475
FXUS63 KIWX 100226
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
926 PM EST THU JAN 9 2025
KEY MESSAGES
- WIDESPREAD LIGHT SNOW (2-4") FRIDAY INTO FRIDAY NIGHT, MAINLY
DURING THE AFTERNOON HOURS. SLIPPERY TRAVEL CONDITIONS ARE
POSSIBLE.
- CONTINUED NEAR TO BELOW NORMAL TEMPERATURES THROUGH THIS
WEEKEND.
- ARCTIC AIR AND CHANCES FOR LAKE EFFECT SNOW AND SUB-ZERO WIND
CHILLS ARRIVE FOR THE FIRST HALF OF NEXT WEEK.
UPDATE
ISSUED AT 925 PM EST THU JAN 9 2025
NO SIGNIFICANT CHANGES IN FORECAST THINKING THIS EVENING WITH AN
INITIAL PERUSAL OF INCOMING 00Z DATA. LOW AND MID LEVEL
MOISTURE TRANSPORT WILL INCREASE LATE TONIGHT INTO EARLY FRIDAY
MORNING, PARTICULARLY ACROSS NORTHWEST INDIANA AND SOUTHWEST
LOWER MICHIGAN. NEAR TERM GUIDANCE CONTINUES TO DEVELOP SOME
LIGHT PRECIP AMOUNTS ALONG THIS MOISTURE TRANSPORT AXIS AND
APPEARS TO BE TIED TO THE LEADING EDGE OF SOME WEAK MID LEVEL
MOISTURE CONVERGENCE IN THE 700-500 MB LAYER, ALONG WITH AN
ACTIVE ZONE OF DPVA DOWNSTREAM OF POSITIVELY TILTED UPSTREAM
TROUGH. TIMING STILL A BIT UNCERTAIN IN TERMS OF MORNING COMMUTE
IMPACTS, BUT CURRENT THINKING IS ANY IMPACT TO AM COMMUTE WOULD
BE CONFINED TO THE FAR NORTHWEST FOLLOWING THE ABOVE FORCING
MECHANISMS. FAVORABLE UPPER LEVEL DYNAMICS OVERSPREAD AREA
FRIDAY AFTERNOON AS STRONG SHEARED VORTICITY MAX WILL ACCOMPANY
A 140+ KNOT UPPER JET STREAK. LIMITING FACTORS FOR HIGHER
ACCUMS THIS EVENT APPEAR TO BE NO REAL GOOD NORTHWARD MOISTURE
TRANSPORT SURGE DUE TO POSITIVELY TILTED, PROGRESSIVE NATURE OF
THIS TROUGH. IN TERMS OF BANDED SNOW, MARGINALLY FAVORABLE
INGREDIENTS APPEAR TO BE CONFINED TO SOUTHEAST LOCATIONS DURING
THE AFTERNOON HOURS ON FRIDAY, BUT ELEVATED INSTABILITY IS
HIGHLY ELEVATED IN NATURE AND VERTICALLY OFFSET FROM STRONGER
850-700 MB VERTICAL MOTION IN A MORE STABLE ENVIRONMENT. GIVEN
THESE FACTORS, STILL FEEL THAT PREVIOUS FORECAST OF WIDESPREAD
1-3" OR 2-4" ACCUMS SEEM IN ORDER AND WILL CONTINUE TO HOLD OFF
ON HEADLINES AT THIS TIME.
DISCUSSION
ISSUED AT 146 PM EST THU JAN 9 2025
A DEEP, VERY ELONGATED TROUGH MOVING ACROSS THE CENTRAL US
TODAY WILL BRING MORE SNOW INTO THE AREA TOMORROW AND TOMORROW
NIGHT. AS PREVIOUSLY MENTIONED, THIS SYSTEM WILL HAVE TWO
POCKETS OF ENERGY. ONE OVER THE NORTHERN MIDWEST AND A MORE
MOIST DISTURBANCE OVER THE SOUTHERN PLAINS. MOISTURE WILL
INITIALLY BE LIMITED FOR OUR REGION WITH VERY DRY AIR CURRENTLY
IN PLACE, AS DEWPOINTS ARE IN THE TEENS TO SINGLE DIGITS.
