361
FXUS63 KLOT 061802
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1202 PM CST FRI FEB 6 2026
KEY MESSAGES
- SCATTERED MAINLY NON-ACCUMULATING SNOW SHOWERS AND FLURRIES
NEAR THE LAKE THIS AFTERNOON INTO THE EARLY EVENING.
- PERIOD OF LAKE EFFECT SNOW POSSIBLE TONIGHT THROUGH SATURDAY
IN PARTS OF NORTHWEST INDIANA.
- A PATTERN SHIFT WILL OCCUR NEXT WEEK TOWARDS WARMER,
AND POTENTIALLY WETTER, CONDITIONS.
UPDATE
ISSUED AT 1202 PM CST FRI FEB 6 2026
THE MAIN TWEAK TO THE FORECAST WAS TO ADD MENTION OF SCATTERED
SNOW SHOWERS AND FLURRIES NEAR THE LAKE THIS AFTERNOON AND THEN
NEAR/EAST OF I-57 THIS EVENING. UPSTREAM RADAR NORTH OF THE
MILWAUKEE AREA SHOWS MAINLY LIGHT ECHOES INDICATIVE OF FLURRIES,
THOUGH THERE HAS BEEN OCCASIONAL ENHANCEMENT CLOSER TO THE
SHORE. AN AREA OF LAKE AIDED/INDUCED CONVERGENCE OVER FAR
NORTHEAST ILLINOIS AND FAR NORTHWEST INDIANA MAY HELP LOCALLY
ENHANCE PRECIP RATES.
WITH THIS BEING SAID, FORECAST SOUNDINGS ONLY SHOW CLOUD TOP
TEMPS AS LOW AS -13 TO -14C, WHICH SUGGESTS MOST OF THE SATURATION
AND STEEPER LAPSE RATES WILL RESIDE BELOW THE FAVORED -12 TO -18C
DGZ. SMALL, POOR QUALITY SNOWFLAKES SHOULD BE THE RESULT, WHICH
MAY BE CAPABLE OF CAUSING BRIEF RELATIVELY LOW VISIBILITY IN
ANY HEAVIER BURSTS. WITH TEMPERATURES CURRENTLY ABOVE FREEZING
LIKELY AND THEN FALLING TO NEAR FREEZING DURING THE SNOW, THE
SNOW SHOWERS SHOULD BE PRIMARILY A VISIBILITY ISSUE, COLLOQUIALLY
KNOWN AS "WHITE RAIN" (LITTLE/NO ACCUMULATION EXPECTED).
WINDS HAVE GENERALLY UNDERPERFORMED VS. PREVIOUS EXPECTATIONS
THUS FAR, THOUGH SHOULD UPTICK OVER THE NEXT FEW HOURS, PEAK IN
THE MID AFTERNOON AND EARLY EVENING WITH NORTHERLY GUSTS UP TO
30-35 MPH (UP TO 40 MPH NEAR THE LAKE IN NORTHWEST INDIANA).
CASTRO
DISCUSSION
ISSUED AT 323 AM CST FRI FEB 6 2026
THROUGH TODAY:
WATER VAPOR IMAGERY THIS MORNING SHOWS A POTENT SHORTWAVE DIVING
SOUTH INTO THE WESTERN GREAT LAKES. AN AREA OF SNOW ASSOCIATED
WITH THIS SHORTWAVE COVERS MUCH EASTERN/SOUTHEASTERN WISCONSIN.
RADAR PRESENTATION OF THIS SNOW DEFINITELY IS CONVECTIVE IN
NATURE, UNSURPRISINGLY GIVEN THE STEEP MID LEVEL LAPSE RATES
ACROSS THE REGION. HAVE SEEN A NUMBER "UNKNOWN PRECIPITATION"
REPORTS FROM AWOS/ASOS SITES ACROSS WISCONSIN, GIVEN THE HIGH
CLOUD BASES AND CONVECTIVE NATURE OF THE PRECIPITATION, SUSPECT
THIS IS GRAUPEL OR SNOW PELLETS.
