419
FXUS63 KILX 042000
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
257 PM CDT SAT JUL 4 2026
KEY MESSAGES
- DANGEROUS HEAT AND HUMIDITY OVER CENTRAL AND SOUTHEAST IL THIS
AFTERNOON, PARTICULARLY NEAR AND SOUTH OF I-72 WILL IMPROVE AS
A LINE OF THUNDERSTORMS TRACKS EASTWARD ACROSS CENTRAL IL
DURING MID AFTERNOON INTO EARLY EVENING. HEAT INDEX VALUES ARE
EXPECTED TO PEAK BETWEEN 97 AND 105 DEGREES THIS AFTERNOON
BEFORE THE RAINS, WITH THE HIGHEST VALUES SOUTH OF I-72.
- SCATTERED STRONG TO SEVERE THUNDERSTORMS WILL TRACK EASTWARD
ACROSS CENTRAL IL THROUGH EARLY EVENING. THERE IS A SLIGHT
CHANCE OF SEVERE STORMS MAINLY ALONG AND EAST OF THE IL RIVER,
WITH DAMAGING WINDS THE PRIMARY SEVERE WEATHER THREAT ALONG
HAIL AND LOCALIZED TORRENTIAL RAINFALL OF 1-3 INCHES THAT
COULD LEAD TO MINOR FLOODING ESPECIALLY IN URBAN AREAS.
- A BREAK FROM THE HEAT WAVE ARRIVES EARLY NEXT WEEK. FOLLOWING
A FINAL ROUND OF SCATTERED SHOWERS AND THUNDERSTORMS ON
SUNDAY, A COLD FRONT WILL BRING A STRETCH OF DRY AND
COMFORTABLE WEATHER WITH HIGHS IN THE 80S FROM MONDAY THROUGH
WEDNESDAY.
DISCUSSION
ISSUED AT 255 PM CDT SAT JUL 4 2026
HEAT AND HUMIDITY
THE HEAT ADVISORY FOR ALL CWA EXCEPT KNOX, STARK AND MARSHALL
COUNTIES GOES UNTIL 7 PM FOR PEAK HEAT INDICES OF 97-105F. A
LINE OF THUNDERSTORMS NEAR THE IL RIVER WILL TRACK EASTWARD
ACROSS CENTRAL AND EASTERN IL INTO EARLY EVENING, AND WILL SEE
HEAT INDICES DROP AFTER CONVECTION MOVES THROUGH. ALSO SEEING
SCATTERED CONVECTION OVER HEART OF CWA FROM LINCOLN EASTWARD TO
DANVILLE AND HEAT INDICES DROPPING IN THESE AREAS TOO WITH THE
RAIN. WE ENVISION THE HEAT ADVISORY TO BE CANCELLED EARLY OVER
PORTIONS OF CENTRAL IL DUE TO RAIN COOLED AIR. HEAT INDICES NOT
AS HOT ON SUNDAY AFTERNOON, PEAKING IN THE UPPER 80S/LOWER 90S
SO NO HEAT HEADLINES PLANNED ON SUNDAY OVER CENTRAL AND
SOUTHEAST IL. SO WE APPEAR TO BE IN THE FINAL STRETCH OF A
WEEK'S LONG HEAT WAVE THAT START OVER CENTRAL/SE IL ON SUNDAY
AFTERNOON JUNE 28TH.
SEVERE AND HEAVY RAINFALL POTENTIAL THIS WEEKEND
A SEVERE THUNDERSTORM WATCH IS IN EFFECT UNTIL 7 PM TODAY FROM
STARK, PEORIA, TAZEWELL, LOGAN, MACON, MOULTRIE, COLES AND EDGAR
COUNTIES NORTHEAST.
AN MCV NEAR THE IA/IL BORDER HAS A SWIRL OF CONVECTION AROUND IT
INCLUDING BANDS INTO CENTRAL IL NEAR THE IL RIVER, AND FROM
LINCOLN EASTWARD TO WEST OF DANVILLE. ISOLATED THUNDERSTORMS
HAD RECENTLY DEVELOPED IN SOUTHEAST IL SOUTH OF I-70. MODERATELY
UNSTABLE TROPICAL AIRMASS OVER CWA WITH MLCAPES 2000-3500 J/KG
AND MUCAPES 3000-4000 J/KG. WEAK WIND SHEAR STILL WITH EFFECTIVE
BULK SHEAR VALUES LESS THAN 25 KTS OVER CENTRAL AND SOUTHERN
IL. PWATS HAVE INCREASE TO 1.8-2 INCHES AT MID AFTERNOON OVER
MUCH OF IL SUPPORTING HEAVY RAIN CHANCES. WPC HAS MARGINAL TO
SLIGHT CHANCE OF EXCESSIVE RAINFALL INTO EARLY EVENING WITH THE
SLIGHT CHANCE OVER NE CWA. HREF LPMM HAS POCKETS OF 1.5-3 INCHES
OF RAIN IN LESS THAN 6 HOURS OVER CENTRAL AND NE CWA INTO EARLY
EVENING. CLINTON JUST HAD 0.6 INCHES OF RAIN IN 20 MINUTES
WHICH IS 1.8 INCH PER HOUR RATE. NORTHERN IL, NORTH OF CWA HAS A
FLOOD WATCH IN EFFECT THROUGH 10 PM THIS EVENING.
