674
FXUS63 KILX 162248
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
548 PM CDT THU OCT 16 2025
KEY MESSAGES
- SEASONABLY WARM WEATHER STICKS AROUND THROUGH FRIDAY. MUCH
COOLER TEMPERATURES RETURN EARLY NEXT WEEK.
- THERE IS CURRENTLY A LOW (5-15%) RISK FOR SEVERE WEATHER TO
OCCUR SATURDAY AFTERNOON AND EVENING IN AREAS EAST OF THE
ILLINOIS RIVER VALLEY. THIS RISK IS PRIMARILY DRIVEN BY THE
POTENTIAL FOR DAMAGING THUNDERSTORM WINDS.
- PERIODS OF HEAVY RAIN WILL OCCUR SATURDAY AFTERNOON AND EVENING.
THERE IS CURRENTLY A HIGH (50-80%) CHANCE THAT RAINFALL TOTALS
WILL EXCEED 1" IN AREAS EAST OF THE ILLINOIS RIVER VALLEY;
SOURCE: LATEST 13Z NBM.
DISCUSSION
ISSUED AT 147 PM CDT THU OCT 16 2025
|SYNOPTIC PATTERN|
AFTERNOON WATER VAPOR IMAGERY SHOWS A CLOSED, UPPER-LEVEL LOW
OVER THE MIDDLE ROCKIES. MODEL GUIDANCE INDICATES THIS FEATURE AND
ITS ASSOCIATED SURFACE LOW WILL MOVE INTO MANITOBA BY FRIDAY
MORNING, BECOMING OCCLUDED AND SLOWING THE COLD FRONT'S EASTWARD
PROGRESS. BY FRIDAY EVENING, THE COLD FRONT WILL STRETCH FROM
MINNEAPOLIS TO DODGE CITY, KANSAS.
THE FRONT WILL ACCELERATE SIGNIFICANTLY BY SATURDAY MORNING AS AN
UPPER-LEVEL JET MAXIMUM AND A COMPACT, MID-LEVEL SHORTWAVE TROUGH
MOVE ACROSS THE SOUTHERN PLAINS TOWARDS THE MISSOURI OZARKS. A
DEEPENING SURFACE LOW WILL DEVELOP ACROSS THE MID- MISSISSIPPI
VALLEY SATURDAY, LEADING TO INCREASED WINDS AND THUNDERSTORM
COVERAGE WITHIN THE WARM SECTOR. GUSTY WINDS, MUCH COOLER
TEMPERATURES, AND LINGERING SHOWERS ARE THEN EXPECTED INTO SUNDAY
MORNING BEFORE THE SURFACE LOW AND COLD FRONT DEPART EASTWARD.
MONDAY WILL SEE A QUICK REBOUND IN TEMPERATURES, DRIVEN BY BREEZY
SOUTHERLY WINDS PRECEDING YET ANOTHER FAST-MOVING FRONTAL SYSTEM.
AS THIS COLD FRONT MOVES ACROSS CENTRAL ILLINOIS ON TUESDAY
MORNING, EXPECT ANOTHER ROUND OF SCATTERED SHOWERS AND
THUNDERSTORMS.
SEASONABLY COOLER WEATHER IS EXPECTED BY THE MIDDLE OF NEXT WEEK,
WITH SOME FORECAST GUIDANCE INDICATING A TREND TOWARD FROSTY
CONDITIONS BY WEDNESDAY MORNING.
|SEVERE WEATHER POTENTIAL|
BY SATURDAY MIDDAY, A STRONG KINEMATIC PROFILE IS EXPECTED TO
DEVELOP ACROSS OUR REGION. HOWEVER, THE THERMODYNAMIC ENVIRONMENT
PRECEDING THE COLD FRONT REMAINS UNCERTAIN. CURRENT ENSEMBLE
GUIDANCE SHOWS CONSIDERABLE SPREAD IN THE TIMING AND POSITION OF
ADDITIONAL LOW-PRESSURE DEVELOPMENT ALONG THE FRONT. SPECIFICALLY,
THE GEFS DEPICTS A FASTER AND MORE NORTHERLY LOW-PRESSURE SYSTEM,
WHILE THE EPS AND AIFS ENSEMBLES SUGGEST A SLOWER AND MORE
SOUTHERLY SURFACE LOW.
A GEFS-LEANING SCENARIO WOULD BRING MORE FAVORABLE MOISTURE
RETURN AND INSTABILITY, AND THUS CONVECTIVE COVERAGE, TO A LARGER
AREA OF ILLINOIS. CONVERSELY, AN EPS/AIFS ENSEMBLE-LEANING
SCENARIO WOULD CONFINE THE BETTER THERMODYNAMIC CONDITIONS AND
COVERAGE TO SOUTHERN ILLINOIS. AT PRESENT, BOTH SCENARIOS ARE
EQUALLY PROBABLE. WE ANTICIPATE THAT HIGH-RESOLUTION GUIDANCE FROM
THIS EVENING'S 00Z SUITE OF CAMS WILL HELP TO RESOLVE THIS
PATTERN.
