345
FXUS63 KILX 011044
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
544 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 /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 530 AM CDT THU OCT 1 2026
AN ORGANIZED BAND OF SHOWERS PRODUCING MVFR CEILINGS AND
VISIBILITIES WILL SPREAD SOUTHEASTWARD ACROSS THE TERMINALS THIS
AFTERNOON INTO EARLY EVENING. WHILE BRIEF DROPS TO IFR
THRESHOLDS REMAIN POSSIBLE WITHIN HEAVIER CORES, CONFIDENCE IS
INSUFFICIENT TO INTRODUCE EXPLICIT TAF MENTIONS AT THIS TIME.
SURFACE WINDS WILL TRANSITION FROM SOUTHERLY THIS MORNING TO
NORTHERLY TONIGHT BEHIND AN ADVANCING SURFACE COLD FRONT.
ENHANCED PRESSURE GRADIENT WILL SUPPORT FREQUENT GUSTS OF 20-25
KT, PARTICULARLY AT KDEC AND KCMI, BEFORE WINDS WANE THIS
EVENING.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...MJA
DISCUSSION...MJA
AVIATION...MJA
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