122
FXUS63 KLOT 070002
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
602 PM CST FRI FEB 6 2026
KEY MESSAGES
- STILL EXPECTING SCATTERED MAINLY NON-ACCUMULATING SNOW SHOWERS
AND FLURRIES NEAR THE LAKE INTO THE EARLY EVENING. LAKE EFFECT
SNOW SHOWERS ARE POSSIBLE INTO PARTS OF NORTHWEST IN LATER
TONIGHT-SATURDAY, MAINLY NORTHEAST PORTER CO. AND POINTS EAST.
- SOLIDLY BELOW NORMAL TEMPERATURES WILL RETURN TONIGHT THROUGH
SATURDAY, MODERATING TO CLOSER TO NORMAL ON SUNDAY.
- MILDER CONDITIONS ARE IN STORE NEXT WORKWEEK, ESPECIALLY
EARLY, THOUGH THE PATTERN DOESN'T CURRENTLY APPEAR FAVORABLE
FOR ANY SIGNIFICANT MOISTURE LADEN STORM SYSTEMS.
DISCUSSION
ISSUED AT 244 PM CST FRI FEB 6 2026
THROUGH SATURDAY:
A SECONDARY COLD FRONT WAS MOVING SOUTHWARD ACROSS NORTHERN
ILLINOIS AS OF EARLY AFTERNOON, WITH MUCH STRONGER COLD AIR
ADVECTION IN THE WAKE OF THIS FRONT THROUGH TONIGHT, BRINGING A
PERIOD OF BLUSTERY NORTH-NORTHWEST WINDS THROUGH THIS EVENING.
IN THE NEAR TERM, THROUGH EARLY EVENING, STILL EXPECTING
MARGINAL SNOW SHOWERS NEAR THE LAKE AS AN ZONE OF LAKE
AIDED/INDUCED CONVERGENCE SETS UP JUST INLAND OF THE LAKE INTO
EARLY EVENING. INITIAL SCATTERED SNOW SHOWERS INTO FAR
NORTHWEST INDIANA SHOULD ALSO SHIFT INTO AREAS NEAR THE LAKE IN
NORTHEAST ILLINOIS AND THEN SPREAD INLAND NEAR/EAST OF I-57 THIS
EVENING BEFORE DISSIPATING.
FORECAST SOUNDINGS ONLY SHOW CLOUD TOPS AS COLD AS -13 TO -14C,
WHICH CONTINUES TO SUGGEST THAT MOST OF THE SATURATION AND
STEEPER LAPSE RATES WILL RESIDE BELOW THE FAVORED -12 TO -18C
DGZ. WITH TEMPERATURES AS OF THIS WRITING WELL ABOVE FREEZING
AND THEN FALLING TO NEAR TO SLIGHTLY BELOW FREEZING AFTER
SUNSET, THE SNOW SHOWERS SHOULD BE PRIMARILY A PERIODIC REDUCED
VISIBILITY (DOWN TO 2-4 MILES AT TIMES IN ANY HEAVIER BURSTS)
ISSUE. THIS CAN BE COLLOQUIALLY CALLED "WHITE RAIN", AS LITTLE
TO NO SNOW ACCUMULATIONS OF NOTE ARE ANTICIPATED.
BEYOND THE EARLY EVENING SNOW SHOWERS NEAR THE LAKE, THE MAIN
STORY WILL BE THE ABRUPT RETURN TO COLD CONDITIONS OVERNIGHT.
