213
FXUS63 KILX 021733
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1233 PM CDT THU JUL 2 2026
KEY MESSAGES
- HOT AND HUMID WEATHER WITH PEAK AFTERNOON HEAT INDEX READINGS
OF 100 TO 110 WILL CONTINUE THROUGH FRIDAY, AND WILL LIKELY
REACH 100 TO 105 ON SATURDAY AFTERNOON, HIGHEST IN SOUTHEAST
IL.
- A LOW RISK FOR SEVERE WEATHER EXISTS BOTH FRIDAY AND SATURDAY.
THE HIGHEST PROBABILITY (15-30% CHANCE) FOR SCATTERED DAMAGING
WIND GUSTS WILL FOCUS ALONG/NORTH OF A PEORIA TO PONTIAC LINE
FRIDAY AFTERNOON AND EVENING.
- THERE IS A MARGINAL RISK (5-15% CHANCE) FOR EXCESSIVE RAINFALL
WITH SOME OF THE THUNDERSTORMS THIS WEEKEND...PARTICULARLY ON
SATURDAY.
DISCUSSION
ISSUED AT 400 AM CDT THU JUL 2 2026
**** HEAT AND HUMIDITY ****
TYPICAL SUMMERTIME HEAT AND HUMIDITY WILL CONTINUE INTO THE
FIRST PART OF THE HOLIDAY WEEKEND. HEAT INDEX READINGS WILL PEAK
AT 105-110 DEGREES ALONG/SOUTH OF THE I-72 CORRIDOR BOTH TODAY
AND FRIDAY. AFTER THAT, INCREASING CLOUD COVER AND THUNDERSTORM
CHANCES WILL LEAD TO A GRADUAL EASING OF THE HEAT OVER THE
WEEKEND. AS UPPER RIDGING SHIFTS WESTWARD AND RE-ESTABLISHES
OVER THE DESERT SOUTHWEST, WEAK W/NW FLOW ACROSS THE MIDWEST
WILL HELP DROP AIR TEMPERATURES BACK TO SEASONAL NORMALS IN THE
MIDDLE TO UPPER 80S SUNDAY THROUGH WEDNESDAY.
**** LOW SEVERE WEATHER RISK FRIDAY AND SATURDAY ****
AS THE UPPER FLOW PATTERN BECOMES ZONAL, A SERIES OF SHORT-WAVE
TROUGHS WILL TRIGGER SEVERAL ROUNDS OF CONVECTION ACROSS PARTS
OF THE REGION FRIDAY THROUGH SUNDAY. WITH SURFACE DEWPOINTS
REMAINING IN THE MIDDLE TO UPPER 70S, SBCAPE VALUES WILL EXCEED
3000J/KG BOTH FRIDAY AND SATURDAY AFTERNOONS. WHILE THE
ATMOSPHERE WILL BE MOIST AND STRONGLY UNSTABLE, DEEP-LAYER SHEAR
WILL BE LARGELY ABSENT AS EVIDENCED BY NAM 0-6KM BULK SHEAR
VALUES OF JUST 20-25KT. A SHORT-WAVE AND/OR MCV IS EXPECTED TO
TRACK FROM SOUTH DAKOTA/NEBRASKA INTO THE SOUTHERN GREAT LAKES
ON FRIDAY, ENHANCING SHEAR VALUES ACROSS WISCONSIN AND NORTHERN
ILLINOIS WHERE SEVERE PROBABILITIES HAVE BEEN INCREASED TO
15-30%. NORTH-CENTRAL ILLINOIS WILL BE ON THE SOUTHERN FRINGE
OF THE BETTER SHEAR, SO AM EXPECTING MINIMAL WIDESPREAD STORM
ORGANIZATION. SEVERAL CAMS INCLUDING THE 00Z RRFS SHOW A
CLUSTER OF THUNDERSTORMS FORMING IN ADVANCE OF THE MCV ACROSS
EASTERN IOWA/NORTHWESTERN ILLINOIS TOWARD MIDDAY FRIDAY, THEN
TRACKING EASTWARD THROUGH THE CHICAGO AREA DURING THE AFTERNOON.
