686
FXUS63 KIWX 150805
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
305 AM EST MON DEC 15 2025
KEY MESSAGES
- BELOW ZERO WIND CHILLS FOR THE MORNING COMMUTE, COLDEST SOUTH
OF US-30 WITH VALUES OF -15 OR SLIGHTLY COLDER.
- BREEZY AND CONTINUED COLD TODAY. DRIFTING SNOW IN RURAL AREAS
MAY CAUSE SOME MINOR TRAVEL ISSUES.
- CHANCES FOR RAIN RETURN WEDNESDAY NIGHT INTO THURSDAY, WITH
PRECIPITATION POSSIBLY ENDING AS A RAIN/SNOW MIX.
- LARGE TEMPERATURE SWINGS FRIDAY THROUGH SUNDAY, WITH THE
COLDEST DAY BEING FRIDAY (HIGHS IN THE 20S).
DISCUSSION
ISSUED AT 255 AM EST MON DEC 15 2025
LAKE EFFECT CLOUDS AND FLURRIES WILL CONTINUE TO SLOWLY
DIMINISH/SHIFT NE AS THE SFC AND LOW LEVEL FLOW HAS BECOME SW. FAR
SW PARTS OF THE AREA THAT HAVE BEEN CLEAR SINCE SUNSET CURRENTLY
HAVE AIR TEMPS EITHER SIDE OF ZERO DEGREES VS FAR NE PARTS OF THE
AREA IN THE MID TEENS. WINDS ARE CONSIDERABLY LOWER THAN THIS TIME
LAST NIGHT, BUT WITH SUCH COLD AIR TEMPS EVEN A 5 TO 7 MPH WIND IS
MORE THAN ENOUGH TO SEND WIND CHILLS TO -10 TO AS MUCH AS -15 DEGREES
WIND SPEEDS ARE STILL FORECASTED TO INCREASE SOMEWHAT TOWARDS 12Z,
AND MORESO AFTER SUNRISE AS A BRIEFLY TIGHTENING PRESSURE GRADIENT
OCCURS WITH SOME GUSTS OF 25 TO 30 MPH FROM MID MORNING INTO EARLY
AFTERNOON. THIS IS LIKELY TO CAUSE AN INCREASE IN DRIFTING SNOW
ALONG WITH POSSIBLY SOME BRIEFLY REDUCED VISIBILITIES IN RURAL
AREAS. OPTED TO GO PATCHY BLOWING SNOW ALL AREAS MID MORNING
INTO LATE AFTERNOON. WILL DEFER ANY SPS OR INCREASED MESSAGING
TO INCOMING DAY SHIFT. WINDS WILL DIMINISH TONIGHT WITH MOSTLY CLEAR
SKIES ALLOWING FOR OVERNIGHT LOWS TO DROP INTO THE TEENS (SINGLE
DIGIT WIND CHILLS).
UPPER LEVEL FLOW BECOMES MORE ZONAL WITH WAA CONTINUING TO
INCREASE AS 850 MB TEMPS CLIMB BACK ABOVE ZERO (ROUGHLY +4 TO +8
INITIALLY) TO BRING THE START OF A THAW FOR THE AREA AS HIGHS CLIMB
ABOVE FREEZING TUESDAY. A WEAK TROUGH WILL SCOOT BY TO THE NORTH
TUESDAY, BRIEFLY SLOWING THE WAA. YET ANOTHER WAVE MOVES INTO THE
PACIFIC NW TUESDAY NIGHT AND THE QUICKLY MOVES E, DEEPENING AS IT
DOES. A MORE PRONOUNCED SURGE OF WARMER AIR AND INCREASED MOISTURE
WILL COMMENCE FOR WED INTO THU. RAIN CHANCES WILL INCREASE (80-90%)
DURING THE DAY THURSDAY WITH HIGHS REACHING THE MID 40S TO POSSIBLY
NEAR 50 IN THE SOUTH. WHILE FINER DETAILS WILL NEED TO BE SORTED OUT,
THE PRECIP LATE THURSDAY INTO THU EVENING MAY END AS RAIN/SNOW MIX
AS 850 MB TEMPS PLUMMET (HIGHS IN THE 20S FOR FRIDAY).
INTO THE UPCOMING WEEKEND, THE PROCESS SORT OF RESTARTS WITH A
FLATTENING OF UPPER LEVEL HEIGHTS AND AT LEAST A RETURN TO CLOSE TO
NORMAL, IF NOT SOMEWHAT ABOVE NORMAL TEMPERATURES. PRECIP
CHANCES APPEAR LIMITED AT THIS POINT.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1222 AM EST MON DEC 15 2025
LAKE EFFECT STRATUS DECK WILL FINALLY ERODE IN THE NEXT FEW
HOURS AS SOUTHWESTERLY FLOW INCREASES AHEAD OF THE NEXT
SHORTWAVE. THIS WAVE IS WEAK AND WILL PASS NORTH OF THE AREA SO
NO PRECIP OR LOW CLOUDS ARE EXPECTED. HOWEVER, TIGHTENING
GRADIENT WILL SUPPORT SW WIND GUSTS AROUND 25 KTS DURING THE
DAY. THIS COULD LEAD TO SOME PATCHY BLOWING AND DRIFTING SNOW
BUT CONFIDENCE IN VIS REDUCTION IS LOW GIVEN MARGINAL WIND
SPEEDS. ELEVATED WARM/MOIST AIR ADVECTION WILL ALSO BRING A FAIR
AMOUNT OF MIDDLE AND HIGH CLOUDS. SOME MODELS SUGGEST ENOUGH
LOW LEVEL MOISTURE TO SUPPORT SOME 3-5 KFT CLOUDS TODAY BUT MOST
GUIDANCE KEEPS THE LOWER LEVELS DRY AND WILL THEREFORE HOLD
WITH JUST A SCT MENTION.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...GALE WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LMZ043-046.
DISCUSSION...FISHER
AVIATION...AGD
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