453
FXUS63 KILX 160517
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1217 AM CDT THU APR 16 2026
KEY MESSAGES
- THERE IS A 50-70% CHANCE FOR SCATTERED THUNDERSTORMS THROUGH
THIS EVENING. SOME OF THESE STORMS COULD BE SEVERE, INCLUDING
HEAVY RAINFALL.
- THERE IS ANOTHER RISK FOR SEVERE STORMS LATE FRIDAY EVENING THROUGH
SATURDAY.
- MUCH COOLER WEATHER RETURNS THIS WEEKEND. THERE IS A LOW
CHANCE FOR FROST SATURDAY NIGHT NORTH OF INTERSTATE 70, AND A
HIGHER CHANCE AREAWIDE SUNDAY NIGHT.
UPDATE
ISSUED AT 753 PM CDT WED APR 15 2026
CLUSTERS OF STRONG TO SEVERE THUNDERSTORMS EXTEND FROM SOUTHERN
WISCONSIN TO SOUTHWEST MISSOURI EARLY THIS EVENING. WHILE THE
MAIN SHORTWAVE IS MOVING THROUGH EASTERN NEBRASKA, SOME MORE
SUBTLE IMPULSES ARE HELPING TO FUEL THE ONGOING STORMS. LATEST
HRRR RUNS HAVE BEEN STRUGGLING WITH SOME CONSISTENCY ON THE
OVERALL TRENDS, BUT THE BIGGER SEVERE THREAT IN OUR CWA WILL BE
WEST OF I-55 INTO LATE EVENING.
MAIN FORECAST UPDATES HAVE BEEN TO TWEAK THE RAIN CHANCES
THROUGH THURSDAY.
DISCUSSION
ISSUED AT 221 PM CDT WED APR 15 2026
A SHORTWAVE TROUGH OVER THE CENTRAL PLAINS WILL PIVOT INTO WESTERN
IOWA THIS EVENING AND SERVE AS ONE OF THE MAIN FORCING MECHANISMS
FOR THUNDERSTORM DEVELOPMENT ACROSS A GOOD PORTION OF THE CENTRAL US
THIS EVENING, INCLUDING CENTRAL ILLINOIS. LINGERING RAIN SHOWERS
WILL CONTINUE TO IMPACT PARTS OF EASTERN AND SOUTHEAST ILLINOIS THIS
AFTERNOON, WITH A LULL IN PRECIPITATION FURTHER WEST. SEVERAL
SHORTWAVE IMPULSES AHEAD OF THE MAIN UPPER WAVE MAY BRING PERIODS OF
SHOWERS AND STORMS WORKING ACROSS THE AREA FROM LATE AFTERNOON INTO
THIS EVENING WITH THE LATEST CAMS SHOWING ISOLATED ACTIVITY
SPREADING IN AS EARLY AS 21Z/4 PM WEST OF THE ILLINOIS RIVER.
ENVIRONMENTAL CONDITIONS HAVE BEEN SLOW TO IMPROVE DUE TO
WIDESPREAD CLOUD COVER FROM MORNING STORMS. RAP FORECAST
ANALYSIS SUGGESTS SBCAPE WILL APPROACH 1500 J/KG IN WESTERN
ILLINOIS OVER THE NEXT FEW HOURS WITH DEEP LAYER SHEAR UP AROUND
40 KTS, WHICH IS SUFFICIENT FOR STORM ORGANIZATION. ALTHOUGH
THE MAIN SURFACE FRONT REMAINS DISPLACED OFF TO OUR NORTH,
BETTER FORCING FROM THE APPROACHING WAVE SHOULD SUPPORT ISOLATED
TO SCATTERED THUNDERSTORMS THROUGH THIS EVENING. HODOGRAPHS
FAVOR SUPERCELL/MULTICELLULAR STORM MODES, POSING A THREAT FOR
ALL SEVERE HAZARDS. ALTHOUGH TIMING AND COVERAGE OF LATE
AFTERNOON/EARLY EVENING STORMS REMAINS LOW, CAM OUTPUT BECOMES
MORE CONSISTENT LATER THIS EVENING AS A LINEAR MCS WORKS THROUGH
THE AREA AS THE SURFACE FRONT NEARS. ALTHOUGH INSTABILITY WILL
WANE SOME BY THEN, THE THREAT FOR DAMAGING WINDS WILL STILL BE A
THREAT.
