048
FXUS63 KILX 301432
AFDILX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LINCOLN IL
932 AM CDT WED JUL 30 2025
KEY MESSAGES
- A HEAT ADVISORY REMAINS IN EFFECT TODAY FOR LOCATIONS ALONG AND
SOUTH OF A TAYLORVILLE TO PARIS LINE WHERE HEAT INDEX VALUES
WILL ONCE AGAIN PEAK AT 100-105 DEGREES THIS AFTERNOON.
- A COUPLE ROUNDS OF THUNDERSTORMS WILL IMPACT CENTRAL ILLINOIS
THROUGH THIS EVENING. THERE IS A LOW PROBABILITY (5-15% CHANCE)
THAT A FEW OF THE CELLS WILL PRODUCE DAMAGING WIND GUSTS.
- DUE TO COPIOUS ATMOSPHERIC MOISTURE AND WET SOIL CONDITIONS, A
FLOOD WATCH IS IN EFFECT FOR LOCATIONS ALONG AND NORTHWEST OF A
RUSHVILLE TO CLINTON LINE THROUGH TONIGHT.
UPDATE
ISSUED AT 932 AM CDT WED JUL 30 2025
LINE OF STORMS WAS APPROACHING THE IL RIVER MID-MORNING. HAD A
REPORT FROM EXTREME SE IA OF 1 INCH HAIL AROUND 8 AM, OTHERWISE
30-40 MPH WIND GUSTS HAVE BEEN COMMON ALONG THE LINE. RECENT RADAR
DATA INDICATE THE GUST FRONT HAS PUSHED OUT EAST OF THE LEADING
EDGE OVER MOST OF CENTRAL IL, WITH THE SCHUYLER-ADAMS CO PORTION
OF THE LINE JUST SLIGHTLY OUTFLOW DOMINANT. THE MOST INTENSE
UPDRAFTS HAVE BEEN IN THIS PART OF THE LINE AND QUINCY RECENTLY
GUSTED TO 44 KT. MODERATE INSTABILITY IS PRESENT OVER CENTRAL IL,
MLCAPE NEAR 2500 J/KG, WITH EFFECTIVE DEEP LAYER SHEAR AROUND 30
KT. DCAPE NEAR 1K J/KG WOULD SUPPORT POCKETS OF DAMAGING WIND
GUSTS AS THE LINE PROGRESSES EAST ACROSS CENTRAL IL THROUGH EARLY
AFTERNOON. LATEST HRRR RUNS HAVE SHOWN ISOLATED 50 KT GUSTS, SO
THIS WILL BE THE FOCUS OVER THE NEXT FEW HOURS.
25
DISCUSSION
ISSUED AT 354 AM CDT WED JUL 30 2025
..PATCHY DENSE FOG EARLY THIS MORNING
BOUNDARY LAYER MOISTURE REMAINS ABUNDANT ACROSS CENTRAL ILLINOIS
EARLY THIS MORNING AS EVIDENCED BY 08Z/3AM SURFACE DEWPOINTS IN
THE LOWER TO MIDDLE 70S. THANKS TO CLEAR SKIES AND NEARLY CALM
WINDS, FOG HAS DEVELOPED...WITH A FEW SPOTS OCCASIONALLY DIPPING
TO LESS THAN 1 MILE VISIBILITY. CAMS SUGGEST VISBYS WILL SLOWLY
DECREASE OVER THE NEXT COUPLE OF HOURS, BUT DO NOT INDICATE
WIDESPREAD DENSE FOG. IR SATELLITE IMAGERY IS SHOWING CONVECTIVE
DEBRIS SPILLING INTO THE AREA FROM THE NORTHWEST, SO A HIGH
OVERCAST WILL DEVELOP AND LIKELY PREVENT VISBYS FROM COMPLETELY
TANKING. WILL ADD PATCHY DENSE FOG WORDING TO THE FORECAST AND
HIGHLIGHT WITH A SPECIAL WEATHER STATEMENT.
..HEAT ADVISORY ACROSS SOUTH-CENTRAL ILLINOIS TODAY
ONE MORE DAY OF OPPRESSIVE HEAT AND HUMIDITY WILL OCCUR: HOWEVER,
THE HIGHEST HEAT INDEX READINGS WILL BE CONFINED TO LOCATIONS
ALONG AND SOUTH OF A TAYLORVILLE TO PARIS LINE DUE TO INCREASED
CLOUD COVER AND RAIN CHANCES FURTHER NORTH. WITH HIGH TEMPERATURES
REACHING THE LOWER TO MIDDLE 90S AND HEAT INDEX VALUES PEAKING AT
100-105 DEGREES, THE HEAT ADVISORY FOR THE SE KILX CWA WILL REMAIN
IN EFFECT UNTIL 7PM.
..MARGINAL RISK FOR SEVERE WEATHER THROUGH TONIGHT
CLUSTERS OF THUNDERSTORMS HAVE DEVELOPED NEAR A STATIONARY FRONTAL
BOUNDARY ON THE NOSE OF A 30KT 850MB JET ACROSS EASTERN NEBRASKA
INTO WESTERN/CENTRAL IOWA EARLY THIS MORNING. ONE OF THE CLUSTERS
HAS ORGANIZED INTO A LINE FROM DES MOINES TO JUST NORTH OF THE
KANSAS CITY METRO. WHILE THE STORMS WILL GENERALLY WEAKEN AS THEY
TRACK FURTHER EASTWARD AWAY FROM THE JET, RADAR TIMING TOOLS SHOW
THEM SPILLING INTO THE ILLINOIS RIVER VALLEY BETWEEN 8AM AND 10AM.
