775
FXUS63 KILX 150841
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
341 AM CDT WED JUL 15 2026
KEY MESSAGES
- HOT AND HUMID WEATHER CONTINUES THROUGH AT LEAST SATURDAY WITH
MAXIMUM AFTERNOON HEAT INDICES BETWEEN 95 AND 104 DEGREES.
- THERE IS A 20-30% CHANCE OF SHOWERS AND THUNDERSTORMS
THURSDAY AFTERNOON INTO THURSDAY NIGHT. A BETTER CHANCE OF
SHOWERS AND THUNDERSTORMS (60-80%) ARRIVES FRIDAY ESPECIALLY
FRIDAY AFTERNOON. WPC HAS MARGINAL RISK OF EXCESSIVE RAINFALL
OVER THE AREA FRIDAY.
DISCUSSION
ISSUED AT 330 AM CDT WED JUL 15 2026
WEAK 1020 MB SURFACE HIGH PRESSURE RIDGE OVER IOWA AND RIDGING
OVER CENTRAL IL HAS BROUGHT CLEAR SKIES AND CALM WINDS TO CWA.
WITH TEMPS COOLING TO NEAR DEWPOINTS IN THE UPPER 60S TO AROUND
70F, WE ARE SEEING PATCHY SHALLOW GROUND FOG DEVELOPING PAST FEW
HOURS OVER THE AREA. LATEST MODEL GUIDANCE LIKE THE HRRR, RAP13
AND GFSLAMP SHOW PATCHY FOG CONTINUING TO DEVELOP OVER CENTRAL
IL THROUGH SUNRISE AND COULD GET LOCALLY DENSE IN SPOTS
ESPECIALLY SOUTH OF I-74 TO ALONG I-72. THE PATCHY FOG SHOULD
LIFT QUICKLY BY MID MORNING SIMILAR TO PAST FEW MORNINGS. MAY
SEE PATCHY FOG REDEVELOP OVERNIGHT INTO EARLY THU MORNING,
THOUGH LATEST CAMS SHOW LESS VISIBILITIES RESTRICTIONS OVER CWA
OVERNIGHT THAN WHAT THEY ARE SHOWING EARLY THIS MORNING.
A REX BLOCK PATTERN CONTINUED OVER THE CENTRAL AND EASTERN US
WITH A STRONG UPPER LEVEL RIDGE OVER THE UPPER MIDWEST INTO THE
OHIO RIVER VALLEY, AND A WEAK UPPER LEVEL LOW/TROF OVER THE
SOUTHERN STATES. THIS HAS BROUGHT DRY AND VERY WARM WEATHER TO
CENTRAL/SE IL DURING THE PAST FEW DAYS ALONG WITH A HEAT WAVE AT
MID WEEK. THE STRONG 500 MB HIGH TO REMAIN JUST NORTH/NE OF CWA
WITH OUR 500 MB HEIGHTS OF 594-597 DECAMETERS TODAY (HIGHEST NE
OF I-74). THIS SHOULD CONTINUED DRY AND HOT WEATHER TODAY WITH
MOSTLY SUNNY SKIES AS FEW TO SCATTERED CUMULUS CLOUDS (3-5K FT
BASES) APPEAR LATER MORNING/AFTERNOON. ISOLATED CONVECTION
SHOULD STAY SOUTH OF CWA OVER SOUTHERN IL THIS AFTERNOON/EARLY
EVENING MAINLY SOUTH OF I-64. HIGHS IN THE LOWER 90S TODAY WITH
DEWPOINTS IN THE LOW TO MID 70S, GIVING AFTERNOON HEAT INDICES
PEAKING FROM 97-103F, HIGHEST FROM I-74 NORTH. THIS WILL FALL A
FEW DEGREES SHY OF HEAT ADVISORY CRITERIA OF 105F THOUGH HEAT
ADVISORIES THIS AFTERNOON ARE NOT TOO FAR AWAY IN CENTRAL AND
NORTHERN INDIANA ALONG WITH AIR QUALITY ALERTS (AIR QUALITY
ALERTS GO INTO NORTHEAST IL TOO TODAY AND EVENING). MUGGY LOWS
OVERNIGHT IN THE LOWER 70S.
