296
FXUS63 KIWX 161718
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1218 PM EST TUE DEC 16 2025
KEY MESSAGES
- MODERATING TEMPERATURES AND BREEZY AT TIMES THROUGH THURSDAY.
- PERIODS OF RAIN LATE WEDNESDAY NIGHT INTO THURSDAY, POSSIBLY
MIXING OR ENDING AS SNOW SHOWERS THURSDAY NIGHT INTO FRIDAY.
- WINDY AND BRIEFLY COLDER CONDITIONS ON FRIDAY.
- NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES RETURN FOR THE
WEEKEND.
DISCUSSION
ISSUED AT 333 AM EST TUE DEC 16 2025
AN INCREASING LOW LEVEL FLOW, AHEAD OF A WEAK UPPER LEVEL TROUGH,
WILL ALLOW THE START OF ABOVE FREEZING TEMPERATURES. ALTHOUGH LOW
LEVEL TEMPS WILL CLIMB SEVERAL DEGREES ABOVE ZERO, A COMBINATION OF
A STRONG INVERSION AND THE WIDESPREAD SNOW PACK, WILL LIMIT THE
IMPACTS OF THE WAA. HIGHS SHOULD STILL REACH INTO THE MID 30S, BUT
HIGHER DEWPOINTS WHICH HELP RIPEN AND MELT THE SNOWPACK WILL BE
LAGGING. WINDS WILL INCREASE MID MORNING INTO THE EVENING HOURS AS
SOME MIXING TAKES PLACE OF THE HIGHER WIND FIELDS, BUT ONCE AGAIN
THE INVERSION WILL LIKELY KEEP STRONGER GUSTS IN CHECK. LOWS TONIGHT
WON'T DIFFER A BUNCH FROM TODAYS HIGHS AS CLOUDS HELP LIMIT THE
DROP. CAN'T RULE OUT A BIT OF FOG AND EVEN SOME FREEZING DRIZZLE IN
THE FAR SOUTH LATE TONIGHT AS LOW LEVEL MOISTURE INCREASED A BIT,
BUT HAVE LEFT ANY MENTION OUT.
A WARM FRONT WILL DEVELOP AND PUSH NORTH LATER WED INTO WED NIGHT,
BRINGING INCREASING LOW LEVEL TEMPERATURES AND DEWPOINTS THAT SHOULD
ALLOW FOR A MORE EFFECTIVE MELTING OF THE SNOWPACK (DEWPOINTS
USUALLY MID-UPPER 30S OR HIGHER). THESE FACTORS AND THE RELEASED
MOISTURE UNDER A STRENGTHENING INVERSION MAY SET THE STAGE FOR MORE
WIDESPREAD FOG AS WELL AS SOME DRIZZLE/LIGHT RAIN LATE WED NIGHT
INTO EARLY THURSDAY DESPITE THE INCREASED LOW LEVEL FLOW. LEFT
INCLUSION OF THIS TO LATER FORECASTS FOR THE TIME BEING. A BETTER
CHANCE FOR RAINFALL MOVES IN THURSDAY AHEAD OF THE COLD FRONT WHEN
MUCH STRONGER DYNAMICS ARRIVE TO SQUEEZE OUT ONE QUARTER TO ONE HALF
INCH OF RAIN. WINDS WILL INCREASE AHEAD OF THE FRONT WITH GUSTS UP
TO 30 MPH. HIGHS THURSDAY WILL TOP OUT WELL INTO THE 40S WITH A FEW
50S POSSIBLE ACROSS THE SOUTH, BEFORE THE FRONT SWEEPS THROUGH WITH
STEADILY FALLING TEMPERATURES THURSDAY AFTERNOON INTO THURSDAY
NIGHT (EASILY A 25 TO 30 DEGREE TEMPERATURES DROP). THE CAA WILL
ALLOW A BIT MORE EFFECTIVE MIXING OF WINDS TO THE SFC, WITH GUSTS OF
35 MPH OR SLIGHTLY HIGHER POSSIBLE. THE COLD AIR WILL SWITCH ANY
PRECIP TO SNOW (BETTER CHANCES IN MI WHERE SOME LAKE ENHANCED SNOW
SHOWERS COULD BRING SOME MINOR ACCUMULATIONS THURSDAY NIGHT.
A BLUSTERY DAY IS IN STORE FOR FRIDAY WITH HIGHS ONLY RECOVERING
INTO THE MID 20S AND MORNING WIND CHILLS NEAR ZERO. LAKE EFFECT
SHOULD BE SLOWLY WINDING DOWN AS THE CORE OF THE COLDEST LOW LEVEL
AIR QUICKLY BEGINS TO PULL AWAY WITH THE TROUGH. BY THE WEEKEND,
TEMPERATURES HEAD BACK INTO THE 30S AND 40S.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1217 PM EST TUE DEC 16 2025
WITHIN THIS WAA PATTERN, PLENTY OF DRY WEATHER KEEPS US IN VFR
CONDITIONS FOR THE FIRST PART OF THIS TAF PERIOD. THE TRANSITION
HAPPENS WEDNESDAY MORNING AS A COLD FRONT USHERS IN CAA ALLOWING FOR
A PERIOD OF MVFR CIGS AND PERHAPS SOME FOG AS DEW POINTS CLIMB INTO
THE 30S ALLOWING FOR MELTING OF SNOW, WHICH IS TRAPPED UNDER THE
INVERSION. THIS FOG DOES COME WITH SOME UNCERTAINTY THOUGH AS WINDS
MAY STAY EXCITED INTO WEDNESDAY MORNING KEEPING FOG AT BAY OR AT
LEAST AT A LITTLE BIT HIGHER VIS. HAVE OPTED FOR A TEMPO GROUP AT
SBN, BUT HAVE DECIDED TO LEAVE IT OUT OF FWA AT THIS TIME GIVEN MORE
UNCERTAINTY THERE.
WINDS START OUT OF THE SOUTHWEST AND VEER MORE WESTERLY WITH TIME.
SUSTAINED WINDS AT OR ABOVE 10 KTS BECOMES MORE LIKELY THIS
AFTERNOON INTO THE EVENING WITH GUSTY WINDS APPROACHING 25 KTS
OVERNIGHT BEFORE STARTING TO TAIL OFF WEDNESDAY MORNING.
LLWS IS POSSIBLE WITH THIS SETUP AND HAVE IT IN THERE, BUT THE SETUP
IS IN THE WARM SECTOR AHEAD OF THE COLD FRONT WHICH IS AN UNUSUAL
SPOT FOR IT. HAVE OPTED TO PUT IT IN THERE, BUT IT'S VERY MARGINAL
AND COULD JUST AS EASILY SEE IT REMOVED IN THE NEXT ISSUANCE.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST WEDNESDAY FOR LMZ043-046.
DISCUSSION...FISHER
AVIATION...ROLLER
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