731
FXUS63 KIWX 180733
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
233 AM EST TUE FEB 18 2025
KEY MESSAGES
- VERY COLD CONDITIONS WILL PERSIST THROUGH THE WEEK WITH HIGHS
IN THE TEENS TO LOWER 20S AND OVERNIGHT LOWS IN THE SINGLE
DIGITS TO LOWER TEENS. WIND CHILLS WILL BE AS COLD AS 5 TO 10
BELOW ZERO EACH MORNING.
- SNOW ACCUMULATION CHANCES THIS WEEK EXIST MAINLY IN THE
NORTHWEST FLOW LAKE EFFECT PRONE AREAS DOWNWIND OF LAKE
MICHIGAN. LAKE EFFECT SNOW SHOWERS WILL PERSIST IN NORTHWEST
INDIANA AND SOUTHWEST LOWER MICHIGAN TODAY INTO TONIGHT, WITH
ADDITIONAL CHANCES WEDNESDAY NIGHT INTO THURSDAY.
- TEMPERATURES CLIMB BACK ABOVE FREEZING BY WEEKEND.
DISCUSSION
ISSUED AT 228 AM EST TUE FEB 18 2025
AFTER A BRUTALLY COLD DAY YESTERDAY WHERE WIND CHILLS STRUGGLED
TO REACH ABOVE ZERO, ANOTHER VERY COLD MORNING IS ON TAP TODAY.
TEMPERATURES HAVE FALLEN INTO THE SINGLE DIGITS ONCE AGAIN AS
RECENT SNOWPACK AIDS IN RADIATIONAL COOLING AT THE SURFACE. HAVE
OPTED TO ISSUE ANOTHER SPS AS MORNING WIND CHILLS OF 5 TO 15
BELOW ZERO WILL BE JSUT SHY OF COLD WEATHER ADVISORY CRITERIA.
CONTINUE TO USE CAUTION ON AREA ROADWAYS TODAY, ESPECIALLY ON
SECONDARY AND UNTREATED ROADS. SNOW HAS BLOWN ONTO ROADWAYS OVER
THE PAST FEW DAYS AND QUICKLY FROZEN INTO BLACK ICE IN SOME
AREAS. KEEP THIS IN MIND FOR THE TUESDAY MORNING COMMUTE, AS
THERE COULD STILL BE SOME LINGERING SLICK SPOTS! TEMPERATURES
WILL ONCE AGAIN ONLY BE IN THE TEENS FOR HIGHS THIS AFTERNOON AS
HIGH PRESSURE SPREADS EAST.
LAKE EFFECT SNOW SHOWERS PERSIST TODAY DOWNWIND OF LAKE MICHIGAN IN
NORTHWEST INDIANA AND SOUTHWEST LOWER MICHIGAN. WINDS HAVE STARTED
TO GRADUALLY SWITCH FROM WEST TO NORTHWEST OVERNIGHT; NORTHWEST
WINDS WILL PERSIST TODAY BEFORE FLOW BECOMES NORTH-NORTHWEST
TONIGHT. THE LAKE EFFECT SNOW SHOWERS WILL LIKELY BE SCATTERED
AND LIGHT TO MODERATE IN INTENSITY TODAY AND TONIGHT AS LOW
CONVERGENCE IS WEAK AS ARE LAPSE RATES AND DELTA-TS. OVERALL,
SNOW ACCUMUALTIONS WILL BE 1-2" (WITH ISOLATED HIGHER AMOUNTS TO
3" IN NORTHERN BERRIEN COUNTY) THROUGH EARLY WEDNESDAY.
