841
FXUS63 KLOT 142358
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
658 PM CDT WED OCT 14 2026
KEY MESSAGES
- A FALL STORM SYSTEM WILL MOVE THROUGH THE AREA THURSDAY AND
FRIDAY, BRINGING PERIODS OF RAIN SHOWERS AND GUSTY
NORTHWESTERLY WINDS (THE LATTER PRIMARILY ON FRIDAY).
- FROSTY AND NEAR-FREEZING CONDITIONS ARE FAVORED AWAY FROM
LAKE MICHIGAN FRIDAY NIGHT INTO SATURDAY.
- AFTER THE BRIEF PERIOD OF CHILLY WEATHER, THERE WILL BE A
WARMING TREND THIS WEEKEND INTO EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 310 PM CDT WED OCT 14 2026
THROUGH THURSDAY NIGHT:
OTHER THAN A FEW SPITS OF DRIZZLE NEAR LAKE MICHIGAN, MOST OF
THE AREA HAS SINCE DRIED OUT FROM THE OVERNIGHT AND EARLY
MORNING SHOWERS AND THUNDERSTORMS. THE COMBINATION OF OVERCAST
SKIES AND PERSISTENT ONSHORE NORTHEASTERLY WINDS HAVE HELD
TEMPERATURES IN THE LOW TO MID 60S NEAR/NORTH OF I-80. FARTHER
SOUTH, A THINNING OF THE STRATUS LAYER WITH OCCASIONAL PEEKS OF
SUNSHINE HAS ALLOWED TEMPERATURES TO WARM INTO THE UPPER 60S
AND LOWER 70S. GENERALLY EXPECT THE CLOUD COVER TO FILL BACK IN
THROUGH THIS EVENING AND OVERNIGHT WITH TEMPERATURES ONLY
DROPPING INTO THE 50S.
A FALL STORM SYSTEM REMAINS ON TRACK TO LIFT ACROSS THE REGION
ON THURSDAY WHICH WILL BRING WIDESPREAD SHOWERS AND A FEW
RUMBLES OF THUNDER TO THE AREA. THE GREATEST SHOWER COVERAGE IS
CURRENTLY FAVORED LATE MORNING THROUGH THE AFTERNOON. HI-RES
GUIDANCE CONTINUES TO DEPICT A RELATIVE MINIMUM IN PRECIPITATION
DEVELOPING ON THE SOUTHWEST SIDE OF THE SURFACE LOW DURING THE
LATE AFTERNOON AND EARLY EVENING. DEPENDING ON HOW FAR NORTH THE
LOW TRACKS, INCREASING INSTABILITY SOUTHEAST OF THIS DRY WEDGE
MAY LIFT INTO THE FAR SOUTHERN FORECAST AREA, SOUTH OF A PONTIAC
TO RENSSELAER LINE. WHILE THE BETTER INSTABILITY REMAINS
FARTHER SOUTH INTO CENTRAL AND SOUTHERN ILLINOIS, AN ISOLATED
STRONGER STORM CAN'T BE RULED OUT. ANY MORE ROBUST SHOWERS AND
EMBEDDED THUNDERSTORMS WILL BE CAPABLE OF EFFICIENT RAINFALL
RATES FOR THIS TIME OF YEAR IN THE PRESENCE OF PWATS
POTENTIALLY UPWARDS OF 1.5-2". THE LIMITED COVERAGE OF STRONGER
SHOWERS/STORMS SHOULD KEEP ANY FLOODING POTENTIAL TIED MAINLY TO
PONDING ON ROADWAYS AND POOR DRAINAGE SPOTS.
