665
FXUS63 KIWX 192336
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
636 PM EST WED FEB 19 2025
KEY MESSAGES
- A PERIOD OF LIGHT SNOW EXPECTED THIS EVENING INTO EARLY
THURSDAY. LIGHT ACCUMULATIONS UP TO 1" EXPECTED.
- WIND CHILLS AS LOW AS -10 THURSDAY MORNING, COLDEST ALONG AND
SOUTH OF US 30 IN INDIANA.
- PERIODS OF HEAVY LAKE EFFECT SNOW LATE TONIGHT INTO THURSDAY
IN NORTHWEST FLOW PRONE AREAS DOWNWIND OF LAKE MICHIGAN.
REDUCED VISIBILITIES AND DIFFICULT TRAVEL EXPECTED, MAINLY IN
AREAS UNDER A WINTER WEATHER ADVISORY.
DISCUSSION
ISSUED AT 238 PM EST WED FEB 19 2025
MAIN FOCUS REMAINS ON LIGHT SYSTEM SNOW THIS EVENING INTO THE EARLY
OVERNIGHT, TRANSITIONING TO PURE LAKE EFFECT SNOW FOR OUR NW FLOW
SNOW BELTS LATER TONIGHT THROUGH THURSDAY EVENING.
SHORTWAVE AND DEEPER MOISTURE, CURRENTLY OVER EASTERN IA, WILL
TRANSLATE EAST THROUGH THE AREA TONIGHT AS A WEAK CLOSED LOW.
ASSOCIATED MODEST DEEP LAYER ASCENT OVER STEEPENING LOW LEVEL
LAPSE RATES (WITHIN A PORTION OF THE DGZ) TO PROMOTE THIS LIGHT
SNOW, PARTICULARLY ALONG AND SOUTHEAST OF US 24 NEAR THE NOSE OF
A 70 KT MID LEVEL JET. LIGHT SNOW ACCUMS OF A HALF INCH TO INCH
SHOULD TEND TO STICK ON UNTREATED ROADS GIVEN LINGERING COLD
SFC TEMPS.
ATTENTION THEN TURNS TO LAKE EFFECT/ENHANCED SNOW, MOST ORGANIZED IN
THE 06-18Z WINDOW ON THURSDAY WHEN 0-2KM THETA-E LAPSE RATE VALUES
TREND NEGATIVE WITHIN A DEVELOPING LONG LAKE AXIS THERMAL TROUGH.
MODEL SOUNDINGS/X-SECTIONS ALSO CONTINUE TO SUGGEST OMEGA AND
SATURATION WITH RESPECT TO ICE MAXIMIZED WITHIN A PORTION OF THE DGZ
WITH SIGNS OF SEEDING ON THE BACKSIDE OF THE EXITING UPPER WAVE.
THIS LONG AXIS FETCH, AND SUPPORTIVE THERMODYNAMIC PARAMETERS,
SUGGEST A DECENT POTENTIAL FOR 1"/HR RATES (12Z HREF 10-30%
PROBS) AND LOCALLY HEAVY SNOW TOTALS (HREF MAX TOTALS EXCEED 8"
IN BERRIEN CT) WITHIN ANY BANDED ELEMENTS. POTENTIAL FAILURE
POINTS COULD BE EMBEDDED DISRUPTING MESOLOWS AND/OR AN EARLIER
BREAKDOWN OF THE LAKE AGGREGATE TROUGH.
THERE SHOULD BE A TREND TOWARD LESS ORGANIZED, CELLULAR, MULTIBANDS
THURSDAY AFTERNOON INTO THURSDAY EVENING AS TRAJECTORIES SLIGHTLY
BACK WITH THE CONVERGENT LAKE PLUME EVENTUALLY RELEASING FROM THE
EASTERN LAKE MI SHORELINE. THE ONLY CHANGE IN HEADLINES FOR THIS
PACKAGE WAS TO ADD ELKHART CT INTO THE WINTER WEATHER ADVISORY.
CONSIDERED UPGRADING BERRIEN CT TO A WINTER STORM WARNING
(CRITERIA IS >8"), BUT OPTED TO HOLD OFF FOR NOW WITH PROBABILISTIC
DATA FAVORING TOTALS MORE IN THE 4-6" RANGE OVERALL IN THE
COUNTY. DID ISSUE A SPS FOR THE REST OF AREA TO COVER MORE OF A
NUISANCE IMPACT TO TRAVEL AND WIND CHILLS AS COLD AS -10 BY
DAYBREAK THURSDAY.
FRIDAY THROUGH EARLY NEXT WEEK WILL FEATURE A MODERATING TREND AS
RETURN WSW FLOW SETS UP UNDER A LOWER AMPLITUDE FLOW REGIME ALOFT. A
FEW MID LEVEL SHORTWAVES WILL TAKE AIM ON THE GREAT LAKES NEXT WEEK
WITH LOW PERIODIC CHANCES FOR PRECIPITATION. AS EXPECTED, THERE ARE
SIZABLE DIFFERENCES WITHIN THE ENSEMBLE GLOBAL SYSTEMS REGARDING
TRACK AND TIMING OF THESE MID LEVEL FEATURES RESULTING IN LOW
PREDICTABILITY IN DAILY RAIN/SNOW CHANCES.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 624 PM EST WED FEB 19 2025
SHORTWAVE TROUGH OVER WRN IL WILL WRAP UP EWD INTO WRN OH BY
DAYBREAK THU. LACK OF BETTER MOISTURE WITH THIS SYS AND
PREVAILING DRY LOW LEVELS HINDERING SFC SNOW ATTM. THIS SHOULD
IMPROVE IN TIME ESPECIALLY IN LIGHT OF DOWNSTREAM LAKE MOISTURE
PLUME WITH EVENTUAL SEEDER-FEEDER MECHANISM AT PLAY WITH LIGHT
SNOW DEVELOPING THIS EVENING.
IN WAKE OF THIS SYS ROBUST LAKE AGGREGATE THERMAL TROUGHING
REDEVELOPS WITH IMPRESSIVE LONG AXIS FETCH DEVELOPING DOWN THE
LENGTH OF LAKE MICHIGAN. SIGNS OF THIS ALREADY UNDERWAY ACROSS
THE UP AND EXPECT RAPID DEVELOPMENT OF A PRIMARY SINGLE BAND BY
LATE EVENING WITH PROBABLE MESOVORT FORMATION AS IT EVOLVES
SOUTHWARD. SLOW EWD ROTATION OF UPPER LOW LOOKS TO LOCK THIS IN
THROUGH MUCH OF THU INVOF KSBN WITH PREVAILING LIFR CONDITIONS
IN MOD-HVY SNOW AND LIKELY SPREADING INTO THE KFWA VCNTY TOWARD
EARLY AFTN. HOWEVER SPREAD IN CAM BASED GUIDANCE ON BAND
ORIENTATION AND INTENSITY HANDCUFFS GREATER DETAIL AND WILL
AWAIT LATER GUIDANCE AND FORECASTS TO TUNE THIS FURTHER.
IWX WATCHES/WARNINGS/ADVISORIES
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST /6 PM CST/ THURSDAY FOR
INZ005-103-104-204.
OH...NONE.
MI...WINTER WEATHER ADVISORY UNTIL 7 PM EST THURSDAY FOR MIZ078-177-
277.
MARINE...SMALL CRAFT ADVISORY FROM 4 AM THURSDAY TO 4 AM EST FRIDAY FOR
LMZ043-046.
DISCUSSION...STEINWEDEL
AVIATION...T
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page