SOME OF THESE CELLS WILL LIKELY DEVELOP FURTHER SOUTH INTO THE
HIGHLY UNSTABLE AIRMASS ACROSS CENTRAL ILLINOIS...POSING A RISK
FOR A FEW DAMAGING WIND GUSTS WITH THE STRONGEST STORMS
ALONG/NORTH OF THE I-72 CORRIDOR. FURTHER NORTH FROM THE PEORIA
AREA NORTHWARD, THE RISK FOR SEVERE IS A BIT HIGHER...BUT STILL
LIMITED BY THE OVERALL LACK OF SHEAR. AN OUTFLOW BOUNDARY WILL
SETTLE SOUTHWARD ON SATURDAY, LEADING TO A HIGHER PROBABILITY
(40-70% CHANCE) OF SHOWERS AND THUNDERSTORMS ACROSS ALL OF
CENTRAL ILLINOIS. A MARGINAL RISK (LEVEL 1 OF 5) FOR SEVERE
WEATHER EXISTS AS A FEW OF THE CELLS MAY BE CAPABLE OF DAMAGING
WIND GUSTS. SCATTERED THUNDERSTORMS WILL CONTINUE MAINLY EAST OF
THE I-55 CORRIDOR ON SUNDAY: HOWEVER, DECREASING INSTABILITY
WILL LEAD TO AN EVEN LOWER SEVERE RISK AT THAT TIME.
WHILE THE HOLIDAY WEEKEND WILL NOT BE A COMPLETE WASH-OUT,
CENTRAL ILLINOIS RESIDENTS SHOULD KEEP A CLOSE EYE ON THE
FORECAST AND BE AWARE THAT SOME OUTDOOR ACTIVITIES MAY BE
IMPACTED.
**** POCKETS OF HEAVY RAINFALL THIS WEEKEND ****
WITH SURFACE DEWPOINTS HOVERING IN THE MIDDLE TO UPPER 70S AND
PRECIPITABLE WATER VALUES INCREASING TO 1.75-2.25, THUNDERSTORMS
WILL BE EFFICIENT RAIN-PRODUCERS THIS WEEKEND. IN ADDITION, SLOW
STORM MOVEMENT WILL ALLOW SOME OF THE STRONGER CELLS TO DROP
HEAVY RAINFALL. WHILE NOT ALL LOCATIONS WILL GET HEAVY RAIN, A
FEW SPOTS MAY EXPERIENCE EXCESSIVE RAINFALL RATES THAT LEAD TO
LOCALIZED FLASH FLOODING. AS A RESULT, WPC HAS HIGHLIGHTED ALL
OF CENTRAL AND SOUTHEAST ILLINOIS WITH A MARGINAL RISK (5-15%
CHANCE) OF EXCESSIVE RAINFALL ON SATURDAY.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1235 PM CDT THU JUL 2 2026
VFR CONDITIONS WILL PREVAIL THROUGH MUCH OF THE 18Z TAF PERIOD
FOR THE CENTRAL IL AIRPORTS. SCATTERED TO OCCASIONALLY BROKEN
DIURNAL CUMULUS CLOUDS (BROKEN CEILINGS MORE LIKELY ALONG I-74)
WITH BASES OF 2-4K FT THIS AFTERNOON WILL LIKELY REDEVELOP
AFTER 15Z/10 AM FRIDAY. LATEST CAMS SHOW BANDS OF SHOWERS AND
THUNDERSTORMS DEVELOPING AND MOVING OVER NORTHERN/NW IL DURING
THIS EVENING AND GETTING CLOSE TO PIA BETWEEN 05-09Z WHERE VCTS
ADDED. WILL NEED TO WATCH IF THIS CONVECTION GETS AS FAR SE AS
BMI OVERNIGHT AFTER 08Z/3 AM. SW WINDS NEAR 10 KTS WITH FEW
GUSTS 15-20 KTS THIS AFTERNOON AT PIA AND BMI, TO BE SOUTH AT
4-8 KTS AFTER SUNSET AND SW AT 7-10 KTS AFTER 15Z/10 AM FRIDAY.
ILX WATCHES/WARNINGS/ADVISORIES
EXTREME HEAT WARNING UNTIL MIDNIGHT CDT TONIGHT FOR ILZ027>031-
036>038-041.
EXTREME HEAT WARNING UNTIL 7 PM CDT FRIDAY FOR ILZ040-042>057-
061>063-066>068-071>073.
KEY MESSAGES...BARNES
DISCUSSION...BARNES
AVIATION...07
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