FRIDAY:
IN THE WAKE OF THE DEPARTING STORM SYSTEM AND ASSOCIATED STRONG
COLD FRONT, THE SURFACE PRESSURE GRADIENT INCREASES MARKEDLY
ACROSS THE AREA ON FRIDAY. THIS WILL LEAD TO BLUSTERY NORTHWEST
WINDS GUSTING UP TO 30-40+ MPH, HIGHEST ALONG THE NORTHWEST
INDIANA LAKESHORE. IN ADDITION, MODEL GUIDANCE HAS TRENDED
SLIGHTLY MORE SATURATED WITHIN THE LOW-CLOUD LAYER WHICH MAY
SUPPORT THE REDEVELOPMENT OF GUSTY DIURNAL SHOWERS. WEAK
INSTABILITY WITHIN THE LAYER AND COLDER CLOUD TOPS MAY SUPPORT
SOME GRAUPEL AS WELL. TEMPERATURES ON FRIDAY WILL LIKELY
STRUGGLE TO WARM OUT OF THE LOW TO MID 50S, MAKING FOR THE
COLDEST DAY OF THE SEASON SO FAR.
AS THE NORTHWESTERLY WINDS BEGIN TO TURN MORE NORTHERLY OVER
LAKE MICHIGAN, A BROKEN BAND (OR BANDS) OF LAKE EFFECT RAIN
SHOWERS WILL FOCUS INTO NORTHWEST INDIANA LATE FRIDAY AFTERNOON
THROUGH THE EVENING. WAVES ARE ALSO EXPECTED TO INCREASE AND MAY
LEAD TO MINOR LAKESHORE FLOODING OR EROSION, PARTICULARLY ALONG
THE PORTER COUNTY SHORE.
FRIDAY NIGHT ONWARD:
SKIES WILL QUICKLY CLEAR OUT AFTER MIDNIGHT FRIDAY, WHICH WILL
ALLOW FOR EFFICIENT RADIATIONAL COOLING AMIDST AN ALREADY COOLER
AIRMASS. THIS WILL LIKELY LEAD TO AREAS OF FROST DEVELOPMENT
OUTSIDE OF CHICAGO AND AWAY FROM LAKE MICHIGAN, COVERAGE
DEPENDENT UPON HOW LIGHT WINDS END UP. CAN'T RULE OUT
TEMPERATURES IN PORTIONS OF INTERIOR NORTHERN ILLINOIS DROPPING
INTO THE LOWER 30S. HOWEVER, CONFIDENCE IS NOT HIGH ENOUGH FOR A
FREEZE WATCH WITH THIS UPDATE.
WHILE STILL COOLER ON SATURDAY WITH TEMPERATURES IN THE 50S TO
AROUND 60, A RETURN OF SOUTHWESTERLY LOW-LEVEL FLOW WILL BEGIN A
GRADUAL WARMING TREND THAT CONTINUES THROUGH EARLY NEXT WEEK,
BRINGING A RETURN TO ABOVE NORMAL TEMPERATURES.
PETR
AVIATION /00Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 658 PM CDT WED OCT 14 2026
KEY AVIATION FORECAST MESSAGES:
- PATCHY MVFR CEILINGS THIS EVENING/OVERNIGHT.
- RAIN DEVELOPS EARLY THURSDAY MORNING, WITH CONDITIONS
DETERIORATING THROUGH LOW-MVFR INTO IFR BY LATE
MORNING/MIDDAY.
- PERIOD OF LIFR CEILINGS POSSIBLE LATER AFTERNOON/EARLY EVENING
ESPECIALLY FOR CHICAGO TERMINALS.
EARLY EVENING SURFACE ANALYSIS PLACES A NEARLY STATIONARY
FRONTAL BOUNDARY ACROSS THE LOWER OHIO VALLEY, WHILE HIGH
PRESSURE WAS CENTERED OVER THE NORTHERN GREAT LAKES. NORTHEAST
WINDS ALONG THE SOUTHERN PERIPHERY OF THE HIGH, COMBINED WITH
SOME LINGERING LOW-LEVEL MOISTURE HAS MAINTAINED SOME PATCHY
MVFR CEILINGS ACROSS PARTS OF NORTHEAST IL AND SOUTHEAST WI.