SEVERE WEATHER IS NOT EXPECTED: HOWEVER, ABUNDANT LIGHTNING AND
LOCALLY HEAVY DOWNPOURS WILL BE LIKELY.
THE INITIAL LINE OF CONVECTION WILL DIURNALLY WEAKEN AS IT ENTERS
THE WESTERN CWA, BUT MAY RE-INVIGORATE FURTHER EAST ALONG THE I-55
CORRIDOR BY MIDDAY AS HREF SBCAPES PEAK AT 2500-3000J/KG. AS A
SHORT-WAVE TROUGH APPROACHES FROM THE NORTHWEST, DEEP-LAYER SHEAR
WILL INCREASE...WITH NAM 0-6KM BULK SHEAR VALUES REACHING 25-35KT.
THINK THE COMBINATION OF MODERATELY STRONG INSTABILITY AND DECENT
SHEAR WILL BE ENOUGH TO SUPPORT SOME STORM ORGANIZATION...LEADING
TO AT LEAST A LOW RISK FOR SCATTERED DAMAGING WIND GUSTS. LATEST
OUTLOOK FROM SPC HIGHLIGHTS ALL OF CENTRAL ILLINOIS WITH A
MARGINAL RISK FOR SEVERE, BUT WOULD NOT BE SURPRISED IF THIS IS
UPGRADED TO A SLIGHT RISK LATER THIS MORNING. ONCE THE INITIAL
LINE PASSES AND/OR DISSIPATES THIS AFTERNOON, ADDITIONAL CELLS MAY
FORM ALONG RESIDUAL OUTFLOW BOUNDARIES OR A SLOWLY-MOVING COLD
FRONT DROPPING SOUTHEASTWARD OUT OF IOWA. THE END RESULT MAY BE
ANOTHER ROUND OF THUNDERSTORMS THIS EVENING. ANY SEVERE RISK WILL
BE REALIZED DURING THE EVENING, WITH LINGERING CONVECTION
WEAKENING OVERNIGHT AS INSTABILITY WANES.
..FLOOD WATCH THROUGH TONIGHT
AS STATED ABOVE, A COUPLE ROUNDS OF THUNDERSTORMS ARE ANTICIPATED
TODAY AND TONIGHT. MIDWEST REGIONAL CLIMATE CENTER (MRCC) ANALYSIS
SHOWS MOST LOCATIONS ALONG/NORTH OF A RUSHVILLE TO CLINTON LINE
HAVE RECEIVED 200-500% OF THEIR MEAN PRECIP OVER THE PAST 7 DAYS.
IN ADDITION, THE LATEST RFC GUIDANCE INDICATES 6-HOUR FLASH FLOOD
CRITERIA OF JUST 1.50 TO 2 INCHES ACROSS THIS AREA. GIVEN
PRECIPITABLE WATER VALUES IN EXCESS OF 2 INCHES, HAVE OPTED TO
ISSUE A FLOOD WATCH THROUGH TONIGHT. THINK THE PRIMARY RISKS WILL
OCCUR WHEN STRONGER STORMS DEVELOP OVER URBAN AREAS OR WHEN ONE OR
MORE STORMS IMPACT LOW-LYING FLOOD-PRONE LOCATIONS.
BARNES
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 553 AM CDT WED JUL 30 2025
LINE OF CONVECTION CURRENTLY WEST OF THE MISSISSIPPI RIVER WILL
CONTINUE TRACKING EASTWARD IN A WEAKENING STATE OVER THE NEXT FEW
HOURS AND SHOULD REACH KPIA BY 15Z. THE EVOLUTION OF THE LINE
FURTHER EAST IS LESS CERTAIN AS SOME MODELS SUGGEST IT WILL COMPLETELY
DISSIPATE WHILE OTHERS SHOW IT MAINTAINING OR EVEN STRENGTHENING
DURING PEAK HEATING. GIVEN FAVORABLE MOISTURE/INSTABILITY, HAVE
SIMPLY TIMED THE LINE TO I-55 BY 17Z AND TO KCMI BY AROUND 19Z.
ADDITIONAL STORMS WILL LIKELY FIRE ALONG RESIDUAL OUTFLOW BY LATE
AFTERNOON/EARLY EVENING, ALTHOUGH EXACT TIMING IS UNCERTAIN.
BASED ON HRRR/RAP TRENDS, HAVE MAINTAINED A PROB30 GROUP FOR
THUNDER AT ALL TERMINALS...BEGINNING AT KPIA BY 20Z, THEN FURTHER
EAST TO KCMI BY 23Z. ANY CONVECTION WILL DIMINISH TO JUST SHOWERS
AFTER 03Z/04Z ONCE A COLD FRONT SETTLES SOUTHWARD TOWARD I-70.
WINDS WILL INITIALLY BE LIGHT/VARIABLE, THEN WILL BECOME NE AFTER
FROPA. ONCE WINDS SWING AROUND TO N/NE, MVFR CEILINGS WILL DEVELOP
AND SPREAD SOUTHWARD ACROSS CENTRAL ILLINOIS TONIGHT INTO
THURSDAY MORNING. APPROXIMATE TIMING FOR MVFR AT KPIA IS AROUND
03Z, THEN FURTHER SOUTH TO KSPI/KDEC BY 08Z.
BARNES
ILX WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH THURSDAY MORNING FOR ILZ027>031-036>038-
040>043-047-048.
HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ052-054>057-
061>063-066>068-071>073.
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