996
FXUS63 KLOT 070457
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1057 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 /06Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 1057 PM CST FRI FEB 6 2026
KEY MESSAGES FOR 06Z TAFS:
- BLUSTERY NORTH WINDS GUSTING 20-25 KT GRADUALLY DIMINISH
OVERNIGHT, BECOMING LIGHT AND VARIABLE BY EARLY SATURDAY
AFTERNOON AND LIGHT SOUTHEAST SATURDAY NIGHT.
- LOW PROBABILITY (<25%) FOR A 3-4 HOUR PERIOD OF LIGHT SNOW
TOWARD/AFTER MIDNIGHT SATURDAY NIGHT.
BLUSTERY NORTHERLY WINDS WILL PERSIST INTO THE OVERNIGHT HOURS
IN THE WAKE OF A COLD FRONT. GUSTS 20-25 KT WILL GRADUALLY
DIMINISH PREDAWN, WITH WINDS REMAINING NORTH-NORTHWEST SATURDAY
MORNING. SURFACE HIGH PRESSURE WILL SPREAD ACROSS THE AREA
DURING THE MIDDAY/AFTERNOON HOURS, WHICH WILL RESULT IN A FEW
HOUR PERIOD OF LIGHT AND SOMEWHAT VARIABLE WINDS, WHICH SHOULD
BECOME LIGHT EAST-SOUTHEAST BY SATURDAY EVENING AND INCREASE
INTO THE 5-10 KT RANGE OVERNIGHT.
LINGERING VFR LAKE-INDUCED STRATOCU WILL PERSIST MAINLY AT GYY
OVERNIGHT AND INTO SATURDAY MORNING. OTHERWISE, MAINLY CLEAR
SKIES ARE EXPECTED UNTIL SATURDAY AFTERNOON WHEN INCREASING VFR
HIGH CLOUDS DEVELOP AND EVENTUALLY THICKEN AND LOWER INTO A
MID-DECK SATURDAY EVENING. LOW-LEVELS WILL REMAIN QUITE DRY
ACROSS THE REGION SATURDAY NIGHT, THOUGH THERE REMAINS A SIGNAL
FOR LIGHT SNOW TO DEVELOP NEAR BUT MAINLY NORTH/NORTHEAST OF THE
TERMINALS SATURDAY NIGHT. A SMALL SUBSET OF MODEL RUNS DO DEPICT
DEVELOPMENT OVER THE AREA HOWEVER, THOUGH WHILE THIS CAN'T BE
COMPLETELY DISREGARDED THE CURRENT POTENTIAL (<25%) IS NOT HIGH
ENOUGH TO INCLUDE IN TAFS AT THIS TIME. IF IT WERE TO OCCUR,
TIMING LOOKS TO BE AFTER ABOUT 03Z AT RFD AND AFTER 05Z FOR
CHICAGO SITES.
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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