030
FXUS63 KILX 010801
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
301 AM CDT THU OCT 1 2026
KEY MESSAGES
- MULTIPLE ROUNDS OF WIDESPREAD RAIN WILL TRACK ACROSS THE
REGION THIS AFTERNOON THROUGH FRIDAY MORNING. BROAD RAINFALL
TOTALS OF 0.25 TO 0.75 INCHES ARE EXPECTED, THOUGH LOCALIZED
HEAVY RAIN BANDS COULD PRODUCE ISOLATED AMOUNTS OF 2 TO 3
INCHES.
- TEMPERATURES DROP SIGNIFICANTLY HEADING INTO THE WEEKEND, WITH
HIGHS IN THE UPPER 60S FRIDAY AND SATURDAY, AND OVERNIGHT LOWS
FALLING INTO THE 40S.
- CRISP, QUIET AUTUMN WEATHER WILL REMAIN ACROSS THE REGION
THROUGH EARLY NEXT WEEK BEFORE TEMPERATURES WARM BACK INTO THE
70S BY MID-WEEK.
DISCUSSION
ISSUED AT 258 AM CDT THU OCT 1 2026
AN UPPER-LEVEL LOW REMAINS CENTERED OVER SE COLORADO PER EARLY
MORNING GOES WATER VAPOR IMAGERY. DOWNSTREAM, COMPACT MID-LEVEL
SHORTWAVES CONTINUE TRAVERSING THE OZARKS AND UPPER/MID-
MISSISSIPPI VALLEY, PROVIDING SUFFICIENT SYNOPTIC LIFT FOR
SHOWERY PRECIPITATION OVER NORTHERN MISSOURI. MEANWHILE, AN
ELONGATED LOW-LEVEL JET (LLJ) AXIS STRETCHING FROM THE SOUTHERN
PLAINS TO THE GREAT LAKES IS VEERING AHEAD OF AN APPROACHING,
SLOW-MOVING COLD FRONT, DRIVING WARM AIR ADVECTION AND DEEP
ISENTROPIC ASCENT TO FURTHER BOLSTER RAIN ACTIVITY.
BY MIDDAY, THE SOUTHWEST U.S. UPPER-LEVEL TROUGH IS FORECAST TO
OPEN UP AND EJECT NORTHEASTWARD INTO THE MID-MISSISSIPPI
VALLEY, POSITIONING ITSELF PARALLEL TO THE SLUGGISH SURFACE
FRONTAL BOUNDARY. STRONG UPPER-LEVEL DYNAMICS, COMBINED WITH A
PLUME OF RICH TROPICAL MOISTURE AND FOCUSED FRONTAL FORCING,
WILL SET THE STAGE FOR MULTIPLE ROUNDS OF WIDESPREAD RAINFALL
BEGINNING THIS AFTERNOON AND LASTING THROUGH EARLY FRIDAY
MORNING.
THE LATEST 00Z REFS LPMM QPF GUIDANCE INDICATES BROAD TOTALS
RANGING FROM 0.25" TO 0.75" EAST OF THE ILLINOIS RIVER VALLEY
INTO SOUTHEAST ILLINOIS. NEVERTHELESS, ROBUST FRONTOGENETICAL
FORCING AND HIGH MOISTURE FLUX ALONG THE SLOW-MOVING BOUNDARY
FAVOR NARROW MESOSCALE RAIN BANDING. UNDERNEATH THESE LOCALIZED
BANDS, RAINFALL ACCUMULATIONS OF 2" TO 3" REMAIN ENTIRELY
POSSIBLE ACROSS THE CWA.
DRIER CONDITIONS WILL QUICKLY OVERSPREAD THE REGION FROM
NORTHWEST TO SOUTHEAST FRIDAY MORNING AS THE FRONTAL BOUNDARY
EXITS AND AN EXPANSIVE CONTINENTAL POLAR (CP) HIGH PUSHES EAST
ACROSS THE MIDWEST AND GREAT LAKES. STRONG POST-FRONTAL COLD AIR
ADVECTION WILL DRIVE A PRONOUNCED AIRMASS CHANGE, REPLACING
EARLY-WEEK WARMTH WITH SEASONAL FALL CONDITIONS. HIGHS ON FRIDAY
AND SATURDAY WILL DROP INTO THE UPPER 60S, WHILE OVERNIGHT LOWS
FALL INTO THE 40S. ENSEMBLE MODELS SHOW HIGH CONFIDENCE THAT
THIS EXPANSIVE CANADIAN SURFACE HIGH WILL REMAIN ENTRENCHED
THROUGH EARLY NEXT WEEK, PROLONGING A PERIOD OF TRANQUIL, CRISP
AUTUMN WEATHER.
A WARMING TREND TAKES HOLD BY MID-WEEK AS A POTENT MID-LEVEL
TROUGH DIGS FROM THE CANADIAN PRAIRIES TOWARD THE GREAT LAKES,
SHIFTING THE SURFACE HIGH EASTWARD. SOUTHWARD VEERING SURFACE
WINDS AHEAD OF AN ADVANCING COLD FRONT WILL SUBSEQUENTLY BOOST
TEMPERATURES BACK INTO THE MID- TO UPPER-70S.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1212 AM CDT THU OCT 1 2026
SHOWERS FALLING FROM A VFR CLOUD DECK WILL BE SCATTERED ACROSS
THE CENTRAL IL TERMINALS TONIGHT. A MORE SOLID AREA OF -SHRA
ASSOCIATED WITH MVFR CEILING AND VISIBILITY IS FORECAST TO MOVE
IN FROM THE NORTHWEST THIS AFTERNOON, AND PERSIST THROUGH THIS
EVENING. THERE IS A CHANCE CONDITIONS WILL DROP TO IFR AT TIMES,
BUT CONFIDENCE IS TOO LOW TO INCLUDE IN TAFS. WINDS WILL
GRADUALLY VEER FROM THE SOUTH TONIGHT, TO THE NORTH BY THIS
EVENING AS A COLD FRONT PUSHES THROUGH. SPEEDS WILL BE HIGHEST
AT KDEC- KCMI, WHERE 20-25 KT GUSTS WILL BE COMMON DURING THE
DAY.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...MJA
DISCUSSION...MJA
AVIATION...25
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