590
FXUS63 KILX 121908
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
208 PM CDT THU MAR 12 2026
KEY MESSAGES
- WIND GUSTS UP TO 50 MPH DEVELOP TONIGHT AND CONTINUE THROUGH
MIDDAY FRIDAY, NECESSITATING A WIND ADVISORY FOR ALL OF CENTRAL
AND SOUTHEAST ILLINOIS.
- A STRONG COLD FRONT SUNDAY BRINGS A RISK OF SEVERE STORMS FOR
THE AFTERNOON AND EVENING, FOLLOWED BY A CHANGEOVER TO SNOW
SUNDAY NIGHT.
- SHARPLY COLDER AIR BEHIND THE STORM SYSTEM WILL DRIVE WIND
CHILLS BELOW ZERO FOR SUNDAY NIGHT AND MONDAY NIGHT.
DISCUSSION
ISSUED AT 208 PM CDT THU MAR 12 2026
THE PRIMARY SHORT-TERM FORECAST CONCERN INVOLVES IMPACTFUL WIND
GUSTS TONIGHT THROUGH FRIDAY AFTERNOON. AS A SUB-990 MB SURFACE
LOW TRACKS ACROSS THE UPPER MIDWEST, THE TIGHT PRESSURE GRADIENT
BETWEEN THIS LOW AND HIGH PRESSURE OVER THE SOUTHEAST CONUS
RESULTS IN SUSTAINED SOUTHWESTERLY WINDS OF 20-30 MPH, GUSTING
NEAR 45 MPH TONIGHT. FORECAST SOUNDINGS FROM THE RAP AND HRRR SHOW
A 50-60 MPH LOW- LEVEL JET AT 1-2 KFT AGL. WHILE A NEAR-SURFACE
STABLE LAYER OFTEN LIMITS OVERNIGHT MIXING, THE STRENGTH OF THE
GRADIENT SUPPORTS ADVISORY LEVEL WINDS DURING THE OVERNIGHT
PERIOD. LIFT AHEAD OF A SOUTHEASTWARD ADVANCING COLD FRONT WILL
BRING IN INCREASE IN MID LEVEL CLOUDS TONIGHT, AND A 20-30% CHANCE
OF SPRINKLES/SHOWERS MAINLY NORTH OF I-72. ANY SHOWERS WOULD HAVE
THE POTENTIAL TO MIX DOWN THE HIGHER MOMENTUM AIR ALOFT, MAKING A
FEW 50+ MPH GUSTS POSSIBLE. WINDS BACK WSW TO WNW BEHIND THE
FRONTAL PASSAGE FRIDAY MORNING. DIURNALLY INCREASING MIXING DEPTHS
TO THE BASE OF THE WANING LLJ WILL BRING A QUICK SURGE OF HIGHER
WIND GUSTS AFTER SUNRISE, LIKELY IN THE 45-55 MPH RANGE, WITH THE
HIGHER END GUSTS GRADUALLY LOWERING THROUGH MIDDAY. THIS WILL BE
CLOSE TO HIGH WIND WARNING CRITERIA (SUSTAINED 40+ MPH OR GUSTS
58+ MPH) AND WE'LL BE MONITORING THE NEED FOR EVENTUAL HEADLINE
UPGRADE, MAINLY ACROSS THE NORTHERN CWA. WINDS TO RAPIDLY DECREASE
FRIDAY AFTERNOON AND EVENING AS SURFACE RIDGING BUILDS IN FROM
THE WEST.
ATTENTION THEN SHIFTS TO SUNDAY AS A MEDIUM RANGE GUIDANCE SHOWS
A CLASSIC DEEPENING MID LATITUDE CYCLONE AFFECTING THE MIDWEST.
AHEAD OF THE LOW, WARM- SECTOR TEMPERATURES WILL SURGE INTO THE
60S SUNDAY. DEEP- LAYER SHEAR OF 45-50 KNOTS SUPPORTS ORGANIZED
CONVECTION ALONG/AHEAD OF THE ADVANCING COLD FRONT SUNDAY
AFTERNOON TO EVENING. AT THIS POINT LOW-LEVEL MOISTURE RETURN
REMAINS A LIMITING FACTOR FOR WIDESPREAD SEVERE WEATHER, HOWEVER
THE STRONG BACKGROUND WIND FIELD AND DEEPENING LOW MAKE DAMAGING
GUSTS A CONCERN WITHIN ANY DEVELOPING LINES OF STORMS. CSU-MLP
HIGHLIGHTS AREAS EAST OF I-55 FOR THE BETTER SEVERE POTENTIAL,
WHILE THE LATEST SPC OUTLOOK KEEPS THE NORTHERN EDGE OF THE RISK
AREA OVER SOUTHERN IL.