HEAVY RAIN IS ALSO A CONCERN THROUGH TONIGHT, ESPECIALLY OVER
AREAS THAT PICKED UP 1-2"+ THIS MORNING (ALONG A RUSHVILLE TO
BLOOMINGTON LINE). WARM CLOUD DEPTHS, HIGH PWATS, AND THE
POTENTIAL FOR REPEATING ROUNDS OF STORMS COULD LEAD TO A
LOCALIZED FLASH FLOODING THREAT. THE 15.12Z HREF 24 HOUR LPMM
SHOWS POCKETS OF 2"+ OVER PARTS OF THE AREA, THOUGH CONFIDENCE
IN THE EXACT LOCATION OF THESE AMOUNTS REMAINS LOW.
A BREAK FROM STORMS IS EXPECTED ON THURSDAY AS LARGE-SCALE
SUBSIDENCE OVERSPREADS THE AREA BEHIND THE DEPARTING UPPER
SHORTWAVE. HOWEVER, THE THREAT FOR MORE THUNDERSTORMS RETURNS FRIDAY
EVENING INTO SATURDAY AS A COMPACT UPPER SHORTWAVE TRACKS THROUGH
THE UPPER MISSISSIPPI VALLEY AND SENDS A COLD FRONT THROUGH THE
AREA. THE FRONT LOOKS TO APPROACH THE MISSISSIPPI RIVER FRIDAY
EVENING THEN WORK THROUGH CENTRAL ILLINOIS DURING THE OVERNIGHT
HOURS. THE HIGHEST RISK FOR SEVERE WEATHER IS CURRENTLY EXPECTED
JUST WEST OF HERE WHERE INSTABILITY AND SHEAR WILL BE STRONGEST
DURING A DIURNALLY FAVORABLE TIME. HOWEVER, SUFFICIENT CAPE/SHEAR
PARAMETERS THROUGH THE OVERNIGHT HOURS COULD STILL SUPPORT THE
DEVELOPMENT OF SCATTERED SEVERE STORMS.
TEMPERATURES TURN MUCH COOLER BY THE WEEKEND. OVERNIGHT LOWS
SATURDAY AND SUNDAY NIGHTS LOOK TO DIP DOWN INTO THE MIDDLE TO UPPER
30S, WHICH INTRODUCES THE POSSIBILITY FOR FROST. CHANCES ARE LOWER
SATURDAY NIGHT DUE TO LINGERING CLOUD COVER AND BREEZIER WINDS, WITH
HIGHER CHANCES SUNDAY NIGHT WHEN WINDS ARE LIGHTER.
TEMPERATURES MODERATE BY THE MIDDLE PARTS OF NEXT WEEK AS UPPER
RIDGING AMPLIFIES OVER THE WEST-CENTRAL US. PRECIPITATION CHANCES
LOOK MINIMAL THROUGH MUCH OF NEXT WEEK WITH GLOBAL MODELS HINTING AT
A WETTER PATTERN SETTING UP BY THE END OF NEXT WEEK INTO NEXT
WEEKEND.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1217 AM CDT THU APR 16 2026
AREA OF RAIN WILL EXIT THE EASTERN TERMINALS OVER THE NEXT HOUR
OR SO. THERE IS A LOW (20-40% CHANCE) THAT MVFR STRATOCU WILL
DEVELOP NEAR/AFTER DAYBREAK, OTHERWISE CONDITIONS WILL BE VFR
THROUGH THE FORECAST. SOUTHWEST WINDS WILL REMAIN GUSTY NEAR 25
KT UNTIL LATE AFTERNOON, THEN GO LIGHT AS SURFACE RIDGING
BUILDS IN.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...NMA
UPDATE...GEELHART
DISCUSSION...NMA
AVIATION...25
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