261
FXUS63 KILX 152341
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
641 PM CDT MON JUN 15 2026
KEY MESSAGES
- SEVERE STORMS ARE POSSIBLE ON TUESDAY AND WEDNESDAY. FOR
TUESDAY, THERE IS A MARGINAL RISK (LEVEL 1 OF 5) EAST OF THE
IL RIVER. FOR WEDNESDAY, THERE IS AN ENHANCED RISK (LEVEL 3
OF 5). REVIEW YOUR SEVERE THUNDERSTORMS SAFETY PLAN, AND STAY
WEATHER AWARE OVER THE COMING DAYS.
- BREEZY WIND GUSTS ARE LIKELY ON WEDNESDAY, WITH SOUTHWESTERLY
GUSTS OF 30-45 MPH.
DISCUSSION
ISSUED AT 135 PM CDT MON JUN 15 2026
VIS SATELLITE SHOWS SCATTERED DIURNAL CUMULUS HAVE DEVELOP
ACROSS THE REGION. PLEASANT CONDITIONS PERSIST, WITH TEMPS IN
THE LOW 70S AND DEWPOINTS IN THE UPPER 40S. QUIET CONDITIONS
PREVAIL THROUGH TONIGHT, WITH SEASONABLY COOL TEMPS AS LOWS FALL
INTO THE MID-50S ONCE AGAIN, WHICH IS ABOUT 5-10 DEGREES BELOW
NORMAL. AN EXPANSIVE, SYNOPTIC SCALE TROUGH WAS POSITIONED NEAR
THE HUDSON BAY, AND MULTIPLE EMBEDDED SHORTWAVES WILL RESULT IN
SEVERE STORM CHANCES RETURNING TO THE FORECAST BOTH TUES AND
WED, WITH THE GREATEST CONCERN BEING ON WED.
*** TUESDAY ***
AT 18Z/1PM MON, SATELLITE IMAGERY REVEALED A SHORTWAVE DIGGING
SOUTHEAST ACROSS NORTH DAKOTA. AS THIS WAVE CONTINUES SE, A SFC
LOW IS EXPECTED TO TRACK INTO WI BY TUES AM, WITH THE ASSOCIATED
COLD FRONT BRINGING A SCATTERED/BROKEN LINE OF SHOWERS AND
STORMS INTO THE CWA.
CAMS DEPICT A RELATIVELY CONSISTENT PRECIP TIMING AS THE COLD
FRONT SWINGS ACROSS THE AREA OVER THE COURSE OF THE DAY TUES
(GIVE OR TAKE A FEW HOURS). BASED ON THESE CAMS, THE BEST GUESS
OF PRECIP TIMING IS 6-8 AM WEST OF THE IL RIVER, 7-10 AM FROM
THE IL RIVER TO I-55, LATE MORNING FROM I-55 TO I-72/DANVILLE,
AND DURING THE AFTERNOON ALONG AND SOUTH OF I-72/DANVILLE. BASED
ON THIS DIURNAL TIMING, THE BEST CHANCE FOR ANY STRONGER STORMS
WILL BE EAST OF THE IL RIVER, AS DAYTIME HEATING LEADS TO
GRADUALLY BUILDING INSTABILITY. HREF MEMBERS GENERALLY DEPICT
PEAK INSTABILITY VALUES BETWEEN 500-1500 J/KG. THESE VALUES ARE
ON THE LOWER SIDE FOR MID-JUNE, BUT NEVERTHELESS WHEN COMBINED
WITH DEEP LAYER SHEAR VALUES OF 40+ KTS THE PARAMETER SPACE WILL
BE SUFFICIENT FOR STRONG TO SEVERE STORMS. THE MARGINAL RISK
(LEVEL 1 OF 5) WAS EXPANDED TO INCLUDE MOST AREAS EAST OF THE IL
RIVER, AND ALL HAZARDS ARE POSSIBLE.
*** WEDNESDAY ***
ANOTHER POTENT SHORTWAVE AND ASSOCIATED SFC LOW PRESSURE
APPROACHES FROM THE NORTHWEST WED PM, AND CENTRAL IL IS
EXPECTED TO BE FIRMLY WITHIN THE WARM SECTOR AS LATEST GUIDANCE
TRACKS THE SFC LOW NEAR THE IA/MN BORDER. THIS WAVE WILL FEATURE
SEASONABLY STRONG KINEMATICS/WIND SHEAR. DETERMINISTIC MODEL
FORECASTS SUGGEST A POTENT LOW-LEVEL JET DEVELOPING WED EVE,
WITH 850MB WINDS APPROACHING OR EXCEEDING 60 KTS, WHICH WOULD BE
NEAR OR ABOVE THE HIGHEST VALUES SAMPLED IN THE ILX SOUNDING
CLIMATOLOGY FOR MID-JUNE. SIMILARLY, THE ECMWF ENS MEAN WIND
SPEEDS AT 500MB, 700MB, AND 850MB ARE ALL ABOVE THE 99TH
PERCENTILE OF THE MODEL CLIMATOLOGY FOR MID- JUNE. COMBINED WITH
JUNE THERMODYNAMICS/INSTABILITY VALUES (2000- 3000 J/KG) AND
AMPLE ASCENT FROM AN APPROACHING FRONT AND UPPER WAVE, THERE IS
GROWING CONCERN THAT A SEVERE THUNDERSTORM OUTBREAK WILL OCCUR.
