816
FXUS63 KILX 160746
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
246 AM CDT SAT MAY 16 2026
KEY MESSAGES
- PERIODS OF THUNDERSTORMS WILL TRACK ACROSS CENTRAL ILLINOIS
TODAY, BRINGING A MARGINAL RISK (LEVEL 1 OF 5) FOR 60 MPH
WIND GUSTS AND GOLF BALL-SIZED HAIL.
- SLOW-MOVING STORMS WILL BRING A RISK OF LOCALIZED FLOODING
TODAY, PRODUCING ISOLATED RAINFALL TOTALS OF 3 TO 4 INCHES IN
EAST-CENTRAL OR SOUTHEAST ILLINOIS.
- A SEPARATE, MUCH STRONGER STORM SYSTEM WILL BRING A THREAT OF
ORGANIZED, HIGH-IMPACT SEVERE WEATHER TO THE AREA IN THE
MONDAY-TUESDAY TIMEFRAME.
- A MODERATE HEAT RISK WILL PERSIST THROUGH TUESDAY,
PARTICULARLY IMPACTING INDIVIDUALS SENSITIVE TO HIGH
TEMPERATURES OR THOSE LACKING SUFFICIENT COOLING AND
HYDRATION.
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 /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1246 AM CDT SAT MAY 16 2026
SCATTERED TSRA EXPECTED TO DEVELOP AFTER 10Z-12Z, CONTINUING
THROUGH MORNING HOURS, AND HAVE INCLUDED PROB30 FOR TSRA WITH
MVFR VSBY FOR THIS ACTIVITY. WHILE NOT INCLUDED IN TAFS, BRIEFLY
WORSE CONDITIONS POSSIBLE IN STORMS. PREDICTABILITY OF STORMS
LATER IN THE DAY IS TOO LOW FOR MENTION IN TAFS, BUT THERE
REMAINS A LOW CHANCE FOR STORMS THE REMAINDER OF THE 24 HOUR TAF
FORECAST PERIOD. LOW LEVEL WIND SHEAR WILL CONTINUE THROUGH MUCH
OF THE NIGHT FROM KSPI-KBMI EASTWARD DUE TO A SW 40 KT WIND
ALOFT. OTHERWISE, SURFACE WINDS S 10-12 KTS OVERNIGHT, WITH
GUSTS TO AROUND 20 KTS DEVELOPING BY 18Z FOR MOST OF THE AREA.
GUSTS DECREASING AFTER 00Z.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...MJA
DISCUSSION...MJA
AVIATION...37
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