277
FXUS63 KLOT 231127
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
627 AM CDT THU JUL 23 2026
KEY MESSAGES
- TODAY THROUGH SATURDAY WILL BE BEAUTIFUL WITH PLEASANT
TEMPERATURES AND RELATIVELY LOW HUMIDITY LEVELS.
- HEAT AND HUMIDITY WILL RETURN TO THE REGION SUNDAY AND
CONTINUE INTO MONDAY. THE MAGNITUDE OF HEAT MAY REQUIRE HEAT
HEADLINES AT SOME POINT.
- MULTIPLE ROUNDS OF SEVERE STORMS WITH DESTRUCTIVE WINDS AND
FLASH FLOODING MAY OCCUR IN THE GREAT LAKES REGION SUNDAY AND
MONDAY (BUT THERE ARE NO GUARANTEES THAT OUR AREA IS
IMPACTED).
DISCUSSION
ISSUED AT 237 AM CDT THU JUL 23 2026
THE CENTER OF A SPRAWLING HIGH PRESSURE SYSTEM WILL CONTINUE TO
MEANDER SOUTHWARD THROUGH THE REGION TODAY OFFERING A
CONTINUATION OF DOWNRIGHT PLEASANT MID-JULY WEATHER. AMIDST
LITTLE TO NO WIND, TEMPERATURES TODAY WILL RISE INTO THE MID TO
LOCALLY UPPER 70S. A LAKE BREEZE WILL PUSH INLAND THIS AFTERNOON
THOUGH THE LIMITED MARINE/LAND AIRMASS TEMPERATURE DIFFERENCE
WILL SIMILARLY LIMIT THE DEGREE OF COOLING BEHIND THE BOUNDARY.
A DIURNAL CUMULUS CLOUD DECK WILL DEVELOP BY MID-AFTEROON AND
FADE THIS EVENING AND HUMIDITY LEVELS WILL REMAIN QUITE
COMFORTABLE (DEW POINTS IN THE UPPER 40S TO LOWER 50S). ALL IN
ALL, TODAY WILL BE A "CHAMBER OF COMMERCE" TYPE DAY.
TONIGHT INTO TOMORROW MORNING, A SERIES OF WEAK UPPER-LEVEL
SHORT- WAVELENGTH TROUGHS WILL RIPPLE THROUGH THE MIDDLE
MISSISSIPPI RIVER VALLEY. DRY LOW-LEVEL AIR WILL LIMIT THE
OPPORTUNITY FOR ANY RAINFALL WITH EITHER RIPPLE IN OUR AREA.
WITH THAT SAID, AN INCREASE IN MID- LEVEL CLOUDS WILL HOLD LOW
TEMPERATURES IN THE MID TO UPPER 50S. FRIDAY AND SATURDAY LOOK
LIKE GORGEOUS DAYS AS WELL WITH HIGHS AROUND 80, CONTINUED
MODEST HUMIDITY LEVELS, AND SOUTH TO SOUTHWESTERLY BREEZES.
SUNDAY ONWARD, AGGREGATE TROUGHING WILL DEVELOP ALONG THE
PACIFIC COAST ENABLING EXPANSIVE UPPER-LEVEL RIDGING TO EXPAND
ACROSS THE NORTHERN UNITED STATES. A QUINTESSENTIAL SUMMERTIME
PATTERN IS HENCE EXPECTED TO SET-UP WITH AN EASTWARD-EXPANDING
DOME OF HOT AIR. THE HEAT WILL ARRIVE TO OUR LOCAL AREA ON
SUNDAY AND CONTINUE INTO MONDAY WITH 850MB TEMPERATURES RISING
INTO THE +21 TO +23C RANGE SUPPORTING HIGHS IN THE LOWER 90S.
HUMIDITY LEVELS WILL ALSO BE ON THE RISE WITH
EVAPOTRANSPIRATIONALLY-ENHANCED DEW POINTS RISING INTO THE MID
70S (IF NOT HIGHER). AS A RESULT, SUNDAY AND MONDAY ALREADY HAVE
OUR ATTENTION FOR POTENTIAL HEAT HEADLINES ACROSS THE AREA.
SUNDAY INTO MONDAY ALSO CONTINUE TO HAVE OUR ATTENTION FOR A
THREAT FOR SEVERE WEATHER AND FLASH FLOODING IN THE BROAD
REGION. CONCEPTUALLY, THE OVERLAP OF STOUT NORTHWESTERLY FLOW
AND STEEP MID-LEVEL LAPSE RATES ON THE EASTERN EDGE OF THE
UPPER-LEVEL RIDGE ATOP MOISTURE-LADEN INSTABILITY ACROSS THE
GREAT LAKES WILL BE SUPPORTIVE OF QUINTESSENTIAL SUMMERTIME
DESTRUCTIVE WIND-PRODUCING THUNDERSTORM CLUSTERS. ENSEMBLE
GUIDANCE ALREADY EXHIBITS FAIR CONSISTENCY IN SHOWING A NOTABLE
SHORTWAVE (ORIGINATING FROM AGGREGATE PACIFIC TROUGHING TO THE
WEST) SHEDDING EASTWARD AND ARRIVING IN THE GREAT LAKES ON
MONDAY, WHICH MAY OFFER THE PEAK COVERAGE OF SEVERE WEATHER IN
THE REGION. WHETHER OR NOT OUR LOCAL AREA IS IMPACTED BY THE
UPCOMING MCS TRAIN OR WE JUST STAY BAKING IN THE HEAT IS
SOMETHING WE'LL ASSESS AS WE GET CLOSER. NEVERTHELESS, DID TOUCH
BASE WITH SPC TO COLLABORATE ON THE INTRODUCTION OF SEVERE
WEATHER PROBABILITIES IN THE BROAD GREAT LAKES REGION FOR SUNDAY
AND MONDAY.
BORCHARDT
AVIATION /12Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 627 AM CDT THU JUL 23 2026
THERE ARE NO KEY CONCERNS FOR THE 12Z TAF PERIOD.
EXPECT LIGHT WINDS TODAY BELOW 10 KT. THE DAY IS STARTING OFF
VARIABLE (FAVORING W) BEFORE A LAKE BREEZE MOVES OVER FLIPPING
DIRECTION TO E AT CHICAGO SITES DURING THE EARLY PART OF THE
AFTERNOON. DIRECTION WILL VEER OVER TO SW DURING THE NIGHT, ALL
WHILE REMAINING LIGHT. EXPECT VFR THROUGHOUT THE PERIOD.
DOOM
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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