IN RELATION TO AN APPROACHING FRONT, DEEP LAYER SHEAR VECTOR
CROSSING ANGLES ARE CLOSER TO 45 DEGREES, WHICH IS A LARGER
CROSSING ANGLE THAN OTHER RECENT EVENTS AND MAY SUPPORT A LONGER
WINDOW FOR DISCRETE OR SEMI-DISCRETE STORM MODES. NEVERTHELESS,
THE LINEAR ASCENT AND EVENTUAL COLD POOL INTERACTIONS ARE
EXPECTED TO RESULT IN UPSCALE GROWTH INTO WED EVENING. ALL
HAZARDS ARE POSSIBLE, BUT DAMAGING STRAIGHT-LINE WIND GUSTS AND
STRONG TORNADOES (INCLUDING LINE-EMBEDDED TORNADOES) ARE THE TOP
CONCERNS.
RECENT MODELS HAVE TRENDED SLIGHTLY NORTHEAST WITH THE SYSTEM,
SO THE DETAILS ARE NOT YET SET IN STONE. THERE IS ALSO SOME
POTENTIAL FOR MORNING CONVECTION, WHICH AS ALWAYS ADDS A WRINKLE
TO THE AFTERNOON/EVENING FORECAST. THE LATEST OUTLOOK MAINTAINS
AN ENHANCED RISK (LEVEL 3 OF 5) ACROSS A LARGE PORTION OF THE
ILX COVERAGE AREA. GIVEN THE CONCERNING PARAMETER SPACE, AN
UPGRADE TO A MODERATE RISK (LEVEL 4 OF 5) MAY BE WARRANTED IN
FUTURE OUTLOOKS IF FORECAST CONFIDENCE INCREASES REGARDING THE
IMPACT OF THE MORNING STORMS AND THE PLACEMENT OF THE GREATEST
SEVERE RISK.
PRECIPITABLE WATER (PWAT) VALUES ARE FORECAST TO BE QUITE HIGH,
POTENTIALLY IN EXCESS OF 2". THE ROBUST KINEMATICS WILL IN
THEORY LIMIT THE RESIDENCE TIME OF ANY ONE UPDRAFT OVER A GIVEN
LOCATION, HOWEVER, CORFIDI VECTORS SUGGEST BACK-BUILDING STORM
MOTIONS OF JUST 10-15 KTS, WHICH COULD LEAD TO SOME HEAVIER
RAINFALL TOTALS WHERE BACK-BUILDING/TRAINING DOES OCCUR. CAMS
DON'T QUITE CAPTURE THE FULL EVENT YET, BUT HIGH-END RAINFALL
AMOUNTS (90TH PERCENTILE) FROM THE NBM ARE ON THE ORDER OF 2-3".
THERE IS A SLIGHT RISK (LEVEL 2 OF 4) OF EXCESSIVE RAINFALL.
EVEN IN ADVANCE OF THE STORMS ON WED, THE STRONG KINEMATICS OF
THIS SYSTEM WILL RESULT IN STOUT SYNOPTIC WIND GUSTS AS PBL
MIXING TRANSPORTS STRONGER WINDS TO THE SFC. THERE IS A HIGH
LIKELIHOOD (60- 80%) OF 30-40 MPH WIND GUSTS, AND GUSTS
EXCEEDING WIND ADVISORY (45+ MPH) ARE POSSIBLE (30-50%). THE
STRONGEST GUSTS SYNOPTIC GUSTS WILL BE OUT OF THE SOUTH-
SOUTHWEST, MEANING POTENTIAL TRAVEL DIFFICULTIES WOULD BE MOST
NOTICEABLE ON EAST-WEST ORIENTED ROADS SUCH AS I-72 OR I-74. A
WIND ADVISORY MAY BE NEEDED.
*** REST OF THE WEEK ***
GLOBAL ENSEMBLES GENERALLY SUGGEST TROUGHING PERSISTING ACROSS
THE UPPER MIDWEST LATE WEEK INTO THE WEEKEND, FAVORING BELOW
NORMAL TEMPS. THE LATEST DETERMINISTIC NBM KEEPS HIGHS IN THE
UPPER 70S TO LOW 80S ACROSS MUCH OF THE REGION THURS-SUN. THE
PATTERN REMAINS UNSETTLED, WITH OCCASIONAL PRECIP CHANCES AS
ADDITIONAL EMBEDDED WAVES APPROACH FROM THE NW. IT IS STILL A
BIT SOON TO FULLY ASSESS THE SEVERE POTENTIAL, BUT FOR NOW
MACHINE LEARNING GUIDANCE KEEPS THE PROBABILITY BELOW 15% EACH
DAY. THE 6-10 AND 8-14 DAY OUTLOOKS BOTH FAVOR BELOW NORMAL
TEMPS AND ABOVE NORMAL PRECIPITATION.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 641 PM CDT MON JUN 15 2026
A COLD FRONT WILL PASS THROUGH THE CENTRAL IL TERMINALS TUESDAY,
PRODUCING A LINE OF SCATTERED THUNDERSTORMS FROM AROUND 12Z-18Z,
WITH SOME POTENTIAL FOR A FEW ADDITIONAL SHOWERS AND
THUNDERSTORMS LINGERING LATER INTO THE AFTERNOON AT KDEC AND
KCMI. OTHER THAN BRIEF MVFR CONDITIONS IN THUNDERSTORMS,
CONDITIONS ARE EXPECTED TO BE GENERALLY VFR THE UPCOMING 24
HOURS. WIND WSW 5-10 KTS BECOMING SW AROUND 5 KTS AFTER 05Z. SW
WINDS INCREASING TO 10-15 KTS WITH GUSTS 20-25 KTS AFTER 12Z.
WINDS VEERING TO WSW AND INCREASING TO 15-20 KTS WITH GUSTS
AROUND 25 KTS BY 18Z.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...ERWIN
DISCUSSION...ERWIN
AVIATION...37/ERWIN
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