797
FXUS63 KLOT 242323
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
623 PM CDT FRI JUL 24 2026
KEY MESSAGES
- HEAT AND HUMIDITY WILL RETURN TO THE REGION SUNDAY AND
CONTINUE INTO MONDAY, POTENTIALLY REQUIRING HEADLINES FOR AT
LEAST SOME AREAS.
- SOME POTENTIAL FOR THUNDERSTORMS LATE SUNDAY THROUGH MONDAY
NIGHT, BUT PREDICTABILITY IN TIMING, LOCATION, AND COVERAGE OF
STORMS IS VERY LOW THIS FAR OUT.
DISCUSSION
ISSUED AT 112 PM CDT FRI JUL 24 2026
A NARROW BAND OF MID-LEVEL FRONTOGENESIS AND ASSOCIATED
SPRINKLES/LIGHT SHOWERS WILL CONTINUE TO SHIFT SOUTH OF THE
REGION THROUGH LATE THIS AFTERNOON.
TOMORROW, A SHORTWAVE AT THE LEADING EDGE OF AN ADVANCING EML
PLUME WILL SLIDE ACROSS THE REGION AND INTERACT WITH A SECONDARY
WAVE WELL TO OUR SOUTH. WHILE THE MAIN SHORTWAVE LOOKS FAIRLY
ROBUST, IT WILL BE ACCOMPANIED BY SHARPLY-WARMING AND DRYING
CONDITIONS IN THE 700-600 MB LAYER LEADING TO INCREASING
CONVECTIVE INHIBITION. MOISTURE LOOKS FAIRLY SHALLOW, LIKELY
TRAPPED UNDER 750 MB, BUT SUFFICIENT TO SUPPORT SOME SPRINKLES
OR SPOTTY SHOWERS SATURDAY MORNING, MOSTLY NEAR/SOUTH OF I-80.
THIS ACTIVITY WILL PUSH EAST OF THE REGION THROUGH EARLY
AFTERNOON. FORECAST SOUNDINGS SUGGEST WE'LL LIKELY HOLD ONTO AT
LEAST SOME CU/STRATOCU THROUGH THE DAY, BUT SHOULD SEE AT LEAST
SOME CLEARING, PARTICULARLY WEST OF THE FOX VALLEY.
LOW-LEVEL MOISTURE WILL INCREASE THROUGH SATURDAY AFTERNOON AND
OVERNIGHT AS THE NEAR-SURFACE FLOW TURNS SOUTH TO
SOUTHWESTERLY. MIGHT SEE SOME PATCHY/SHALLOW FOG DEVELOPMENT
TOWARDS SUNDAY MORNING AS THE INCREASED BL MOISTURE SURGES
NORTHWARD, ALTHOUGH CURRENT SOUNDINGS SHOW FAIRLY ROBUST FLOW
DOWN LOW WHICH WILL PROBABLY LIMIT THE AREAL EXTENT. FINALLY,
THERE'S BEEN A MODEST SIGNAL FOR A DISORGANIZED CONVECTIVE
COMPLEX DEVELOPING WELL TO OUR NORTH (AND PERHAPS A SECOND AREA
ACROSS IOWA) SATURDAY EVENING. WHILE DEEP LAYER FLOW AND
THICKNESSES ORIENTATIONS WOULD SUPPORT A GENERAL SOUTHEAST TO
SOUTH MOTION, THE ENVIRONMENT LOOKS INCREDIBLY STRONGLY CAPPED
AND WOULD LIKELY REQUIRE AN INTENSE/MATURE MCS TO RESULT IN MORE
SIGNIFICANT CONVECTIVE CHANCES IN OUR AREA TOWARDS EARLY SUNDAY
MORNING. NOT SEEING A STRONG SIGNAL FOR THIS AT THIS TIME, AND
AS A RESULT, WILL CONTINUE WITH THE PRECIP-FREE FORECAST DURING
THIS PERIOD.