ANTICIPATE THIS AREA OF SNOW, MIXED AT TIMES WITH GRAUPEL,
SLEET, OR SNOW PELLETS, TO OVERSPREAD ABOUT THE NORTHEAST HALF
OR SO OF OUR CWA DURING THE PREDAWN HOURS, THEN RAPIDLY END FROM
NORTHWEST TO SOUTHEAST DURING THE EARLY-MID MORNING HOURS. MOST
CONCENTRATED AREA OF PRECIP AND HIGHEST AMOUNTS SHOULD END UP
OVER THE CHICAGO METRO AREA INTO EXTREME NORTHWEST INDIANA,
WHEN A QUICK INCH OR SO OF SNOW COULD FALL THIS MORNING.
CERTAINLY POSSIBLE THAT THERE COULD BE SOME HEAVIER BURSTS OF
SNOW WITH THE MORE INTENSE CONVECTIVE ELEMENTS. ROADWAYS
IMPACTS ARE LIKELY DURING THE RUSH HOUR THIS MORNING.
OPTED TO REMOVE FREEZING DRIZZLE FROM THE FORECAST AS LOW LEVELS
SHOULD BE TOO DRY FOR DRIZZLE AND CLOUD BASES TOO HIGH. OPTED TO
MAINTAIN A SLIGHT CHANCE FOR SOME FREEZING RAIN, BUT PLAN TO
DOWNPLAY THAT THREAT IN MESSAGING AS CONVECTION DEEP ENOUGH FOR
PRECIPITATION SHOULD ALSO BE DEEP ENOUGH TO HAVE ICE NUCLEI
PRESENT TO SUPPORT SNOW, GRAUPEL, OR SNOW PELLETS. WHILE SNOW
LOOKS TO HIT AT AN INOPPORTUNE TIME, TOTALS SHOULD BE TOO LIGHT
TO WARRANT A WINTER WEATHER ADVISORY, SO PLAN TO RE-ISSUE AND
FRESHEN UP THE SPECIAL WEATHER STATEMENT.
GUSTY NORTH-NORTHWEST WINDS WILL DEVELOP THIS MORNING AND
CONTINUE THROUGH THE AFTERNOON. WHILE THERE COULD BE A COUPLE
HOURS WITH SOME BREAKS IN THE CLOUDS, STRATOCUMULUS SHOULD FILL
BACK IN THIS AFTERNOON. THE CLOUD COVER MAY TEMPER THE MAGNITUDE
OF THE GUSTS SOME, BUT FORECAST SOUNDINGS DEPICT STEEP LOW LEVEL
LAPSE RATES TAPPING INTO 35-40KT WINDS A FEW THOUSAND FEET OFF
THE DECK. CERTAINLY POSSIBLE WE COULD SEE A COUPLE GUSTS TO 40
MPH TODAY, PARTICULARLY WITH ANY CLEARING/PARTIALLY CLEARING.