LOWS BY EARLY SATURDAY WILL DIP INTO THE HIGH POSITIVE SINGLE
DIGITS AND LOWER TEENS (MID TEENS NEAR LAKE IN NW IN). WINDS
WILL THANKFULLY BE DIMINISHING, BUT NONETHELESS, MINIMUM WIND
CHILLS NEAR TO SLIGHTLY BELOW ZERO ARE FORECAST. LAKE EFFECT
SNOW SHOWERS WILL REDEVELOP OVER SOUTHEASTERN LAKE MICHIGAN LATE
THIS EVENING AND THEN GRADUALLY PUSH TOWARDS NORTHEASTERN PORTER
COUNTY INTO EARLY SATURDAY. FORECAST INVERSION HEIGHTS ARE
QUITE MARGINAL AT 5KFT OR LESS, LIMITING THE INTENSITY OF THE
LAKE EFFECT SNOW SHOWERS. IT APPEARS THE FOCUS OVERNIGHT INTO
SATURDAY MORNING SHOULD BE INTO LAPORTE COUNTY, THOUGH GENERALLY
LIGHT SNOW MAY STILL BE ABLE TO SNEAK INTO NORTHEAST PORTER
BEFORE THE ACTIVITY SHIFTS EAST SATURDAY AFTERNOON. IF ANY
LIGHT ACCUMULATIONS OCCUR, TEMPERATURES WILL BE COLD ENOUGH FOR
SNOW TO COAT ROADS AND CAUSE SOME IMPACTS (20-30% CHANCE IN
NORTHEASTER PORTER CO.).
ASIDE FROM THE LOWER END LAKE EFFECT SNOW POTENTIAL, SATURDAY
WILL BE QUIET AND CHILLY WITH HIGHS IN THE 21-28F RANGE, VERSUS
NORMAL VALUES IN THE LOWER TO MID 30S FOR FEBRUARY 7TH.
SATURDAY NIGHT THROUGH FRIDAY:
A FAST MOVING CLIPPER SYSTEM AND ITS ASSOCIATED SNOW CHANCES
MAY BRUSH BY JUST TO OUR NORTH AND EAST SATURDAY NIGHT-EARLY
SUNDAY, WITH OTHERWISE NOT AS COLD CONDITIONS AS TONIGHT-EARLY
SATURDAY. INTO NEXT WEEK, MID-UPPER RIDGING IN THE WESTERN
CONUS THAT HAS BEEN SEMI-PERMANENT THIS WINTER (AND BROUGHT
RELENTLESS NORTHWEST FLOW INTO OUR REGION) WILL FINALLY SLIDE
EAST. THE RESULT WILL BE A SUBSTANTIAL WARM-UP LOCALLY MONDAY
INTO TUESDAY FOLLOWING NEAR SEASONABLE CONDITIONS ON SUNDAY.
A PREDOMINANT BROAD WESTERN TROUGHING AND EASTERN/SOUTHEASTERN
CONUS RIDGING REGIME IS OFTEN UNSEASONABLY MILD IN THE COOL
SEASON, AND GENERALLY NEAR TO ABOVE NORMAL PRECIPITATION WISE.
COMPLETELY FROZEN GROUND AND EXTENSIVE THICK RIVER ICE INTO SUCH
A STRETCH WOULD BE POTENTIALLY PROBLEMATIC. HOWEVER, UPSTREAM
HIGH LATITUDE BLOCKING CENTERED NORTHEAST OF HUDSON BAY (A WEST
BASED NEGATIVE NORTH ATLANTIC OSCILLATION/-NAO) SHOULD TEND TO
SUPPRESS MID- LEVEL HEIGHTS AND THE LOWER TO MID-LEVEL
BAROCLINIC ZONE SOUTHWARD TO AN EXTENT. THIS MAY VERY WELL
PRECLUDE ANY MEANINGFUL PRECIPITATION UNTIL LATER IN THE WEEK.
AS IT STANDS, THE BLENDED GUIDANCE HELD ONTO SOME CHANCE FOR
RAIN TUESDAY NIGHT INTO EARLY WEDNESDAY, WHICH SHOULD DIMINISH
IN SUBSEQUENT UPDATES IF RECENT ENSEMBLE TRENDS HOLD.
