540
FXUS63 KILX 150729
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
229 AM CDT THU OCT 15 2026
KEY MESSAGES
- SCATTERED SHOWERS WILL DEVELOP THIS MORNING, BECOME MORE
NUMEROUS THROUGH MIDDAY, AND TAPER OFF FROM WEST TO EAST
TONIGHT. THUNDERSTORMS ARE ALSO POSSIBLE, ESPECIALLY THIS
AFTERNOON AND EVENING. RAINFALL AMOUNTS ARE LIKELY TO BE
AROUND A HALF INCH FOR MOST AREAS, BUT LOCALIZED SWATHS OF 1
TO 3 INCHES ARE POSSIBLE THIS AFTERNOON AND EVENING.
- STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON
AND EVENING NEAR AND SOUTH OF I-72. SPC HAS A MARGINAL (LEVEL
1 OF 5) RISK FOR SEVERE WEATHER, INCLUDING A 5 PERCENT
DAMAGING WIND RISK AND 2 PERCENT TORNADO RISK.
- WIND GUSTS OF 30 TO 40 MPH ARE LIKELY FRIDAY MORNING THROUGH
AFTERNOON. THE STRONGER WINDS WILL BE NORTHWEST OF I-55.
- MUCH COOLER WEATHER WILL SETTLE INTO THE REGION FRIDAY
THROUGH THE WEEKEND POTENTIALLY RESULTING IN AREAS OF FROST
BOTH SATURDAY AND SUNDAY MORNINGS.
DISCUSSION
ISSUED AT 229 AM CDT THU OCT 15 2026
A COLD FRONT NOW WELL SOUTH OF THE AREA EARLY THIS MORNING WILL LIFT
NORTHWARD AS A SURFACE LOW DEVELOPING IN THE SOUTHERN PLAINS LIFTS
NORTHEASTWARD TOWARD CENTRAL IL. THE FRONT SHOULD LIFT THROUGH
CENTRAL IL DURING THE AFTERNOON HOURS, BRINGING 70 DEGREE DEWPOINTS
TO MUCH OF THE AREA AND SBCAPE VALUES OF 1000-1500 J/KG TO AROUND TO
I-72 CORRIDOR, COINCIDENT WITH 40-50 KT DEEP LAYER SHEAR. 150-250
STORM RELATIVE HELICITY VALUES ARE ALSO FORECAST IN THIS AREA,
SUGGESTING A FEW TORNADOES WILL BE POSSIBLE. SPC HAS A MARGINAL RISK
FOR SEVERE THUNDERSTORMS FOR A THREAT OF LOCALLY DAMAGING WIND GUSTS
AND A FEW TORNADOES POSSIBLE. THE COLD FRONT TRAILING THE LOW SHOULD
BEGIN TO PUSH INTO WEST CENTRAL IL BY AFTERNOON, AND CROSS THE
REMAINDER OF CENTRAL AND SOUTHEAST IL THROUGH THE EVENING HOURS.
HIGH RESOLUTION MODELS DEPICT SCATTERED SHOWERS DEVELOPING MAINLY
WEST OF I-57 THIS MORNING AS AN INITIAL UPPER LEVEL DISTURBANCE AND
LOW LEVEL MOIST-WARM ADVECTION TAKES PLACE. A SMALL BREAK IS THEN
DEPICTED BEFORE ANOTHER DISTURBANCE AND THE WARM FRONT APPROACHES
MID MORNING INTO EARLY AFTERNOON. WHILE MANY HIGH-RES MODELS
DECREASE SHOWER COVERAGE DURING THE AFTERNOON HOURS, THIS IS ALSO
THE PERIOD WHERE A FEW MODELS DEPICT A FEW SUPERCELLS DEVELOPING IN
THE WARM SECTOR BEHIND THE WARM FRONT, WITH SIGNIFICANT SCATTER
AMONG MODEL SOLUTIONS ON WHEN/WHERE BREAKS OR SUPERCELLS WILL BE
DEVELOPING. MORE CONSISTENCY DEVELOPS WITH CLEARING BEHIND THE COLD
FRONT, AS SHOWERS LOOK TO END WEST OF I-55 BY MIDNIGHT, WEST OF I-57
BY 4 AM FRIDAY, AND THROUGHOUT IL BY 7 AM FRIDAY. HIGH RESOLUTION
MODEL ENSEMBLES DEPICT AVERAGE PRECIPITATION AMOUNTS OF AROUND A
HALF INCH, BUT ALSO DEPICT A FEW SWATHS OF 1 TO 3 INCHES. THIS
RAINFALL WILL GENERALLY BE BENEFICIAL WITH MOSTLY DRY CONDITIONS
PRECEDING THE PAST FEW DAYS, BUT 2 TO 3 INCH AMOUNTS COULD PRODUCE
SOME LOCALLY EXCESSIVE AMOUNTS AND WPC INDICATES A MARGINAL RISK FOR
EXCESSIVE RAINFALL FROM AROUND I-72 SOUTHWARD.
