308
FXUS63 KLOT 120540
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1240 AM CDT MON OCT 12 2026
KEY MESSAGES
- RECORD WARMTH IS LIKELY ON MONDAY, ALONG WITH BREEZY/GUSTY
SOUTHWESTERLY WINDS.
- SHOWERS LIKELY AND SOME EMBEDDED THUNDERSTORMS TUESDAY NIGHT
INTO WEDNESDAY MORNING, AND AGAIN ON THURSDAY.
- TURNING MUCH COOLER INTO NEXT WEEKEND.
DISCUSSION
ISSUED AT 235 PM CDT SUN OCT 11 2026
TONIGHT THROUGH TUESDAY:
UNSEASONABLE WARMTH WILL CONTINUE TO BE THE STORY FOR A FEW MORE
DAYS, PARTICULARLY ON MONDAY. TONIGHT, GIVEN DEW POINTS THIS
AFTERNOON IN THE MID TO UPPER 50S IN MOST SPOTS, LIGHT
SOUTHERLY WINDS WILL ENABLE OVERNIGHT LOWS SHOULD TO FALL INTO
THE UPPER 50S TO LOWER 60S (LOCALLY MID 50S) AWAY FROM CHICAGO.
THESE READINGS ARE STILL 10-15F ABOVE AVERAGE FOR THE DATE,
PROVIDING A VERY MILD STARTING POINT FOR MONDAY'S WARMTH.
SOME HIGH CLOUD COVER TO START THE DAY WILL GIVE WAY TO PLENTY
OF SUNSHINE THROUGH THE AFTERNOON. FORECAST SOUNDINGS SUPPORT
SOUTHWESTERLY WINDS GUSTING UP TO 25 TO 30 MPH. WITH RECENT
DRYNESS AND 925 MB TEMPS IN THE LOWER TO MID 20S CELSIUS, THE
SETUP LOOKS PRIME FOR TEMPS OVERPERFORMING, REACHING THE MID TO
UPPER 80S. RECORD HIGHS FOR OCTOBER 12TH ARE RELATIVELY LOW
COMPARED TO SURROUNDING DAYS, MAKING RECORD HIGHS A DECENT BET
AT CHICAGO AND ROCKFORD (SEE CLIMATE SECTION BELOW).
CAN'T COMPLETELY RULE OUT SOME HIGH BASED SPRINKLES IN SPOTS ON
MONDAY NIGHT IN ADVANCE OF AN APPROACHING COLD FRONT TRAILING
FROM SURFACE LOW PRESSURE OVER NORTHERN LAKE MICHIGAN BY EARLY
TUESDAY. THE COLD FRONT WILL OTHERWISE MOVE ACROSS THE AREA
WITH LITTLE FANFARE ON TUESDAY. EXCEPTIONALLY MILD CONDITIONS
(60S TO AROUND 70F) TO START TUESDAY AND VERY WEAK COLD
ADVECTION WILL RESULT IN ANOTHER DAY OF SUMMER-LIKE TEMPS,
THOUGH NOT QUITE AS WARM AS THOSE ON MONDAY.
TUESDAY NIGHT THROUGH SUNDAY:
ANAFRONTAL SHOWERS AND SOME EMBEDDED THUNDERSTORMS ARE EXPECTED
AT TIMES LATER TUESDAY EVENING INTO WEDNESDAY MORNING. THIS WILL
OCCUR AS IMPULSES RIDING FAIRLY ROBUST WEST-SOUTHWEST MID-LEVEL
FLOW INTERACT WITH MOISTURE AND MODEST ELEVATED INSTABILITY
ATOP THE BAROCLINIC ZONE OVER THE REGION. THERE'S SOME
UNCERTAINTY WITH SPECIFICS IN THIS PERIOD, INCLUDING THE
POTENTIAL FOR AXES OF HIGHER QPF. ALL IN ALL, THE FAIRLY HIGH
POPS IN THE OFFICIAL FORECAST APPEAR WARRANTED. HIGH PRESSURE
BUILDING DOWN FROM THE NORTHERN GREAT LAKES WILL SHIFT SHOWERS
PRIMARILY SOUTH OF I-80 BY MID WEDNESDAY MORNING. ANY
ADDITIONAL AFTERNOON SHOWERS WILL PROBABLY BE CONFINED TO MAINLY
SOUTH OF THE ILLINOIS AND KANKAKEE RIVER VALLEYS (AND PERHAPS
EVEN PRIMARILY SOUTH OF US-24). HIGHS ON WEDNESDAY, WHILE STILL
ABOVE AVERAGE FOR THE DATE, WILL BE NOTICEABLY COOLER THAN
TUESDAY, PARTICULARLY ALONG THE LAKEFRONT (MID-UPPER 60S) DUE TO
STEADY NORTHEAST WINDS.
