126
FXUS63 KLOT 170457
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1057 PM CST SUN NOV 16 2025
KEY MESSAGES
- PERIODS OF RAIN LATE MONDAY INTO TUESDAY.
- ADDITIONAL PERIODS OF RAIN/SHOWERS ARE LIKELY THURSDAY-
THURSDAY NIGHT, POSSIBLY LINGERING INTO THE START OF NEXT
WEEKEND.
DISCUSSION
ISSUED AT 300 PM CST SUN NOV 16 2025
THROUGH TUESDAY:
WEAK SURFACE HIGH PRESSURE MOVING OVERHEAD TONIGHT INTO EARLY
MONDAY COMING OFF THE VERY LOW DEW POINTS THIS AFTERNOON WILL
YIELD GOOD RADIATIONAL COOLING CONDITIONS. LEANED TOWARDS COLDER
GUIDANCE IN FAVORED COOL SPOTS OF NORTHERN ILLINOIS (LOCALIZED
LOW 20S), WITH MID-UPPER 20S ELSEWHERE EXCEPT LOW-MID 30S IN
CHICAGO AND NEAR THE NW INDIANA SHORE.
MONDAY WILL START OUT CALM AND DRY WITH CLEAR/MOSTLY SUNNY SKIES
GIVING WAY TO INCREASING HIGH CLOUDS AND THEN GRADUALLY LOWERING
BASES DURING THE AFTERNOON. THIS WILL BE IN ADVANCE OF A CLOSED
MID-UPPER LOW AND ASSOCIATED WEAK SURFACE LOW PRESSURE TRACKING
EASTWARD ACROSS THE CENTRAL PLAINS.
WARM ADVECTION ALOFT WILL TIGHTEN THE THERMAL GRADIENT DRAPED
ACROSS THE REGION, WITH F-GEN PROCESSES LIKELY RESULTING IN THE
DEVELOPMENT OF BANDED PRECIP INTO THE EVENING, INITIALLY ALOFT
DUE TO THE VERY DRY ANTECEDENT LOWER LEVELS. SOME SPRINKLES ARE
POSSIBLE TOWARDS SUNSET FOR THE NORTHWEST 2/3 TO 3/4 OF THE CWA.
IT WILL TAKE SOME TIME FOR TOP-DOWN SATURATION TO FULLY FIGHT
THROUGH THE LINGERING DRY AIR, SO STEADY/MEASURABLE PRECIP
COVERAGE MAY BE SOMEWHAT SPOTTY UNTIL LATER IN THE EVENING. IN
ADDITION, DUE TO THE ANTECEDENT DRY LOWER LEVELS, THERE MAY BE
ENOUGH EVAPORATIVE/WET BULB COOLING FOR WET SNOW TO MIX IN
ACROSS PORTIONS OF FAR NORTHERN ILLINOIS, ESPECIALLY DURING THE
EVENING (OR EVEN SPOTTY ICE PELLETS AT ONSET). WELL ABOVE
FREEZING AIR TEMPS AND MILD GROUND TEMPS WILL PRECLUDE ANY
IMPACTS EVEN IF WET SNOW OCCURS, HOWEVER.
INCREASING LARGE SCALE FORCING WILL RESULT IN WIDESPREAD LIGHT
TO AT TIMES MODERATE RAIN OVERNIGHT MONDAY NIGHT INTO EARLY
TUESDAY, ALBEIT PROBABLY STILL WITH SOME BANDED COMPONENT. SOME
EMBEDDED CONVECTIVE ELEMENTS ARE POSSIBLE NEAR/WEST OF I-39,
THOUGH FORECAST SOUNDINGS DON'T LOOK FAVORABLE FOR ANY THUNDER
MENTION. THE FOOTPRINT OF STEADY RAIN WILL PROBABLY CONTRACT AND
FOCUS NORTHEAST HALF OR SO OF THE AREA DURING THE DAY ON TUESDAY
AS THE CLOSED LOW WEAKENS INTO AN OPEN WAVE. LINGERING LIGHT
RAIN WILL TAPER OFF AND END BY MID TO LATE TUESDAY AFTERNOON AS
THE SYSTEM FINALLY EXITS EAST. CLOUDS AND PERIODIC RAIN WILL
KEEP TEMPS DOWN IN THE LOWER-MID 40S IN MOST SPOTS ON TUESDAY.
