130
FXUS63 KILX 161809
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
109 PM CDT SAT MAY 16 2026
KEY MESSAGES
- THERE IS A MARGINAL RISK (LEVEL 1 OF 5) FOR SEVERE WEATHER
THROUGH TONIGHT. THE HIGHEST PROBABILITY FOR THUNDERSTORMS
WITH DAMAGING WIND GUSTS WILL FOCUS ACROSS THE ILLINOIS RIVER
VALLEY FROM LATE EVENING INTO THE OVERNIGHT HOURS.
- WINDY AND VERY WARM CONDITIONS ARE EXPECTED SUNDAY AND MONDAY
AS HIGHS SURGE WELL INTO THE 80S.
- THE NEXT SIGNIFICANT CHANCE FOR CONVECTION WILL COME INTO THE
PICTURE MONDAY INTO TUESDAY AS A SLOW-MOVING COLD FRONT
APPROACHES FROM THE WEST.
DISCUSSION
ISSUED AT 243 AM CDT SAT MAY 16 2026
A COMPLEX MESOSCALE ENVIRONMENT IS UNFOLDING ACROSS THE MIDWEST
THIS MORNING. REGIONAL RADAR MOSAICS HIGHLIGHT A PAIR OF
OUTFLOW BOUNDARIES CURRENTLY SAGGING INTO CENTRAL ILLINOIS,
DOWNSTREAM OF DECAYING CONVECTION OVER IOWA. TO THE WEST, A PAIR
OF SHORTWAVE TROUGHS POSITIONED OVER NORTH-CENTRAL MISSOURI AND
SOUTHEAST NEBRASKA ARE PROGGED TO TRAVERSE THE LOCAL AREA LATER
THIS MORNING INTO THE EARLY AFTERNOON. SUPPORTED BY A MODEST
LOW-LEVEL JET (LLJ), THESE FEATURES WILL ENCOUNTER A
SUFFICIENTLY BUOYANT AIRMASS CHARACTERIZED BY MUCAPE VALUES IN
THE 2500-3000 J/KG RANGE.
EXPECT CONVECTION TO BLOSSOM ACROSS PORTIONS OF CENTRAL
ILLINOIS LATER THIS MORNING AND THROUGHOUT THE AFTERNOON. WHILE
THE RIPPLES IN THE FLOW MAY PROVIDE SOME LOCAL ENHANCEMENT TO
DEEP-LAYER SHEAR, VALUES ARE GENERALLY EXPECTED TO REMAIN AROUND
30 KTS OR LESS. THIS SHOULD LIMIT THE POTENTIAL FOR WIDESPREAD
ORGANIZED SEVERE WEATHER; HOWEVER, A MARGINAL RISK (LEVEL 1 OF
5) REMAINS IN PLACE. THE PRIMARY THREATS WITH THE MORE ROBUST
CORES WILL BE ISOLATED DAMAGING WIND GUSTS UP TO 60 MPH AND
LARGE HAIL UP TO THE SIZE OF GOLF BALLS.
OF ADDITIONAL CONCERN IS THE POTENTIAL FOR LOCALIZED HYDRO
ISSUES. WITH SLOW-MOVING CONVECTIVE OUTFLOWS AND A HIGH-MOISTURE
ENVIRONMENT, TRAINING OR BACKBUILDING CELLS COULD PRODUCE HEAVY
RAINFALL. THE 00Z HREF LPMM QPF INDICATES A SIGNAL FOR 3-4 INCH
TOTALS, PARTICULARLY OVER EAST-CENTRAL OR SOUTHEAST ILLINOIS, A
TREND SUPPORTED BY RECENT HRRR RUNS.
CENTRAL ILLINOIS WILL REMAIN FIRMLY ENTRENCHED IN THE WARM
SECTOR THROUGH THE REMAINDER OF THE WEEKEND. HUMID CONDITIONS
WILL PERSIST WITH TEMPERATURES CLIMBING INTO THE MID-80S. WHILE
ZONAL MID-LEVEL FLOW AND SUBTLE SHORTWAVES MAY TRIGGER ISOLATED
TO WIDELY SCATTERED SHOWERS AND STORMS, THE LACK OF ROBUST DEEP-
LAYER SHEAR (GENERALLY LESS THAN 30 KTS) WILL KEEP THE SEVERE
THREAT DISORGANIZED AND LOW-IMPACT.