THE NEXT PERIOD OF INTEREST FOR SHOWERS AND EMBEDDED
THUNDERSTORMS IS ON THURSDAY. WHILE THERE IS CONSIDERABLE
VARIANCE IN THE EVOLUTION OF KEY SYNOPTIC FEATURES ON THURSDAY,
INCLUDING THE TRACK OF WEAK SURFACE LOW PRESSURE, 60-70% POPS
IN THE OFFICIAL FORECAST APPEAR REASONABLE. A STRONG COLD FRONT
WILL SWEEP ACROSS THE AREA THURSDAY NIGHT, WITH THE COOLEST AIR
MASS OF THE SEASON THUS FAR MOVING IN BEHIND THE FRONT FOR
FRIDAY-SATURDAY. SEASONABLY STRONG (1030S TO AROUND 1040 MB)
HIGH PRESSURE TRANSITING THE REGION MAY SET THE STAGE FOR AREAS
OF FROST OUTSIDE OF CHICAGO FRIDAY NIGHT INTO EARLY SATURDAY AND
SATURDAY NIGHT INTO EARLY SUNDAY, DEPENDING ON HOW COOL SURFACE
TEMPS ACTUALLY GET. EXPECT TEMPS TO QUICKLY MODERATE BACK TO
NEAR SEASONABLE SUNDAY AFTERNOON.
CASTRO
AVIATION /06Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 1240 AM CDT MON OCT 12 2026
FORECAST CONCERNS FOR THE TERMINALS...
- BREEZY SOUTHWEST WINDS MONDAY AFTERNOON WITH GUSTS PEAKING
AROUND 20-25 KTS, LOCALLY HIGHER GUSTS ARE POSSIBLE.
- POTENTIAL FOR LOW-LEVEL WIND SHEAR MONDAY NIGHT IF SUFFICIENT
DECOUPLING OF WINDS CAN OCCUR.
MID-LEVEL RIDGING CONTINUES TO RESIDE OVER THE MISSISSIPPI
VALLEY AND SOUTHERN GREAT LAKES AND IS EXPECTED TO REMAIN IN
PLACE THROUGH THIS TAF CYCLE. WHILE A SUBTLE DISTURBANCE IS
FORECAST TO PIVOT ALONG THE NORTHERN PERIPHERY OF THE RIDGE
MONDAY AFTERNOON, GUIDANCE HAS CONTINUED TO TREND DRIER WITH ANY
POSSIBLE SHOWERS WITH THIS DISTURBANCE. THEREFORE, EXPECT DRY
AND FEW TO SCT VFR SKIES TO PREVAIL THROUGH THIS TAF PERIOD.
LIGHT SOUTH-SOUTHWEST WINDS (AROUND 4-5 KTS) WILL PERSIST
TONIGHT BEFORE WINDS BECOME MORE SOUTHWESTERLY AND INCREASE IN
SPEED BY MIDDAY MONDAY. GUSTS MONDAY AFTERNOON ARE EXPECTED TO
PEAK AROUND 20-25 KTS, BUT THERE IS A CHANCE (20-30%) FOR
LOCALLY HIGHER GUSTS NEAR 28-30 KTS AFTER 20Z. THE GUSTS ARE
EXPECTED TO TAPER AFTER SUNSET MONDAY EVENING, BUT WITH
CONTINUED WARM ADVECTION THERE IS THE CHANCE FOR SOME OCCASIONAL
18-20 KT GUSTS TO LINGER THROUGH MONDAY NIGHT. HOWEVER, IF THESE
OCCASIONAL GUSTS DO NOT MATERIALIZE (IE THE ATMOSPHERE
DECOUPLES) THEN A THREAT FOR LOW-LEVEL WIND SHEAR COULD
MANIFEST AFTER 03Z AS A STRONG 40-50 KT LOW-LEVEL JET DEVELOPS
OVERHEAD, ESPECIALLY AT THE OUTLYING TERMINALS. THE CURRENT
TAFS ARE FAVORING THE BREEZIER CONDITIONS LINGERING AND THUS
HAVE NOT INCLUDED A FORMAL LLWS MENTION BUT WE WILL CONTINUE TO
MONITOR TRENDS AND ADJUST AS NEEDED.
YACK
CLIMATE
ISSUED AT 235 PM CDT SUN OCT 11 2026
HERE ARE THE RECORD WARM TEMPERATURES MOST LIKELY TO BE
THREATENED OR BROKEN EARLY THIS WEEK.
MONDAY OCTOBER 12TH RECORD HIGH TEMPS:
CHICAGO'S CURRENT RECORD HIGH: 84F IN 2008
ROCKFORD'S CURRENT RECORD HIGH: 85F IN 2008
TUESDAY OCTOBER 13TH RECORD HIGHS MIN TEMPS:
CHICAGO'S CURRENT RECORD HIGH MIN: 67F IN 1920
ROCKFORD'S CURRENT RECORD HIGH MIN: 61F IN 2008
NWS CHICAGO
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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