A WEAK COLD FRONT WILL PUSH SOUTHWARD ON TUESDAY, RESULTING IN A
MODEST COOL-DOWN ON WEDNESDAY. IN A CHANGE FROM PREVIOUS
FORECAST CYCLES, THE ECMWF ENSEMBLE SYSTEM (EPS) JUMPED TOWARDS
A NEUTRALLY TILTED WAVE INTERACTING WITH THE BAROCLINIC ZONE
OVER THE REGION THURSDAY-THURSDAY NIGHT. IF THIS SCENARIO
MATERIALIZES, THAT WOULD BE OUR NEXT PERIOD TO WATCH FOR WINTRY
PRECIP IN THE AREA AS EXPANSIVE COOL, DRY HIGH PRESSURE TO OUR
NORTHEAST WOULD BRING LOWER WET BULB TEMPERATURES (AND COOLER
OVERALL THERMAL PROFILES). WHILE THE SIGNAL ON THE EPS (50-60%
OF MEMBERS) CAN'T BE IGNORED, IT'S THE DECIDED MINORITY WITH
RESPECT TO THE OVERALL MULTI-MODEL ENSEMBLE AND AS SUCH, OUR
FORECAST POPS ARE ONLY ABOUT 20% DURING THAT TIMEFRAME.
CASTRO
AVIATION /00Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 602 PM CST FRI FEB 6 2026
KEY MESSAGES FOR THE 00Z TAFS:
- BRIEF MVFR CEILINGS AND FLURRIES/LIGHT SNOW SHOWERS NEAR LAKE
MICHIGAN THIS EVENING, PRIMARILY AFFECTING MDW AND GYY.
- NORTHERLY WINDS (BRIEFLY NORTHEAST AT ORD/MDW EARLY THIS
EVENING) WILL GUST 20-25 KTS THIS EVENING, THEN GRADUALLY
DIMINISH LATE TONIGHT/SATURDAY BEFORE BECOMING LIGHT
SOUTHEAST BY SATURDAY EVENING.
SECONDARY SURFACE COLD FRONT HAS PUSHED THROUGH ORD/MDW/GYY LATE
THIS AFTERNOON, RESULTING IN A TEMPORARY WIND SHIFT TO THE
NORTHEAST. WINDS WILL SLOWLY SHIFT BACK TO THE NORTH MID-LATE
EVENING, WITH OCCASIONAL GUSTS 20-25 KT SLOWLY EASING. A FEW
FLURRIES OR LIGHT SNOW SHOWERS CAN BE EXPECTED MAINLY ALONG/OVER
LAKE MICHIGAN THROUGH MID-EVENING, THOUGH NO VIS REDUCTIONS OR
ACCUMULATIONS ARE EXPECTED FOR THE TERMINALS.
NORTH-NORTHWEST WINDS WILL SLOWLY DIMINISH INTO SATURDAY AS WEAK
SURFACE HIGH PRESSURE SPREADS INTO THE AREA. WINDS MAY GO LIGHT
AND VARIABLE FOR A TIME SATURDAY AFTERNOON BEFORE TURNING LIGHT
SOUTHEAST LATER IN THE DAY AND PERSISTING SATURDAY NIGHT.
ANOTHER FAST MOVING UPPER LEVEL DISTURBANCE IS EXPECTED TO PASS
LARGELY NORTH OF THE TERMINALS SATURDAY NIGHT. MOST CURRENT
MODEL GUIDANCE DEVELOPS PRECIPITATION NORTH/NORTHEAST OF THE
TERMINALS LATE SATURDAY EVENING, AND GIVEN VERY DRY LOW-LEVEL
AIR ACROSS THE AREA THIS LOOKS REASONABLE AT THIS TIME - THOUGH
WE'LL CONTINUE TO BE MONITOR.
RATZER
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 AM CST SATURDAY FOR THE IL
NEARSHORE WATERS.
GALE WARNING UNTIL MIDNIGHT CST TONIGHT FOR THE IN NEARSHORE
WATERS.
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