732
FXUS63 KILX 020701
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
201 AM CDT WED JUL 2 2025
KEY MESSAGES
- HEAT AND HUMIDITY WILL GRADUALLY INCREASE INTO THE WEEKEND, WITH
HIGHS IN THE LOW 90S FOR FRIDAY (JULY 4) AND HEAT INDICES OF 95
TO 100 DEGREES.
- MOSTLY DRY CONDITIONS SHOULD PREVAIL THROUGH AT LEAST SATURDAY
MORNING, THEN OCCASIONAL RAIN CHANCES EXIST SATURDAY NIGHT INTO
NEXT WEEK (20- 50%).
DISCUSSION
ISSUED AT 159 AM CDT WED JUL 2 2025
LIGHT WINDS AND MOSTLY CLEAR SKIES ARE IN PLACE ACROSS CENTRAL IL
EARLY WED MORNING, SAVE FOR A FEW ISOLATED PATCHES OF MID-LEVEL
CLOUDS EVIDENT ON NT MICROPHYSICS SATELLITE IMAGERY. THE SFC
PATTERN REMAINS DIFFUSE TODAY, WITH BROAD, WEAK SFC HIGH PRESSURE
OVER THE OZARKS. AS A RESULT WINDS STAY LIGHT TODAY WITH A
WESTERLY COMPONENT, ALTHOUGH THE EXACT WIND DIRECTION WILL VARY
BETWEEN NW AND SW AT TIMES. BOTH FCST SOUNDINGS AND NAM CU RULE
OUTPUT SUGGEST SCATTERED DIURNAL CU TODAY, WITH CLOUD BASES AROUND
4-6 KFT. TEMPS TODAY WARM A FEW DEGREES RELATIVE TO YESTERDAY,
WITH HIGHS IN THE MID 80S. HOWEVER, DEWPOINTS REMAIN IN THE MID
60S, KEEPING PEAK HEAT INDICES BELOW 90 DEGREES.
OVERALL, MOSTLY DRY CONDITIONS ARE ANTICIPATED THROUGH AT LEAST
FRIDAY (JULY 4TH). A STRAY SHOWER CAN'T BE RULED OUT NEAR/NORTH OF
THE I-74 CORRIDOR ON THURS, DUE IN PART TO THE POTENTIAL FOR
CONVECTION TO DEVELOP DUE TO LLJ CONVERGENCE ACROSS IA TONIGHT
INTO THURS AM, AS WELL AS A SUBTLE IMPULSE ROUNDING THE RIDGE.
THIS ACTIVITY IS MORE LIKELY TO BE FOCUSED ACROSS NORTHERN IL,
WITH JUST A 10% CHANCE ALONG/NORTH OF I-74 (WHICH IS BELOW THE
THRESHOLD TO WARRANT A MENTION IN THE OFFICIAL FORECAST).
UPPER LEVEL HEIGHT RISES BEGIN ON THURS, AND PEAK ON FRI AS THE
UPPER RIDGE AXIS SHIFTS OVER IL (592 DAM AT 500 MB). AS THE SFC
HIGH SHIFTS EAST OF OUR AREA, SOUTHERLY FLOW REESTABLISHES AND
HOT/HUMID CONDITIONS RETURN FOR FRI/SAT, WITH HEAT INDICES OF
95-100 DEGREES. FORTUNATELY, THIS UPPER RIDGE DOES NOT APPEAR TO
HAVE THE SAME STAYING POWER AS THE ONE THAT WAS ASSOCIATED WITH
OUR PREVIOUS HEAT EVENT, AS AN UPPER LOW CURRENTLY OVER CALIFORNIA
IS EXPECTED TO EJECT ONTO THE PLAINS AND LIFT TOWARDS THE UPPER
MIDWEST OVER THE WEEKEND. MODEL CONSENSUS HAS IMPROVED WITH THIS
SYSTEM, BRINGING THE TIMING INTO BETTER FOCUS. IT NOW APPEARS
CENTRAL IL WILL BE DRY FOR MUCH OF SAT, WITH POPS FIRST INTRODUCED
ACROSS WEST-CENTRAL IL DURING THE EVENING (20-30%) AS THE COLD
FRONT GROWS CLOSER. THE MOST LIKELY TIMING FOR THE FRONT SEEMS TO
BE LATE SAT NIGHT INTO SUN, WITH THE HIGHEST POPS SUN AFTERNOON
(30-50%). CURRENT FORECAST STILL KEEPS HEAT INDICES AROUND 95-100
FOR SUN, THOUGH THE POTENTIAL FOR CONVECTION RESULTS IN LOWER
CONFIDENCE IN REACHING THESE NUMBERS COMPARED TO FRI/SAT.
THE QUESTION THEN BECOMES, DOES THIS FRONT PUSH COMPLETELY SOUTH
OF OUR AREA...OR DOES IT STALL OUT AND INCREASE THE DAILY PRECIP
CHANCES INTO NEXT WEEK? THE UPPER RIDGE IS EXPECTED TO AMPLIFY AND
BECOME ANCHORED OVER THE DESERT SW NEXT WEEK, PLACING IL IN THE
PATH OF ANY DISTURBANCES THAT ROUND THE RIDGE, SO ONE WAY OR
ANOTHER THE PATTERN SUPPORTS CONTINUED PRECIP CHANCES INTO NEXT
WEEK. THIS IS ALSO REFLECTED IN THE CPC 6-10 DAY OUTLOOK (VALID
JULY 7 - 11), WHICH LEANS ABOVE NORMAL FOR PRECIP (40% CHANCE).
THE POTENTIAL FOR ORGANIZED SEVERE STORMS APPEARS LOW. WHILE ENS
GUIDANCE HAS A 40-60% CHANCE OF CAPES OVER 2000 J/KG EACH DAY, THE
PROBABILITY OF DEEP LAYER SHEAR OVER 30 KNOTS IS LESS THAN 15%
WELL INTO NEXT WEEK. THE GREATER CONCERN MAY INSTEAD BE LOCALLY
HEAVY RAINFALL, GIVEN THE WEAK FLOW PATTERNS AND A 50-70% CHANCE
FOR PWATS ABOVE THE 90TH PERCENTILE (1.7").
ERWIN
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1151 PM CDT TUE JUL 1 2025
VFR CONDITIONS EXPECTED THROUGH THE PERIOD. WINDS WILL BE LIGHT,
GENERALLY AROUND OR LESS THAN 5 KTS WITH A WESTERLY COMPONENT.
SOME DIURNAL CU IS POSSIBLE THIS AFTERNOON, OTHERWISE SKIES WILL
BE MOSTLY CLEAR.
ERWIN
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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