DEWPOINTS ARE LIKELY TO PUSH INTO THE UPPER 70S SUNDAY
AFTERNOON WITH GENERALLY MUTED MIXING OWING TO THE PRESENCE OF A
FAIRLY ROBUST INVERSION NEAR 850 MB. THE INITIAL MOIST LAYER
LOOKS PRETTY SHALLOW THOUGH, SO MAY BE PRONE TO MIXING OUT A
TOUCH, MAINLY AWAY FROM AGRICULTURAL AREAS. AIR TEMPERATURES
WILL LIKELY ONLY TOP OUT IN THE UPPER 80S/NEAR 90 WHICH WILL
RESULT IN PEAK HEAT INDICES AROUND 100 TO LOCALLY ABOVE 105,
PARTICULARLY ACROSS OUR SOUTH AND WEST LOCALES. IN THE ABSENCE
OF WIDESPREAD THUNDERSTORMS, THE POTENTIAL FOR GREATER COVERAGE
105 DEGREE HEAT INDICES EXISTS ON MONDAY, PERHAPS LOCALLY UP TO
110 NEAR DENSE AGRICULTURAL AREAS WHERE ET IS MAXIMIZED. BREEZY
SOUTHWESTERLY WINDS MAY HELP TAKE SOME OF THE IMPACTS OF THE
HEAT OFF A BIT, BUT EITHER WAY, MONDAY LOOKS UNPLEASANTLY HOT
AND HUMID.
OUR POSITION ALONG THE NORTHEAST PERIPHERY OF AN EXPANSIVE HIGH
CENTERED ACROSS THE FOUR CORNERS REGION WILL OPEN THE POTENTIAL
FOR CONVECTIVE COMPLEXES ROLLING ACROSS THE NORTHERN GREAT
PLAINS AND UPPER MIDWEST SUNDAY INTO MONDAY. THAT SAID, THE
SIGNAL FOR SUCH MCSS IS NOT PARTICULARLY HIGH ACROSS THE
GUIDANCE SUITE. WHILE SEVERAL LOW-AMPLITUDE PERTURBATIONS ARE
EVIDENT IN THE REGION, IN GENERAL, CAPPING LOOKS FORMIDABLE IN
THE REGION WITH A VERY HOT/DRY EML BASE OVERHEAD. CAN'T RULE OUT
THE POTENTIAL FOR A SMALL UNDIAGNOSED RIPPLE IN THE FLOW TO SET
OFF THE MCS CASCADE (LATEST NAM/NAMNEST OUTPUT ON SUNDAY
AFTERNOON FOR EXAMPLE), BUT THIS ISN'T SOMETHING WE CAN
MEANINGFULLY ANTICIPATE MORE THAN A DAY OUT. THERE IS SOMEWHAT
OF A BETTER SIGNAL FOR CONVECTION IN OR VERY NEAR OUR CWA LATE
SUNDAY AFTERNOON INTO MONDAY MORNING, BUT IT'S ALSO ENTIRELY
POSSIBLE ACTIVITY SKIRTS THE AREA TO THE EAST. SLIGHT CHANCE TO
CHANCE POPS WILL COVER THIS POTENTIAL.
A COLD FRONT MONDAY AFTERNOON/MONDAY NIGHT WILL BRING ANOTHER
THREAT FOR STORMS (SOME OF WHICH COULD BE SEVERE) TO THE AREA,
BUT AGAIN THIS SIGNAL IS NOT PARTICULARLY ROBUST AT THIS POINT.
SOMEWHAT LESS HOT/HUMID CONDITIONS WILL RETURN DURING THE MIDDLE
OF NEXT WEEK.
CARLAW
AVIATION /00Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 615 PM CDT FRI JUL 24 2026
CONCERNS:
-MVFR CEILINGS AND FEW SPRINKLES OR LIGHT SHOWERS SATURDAY
MORNING MAINLY WEST OF THE CHICAGO TERMINALS
THE LAKE BREEZE IS SHIFTING BACK TOWARD THE LAKEFRONT, AND THUS
EXPECT WINDS AT ORD/MDW TO SETTLE BACK TOWARD PREVAILING
SOUTH/SOUTHWEST.
A WEATHER DISTURBANCE OVERNIGHT INTO EARLY SATURDAY WILL BRING A FEW
LIGHT SHOWERS OR SPRINKLES TO AREAS SOUTH AND WEST OF THE TERMINALS.
IT IS POSSIBLE A FEW SPRINKLES SNEAK INTO KRFD OR EVEN THE CHICAGO
TERMINALS, BUT CONFIDENCE IS LOW ON OCCURRENCE/DURATION TO PRECLUDE
A TAF MENTION. CEILINGS WILL LOWER DURING THIS TIME TO LOW END VFR
OR MVFR. CLOUDS WILL TEND TO SCATTER IN THE AFTERNOON BEHIND THIS
SYSTEM. WINDS WILL LARGELY REMAIN OUT OF THE SOUTH-SOUTHWEST THROUGH
THE PERIOD WITH THE TYPICAL INCREASE TOWARD 10 KT IN THE EARLY
AFTERNOON.
KMD
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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