641
FXUS63 KLOT 211917
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
217 PM CDT TUE OCT 21 2025
KEY MESSAGES
- STRONG WESTERLY WINDS WILL GUST TO 40 MPH THROUGH THIS
EVENING WITH A FEW HIGHER GUSTS TO 45 MPH POSSIBLE.
- SCATTERED RAIN SHOWERS WILL END FROM WEST TO EAST THIS
EVENING.
- AREAS OF FROST ARE POSSIBLE EARLY THURSDAY MORNING AND ARE
LIKELY FOR MOST OF THE AREA EARLY FRIDAY MORNING.
DISCUSSION
ISSUED AT 217 PM CDT TUE OCT 21 2025
PRIMARY FORECAST CONCERN IS THE WESTERLY WINDS INTO THIS
EVENING. GUSTS TO 40 MPH WILL BE COMMON FOR MUCH OF THE AREA.
THERE MAY BE A FEW HOUR PERIOD AROUND SUNSET WHERE GUSTS AROUND
45 MPH DEVELOP, ESPECIALLY ACROSS NORTHWEST AND WEST CENTRAL IL.
WITH THE EXPECTED SHORT DURATION AND LIMITED AREA OF THE LOCAL
CWA, NOT PLANNING ANY WIND ADVISORY AT THIS TIME AND WIND GUST
TRENDS WILL NEED TO BE MONITORED INTO THIS EVENING. WIND GUSTS
WILL RELAX SLIGHTLY BY LATE EVENING, INTO THE 30-35 MPH RANGE
WHICH WILL CONTINUE INTO WEDNESDAY WITH GUSTS SLOWLY DIMINISHING
WEDNESDAY AFTERNOON AND THEN ENDING WITH SUNSET WEDNESDAY
EVENING.
SCATTERED SHOWERS HAVE DEVELOPED EARLIER THAN GUIDANCE WAS
SHOWING AND ARE MORE WIDESPREAD. HAVE INCREASED POPS TO LIKELY
THROUGH I-80. THESE SHOWERS ARE EXPECTED TO PEAK IN COVERAGE
NEAR SUNSET AND THEN SLOWLY DISSIPATE AND END FROM WEST TO EAST
THROUGH THE EVENING HOURS. THERE IS ANOTHER SMALL CHANCE OF
SHOWERS ACROSS FAR NORTHEAST IL WEDNESDAY AFTERNOON AS A WEAK
WAVE MOVES ACROSS THE WESTERN GREAT LAKES. THERE MAY ALSO BE A
FEW SHOWERS ACROSS NORTHWEST IN, MAINLY NORTHEAST PORTER COUNTY
INTO THURSDAY EVENING.
AREAS OF FROST WILL BE POSSIBLE EARLY THURSDAY MORNING, MAINLY
WEST AND SOUTH OF THE CHICAGO METRO AREA THOUGH THERE IS STILL
SOME UNCERTAINTY, PRIMARILY WITH THE WINDS. GUIDANCE SHOWS WINDS
IN THE 5 TO 10 MPH RANGE AND THIS MAY BE A BIT TOO HIGH FOR
WIDESPREAD FROST. CONVERSELY, IF CLOUDS CLEAR, THESE WINDS MAY
BE TOO HIGH. SO FOR NOW, MADE NO CHANGES TO THE CURRENT
FORECAST.
FROST POTENTIAL LOOKS BETTER FOR THURSDAY NIGHT INTO FRIDAY
MORNING WITH HIGH PRESSURE MOVING ACROSS THE AREA, LIGHT/CALM
WINDS AND CLEAR SKIES SHOULD ALLOW TEMPS TO DROP INTO THE
LOWER/MID 30S AWAY FROM THE LAKE/DOWNTOWN. ALSO MADE NO CHANGES
TO THIS TIME PERIOD WITH AREAS OF FROST FOR MOST OF THE CWA.