THE SYNOPTIC FOCUS SHIFTS SIGNIFICANTLY TOWARD THE MONDAY-
TUESDAY TIMEFRAME AS A POTENT UPPER-LEVEL WAVE PIVOTS OUT OF THE
GREAT BASIN AND LIFTS INTO THE NORTHERN PLAINS. AN ASSOCIATED
COLD FRONT WILL SWEEP INTO THE MID-MISSISSIPPI VALLEY,
ENCOUNTERING A HIGHLY UNSTABLE ENVIRONMENT WITH MLCAPES
EXCEEDING 2500 J/KG. UNLIKE THE WEEKEND ACTIVITY, THIS SYSTEM
WILL BE ACCOMPANIED BY A NOTABLE INCREASE IN KINEMATIC SUPPORT,
WITH DEEP-LAYER SHEAR INCREASING INTO THE 30-40 KT RANGE. THIS
ENVIRONMENT IS CONDUCIVE TO ORGANIZED, HIGH-IMPACT SEVERE
WEATHER, AND THIS PERIOD WILL NEED TO BE MONITORED CLOSELY FOR
POTENTIAL UPGRADES IN RISK CATEGORIES.
MODEL CONSISTENCY BEGINS TO DIVERGE SLIGHTLY BY MID-WEEK
REGARDING THE TIMING OF THE FRONTAL PASSAGE. SHOULD THE FRONT
SLOW, LINGERING MOISTURE AND INSTABILITY COULD SUPPORT RE-
DEVELOPMENT ON WEDNESDAY, LIKELY CONFINED TO AREAS ALONG AND
SOUTH OF THE I-70 CORRIDOR. BY THURSDAY AND FRIDAY, A TRANSITION
TO A COOLER AND MORE STABLE POST-FRONTAL REGIME IS ANTICIPATED
AS HIGH PRESSURE BEGINS TO BUILD INTO THE REGION. MID-RANGE
DETERMINISTIC GUIDANCE DOES SHOW SEMBLANCE OF ANOTHER FRONTAL
PASSAGE IN THE FRIDAY-SATURDAY TIMEFRAME, BUT MOISTURE RETURN
AHEAD OF THE FRONT LOOKS TOO POOR TO SUPPORT APPRECIABLE RAIN
CHANCES THEN, AT LEAST FOR NOW.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 108 PM CDT SAT MAY 16 2026
SHOWERS AND THUNDERSTORMS THAT DEVELOPED ALONG AN OUTFLOW
BOUNDARY THIS MORNING CONTINUE TO PERCOLATE ALONG/JUST SOUTH OF
THE I-72 CORRIDOR EARLY THIS AFTERNOON. THE CONVECTION HAS BEEN
STEADILY DIMINISHING DUE TO AN OVERALL LACK OF INSTABILITY, SO
THE RISK FOR THUNDER AT THE TERMINALS FOR THE REMAINDER OF THE
AFTERNOON IS LOW. MAIN AVIATION FORECAST CHALLENGE WILL BE THE
POTENTIAL FOR CONVECTIVE RE-DEVELOPMENT THIS EVENING INTO THE
OVERNIGHT HOURS AS THE BOUNDARY LIFTS BACK NORTHWARD. MODEL
CONSENSUS SUGGESTS THE GREATEST AREAL COVERAGE OF SHOWERS/STORMS
WILL FOCUS ACROSS THE ILLINOIS RIVER VALLEY...BUT SCATTERED
ACTIVITY COULD DEVELOP FURTHER EAST ALONG THE BOUNDARY AS WELL.
AS A RESULT, HAVE INCLUDED A TEMPO GROUP FOR THUNDER AT KPIA
BETWEEN 07Z AND 11Z...WITH PROB30 AT THE REMAINING TERMINALS.
THE BOUNDARY WILL LIFT WELL NORTHWARD OUT OF THE AREA BY SUNDAY
MORNING, RESULTING IN A RETURN TO DRY CONDITIONS ACROSS THE
BOARD. WINDS WILL INITIALLY BE SOUTHERLY WITH OCCASIONAL GUSTS
OF 15-20KT THIS AFTERNOON. STRONGER GUSTS OF 20-25KT ARE LIKELY
ON SUNDAY AS CENTRAL ILLINOIS PUNCHES INTO THE WARM SECTOR.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...BARNES
DISCUSSION...MJA
AVIATION...BARNES
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