714
FXUS63 KLOT 230726
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
226 AM CDT SAT MAY 23 2026
KEY MESSAGES
- ISOLATED SHOWERS ARE EXPECTED CLOSER TO THE LAKE THROUGH MID
MORNING.
- ANOTHER CHANCE FOR SHOWERS AND ISOLATED THUNDERSTORMS
OVERNIGHT THROUGH MIDDAY TOMORROW.
- ABOVE NORMAL TEMPERATURES ARE EXPECTED THROUGH EARLY NEXT
WEEK.
DISCUSSION
ISSUED AT 226 AM CDT SAT MAY 23 2026
A SURFACE LOW ANALYZED OVER SOUTHEASTERN INDIANA IS GRADUALLY
MOVING NORTHEASTWARD TOWARD SOUTHEASTERN MICHIGAN AND WESTERN
LAKE ERIE. MOISTURE WRAPPING AROUND THE NORTHERN EDGE OF THE
CYCLONIC FLOW IS PROVIDING RAIN SHOWERS IN NORTHERN INDIANA.
MEANWHILE, BANDS OF SHOWERS ALONG THE FAR OUTER EDGE ARE MOVING
WEST OVER LAKE MICHIGAN TOWARD ILLINOIS. COVERAGE OF SHOWERS
THROUGH MID MORNING SHOULD BE CONFINED TO COUNTIES ADJACENT TO
LAKE MICHIGAN, MOSTLY ISOLATED, AND RAIN TOTALS ARE EXPECTED TO
BE A TRACE TO LOCALLY A HUNDREDTH OR TWO. MODELED INSTABILITY IS
MEAGER AT BEST. SO WHILE THE CHANCE OF LIGHTNING IS "NON-ZERO",
IT IS NOT EXPECTED. AS THE SURFACE LOW CONTINUES ITS EASTWARD
TRAJECTORY, SHOWERS WILL ALSO MOVE EAST OVER MICHIGAN FOR DRIER
CONDITIONS BY MID MORNING. WINDS ARE EXPECTED TO BE LIGHT AND
NORTHERLY BEFORE A LAKE BREEZE DEVELOPS IN THE AFTERNOON. HIGH
TEMPERATURES FOR INLAND AREAS ARE EXPECTED IN THE 70S, BUT THE
AFOREMENTIONED LAKE BREEZE SHOULD LIMIT HEATING NEAR THE LAKE
SHORELINE TO THE 60S.
AN UPPER LEVEL TROUGH OVER THE CENTRAL PLAINS WILL MOVE EAST
TOWARD THE WESTERN GREAT LAKES THIS EVENING THROUGH TOMORROW,
DRIVING A SURFACE FRONT FROM WEST TO EAST ACROSS THE FORECAST
AREA. WIDELY SCATTERED SHOWERS OUT AHEAD OF THE FRONT ARE
EXPECTED TO ARRIVE NEAR THE WEST BORDER OF THE FORECAST AREA
EARLY THIS EVENING. MODEL SOUNDINGS SHOW WEAK INSTABILITY WITH
THESE SHOWERS THAT COULD LEAD TO AN ISOLATED THUNDERSTORM. BUT
THE BETTER INSTABILITY, AND BETTER FORCING IN GENERAL, IS
EXPECTED FARTHER WEST ALONG THE FRONT WHICH SHOULD NOT ARRIVE
UNTIL AFTER SUNSET. AFTER SUNRISE, INSTABILITY WILL INCREASE
RENEWING THE CHANCES (20 PERCENT) FOR THUNDER ALONG AND AHEAD
OF THE FRONT. THERE IS SOME MODEL DISAGREEMENT ON THE EXACT
PLACEMENT OF THE FRONT AFTER SUNRISE, BUT THE HIGHEST CONFIDENCE
IN THUNDER DEVELOPMENT ON SUNDAY IS EAST OF INTERSTATE 55.
CURRENT GUIDANCE HAS THE FRONT EXITING THE AREA TO THE EAST
DURING THE AFTERNOON WITH QUIETER CONDITIONS IN ITS WAKE.
AN UPPER LEVEL RIDGE IS EXPECTED TO GROW SUNDAY NIGHT INTO
MONDAY. AS SURFACE HIGH PRESSURE SLIDES OVER CENTRAL ILLINOIS,
SOUTHERLY FLOW WILL ADVECT A WARMER AIR MASS OVER THE AREA.
TEMPERATURES ARE EXPECTED TO CLIMB ABOVE NORMAL INTO THE 80S
BOTH MONDAY AND TUESDAY.