TUESDAY NIGHT THROUGH SUNDAY:
STRATUS SHOULD LINGER TUESDAY NIGHT THROUGH WEDNESDAY NIGHT,
LIMITING THE DIURNAL TEMPERATURE RANGES, AMIDST OTHERWISE QUIET
WEATHER. THE LATE IN THE WORKWEEK TIMEFRAME CONTINUES TO BE THE
MAIN PERIOD OF INTEREST FOR THE NEXT ROUND(S) OF RAIN. ENSEMBLE
GUIDANCE HAS CONTINUED TO EXHIBIT CONSIDERABLE VARIABILITY
REGARDING THE OVERALL SYNOPTIC EVOLUTION, OWING TO THE
TRAJECTORY AND STRENGTH OF A SHORT-WAVE POTENTIALLY EJECTING
NORTHEAST FROM THE SOUTHERN PLAINS.
A WARM FRONT WILL LIFT NORTH ON THURSDAY, PROBABLY PAIRED WITH
INCREASING SHOWER COVERAGE, PARTICULARLY DURING THE AFTERNOON,
LIKELY CONTINUING INTO THURSDAY NIGHT (PERHAPS WITH ISOLATED
EMBEDDED T-STORMS). THIS IS WHEN THE GUIDANCE VARIABILITY
REALLY LOWERS FORECAST CONFIDENCE, WITH THE ECMWF/EPS SUITE THE
MOST BULLISH IN BRINGING THE TROUGH INTO OUR AREA INTO FRIDAY.
EVEN WITHIN THE EPS SUITE, THERE'S LESS THAN HALF MEMBER SUPPORT
FOR THE STRONG, SLOW MOVING SYNOPTIC SYSTEM DEPICTED ON THE 12Z
OPERATIONAL RUN. HOW THIS ALL PLAYS OUT WILL ULTIMATELY
DETERMINE IF FRIDAY ENDS UP HAVING INCLEMENT WEATHER AND THE
UNSETTLED CONDITIONS POSSIBLY EVEN HANGING ON INTO EARLY
SATURDAY. THE WEEKEND SHOULD THEN END ON A DRY AND SEASONABLE NOTE.
CASTRO
AVIATION /06Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 1056 PM CST SUN NOV 16 2025
AVIATION FORECAST CONCERNS FOR THE 06Z TAFS:
- LIGHT NORTHWEST WINDS BECOMING EAST-SOUTHEASTERLY MONDAY
AFTERNOON/NIGHT.
- PRECIPITATION DEVELOPS LATE MONDAY EVENING/OVERNIGHT. CAN'T
RULE OUT SPOTTY SHRA LATE AFTERNOON/EARLY EVENING. SOME MVFR POSSIBLE
AFTER MIDNIGHT.
QUIET VFR WEATHER IS EXPECTED THROUGH MUCH OF MONDAY, AS SURFACE
HIGH PRESSURE RIDGE DRIFTS EAST ACROSS THE REGION. SURFACE WINDS
ARE EXPECTED TO BE GENERALLY LIGHT NORTHWEST-NORTH-NORTHWEST
INTO MONDAY MORNING (THOUGH VARIABLE/CALM CONDITIONS LIKELY IN
SOME SPOTS), BEFORE SHIFTING LIGHT EASTERLY DURING THE
AFTERNOON. SPEEDS WILL COME UP A BIT TO AROUND 10 KTS LATER MONDAY
NIGHT, IN RESPONSE TO LOW PRESSURE MOVING SLOWLY EAST ACROSS
THE PLAINS.
MAINLY CLEAR SKIES ARE EXPECTED INTO MONDAY MORNING, BEFORE VFR
MID AND HIGH CLOUDS THICKEN AND GRADUALLY LOWER INTO THE
AFTERNOON AND EVENING HOURS AHEAD OF AN APPROACHING MID-LEVEL
DISTURBANCE. CAN'T RULE OUT SOME SPOTTY SPRINKLES FROM THIS
MID-DECK DURING THE LATE AFTERNOON HOURS, THOUGH GUIDANCE TRENDS
INDICATE MUCH OF THIS MAY NOT REACH THE GROUND INITIALLY DUE TO
LOW COVERAGE AND DRY LOW-LEVELS. WHILE SURFACE TEMPS WILL BE
ABOVE FREEZING, IF SPOTTY PRECIP WOULD REACH THE SURFACE
EVAPORATIVE COOLING COULD SUPPORT BRIEF SNOW FLAKES OR LIGHT
ICE PELLETS. STEADIER RAIN/MORE FREQUENT RAIN SHOWERS ARE THEN
EXPECTED TO DEVELOP LATE EVENING AND CONTINUE OVERNIGHT. SOME
MVFR DEVELOPMENT IS POSSIBLE IN THIS STEADIER PRECIP INTO EARLY
TUESDAY MORNING.
RATZER
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 9 AM CST MONDAY FOR GARY TO BURNS
HARBOR IN-BURNS HARBOR TO MICHIGAN CITY IN.
VISIT US AT WEATHER.GOV/CHICAGO
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