GUIDANCE TRENDS HAD INDICATED SCATTERING OF THE LOWER CLOUDS
THIS EVENING, THOUGH RECENT OBS TRENDS NEAR LAKE MICHIGAN LEND
LOW CONFIDENCE IN THESE TRENDS THIS EVENING.
LATER TONIGHT INTO EARLY THURSDAY, SURFACE LOW PRESSURE IS
EXPECTED TO DEEPEN ACROSS THE PLAINS IN RESPONSE TO A STRONG
UPPER LEVEL TROUGH. GUIDANCE IS IN GOOD ACQUIREMENT THAT THIS
PROGRESSION WILL LEAD TO AN EXPANSION OF RAIN/SHOWERS INTO THE
REGION EARLY THURSDAY MORNING, WITH A CORRESPONDING GRADUAL
DETERIORATION OF CEILINGS INTO MVFR EARLY AND TO IFR BY LATE
MORNING/MIDDAY, WITH WINDS BECOMING EAST-SOUTHEAST TO SOUTHEAST
THROUGH THE DAY. THERE IS SOME MODEL SUPPORT FOR A PERIOD OF
LIFR CEILINGS AND IFR VIS LATER IN THE AFTERNOON/EARLY EVENING,
ESPECIALLY ACROSS THE CHICAGO TERMINALS, AS THE SURFACE LOW AND
ASSOCIATED FRONTAL ZONE LIFT INTO THE AREA.
AS THE SURFACE LOW TRACKS EAST OF THE AREA THURSDAY EVENING,
WINDS WILL SHIFT TO THE NORTHWEST AND BEGIN TO INCREASE TOWARD
THE END OF THE CURRENT TAF PERIOD. WINDS WILL LIKELY BECOME
LIGHTER AND SOMEWHAT VARIABLE IN THE VICINITY OF THE SURFACE LOW
WITH IFR/LIFR CONDITIONS LIKELY EARLY BEFORE THE INCREASING
NORTHWEST WINDS ALLOW FOR SOME GRADUAL IMPROVEMENT BACK TO MVFR
OVERNIGHT.
RATZER
MARINE
ISSUED AT 310 PM CDT WED OCT 14 2026
STRONG NORTHWESTERLY GALES TO 40 KT AND VERY HAZARDOUS WAVES
ARE FORECAST TO DEVELOP FRIDAY AFTERNOON IN THE WAKE OF A
DEPARTING FALL STORM SYSTEM, BECOMING MORE NORTHERLY INTO FRIDAY
EVENING. ACCORDINGLY, A GALE WATCH HAS BEEN ISSUED FOR THE
ILLINOIS AND NORTHWEST INDIANA NEARSHORE WATERS FROM 1 PM FRIDAY
THROUGH 1 AM SATURDAY.
INCREASING LAKE INDUCED INSTABILITY WILL BECOME SUPPORTIVE OF
THE DEVELOPMENT OF A BAND OF LAKE EFFECT SHOWERS OVER LAKE
MICHIGAN FRIDAY AFTERNOON AND EVENING. WATERSPOUTS ALSO CANNOT
BE RULED OUT WITHIN THE STRONGEST SHOWERS.
PETR
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 PM CDT THURSDAY FOR WINTHROP
HARBOR TO WILMETTE HARBOR IL.
GALE WATCH FROM FRIDAY AFTERNOON THROUGH LATE FRIDAY NIGHT FOR
THE IL AND IN NEARSHORE WATERS.
SMALL CRAFT ADVISORY UNTIL 10 AM CDT THURSDAY FOR WILMETTE
HARBOR TO NORTHERLY IS. IL.
SMALL CRAFT ADVISORY UNTIL 4 AM CDT THURSDAY FOR NORTHERLY IS.
IL TO MICHIGAN CITY IN.
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