BEHIND TONIGHT'S STRONG COLD FRONT, A STRONG PRESSURE GRADIENT
DEVELOPS OVER THE AREA FOR FRIDAY, WHICH SHOULD SET UP 15-20 MPH
NORTHWEST WINDS, WITH GUSTS 30-40 MPH, WITH THE HIGHER VALUES WEST
OF I-55. A POTENT UPPER LEVEL SHORTWAVE AND 500 MB COLD POCKET OF
MINUS 25 C WILL PROMOTE SCATTERED SHOWER ACTIVITY AND CLOUD COVER.
HIGHS SHOULD ONLY REACH THE MID 50S FOR A VERY COLD/BLUSTERY FEEL
COMPARED WITH RECENT RECORD WARMTH.
FRIDAY NIGHT, HIGH PRESSURE WILL MIGRATE EASTWARD TOWARD THE
MISSISSIPPI VALLEY, WEAKENING THE PRESSURE GRADIENT OVER ESPECIALLY
WESTERN PORTIONS OF CENTRAL IL. WITH TEMPERATURES DROPPING INTO THE
MID 30S AND THE LIGHT WINDS, IT APPEARS AREAS OF FROST WILL DEVELOP
WEST OF I-57, BUT TO THE EAST ENOUGH WIND SHOULD REMAIN TO KEEP
TEMPERATURES IN THE UPPER 30S WITHOUT FROST. BY SUNDAY MORNING, THE
HIGH SHOULD MIGRATE TOWARD THE MID-ATLANTIC COAST, WITH WINDS
ALREADY BEGINNING TO PICK UP FROM THE SOUTH BY MORNING.
NEVERTHELESS, MID-30S TEMPERATURES AND FROST POTENTIAL LOOKS TO
COVER THE ENTIRE AREA AS THE WIND WILL LIKELY BE TOO LITTLE/TOO LATE
TO PREVENT IT.
SOUTHERLY FLOW AND A BUILDING RIDGE OF HIGH PRESSURE WILL BRING A
WARMING TREND STARTING SUNDAY, RAISING HIGHS FROM UPPER 50S SATURDAY
TO UPPER 60S SUNDAY. FURTHER WARMING THROUGH MIDWEEK SHOULD BRING
HIGHS TO MID TO UPPER 70S BY WEDNESDAY. DRY CONDITIONS WILL CONTINUE
SATURDAY THROUGH MIDWEEK UNDER THE INFLUENCE OF THE SURFACE HIGH
FOLLOWED BY UPPER RIDGE.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1227 AM CDT THU OCT 15 2026
CEILINGS ARE HOVERING IN THE 3,000 FOOT VICINITY ACROSS CENTRAL
ILLINOIS, BUT SHOULD SOLIDLY BE BELOW 2,000 FEET BY 12Z. AS
FRIDAY MORNING PROGRESSES, CEILINGS SHOULD DETERIORATE FURTHER
AS RAIN MOVES UP FROM THE SOUTHWEST, AND A PERIOD OF IFR
CONDITIONS IS MOST LIKELY AT KPIA (40-70% CHANCE) BY LATE
MORNING. SOME MODEST IMPROVEMENT IS EXPECTED LATER IN THE
AFTERNOON AS A WARM FRONT LIFTS NORTHWARD, WITH A BRIEF PERIOD
OF VFR CONDITIONS POSSIBLE FROM KSPI-KCMI TOWARD 00Z, BUT ANY
IMPROVEMENT WILL BE SHORT LIVED AS MORE LOW CLOUDS FOLLOW THE
ARRIVAL OF A COLD FRONT FROM THE NORTHWEST IN THE EVENING.
EAST/NORTHEAST WINDS ARE EXPECTED TO BECOME MORE SOUTHERLY
TOWARD 18Z AS THE WARM FRONT LIFTS THROUGH. LATE IN THE PERIOD,
EXPECT WEST/NORTHWEST WINDS BEHIND THE COLD FRONT, WITH SOME
GUSTS 20-25 KNOTS FROM KBMI-KSPI WEST.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...37
DISCUSSION...37
AVIATION...GEELHART
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