- IZZI
TONIGHT THROUGH THURSDAY:
A DEEPENING TROUGH IS EXPECTED TO BE TRAVERSING ACROSS THE
GREAT LAKES TONIGHT INTO SATURDAY WITH NORTHERN IL AND NORTHWEST
IN RESIDING ON THE WESTERN PERIPHERY OF SAID TROUGH. WHILE THE
DRYING MID-LEVELS ON THE BACKSIDE OF THE TROUGH WILL ALLOW
PRECIPITATION TO CONCLUDE FOR MOST OF THE AREA THIS
AFTERNOON/EVENING, INCREASING SURFACE CONVERGENCE OVER SOUTHERN
LAKE MICHIGAN WILL DEVELOP A BAND OF LAKE EFFECT SNOW FOR
PORTIONS OF NORTHWEST AND NORTHERN IN. FORECAST SOUNDINGS SHOW
THE LAKE EFFECT PARAMETERS TO BE DECENT WITH ELS AROUND
5000-5500 FT AND STEEP LOW-LEVEL LAPSE RATES (AROUND 7-8C/KM)
RESIDING WITHIN THE DGZ WHICH COULD ALLOW FOR A LOCALIZED COUPLE
INCHES OF ACCUMULATION ESPECIALLY IN EASTERN PORTER COUNTY NEAR
THE CONVERGENCE AXIS. HOWEVER, WITH ELS EXPECTED TO BE LOWERING
OVERNIGHT AS HIGH PRESSURE BUILDS IN AND NORTHWEST WINDS
PUSHING THE BAND MORE INTO NORTHERN IN THERE IS A PLAY FOR THE
BULK OF ANY ACCUMULATION TO STAY EAST OF OUR AREA. GIVEN THE
FINICKY NATURE OF LAKE EFFECT THERE IS A CHANCE THINGS COULD
SHIFT SLIGHTLY AS WE GET CLOSER, BUT FOR NOW HAVE KEPT OUR
OFFICIAL FORECAST MORE IN LINE WITH THE MORE EASTWARD SOLUTIONS
WITH HIGHEST POPS (30-50%) IN EASTERN PORTER COUNTY AND NORTHERN
IN AND ACCUMULATIONS IN THE 0.5-1.0 INCH RANGE (HIGHEST AGAIN
IN EASTERN PORTER COUNTY).
THE LAKE EFFECT WILL GRADUALLY WANE SATURDAY MORNING WITH HIGH
PRESSURE SETTLING OVERHEAD GIVING AS A QUIET BUT CHILLY SATURDAY
WITH HIGHS IN THE MID TO UPPER 20S. HOWEVER, A SHORTWAVE TROUGH
IS FORECAST TO DIVE ACROSS THE WESTERN GREAT LAKES LATE
SATURDAY NIGHT INTO SUNDAY WHICH MAY LEAD TO A PERIOD OF LIGHT
SNOW SHOWERS AND/OR FLURRIES FOR SOME. WHILE GUIDANCE IS IN GOOD
AGREEMENT ON THE SHORTWAVE TRACK AND TIMING, FORECAST SOUNDINGS
SHOW MOISTURE (ESPECIALLY IN THE MID-LEVELS) MAY BE SOMEWHAT OF
A LIMITING FACTOR AND THUS MOST OF OUR AREA MAY REMAIN DRY.
THAT SAID, GIVEN SOME DECENT LOW-LEVEL MOISTURE AND THE
COMBINATION OF WARM ADVECTION AND ASCENT WITH THE WAVE HAVE
OPTED TO INTRODUCE SOME SLIGHT CHANCE (15- 20%) POPS OVER FAR
NORTHEAST IL AND NORTHWEST IN IN CASE SOME SNOW SHOWERS ARE ABLE
TO MATERIALIZE. REGARDLESS ANY SNOW THAT DOES OCCUR DOESN'T
LOOK TO AMOUNT TO MUCH IN THE WAY OF ACCUMULATIONS ASIDE FROM
MAYBE A LIGHT DUSTING.
HEADING INTO NEXT WEEK, THE NORTHWEST ORIENTED UPPER PATTERN
THAT HAS KEPT US IN COLD THESE PAST FEW WEEKS WILL BEGIN TO
BECOME MORE ZONAL (EAST-WEST ORIENTED) BY MONDAY. THIS SHIFT
WILL ALLOW FOR MORE PERSISTENT PERIODS OF WARM ADVECTION WHICH
IN TURN IS EXPECTED TO ALLOW TEMPERATURES TO MODERATE INTO THE
40S TO NEAR 50 BY THE MIDDLE OF THE WEEK. THE ONLY CAVEAT THOUGH
IS A BAROCLINIC ZONE THAT IS FORECAST TO ESTABLISH ACROSS THE
MID-MISSISSIPPI VALLEY AND WESTERN GREAT LAKES WHICH COULD
RESULT IN A GRADIENT IN TEMPERATURES IF IT WERE TO SET UP
OVERHEAD. ADDITIONALLY, A COUPLE OF SHORTWAVES ARE ALSO FORECAST
TO TRAVERSE THROUGH THE ZONAL FLOW (ONE OVER THE UPPER MIDWEST
AND NORTHERN GREAT LAKES AND THE OTHER OVER THE DEEP SOUTH) AND
MAY KICK OFF SOME PRECIPITATION LATE TUESDAY INTO WEDNESDAY. IF
SUFFICIENT MOISTURE CAN BUILD INTO THE AREA THEN PRECIPITATION
SHOULD INITIALLY START OFF AS RAIN TUESDAY EVENING (WITH PERHAPS
AN ISOLATED THUNDERSTORM GIVEN THE 6-7C/KM LAPSE RATES ALOFT)
BEFORE TRANSITIONING TO SNOW (OR A RAIN/SNOW MIX) AS THE
BAROCLINIC ZONE SHIFTS SOUTH AS A COLD FRONT ON WEDNESDAY. WITH
A LOT OF UNCERTAINTY IN QUALITY OF MOISTURE RETURN TO OUR AREA
HAVE OPTED TO MAINTAIN THE 20-40% POPS LATE TUESDAY THROUGH
WEDNESDAY FOR NOW.