ALL THAT ASIDE, THE STORM MODE COULD SHAPE UP TO BE A MESSY ONE.
A LINEAR MODE SEEMS MOST LIKELY ACROSS OUR CWA GIVEN THE NEAR-
PARALLEL ORIENTATION OF THE SHEAR VECTORS WITH RESPECT TO THE COLD
FRONT. A STOUT LLJ VEERING IN AHEAD OF THE FRONT WOULD POINT TO
PRIMARILY A DAMAGING WIND THREAT, WITH NUMEROUS REFLECTIVITY TAGS
SHOOTING UP AHEAD OF THE LINE, AND EVEN SOME ENHANCED BOWING
SEGMENTS WITHIN THE LINE ITSELF.
BEYOND SATURDAY, ANOTHER SNEAKY EPISODE OF SEVERE WEATHER COULD
EVOLVE TUESDAY MORNING AS A COLD FRONT RACES INTO WESTERN
ILLINOIS. CURRENT MODEL GUIDANCE SUGGESTS A LINEAR STORM MODE ONCE
AGAIN. THIS IS DUE TO A NARROW BAND OF FAVORABLE THERMODYNAMICS,
ACCOMPANIED BY A ROBUST/PARALLEL SHEAR PROFILE, PUSHING INTO THE
AREA ALONG THE FRONT. MOREOVER, THE STRONG LLJ AND STEEP LOW-LEVEL
LAPSE RATES AHEAD OF THE FRONT COULD POINT TOWARD A THIN AND
KINKY QLCS SUPPORTIVE OF DAMAGING WINDS AND A BRIEF TORNADO.
|BENEFICIAL RAINFALL|
A SWIFT-DIGGING, MID-LEVEL TROUGH ACROSS THE SOUTHERN PLAINS ON
SATURDAY WILL HELP DRAW GULF MOISTURE NORTHWARD INTO THE LOWER-
AND MID-MISSISSIPPI VALLEYS, IN WHAT COULD BE THE BEST SYNOPTIC
RAIN EVENT IN SOME PARTS OF CENTRAL ILLINOIS IN OVER 10 WEEKS.
A QUICK GLANCE AT CLIMATOLOGY SUGGESTS THAT PWATS ON SATURDAY (>
1.25") WILL BE IN THE WETTEST 95TH PERCENTILE FOR THIS TIME OF
YEAR. THAT IS AN IMPORTANT NOTE AS WE SIFT THROUGH ALL THE
DETERMINISTIC AND ENSEMBLE DATA, ESPECIALLY WITH RESPECT TO THE
UPPER AND LOWER TAILS OF THE DISTRIBUTION. TO THAT POINT, THE
LATEST OPERATIONAL RUN OF THE NBM (13Z) SUGGESTS THAT THE TAILS OF
THE QPF DISTRIBUTION (10TH -90TH PERCENTILE) WILL RANGE BETWEEN
0.2" AND 3" IN AREAS EAST OF THE ILLINOIS RIVER. IN OTHER WORDS,
EVEN IN A BUST SCENARIO, WE CAN EXPECT ABOUT A 0.25" OF RAINFALL.
OBVIOUSLY, THE UP SHOT IS SOMETHING MORE SIGNIFICANT, AND GIVEN
THE ANOMALOUS PWATS THAT WE WILL HAVE IN PLACE, AND A MEAN WIND
(850-300 MB) ROUGHLY PARALLEL TO THE SURFACE FRONT, IT IS NOT
UNREASONABLE THAT THERE COULD BE LOCALIZED RAINFALL AMOUNTS THAT
APPROACH THE UPPER TAIL (90TH PERCENTILE) OF THE QPF DISTRIBUTION.
AGAIN, WE WILL EAGERLY AWAIT THIS EVENING'S 00Z SUITE OF CAMS TO
BEGIN ANALYZING CONVECTIVE TRENDS WITH RESPECT TO WHERE THE AXIS
OF HEAVIEST RAINFALL MIGHT EVOLVE, AND HOW MUCH.
MJA
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 548 PM CDT THU OCT 16 2025
CLEAR SKIES AND SOUTHEAST WINDS UNDER 10 KT WILL DOMINATE THE
CENTRAL IL TERMINALS TONIGHT. PRESSURE GRADIENT TIGHTENS FRIDAY
MORNING, AND WE EXPECT GUSTS NEAR 20 KT TO DEVELOP AND CONTINUE
THROUGH AFTERNOON. MID TO HIGH LEVEL VFR CLOUDS FOR MUCH OF
FRIDAY.
25
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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