967
FXUS63 KIWX 122240
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
540 PM EST SUN JAN 12 2025
KEY MESSAGES
- CHANCES (20-50%) FOR LIGHT SNOW SHOWERS AND DRIZZLE PERSIST
INTO THIS EVENING. LITTLE TO NO SNOW ACCUMULATION EXPECTED.
- COLDER WITH EPISODES OF LIGHT LAKE EFFECT SNOW LATE TONIGHT
THROUGH TUESDAY NIGHT, MAINLY OVER SOUTHWEST MICHIGAN WHERE
MINOR TRAVEL DISRUPTIONS WILL BE POSSIBLE.
- BELOW ZERO WIND CHILLS AT TIMES, ESPECIALLY MONDAY NIGHT AND
TUESDAY NIGHT.
DISCUSSION
ISSUED AT 221 PM EST SUN JAN 12 2025
POCKETS OF LIGHT SNOW ASSOCIATED WITH A WEAK SHORTWAVE AND NARROW
PRE-FRONTAL MOISTURE CHANNEL (2.5-3 G/KG IN THE 85-7H LAYER) NOW
INTO NW IN AND SW MI WILL CONTINUE TO TRANSLATE EAST INTO AREAS
MAINLY NORTH OF US 24 THIS AFTERNOON INTO EARLY THIS EVENING.
PASSAGE OF THE SHORTWAVE AND ASSOCIATED MID LEVEL MOISTURE MAY STRIP
THE CLOUD OF ICE NUCLEI FOR A TIME THIS EVENING. THIS IN CONJUNCTION
WITH AMPLE LOW LEVEL MOISTURE AND ASCENT IN ADVANCE OF AN INCOMING
ARCTIC FRONT MAY SUPPORT PATCHY DRIZZLE/FREEZING DRIZZLE DURING THIS
TIME. AIR TEMPS MAY LUCKILY BE WARM ENOUGH TO MITIGATE ICING
CONCERNS, WITH CONFIDENCE IN DRIZZLE OCCURRING REMAINING ON THE LOW
SIDE REGARDLESS (20%).
TEMPS CRASH INTO MID TEENS TO NEAR 20 LATER TONIGHT INTO MONDAY AS
COLD/BLUSTERY WEST WINDS SETTLE IN BEHIND TONIGHT'S ARCTIC COLD
FRONT. WIND CHILLS ARE FORECAST TO REMAIN RELATIVELY STEADY NEAR
ZERO DEGREES FOR MUCH OF THE DAY ON MONDAY, THEN FALLING INTO THE
SINGLE DIGITS BELOW ZERO FOR MANY MONDAY NIGHT. LAKE EFFECT SNOW
SHOWERS AND FLURRIES WILL ALSO DEVELOP IN THIS REGIME IN OUR
WESTERLY FLOW LES BELTS NEAR AND NORTH OF THE MI STATE LINE. DRY
NATURE TO THE AIRMASS, LACKING RESIDENCE TIME AND SHALLOW INVERSION
HEIGHTS SHOULD LIMIT ACCUMS/IMPACTS MONDAY INTO MONDAY NIGHT.
HOWEVER, IT IS WORTH NOTING THAT ANY POTENTIAL SATURATION IS MODELED
TO BE WITHIN THE DGZ WHICH COULD SUPPORT TIMES OF LIGHT ACCUMS AND
REDUCED VISIBILITIES.
POLAR VORT LOBE, CURRENTLY OVER MANITOBA, WILL SWING SOUTHEAST
THROUGH THE AREA ON TUESDAY WITH A REINFORCING SHOT OF COLD AIR (850
MB TEMPS DROP TO NEAR -20C). BRIEF VEERING AND BETTER LAKE INDUCED
THERMODYNAMICS IN WAKE OF THE ASSOCIATED SECONDARY COLD FRONT COULD
RESULT IN AN UPTICK IN LES COVERAGE TUESDAY INTO TUESDAY EVENING
GIVEN THE SYNOPTIC SUPPORT. AIRMASS WILL ONCE AGAIN BE VERY DRY
HOWEVER WITH SMALL FLAKE SIZE. ELSEWHERE, WILL HAVE TO MONITOR
A FAST MOVING CLIPPER TYPE SYSTEM THAT COULD DROP AN INCH OR SO
OF FLUFFY SNOW THROUGH CENTRAL IL/IN. BUMPED UP POPS (30-50%)
SOUTH OF US 30 ON TUESDAY TO ACCOUNT FOR THIS WAVE.
THE UPPER LEVEL TROUGHING AND CORE OF COLDEST LOW LEVEL AIR WILL
SHIFT EASTWARD FOR THE SECOND HALF OF THE WEEK RESULTING IN A
WELCOMED WARMING TREND (HIGHS INTO THE MID 30S BY FRIDAY). ENSEMBLES
THEN REMAIN IN GOOD AGREEMENT IN COLDER ARCTIC AIR RETURNING LATE IN
THE WEEKEND INTO EARLY NEXT WEEK AS AN EXPANSIVE UPPER LEVEL TROUGH
RETURNS IN RESPONSE TO RENEWED RIDING OVER THE GULF OF ALASKA. THERE
COULD BE A BAROCLINIC WAVE TO WATCH AROUND FRIDAY NIGHT-SATURDAY IN
THIS TRANSITION, THOUGH MODEL SPREAD REMAINS HIGH WITH CHANCE POPS
FOR RAIN AND SNOW RETAINED.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 536 PM EST SUN JAN 12 2025
SCATTERED LIGHT SNOW AND PATCHY FREEZING DRIZZLE PERSIST ACROSS
THE AREA THIS EVENING AS AN ARCTIC COLD FRONT ADVANCES TOWARD
THE AREA. IFR CEILINGS WILL PERSIST AS LOW LEVEL CLOUDS REMAIN
ACROSS MUCH OF THE REGION THIS EVENING AND OVERNIGHT. WINDS ARE
CURRENTLY COMING FROM THE SOUTHWEST AND WILL SWITCH TO BE COMING
FROM THE WEST AS SOON AS 03-06Z BEHIND THE COLD FRONT. WINDS
WILL BE GUSTY THROUGHOUT THE OVERNIGHT AND INTO THE DAY MONDAY
WITH GUSTS TO 25 KTS POSSIBLE. LIGHT LAKE EFFECT SNOW WILL START
UP IN THE AFTERNOON ACROSS SOUTHWEST LOWER MICHIGAN; WHILE SNOW
WILL LIKELY STAY NORTH OF KSBN, IT IS POSSIBLE THERE COULD BE A
FEW SNOW SHOWERS AT THE AIRPORT INTHE AFTERNOON/EVENING.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR LMZ043-046.
DISCUSSION...STEINWEDEL
AVIATION...JOHNSON
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