A WEAK DISTURBANCE MOVING INTO THE MID MS RIVER VALLEY THU TO
GRADUALLY BRING DEEPER TROPICAL MOISTURE NORTHWARD INTO
CENTRAL/SE IL LATER TONIGHT AND THU AS PWATS INCREASE TO 1.75-2.2
INCHES THU AFTERNOON WITH WEAK SSW FLOW. MODELS CONTINUE TO SHOW
ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS DEVELOPING OVER
CENTRAL/SOUTHERN IL THU AFTERNOON. WE HAVE 20-40% CHANCE OF
CONVECTION OVER CWA THU AFTERNOON, HIGHEST OVER SOUTHERN/SW CWA
WITH THE HIGHER POPS OVER SOUTHERN/SW IL WHERE WPC DAY2 HAS
MARGINAL RISK OF EXCESSIVE RAINFALL. CANADIAN WILDFIRES NEAR THE
MN BORDER IS SENDING SMOKE SOUTHWARD ACROSS WI/MI TODAY AND INTO
NORTHEAST PARTS OF IL/IN TONIGHT INTO THU AS BACKDOOR COLD FRONT
MOVES INTO NORTHEAST IL TONIGHT. WE COULD SEE SOME SMOKE ALOFT
MOVING OVER CENTRAL IL INTO THU WHICH WILL INCREASE OUR CLOUD
COVER SOME BUT THE SURFACE SMOKE AND AIR QUALITY ISSUES SHOULD
MOSTLY STAY NE OF CWA THROUGH THU. HIGHS THU IN THE LOWER 90S
WITH AFTERNOON HEAT INDICES IN THE UPPER 90S/LOWER 100S AGAIN.
THE WEAK UPPER LEVEL TROF/DISTURBANCES MOVES OVER IL ON FRIDAY
AND BRINGS OUR BEST CHANCES OF CONVECTION (60-80%) ESPECIALLY
FRI AFTERNOON. WPC DAY3 ERO HAS MARGINAL RISK OF EXCESSIVE
RAINFALL OVER CWA ON FRIDAY ESPECIALLY AFTERNOON HOURS. PWATS
ARE VERY HIGH ON FRIDAY, FROM 2-2.4 INCHES. WE HAVE QUARTER TO
HALF INCH OF QPF ON FRIDAY FROM IL RIVER EAST AND TENTH TO
QUARTER INCH WEST OF THE IL RIVER. THOUGH SOME SPOTS MAY SEE
1-2 INCHES OR MORE IN A SHORT TIME WITH SLOW MOVING CELLS. WE
HAVE MODERATELY STRONG INSTABILITY BUT WEAK WIND SHEAR FRI, SO A
FEW STORMS COULD PRODUCE GUSTY WINDS/WET MICROBURSTS. MAY ALSO
SEE STRONG CELLS THU AFTERNOON THOUGH BEST CHANCE WOULD BE SW
IL. HIGHS FRIDAY IN THE UPPER 80S TO NEAR 90F AND AFTERNOON HEAT
INDICES IN THE UPPER 90S TO AROUND 100.
MODELS ARE TRENDING SLOWER WITH EXISTING THIS WEAK DISTURBANCE
ON SATURDAY SO WE WILL LIKELY CONTINUE CHANCES OF CONVECTION
ESPECIALLY EASTERN IL SAT AFTERNOON. ANOTHER HOT AND HUMID DAY
SAT WITH HIGHS IN THE LOWER 90S AND AFTERNOON HEAT INDEX
READINGS PEAKING AROUND OR JUST ABOVE 100 DEGREES. A WEAKENING
COLD FRONT DROPPING DOWN THROUGH NORTHERN/NE IL TOWARD
CENTRAL IL SUNDAY BUT STILL VERY WARM AND HUMID WITH HIGHS IN
THE UPPER 80S TO AROUND 90F. SW FLOW ON MONDAY RETURNING THE
HOT /HUMID AIR MASS OVER CENTRAL/SE IL BEFORE A STRONGER COLD
FRONT MOVES THROUGH MON NIGHT INTO TUE BRINGING COOLER AND LESS
HUMID AIR BACK INTO THE REGION FOR MIDDLE OF NEXT WEEK (NEXT
TUE-THU). ALSO HAVE 20-30% CHANCE OF CONVECTION MON AND MONDAY
NIGHT AND MAY LINGER CHANCES INTO TUESDAY.
THE CLIMATE PREDICTION CENTER (CPC) 8-14 DAY OUTLOOK FOR JULY
22-28 HAS A 33-40% CHANCE OF BELOW NORMAL TEMPERATURES OVER IL
WHILE PRECIPITATION DURING THIS WEEK IS TRENDING NEAR NORMAL.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1154 PM CDT TUE JUL 14 2026
CALM WINDS AND HIGH BOUNDARY LAYER RH WILL BRING PATCHY MVFR FOG
TO THE CENTRAL IL TERMINALS EARLY THIS MORNING. HIGH-RES MODELS
SHOW HIGHER PROBABILITIES OF IFR VISIBILITY AT TIMES NEAR/WEST
OF I-55, BUT CONFIDENCE OF THIS IMPACTING A TERMINAL IS LOW SO
KEPT OUT OF TAF. OTHERWISE SKIES WILL BE MOSTLY CLEAR AND WINDS
LIGHT/VARIABLE WITH HIGH PRESSURE OVERHEAD.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...07
DISCUSSION...07
AVIATION...25
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