MODELS ARE SUGGESTING A 700 MB WAVE IS EXPECTED TO MOVE
NORTHWARD OUT OF TEXAS TUESDAY NIGHT BEFORE PHASING WITH A
LONGER WAVE OVER THE INTERMOUNTAIN WEST LATE IN THE WEEK. THE
EXPECTATION IS THAT THIS WAVE WOULD SEND A FRONT OVER THE
FORECAST AREA FROM SOUTH TO NORTH AND PROVIDE ANOTHER CHANCE
FOR RAIN TUESDAY NIGHT INTO WEDNESDAY. HOWEVER, AT THIS RANGE
THERE IS STILL MODEL DISAGREEMENT ON THE PROGRESSION OF THIS
WAVE AS WELL AS HOW IT PHASES LATE IN THE WEEK (POTENTIALLY
SETTING UP A STAGNANT PATTERN) LEADING TO LOW END POPS THROUGH
THE END OF THE WEEK, MAINLY SOUTH OF INTERSTATE 80. PERSISTENT
NORTHEAST WINDS LATE IN THE WEEK ARE EXPECTED TO HELP RETURN
HIGH TEMPERATURES BACK TO SEASONAL NORMS.
DK
AVIATION /06Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 109 AM CDT SAT MAY 23 2026
KEY AVIATION FORECAST MESSAGES:
- ARC OF -SHRA OVER SOUTHERN LAKE MICHIGAN WILL GET CLOSE TO
MDW/GYY ~6-8Z.
- MVFR CIGS EXPECTED THROUGH MID MORNING WITH A PERIOD OF IFR
POSSIBLE NEAR THE LAKE (~11-15Z)
- VARIABLE WIND DIRECTIONS POSSIBLE DURING THE DAYTIME HOURS
BEFORE A LAKE BREEZE TURNS WINDS EAST AGAIN IN THE AFTERNOON.
AN ARC OF SHOWERS HAS DEVELOPED OVER SOUTHERN LAKE MICHIGAN A
BIT FARTHER NORTHWEST THAN EXPECTED AND MAY BRIEFLY REACH
MDW/GYY BETWEEN NOW AND ~8Z. OPTED FOR A VCSH MENTION AT MDW TO
ACCOUNT FOR THIS GIVEN THE LIMITED COVERAGE GIVEN IT HAS BEEN
STRUGGLING TO HOLD TOGETHER OVER LAND SO FAR.
CEILINGS HAVE ALSO LOWERED TO MVFR NEAR THE LAKE EARLY THIS
MORNING AND ARE EXPECTED TO GRADUALLY LOWER THROUGH THE
REMAINDER OF THE OVERNIGHT HOURS FROM SOUTHEAST TO NORTHWEST.
GUIDANCE HAS TRENDED A BIT LESS PESSIMISTIC WITH TIME BUT STILL
SUGGEST A BRIEF PERIOD OF IFR CIGS MAY YET OCCUR TOWARD DAYBREAK
NEAR THE LAKE (ORD/MDW/GYY) WITH ONLY SUBTLE TIMING REFINEMENT
MADE WITH THIS UPDATE. CEILINGS THEN STEADILY IMPROVE MID TO
LATE MORNING, RETURNING TO VFR.
WIND DIRECTIONS WILL FAVOR AN EAST TO NORTHEAST DIRECTION
THE REST OF THE OVERNIGHT HOURS NEAR THE LAKE WITH LIGHT AND
VARIABLE CONDITIONS EXPECTED FARTHER INLAND TOWARD RFD. LIGHT
WIND SPEEDS DURING THE MORNING AND EARLY AFTERNOON HOURS TODAY
LEADS TO LOWER CONFIDENCE IN DIRECTIONS, WHICH COULD SEE A BRIEF
PERIOD OF VARIABLE TO NORTHWEST WINDS (<=5KT) BEFORE A
REINFORCING LAKE BREEZE SURGES INLAND IN THE AFTERNOON TURNING
WINDS BACK TO THE EAST. EXPECT FURTHER REFINEMENT WITH LATER
UPDATES.
OUR NEXT WEATHER SYSTEM THEN APPROACHES THE AREA TOWARD THE END
OF THE 30-HR TAF PERIOD. HAVE HELD OFF ON A FORMAL PRECIP
MENTION FOR NOW, THOUGH A MENTION OF -SHRA MAY BE NEEDED WITH
LATER UPDATES.
PETR
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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