718
FXUS63 KIWX 121139
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
639 AM EST SUN JAN 12 2025
KEY MESSAGES
- LIGHT SNOW THIS AFTERNOON AND EVENING NORTH OF US 24. DUSTING
TO 1 INCH OF SNOW EXPECTED.
- VERY COLD MONDAY NIGHT THROUGH THURSDAY MORNING WITH BELOW-
ZERO WIND CHILLS AT TIMES.
- EPISODES OF LAKE EFFECT THROUGH THE WEEK AND A SLIGHT CHANCE
(20%) OF A CLIPPER SYSTEM MIDWEEK.
DISCUSSION
ISSUED AT 251 AM EST SUN JAN 12 2025
WE'LL BE IN THE "WARM" SECTOR OF A WEAK AREA OF LOW PRESSURE
TRACKING THROUGH THE GREAT LAKES TODAY. RADAR RETURNS ARE ONGOING
THANKS TO SUBTLE WARM AIR ADVECTION YET MOST OF THIS IS VIRGA DUE TO
A MIDLEVEL WEDGE OF DRY AIR. THIS IS FORECAST TO ERODE AS UPPER-
LEVEL FORCING IMPROVES AND THE THERMAL GRADIENT ALOFT TIGHTENS. THIS
SHOULD ALLOW FOR TIMES OF LIGHT SNOW TODAY, PRIMARILY WEST OF I-69.
HOWEVER, MOISTURE TRANSPORT IS OVERALL PRETTY MEAGER. WATER VAPOR
TELLS THE STORY WITH NO POLEWARD MOISTURE TRANSPORT FROM THE GULF OR
CENTRAL PACIFIC. BECAUSE OF THIS LACK OF MOISTURE, THE LOW CONCERN
FOR FREEZING DRIZZLE REMAINS AS INDICATED BY A FEW FORECAST
SOUNDINGS. CONFIDENCE IS LOW IN FZDZ OCCURRING, BUT, FEELS
PRUDENT TO LEAN ON THE PERSISTENCE FORECAST.
ONE OF TWO COLD FRONT MOVES THROUGH TONIGHT AS THE LOW LIFT
NORTHEAST INTO ONTARIO. THIS WILL ALLOW LAKE EFFECT SNOW TO DEVELOP
AND PERSIST INTO TUESDAY. LAKE EFFECT SNOW IS PROLONGED AS THE
SECOND OF TWO COLD FRONTS MOVES THROUGH ON TUESDAY. THIS ALSO
BRINGS A SLIGHT CHANCE (20%) FOR LIGHT SNOW SOUTH OF US 24 AMID
A STRENGTHENING 500-MB JET. OUTSIDE OF THE LAKE EFFECT BELT,
MONDAY NIGHT THROUGH WEDNESDAY NIGHT WILL BE BITTERLY COLD AS
LOWS TUMBLE INTO THE SINGLE-DIGITS. BELOW ZERO LOWS ARE POSSIBLE
AT A FEW SITES TUESDAY NIGHT. WIND CHILLS WILL BE WELL BELOW
ZERO.
LATE WEEK FEATURES A BRIEF MODERATION IN TEMPERATURE WITH HIGHS
CREEPING INTO THE MID-30S. THIS OCCURS AS A DEEP TROUGH ENCOMPASSES
THE WESTERN 2/3 OF THE CONUS AND RIDGING NOSES INTO OUR AREA.
DEPENDING ON THE DEPTH OF SAID TROUGH, A LOW IS FORECAST TO EJECT
NORTHEAST THROUGH THE TENNESSEE RIVER VALLEY. IF IT TRACKS FAR ENOUGH
NORTH, WE COULD FACE SOME PRECIPITATION-TYPE ISSUES. FOR NOW,
RETAINED THE RAIN-SNOW CHANCE FOR SATURDAY. SHARPLY COLDER ONCE
MORE AFTER NEXT WEEKEND.
AVIATION /12Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 630 AM EST SUN JAN 12 2025
OUTSIDE OF A FEW POCKETS OF SNOW SHOWERS EXPECTATION IS MAINLY
VFR CONDITIONS WITH MVFR CONDITIONS AFTER 15Z TODAY FOR KSBN AND
AROUND 16Z FOR KFWA WITH LOWER CIGS ARRIVING WITH A SHORTWAVE
TROUGH THAT IS CURRENTLY PUSHING EASTWARD INTO THE REGION.
THIS DISTURBANCE WILL BRING LIGHT SNOW, AND THERE IS STILL LOW
CONFIDENCE THAT SOME FREEZING DRIZZLE MAY MIX IN AT TIMES TODAY
ESPECIALLY AFTER 18Z. HOWEVER, CONFIDENCE IS STILL VERY LOW FOR
THIS OCCURRENCE AND HAVE OPTED TO KEEP MENTION OF THIS OUT OF
THE TAFS AT THIS TIME. AFTER 17Z SUN AT KSBN AND 18Z SUN FOR
KFWA, IFR CONDITIONS WILL PREVAIL WITH THE LIGHT SNOW AND
FURTHER LOWERING OF CIGS. SOUTHERLY WINDS WILL ALSO BECOME GUSTY
(UP TO 25 KTS) AND WILL VEER TO MORE WESTERLY WITH TIME. AFTER
04Z, SNOW WILL BEGIN TO TAPER OFF AND CIGS WILL SLIGHTLY IMPROVE
WITH A RETURN TO MVFR LEVELS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR LMZ043-046.
DISCUSSION...BROWN/STEINWEDEL
AVIATION...ANDERSEN
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