THERE REMAINS QUITE A BIT OF UNCERTAINTY FOR THIS WEEKEND INTO
EARLY NEXT WEEK WITH MODELS SHOWING VARIOUS WEAK WAVES THROUGH
THE WEEKEND AND THEN ANY POSSIBLE PHASING BETWEEN NORTHERN AND
SOUTHERN STREAMS EARLY NEXT WEEK. ONE NOTABLE CHANGE IS A RATHER
STRONG AND LARGE HIGH PRESSURE SOME OF THE MODELS AND THEIR
ENSEMBLES ARE SHOWING ACROSS QUEBEC AND NORTHERN NEW ENGLAND
NEXT WEEK, WHICH MAY TEND TO KEEP PRECIP CHANCES SOUTH AND
SOUTHWEST OF THE LOCAL AREA. BLENDED GUIDANCE HAS LOWERED POPS
INTO SLIGHT CHANCE FOR THE WEEKEND, THEN HIGH CHANCE EARLY NEXT
WEEK AND MADE NO CHANGES AT THIS TIME. CMS
AVIATION /18Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 1212 PM CDT TUE OCT 21 2025
KEY MESSAGES:
- WESTERLY WINDS GUSTING 30 TO 35 KTS THROUGH MUCH OF THE TAF
PERIOD. PEAK GUSTS OF 35-40 KT LATE THIS AFTERNOON AND
EVENING.
- ON-AND-OFF SHOWERS EXPECTED THIS AFTERNOON INTO THIS EVENING.
- MVFR CEILINGS LIKELY LATE THIS AFTERNOON INTO TOMORROW.
WESTERLY WINDS WILL CONTINUE TO BECOME INCREASINGLY GUSTY
THROUGH THE AFTERNOON INTO THIS EVENING. PREVAILING WIND GUSTS
OF 30-35 KT ARE EXPECTED THE REMAINDER OF THE AFTERNOON, WITH A
PERIOD OF STRONGER WINDS (35-40 KT) ALSO LIKELY LATE THIS
AFTERNOON INTO THE EVENING. BEYOND THIS EVENING, A TIGHT
SURFACE PRESSURE GRADIENT WILL CONTINUE TO FOSTER GUSTY WEST
WINDS (~30 KT) ACROSS THE AREA TERMINALS OVERNIGHT AND THROUGH
THE DAY ON WEDNESDAY.
ASIDE FROM THE WINDS, SEVERAL WEATHER DISTURBANCES EMBEDDED
WITHIN A LARGE UPPER-LEVEL LOW PRESSURE AREA OVER THE GREAT
LAKES WILL ALSO LEAD TO SCATTERED TO NUMEROUS SHOWERS OVER THE
AREA THIS AFTERNOON. A FEW OF THESE SHOWERS COULD BRIEFLY KNOCK
VISIBILITIES DOWN TO MVFR LEVELS BEFORE SHOWER COVERAGE WANES
THIS EVENING.
ALSO, EXPECT CIGS TO LOWER TO MVFR EITHER LATE THIS AFTERNOON
OR EARLY THIS EVENING. THESE CIGS ARE EXPECTED TO PERSIST
TONIGHT THROUGH AT LEAST WEDNESDAY MORNING, BEFORE BASES
GRADUALLY INCREASE TO LOWER END VFR WEDNESDAY AFTERNOON.
KJB
MARINE
ISSUED AT 217 PM CDT TUE OCT 21 2025
LOW PRESSURE WILL SLOWLY MOVE ACROSS THE NORTHERN GREAT LAKES
TONIGHT INTO WEDNESDAY, FINALLY LIFTING NORTHEAST WEDNESDAY
NIGHT. THIS WILL ALLOW FOR WINDY CONDITIONS ACROSS THE REGION
WITH WESTERLY GALES TO 40 KNOTS ACROSS SOUTHERN LAKE MICHIGAN
THROUGH MID MORNING WEDNESDAY. ONCE THE GALES END, WESTERLY
WINDS TO 30 KT WILL CONTINUE INTO WEDNESDAY EVENING. CMS
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...GALE WARNING UNTIL 9 AM CDT WEDNESDAY FOR THE IL AND IN
NEARSHORE WATERS.
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