ROBUST COLD ADVECTION BEHIND THE FRONT WILL DRIVE A TRANSITION
FROM RAIN TO SNOW FROM THE NORTHWEST SUNDAY EVENING/NIGHT. 12Z
DETERMINISTIC GUIDANCE SHOWS A RESPECTABLE DEFORMATION ZONE ON
THE BACK SIDE OF THE LOW, AND CORRESPONDINGLY THE LATEST RUNS OF
THE NBM HAVE INCREASED SNOWFALL ACCUMULATIONS OVER CENTRAL IL.
TIGHT MSLP GRADIENT ON THE BACK SIDE OF THE LOW WILL BRING
ANOTHER ROUND OF HIGH WINDS TO THE AREA SUNDAY NIGHT AND MONDAY.
TODAY'S WPC GUIDANCE SHOWS A 60-80% CHANCE OF MINOR IMPACTS AND
20-30% CHANCE OF MODERATE IMPACTS. THIS SYSTEM WILL NEED TO BE
MONITORED OVER THE COMING FORECAST CYCLES AS IT APPEARS IMPACTFUL
WINTER WEATHER WILL OCCUR IN THE REGION, THOUGH CONFIDENCE ON THE
TRACK OF THE LOW AND ASSOCIATED SNOW BAND IS LOW-MEDIUM.
AN UNSEASONABLY COLD, LATE SEASON ARCTIC AIRMASS WILL DIVE
SOUTHEAST ACROSS THE MIDWEST BEHIND THE STORM. THE ECMWF EFI
SHOWS VALUES BETWEEN -0.7 AND -0.8 FOR MONDAY AND TUESDAY,
INDICATING AN UNUSUAL COLD EVENT FOR MID- MARCH. LATEST BLENDED
GUIDANCE SHOWS 20S HIGH TEMPERATURES MONDAY AND LOWS IN THE SINGLE
DIGITS MONDAY NIGHT. BREEZY CONDITIONS THROUGH THE PERIOD WILL
LIKELY DRIVE WIND CHILLS TO THE SINGLE DIGITS BELOW ZERO FOR MOST
OF THE CWA SUNDAY NIGHT AND MONDAY NIGHT.
25
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1214 PM CDT THU MAR 12 2026
VFR THROUGH THE PERIOD. THERE IS A LOW CHANCE (20-30%) FOR A FEW
SHRA TONIGHT AHEAD OF A COLD FRONT. DUE TO THE DRYNESS OF THE
AIRMASS, THIS SHOULD NOT IMPACT CATEGORY SO JUST INCLUDED VCSH.
THE MAIN IMPACT OF THE FRONT FOR ALL OF THE CENTRAL IL TERMINALS
WILL BE AN INCREASE IN WIND SPEED AND GUSTS LATER THIS AFTERNOON,
THROUGH THE REMAINDER OF THE FORECAST. INITIALLY WEST WINDS EARLY
THIS AFTERNOON WILL BACK SOUTHWEST TO SOUTH AHEAD OF THE FRONT
TONIGHT, THEN VEER BACK SOUTHWEST AND EVENTUALLY WEST AFTER THE
FRONTAL PASSAGE TONIGHT INTO FRIDAY MORNING. GUSTS WILL INCREASE
TO 20-30 KT TONIGHT, AND 30-40 KT AFTER SUNRISE, HIGHEST NEAR AND
NORTH OF THE I-74 CORRIDOR. A 55 KT LOW LEVEL JET WILL BRING
MARGINAL LLWS CRITERIA OVERNIGHT, AND INCLUDED THIS MENTION AT ALL
TERMINALS.
25
ILX WATCHES/WARNINGS/ADVISORIES
WIND ADVISORY FROM 10 PM THIS EVENING TO 4 PM CDT FRIDAY FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.
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