THE NEXT CHANCE FOR SYSTEM SNOW COMES WEDNESDAY INTO THURSDAY AS AN
UPPER LEVEL LOW PIVOTS THROUGH THE GREAT LAKES AND AN AREA OF HIGH
PRESSURE BUILDS OVER THE DAKOTAS. THESE TWO FEATURES WILL ALLOW FOR
A WINTER STORM TO DEVELOP TO OUR SOUTH ACROSS THE MID
MISSISSIPPI AND OHIO RIVER VALLEYS TONIGHT THROUGH WEDNESDAY
NIGHT. A FEW LIGHT SNOW SHOWERS ARE POSSIBLE DURING THE DAY
WEDNESDAY (MAINLY ALONG THE US 24 CORRIDOR) AS OUR FORECAST AREA
IS ON THE NORTHERN FRINGES OF THIS SYSTEM. AS THE
AFOREMENTIONED UPPER LEVEL LOW PIVOTS THROUGH LATE WEDNESDAY
WITH AN ATTENDANT 500 MB SHORTWAVE, THIS WILL ALLOW FOR SOME
LIGHT SNOW TO OVERSPREAD THE AREA AND ILLICIT A LAKE EFFECT
RESPONSE AS WINDS BECOME NORTHWESTERLY ONCE AGAIN. THE LAKE
EFFECT SETUP WEDNESDAY EVENING INTO THURSDAY MORNING APPEARS
MUCH FOR FAVORABLE THAN THE LAKE EFFECT TODAY WILL BE. LOW LEVEL
CONVERGENCE IS MUCH MORE PRONOUNCED LATE WEDNESDAY AND THERE
WILL BE A LAKE MICHIGAN TO LAKE SUPERIOR CONNECTION WITH A
NORTHERLY FETCH ALONG THE LONG AXIS OF LAKE MICHIGAN. OTHER
FAVORABLE PARAMETERS INCLUDE DELTA- TS OF -15C, INVERSION
HEIGHTS AROUND 6-8 KFT, AND NEGATIVE THETA E LAPSE RATES. GIVEN
THE LAKE TO LAKE CONNECTION, IT'S CERTAINLY POSSIBLE THAT THIS
SETUP RESULTS IN ONE DOMINANT LAKE EFFECT SNOW BAND THAT EXTENDS
FAR INLAND AS OPPOSED TO A MULTI BAND SETUP. FEW CHANGES WERE
MADE TO POPS AND SNOW AMOUNTS, BUT THIS REMAINS SOMETHING WE
WILL MONITOR IN THE NEXT 24-36 HOURS IN CASE ADJUSTMENTS ARE
NEEDED.
TEMPERATURES FINALLY CLIMB ABOVE FREEZING BY THE WEEKEND AND ANOTHER
DRY STRETCH ENSUES AS HIGH PRESSSURE BUILDS ACROSS THE EASTERN
CONUS.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1239 AM EST TUE FEB 18 2025
WITH THE VERY COLD AIR ADVECTION TAKING PLACE WITHIN THE CURRENT
NORTHWESTERLY FLOW, LOWERED CIGS AND LES AND SHOWERS HAS BEEN
DIRECTED SOUTHEASTWARD OFF OF LAKE MICHIGAN INTO THE VICINITY OF
KSBN. THIS LAKE EFFECT INFLUENCE WILL CONTINUE THROUGH A
MAJORITY OF THIS TAF PERIOD FOR KSBN. MVFR/IFR CATEGORIES FOR
KSBN WITH VSBYS DOWN TO AROUND 2SM IN THE LIGHT SNOW BANDS. SOME
SLIGHT IMPROVEMENT IN VSBYS IS EXPECTED WITH PERIODS OF JUST
LIGHT SNOW SHOWERS. KFWA WILL IN THE SHORT TERM HAVE MVFR CIGS
BUT EXPECTED TO IMPROVE TO VFR CONDITIONS AFTER 23Z TUE.
NORTHWEST TO NORTHERLY WINDS TODAY UP TO 15 KTS FOR BOTH TAF
SITES.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EST THIS EVENING FOR LMZ043-
046.
DISCUSSION...JOHNSON
AVIATION...ANDERSEN
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