DEPENDING ON HOW FAR SOUTH THE AFOREMENTIONED BAROCLINIC ZONE
GETS WEDNESDAY WILL DETERMINE WHETHER OR NOT ADDITIONAL PERIODS
OF PRECIPITATION WILL OCCUR THROUGHOUT THE REST OF THE WEEK AS
MORE SHORTWAVES PIVOT THROUGH THE REGION. GIVEN HOW GUIDANCE
TENDS TO STRUGGLE WITH BAROCLINIC ZONES (ESPECIALLY 5-7 DAYS
OUT) SAW NO REASON TO CHANGE THE 20-30% POPS OFFERED BY THE NBM
THROUGH THE END OF NEXT WEEK. HOWEVER, DO THINK THAT SOME DRY
PERIODS WILL ALSO BE POSSIBLE ESPECIALLY IF THE BAROCLINIC ZONE
CAN SHIFT FAR ENOUGH SOUTH. REGARDLESS, MORE TYPICAL
TEMPERATURES FOR MID-FEBRUARY ARE FORECAST TO CLOSE OUT NEXT
WEEK WITH HIGHS IN THE 30S TO AROUND 40 AND OVERNIGHT LOWS IN
THE 20S.
YACK
AVIATION /18Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 1138 AM CST FRI FEB 6 2026
KEY MESSAGES FOR THE 18Z TAF PERIOD:
* SCATTERED SNOW SHOWERS THIS AFTERNOON AND EARLY EVENING AROUND
CHICAGOLAND
* MVFR CIGS THROUGH THIS AFTERNOON
ANOTHER PUSH OF SNOW SHOWERS IS ANTICIPATED THIS AFTERNOON AND
EARLY EVENING AROUND THE CHICAGOLAND SITES AS A COLD FRONT
SWEEPS ACROSS. COVERAGE LOOKS SCATTERED, BUT THESE SNOW SHOWERS
WILL BE CAPABLE OF BRIEFLY REDUCING VSBYS TO 2 TO 3 SM. A
DUSTING OF ACCUMULATION WILL BE POSSIBLE, PRIMARILY OFF OF
TARMACS.
MVFR CIGS WILL REMAIN THROUGH THE AFTERNOON BEFORE CLEARING
BEHIND THE COLD FRONT EARLY THIS EVENING. FROM THERE, VFR IS
ANTICIPATED FOR THE REST OF THE PERIOD.
NNW WINDS WILL OCCASIONALLY GUST OVER 25 KT THIS AFTERNOON AND
EVENING BEFORE SUBSIDING TO 10 TO 12 KT FOR THE OVERNIGHT.
THEY'LL CONTINUE TO GRADUALLY EASE INTO SATURDAY WITH NEAR 5 KT
EXPECTED BY THE TIME DIRECTION SHIFTS TO SE AROUND MID-
AFTERNOON, POSSIBLY GOING VARIABLE FOR A COUPLE OF HOURS IN THE
PROCESS.
DOOM
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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