148
FXUS63 KIWX 120529
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1229 AM EST SUN JAN 12 2025
KEY MESSAGES
- A PERIOD OF LIGHT SNOW POSSIBLE SUNDAY, MAINLY IN THE
AFTERNOON AND EVENING ALONG AND NORTH OF US 24. MINOR
ACCUMULATIONS POSSIBLE (DUSTING-1").
- VERY COLD MONDAY NIGHT THROUGH THURSDAY MORNING WITH BELOW-ZERO
WIND CHILLS AT TIMES.
- PERIODS OF LAKE EFFECT SNOW IN THE COMING WEEK.
DISCUSSION
ISSUED AT 227 PM EST SAT JAN 11 2025
MID LEVEL RIDGING BUILDING OVERHEAD, AND BACKED/DIMINISHED BOUNDARY
LAYER FLOW, WILL BRING AN END TO ANY LAKE EFFECT SNOW FLURRY
ACTIVITY BY EARLY THIS EVENING. THIS RIDGING WILL BE BRIEF AS A
SHORTWAVE TROUGH AND A WEAK SFC LOW TRACK EAST-NORTHEAST THROUGH
THE UPPER MIDWEST AND WESTERN/NORTHERN GREAT LAKES. WARM
ADVECTION DRIVEN LIGHT SNOW SHOWERS LIKELY DEVELOPS WITHIN A
LEADING 30-40 KT LOW LEVEL JET ON SUNDAY (MAINLY AFTN-EVE).
HOWEVER, LACKING MOISTURE RETURN AND NORTHWARD BYPASS OF BETTER
FORCING SUGGEST MINOR ACCUMS AT BEST (UP TO AN INCH, BEST
CHANCES NORTHWEST OF US 24). STILL CANNOT COMPLETELY RULE OUT
SOME PATCHY DRIZZLE WITH A POTENTIAL MID LEVEL DRY SLOT
SUGGESTING LOW CHANCES (10-20%) FOR SHALLOWER SATURATION AND
THUS INSUFFICIENT ICE NUCLEI. ADDITIONAL SNOW SHOWERS AND LIGHT
ACCUMS THEN CONTINUE INTO SUNDAY NIGHT AS THE PRIMARY SHORTWAVE
AND ARCTIC COLD FRONT TRACK THROUGH.
BLUSTERY/COLD WEST-NORTHWEST FLOW WILL SETTLE IN BEHIND THE ARCTIC
FRONT MONDAY THROUGH WEDNESDAY, WITH TUESDAY LIKELY THE COLDEST DAY
BEHIND A SECONDARY VORT LOB/FRONT DROPPING SOUTH FROM CENTRAL
CANADA. WIND CHILLS WILL LIKELY BE STUCK BELOW ZERO AT TIMES AWAY
FROM A LAKE PLUME THAT WILL MAINLY BE RELEGATED TO NEAR AND NORTH OF
THE MI STATE LINE. ECWMF/GEFS ENSEMBLE BLENDS SHOW A 30-50% FOR WIND
CHILLS <=15 DEGREES BELOW ZERO (ADVISORY LEVELS) FOR A TIME MONDAY
NIGHT, AND AGAIN TUESDAY NIGHT. THIS AIR MASS WILL NO DOUBT IGNITE
THE LES MACHINE FOR OUR WEST TO WEST-NORTHWEST LES BELTS,
PARTICULARLY ON TUESDAY BEHIND THE SECONDARY COLD FRONT. DRY NATURE
TO THE INCOMING ARCTIC AIR WILL LIKELY LIMIT FLAKE SIZE AND
ACCUMULATIONS, THOUGH ROADS MAY BE SLICK IN SPOTS WITH REDUCED
VISIBILITIES.
PATTERN WILL BRIEFLY RELOAD AND FLATTEN OUT A BIT ALLOWING FOR A
WELCOMED BRIEF THAW LATE IN THE WEEK (HIGHS WELL INTO THE 30S BY
FRIDAY). ENSEMBLE GUIDANCE IS THEN IN GOOD AGREEMENT IN UPPER
RIDGING DEVELOPING ACROSS THE NORTHEAST PACIFIC INTO ALASKA NEXT
WEEKEND INTO THE FOLLOWING WEEK. THIS WILL FORCE DEEP LONGWAVE
TROUGHING TO DEVELOP OVER CENTRAL NORTH AMERICA WITH CHANCES
FOR A MORE SEVERE ARCTIC INTRUSION AND/OR THE POTENTIAL FOR AN
ACTIVE STORM TRACK ALONG A BAROCLINIC ZONE.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1215 AM EST SUN JAN 12 2025
VFR CONDITIONS THROUGH ABOUT 10Z SUN FOR KSBN AND 15Z SUN FOR
KFWA BEFORE MVFR CONDITIONS IN LOWER CIGS ARRIVE WITH THE NEXT
INCOMING SHORTWAVE. THE DISTURBANCE WILL BRING LIGHT SNOW, AND
THERE IS LOW CONFIDENCE THAT SOME FREEZING DRIZZLE MAY MIX IN AT
TIMES TODAY. HAVE OPTED NOT TO MENTION IN TAFS DUE TO THE LACK
OF CERTAINTY ON OCCURRENCE/TIMING. AFTER 16Z SUN AT KSBN AND
20Z SUN FOR KFWA IFR CONDITIONS WILL PREVAIL WITH THE LIGHT
SNOW AND FURTHER LOWERING OF CIGS. AFTER 02Z, SNOW WILL BEGIN TO
TAPER OFF AND CIGS WILL SLIGHTLY IMPROVE WITH A RETURN TO MVFR
LEVELS AND WESTERLY WINDS BECOME GUSTY (GUSTS UP TO 25 KTS) IN
THE WAKE OF THE DISTURBANCE.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST MONDAY
FOR LMZ043-046.
DISCUSSION...STEINWEDEL
AVIATION...ANDERSEN
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