THEREFORE, IT MAY TAKE SOME TIME TOMORROW MORNING FOR THE LOWER
LEVELS TO MOISTEN UP AND ACCUMULATING SNOW TO REACH THE GROUND.
WESTERN AREAS COULD START TO SEE SNOW DURING THE MORNING
COMMUTE, BUT AMOUNTS SHOULD BE AN INCH OR LESS. THE BULK OF THE
SNOW WILL ARRIVE DURING THE AFTERNOON AND EVENING, WITH MOST
LOCATIONS SEEING ONLY 2 TO 3 INCHES. LAKE ENHANCEMENT COULD
BRING AROUND 4 INCHES TO BERRIEN COUNTY, MICHIGAN. THE TROUGH
WILL QUICKLY MOVE EAST ON FRIDAY NIGHT WITH JUST SOME LINGERING
LAKE EFFECT POSSIBLE INTO SATURDAY MORNING. OTHERWISE, SATURDAY
WILL BE DRY WITH HIGH PRESSURE BUILDING BACK IN. YET IT WILL
REMAIN COLD ON SATURDAY WITH HIGHS MAINLY IN THE MID 20S.
THE WILL BE SOME SLIGHT WARMING ON SUNDAY AND TEMPERATURES RISE
TO AROUND 30 UNDER SOUTHWEST FLOW ALOFT. THIS WILL BE IN ADVANCE
OF A CLIPPER SYSTEM THAT WILL BRING ANOTHER QUICK SHOT OF LIGHT
SNOW SUNDAY NIGHT INTO MONDAY. UPPER LEVEL TROUGHING WILL THEN
DOMINATE INTO TUESDAY WITH MUCH COLDER TEMPERATURES AND LAKE
EFFECT SNOW. HIGHS ON TUESDAY WILL ONLY BE IN THE TEENS WITH
WIND CHILLS IN THE LOW SINGLE DIGITS. THERE WILL BE A MINOR
WARMING TREND GOING INTO THE MIDDLE OF NEXT WEEK, BUT
TEMPERATURES WILL STILL REMAIN BELOW FREEZING.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 717 PM EST THU JAN 9 2025
SHORT WAVE UPPER RIDGING ACROSS THE SOUTHERN GREAT LAKES WILL
QUICKLY TRANSLATE EASTWARD TONIGHT OPENING UP A MORE PRONOUNCED
SOUTHERLY FLOW FOR LATE TONIGHT INTO EARLY FRIDAY. BETTER LOW
LEVEL MOISTURE IS CONFINED FAR TO THE SOUTH ACROSS THE LOWER MS
VALLEY THIS EVENING, SO THIS MOISTURE TRANSPORT WILL TAKE SOME
TIME TO MAKE IT INTO NORTHERN INDIANA. A LARGE SCALE BUT RATHER
DISJOINTED UPPER LEVEL SYSTEM WITH SLIGHT POSITIVE TILT WILL
MAKE ITS WAY EASTWARD INTO FRIDAY AS A STRONG 150 KNOT UPPER
LEVEL JET STREAM LIFTS THROUGH DOWNSTREAM PORTION OF THIS
TROUGH. THIS LARGE SCALE SYNOPTIC FORCING, MOISTURE ADVECTION,
AND FRONTAL FORCING SHOULD SUPPORT WIDESPREAD LIGHT SNOW ACROSS
THE AREA ON FRIDAY. ACCUMULATIONS SHOULD BE LIMITED BY BETTER
MOISTURE BEING CONFINED ACROSS THE OHIO RIVER VALLEY, BUT A
WIDESPREAD 2-3" SNOW ACCUMULATION STILL APPEARS REASONABLE.
CIGS WILL DETERIORATE TO MVFR FRIDAY MORNING, WITH IFR
CONDITIONS POSSIBLE FRIDAY AFTERNOON. VSBYS MAY DROP BELOW 1
MILE FOR A TIME WITH THE PERIODS OF LIGHT SNOW. SNOW DIMINISHES
LATER FRIDAY EVENING BUT MVFR CONDITIONS SHOULD PERSIST THROUGH
FRIDAY NIGHT.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
UPDATE...MARSILI
DISCUSSION...COBB
AVIATION...MARSILI
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page