARTHER SOUTH WOULD BRING LIGHT SNOW
ACCUMULATIONS INTO THE AREA THURSDAY NIGHT. FOR NOW WE ONLY HAVE
30% POPS NORTH OF I-74. ANOTHER ITEM TO MONITOR WILL BE THE
POTENTIAL FOR FREEZING DRIZZLE SOUTH OF THE LOW TRACK, WHERE DEEP
MOISTURE IS LACKING BUT LIFT IS PRESENT IN A SHALLOWER LAYER WITH
TEMPS ALOFT NEAR -10C.
SEASONABLE/SLIGHTLY ABOVE NORMAL TEMPS THROUGH THURSDAY WILL TREND
A FEW DEGREES BELOW NORMAL BEHIND THE CLIPPER FOR FRI-SUN. AFTER
THAT, ENSEMBLE GUIDANCE SHOWS ZONAL FLOW ESTABLISHING OVER THE
MIDWEST EARLY NEXT WEEK WHICH WOULD BRING ABOVE NORMAL READINGS
BACK TO THE REGION. CPC'S 6-10 DAY OUTLOOK SHOWS NEAR 40% CHANCE
OF ABOVE NORMAL TEMPS, AND 8-14 DAY TRENDING 80-90% CHANCE OF
ABOVE NORMAL.
FOR PRECIP CHANCES IN THE EXTENDED FORECAST, GUIDANCE SHOWS A
NARROW F-GEN BAND OF SNOW AFFECTING PARTS OF THE MIDWEST SATURDAY
INTO SATURDAY NIGHT, BUT WITH POOR CONSISTENCY ON TIMING/PLACEMENT
WILL LEAVE THIS OUT OF THE FORECAST. A BETTER SIGNAL FOR MORE
WIDESPREAD PRECIP ASSOCIATED WITH A SHORTWAVE EARLY NEXT WEEK,
WHEN NBM OFFERS SLIGHT/LOW CHANCE POPS FOR RAIN TUES.
25
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1121 PM CST TUE DEC 17 2024
LOW PRESSURE WILL TRACK SOUTH OF THE TERMINALS BRINGING SCATTERED
SHOWERS TO CENTRAL ILLINOIS OVERNIGHT. COVERAGE WILL BE GREATEST
ALONG AND SOUTH OF I-72. LIGHT EAST TO NORTHEAST WINDS IN PLACE
CURRENTLY WILL GRADUALLY BACK TO NORTH THE OVERNIGHT AND TO THE
NORTHWEST WEDNESDAY MORNING AS THE LOW BEGINS TO PULL AWAY FROM
THE AREA. MVFR CEILINGS, POSSIBLY IFR, WILL ACCOMPANY THE LOW
PASSAGE, THOUGH CONFIDENCE IS LOW IN THE LATTER.
DEUBELBEISS
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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