SPC DAY 1 OUTLOOK HAS SLIGHT RISK OF SEVERE STORMS INTO EARLY
EVENING FOR MAINLY DAMAGING WINDS (15%) RISK OVER MOST OF CWA
(THOUGH MAIN THREAT NOW IS ALONG AND EAST OF THE IL RIVER PER
LATEST RADAR TRENDS). LATEST CAMS GENERALLY SHOW LINE OF
CONVECTION PUSHING EASTWARD FROM THE IL RIVER TO THE IL/IN
BORDER EARLY THIS EVENING (BETWEEN 00-01Z/7-8 PM). HAVE JUST
SLIGHT CHANCES OF SHOWERS/THUNDERSTORMS OVER MOST OF CWA AFTER
DUSK/9 PM TONIGHT FOR THE 4TH OF JULY FIREWORKS ACTIVITIES,
WITH 30% POPS SE OF I-70.
AN UPPER LEVEL LEVEL SHORTWAVE TROUGH WILL BEGIN CROSSING IL ON
SUNDAY, DRAGGING AN ATTENDANT WEAK SURFACE COLD FRONT THROUGH
CENTRAL ILLINOIS. A LINGERING UNSTABLE AIR MASS AHEAD OF THIS
FRONT WILL ALLOW ISOLATED TO SCATTERED SHOWERS AND AND
THUNDERSTORMS TO DEVELOP SUNDAY AFTERNOON/EARLY EVENING
ESPECIALLY SOUTHEAST OF THE IL RIVER. SPC DAY2 OUTLOOK KEEPS
MARGINAL RISK OF SEVERE STORMS OF IL ON SUNDAY AFTERNOON/EVENING
WITH WEAKER INSTABILITY, THOUGH A FEW CELLS COULD BECOME STRONG
WITH GUSTY WINDS ESPECIALLY IN SOUTHEAST IL. WPC DAY2 ERO HAS A
MARGINAL RISK OF EXCESSIVE RAINFALL OVER SOUTHEAST IL SUNDAY
AFTERNOON/EVENING.
NEXT WORK WEEK
ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE IN EAST CENTRAL
AND SOUTHEAST IL MONDAY AFTERNOON WITH WEAK UPPER LEVEL LOW/TROF
OVER THE SOUTHERN GREAT LAKES. OTHERWISE A WELCOME STRETCH OF
SEASONABLE AND GENERALLY DRY WEATHER IS ANTICIPATED FROM MONDAY
THROUGH WEDNESDAY WITH WEAK SURFACE HIGH PRESSURE SETTLING INTO
THE GREAT LAKES REGION AND UPPER LEVEL RIDGING BACK INTO IL
TUE/WED (500 MB HEIGHTS RISE TO 588-590 DECAMETERS). EXPECT
DAYTIME HIGHS TO BE IN THE LOW TO MID 80S MONDAY AND MID TO
UPPER 80S TUE AND WED.
THE MEDIUM TO LONG RANGE FORECAST MODELS SHOW A MORE UNSETTLED
WEATHER PATTERN RETURNING TO IL DURING THE 2ND HALF OF THE WEEK
AS AN UPPER LEVEL TROF MOVES INTO THE AREA. A COLD FRONT TO PUSH
INTO NORTHERN AND POSSIBLY CENTRAL IL AROUND FRIDAY AND STALL
NEAR THE AREA INTO NEXT WEEKEND. HIS SETUP WILL REINTRODUCE
DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS FROM THURSDAY INTO
NEXT WEEKEND. THE CIPS AND CSU-MLP SHOW MARGINAL RISK OF SEVERE
STORMS OVER NW PARTS OF CWA OVERNIGHT WED NIGHT, OVER MORE OF
CWA ON THU AND SOUTHERN/SE CWA ON FRIDAY.
THE CLIMATE PREDICTION CENTER (CPC) 8-14 DAY OUTLOOK FOR JULY
12-18 HAS 33-40% CHANCE OF ABOVE NORMAL TEMPERATURES AND 33-40%
OF BELOW NORMAL PRECIPITATION OVER IL. CPC'S WEEK 3-4 OUTLOOK
FOR JULY 18-31 SHOWS EQUAL CHANCES OF ABOVE OR BELOW NORMAL
TEMPERATURES AND PRECIPITATION.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1245 PM CDT SAT JUL 4 2026
EXPECT SCATTERED TO BROKEN BANDS OF CONVECTION TO DEVELOP AND
SPREAD EASTWARD ACROSS CENTRAL IL DURING THIS AFTERNOON. A FEW
ISOLATED THUNDERSTORMS HAVE DEVELOPED IN PAST HOUR WEST OF I-57
AND TRACKING SLOWLY ENE AT 15 MPH. WE CARRIED TEMPO GROUPS FOR
AROUND 3 HOURS FOR MVFR CONDITIONS FOR THUNDERSTORMS AND COULD
SEE WIND GUSTS OVER 40 KTS WITH STRONGER STORMS. BRUNT OF
CONVECTION TO PASS SE OF CENTRAL IL AIRPORTS AFTER 23-24Z WITH
ISOLATED CONVECTION POSSIBLE FOR A FEW HOURS UNTIL DUSK. HRRR IS
SHOWING MVFR CEILINGS AND POSSIBLE VSBYS WITH FOG DEVELOPING
OVERNIGHT AFTER 06-08Z ESPECIALLY ALONG I-74. IF THESE MVFR
CONDITIONS DEVELOP, EXPECTED THEM TO LIFT TO VFR BETWEEN 14-15Z
SUNDAY MORNING. SW WINDS OF 5-10 KTS EARLY THIS AFTERNOON TO
SWITCH WEST TO NW LATER THIS AFTERNOON AND EVENING, AND VEER
MORE NORTHERLY DURING TONIGHT INTO SUNDAY MORNING.
ILX WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ029-031-
036>038-040>057-061>063-066>068-071>073.
KEY MESSAGES...07
DISCUSSION...07
AVIATION...07
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