532
FXUS63 KIWX 211700
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1200 PM EST THU NOV 21 2024
KEY MESSAGES
- SNOW WILL INCREASE IN COVERAGE AND INTENSITY THROUGH EARLY
AFTERNOON, ESPECIALLY WEST OF US 31. SLUSHY SNOW ACCUMULATIONS
OF 1 TO 3 INCHES POSSIBLE FAR WEST AND NORTHWEST, LESSER
ACCUMULATIONS EAST.
- SOME LAKE EFFECT RAIN SHOWERS ARE POSSIBLE FRIDAY, BUT OVERALL
A QUIET WEEKEND APPEARS TO BE IN STORE.
- RAIN CHANCES RETURN EARLY NEXT WEEK.
UPDATE
ISSUED AT 1025 AM EST THU NOV 21 2024
PREVIOUS FORECAST REMAINS LARGELY INTACT LATE THIS MORNING. LAKE
EFFECT SNOW SHOWERS WHICH BROUGHT HALF INCH TO INCH TYPE
ACCUMULATIONS NORTH OF THE TOLL ROAD HAVE DIMINISHED AS LOW
LEVEL FLOW HAS SLIGHTLY BACKED WEST-SOUTHWEST. SYNOPTIC SNOW
WILL CONTINUE TO WRAP INTO NE IL/NW IN INTO EARLY AFTERNOON.
UPSTREAM OBS HAVE INDICATING A NUMBER OF STATIONS IN THE 1/2SM
TO 1/4SM FOR VSBYS. GREATEST IMPACTS FOR WESTERN PORTIONS OF THE
CWA STILL APPEAR TO BE IN THE 17Z-21Z TIME WITH MOISTURE DEPTHS
GRADUALLY DWINDLING FROM NORTH TO SOUTH INTO THE EVENING. GIVEN
RATHER WARM PAVEMENT TEMPS AND TIME OF DAY OF OCCURRENCE, NOT
CONFIDENT ENOUGH TO GO WITH ADVISORY LEVEL IMPACTS AT THIS TIME,
AND WILL CONTINUE TO HANDLE WITH SPECIAL WEATHER STATEMENTS.
INITIAL LOW LEVEL AIRMASS IS A BIT DRIER THAN ANTICIPATED, AND
THIS MAY HELP TO KEEP PTYPES AS SNOW A LITTLE LONGER THAN
ORIGINALLY ANTICIPATED. THUS, COULD SEE SOME ACCUMULATIONS
AROUND 3 INCHES IN THE FAR WEST-NORTHWEST CLOSER TO STRONGER
SYNOPTIC FORCING. MAY ALSO NEED TO MONITOR LATER TODAY FOR
POTENTIAL OF MESOVORT TO MOVE INLAND WITH A BRIEF ENHANCEMENT
TO PRECIP RATES IN WAKE OF MAIN SYNOPTIC PRECIP. THIS MAY BE AT
A TIME WHEN LOW LEVEL WET BULBS FAVOR LIQUID VS SNOW HOWEVER.
OTHERWISE. NO MAJOR CHANGES TO PREVIOUS FORECAST OTHER THAN TO
CONTINUE THE SHARPENING OF THE WEST-EAST GRADIENT IN SNOW
ACCUMULATIONS GIVEN CURRENT OBSERVATIONAL TRENDS.
DISCUSSION
ISSUED AT 417 AM EST THU NOV 21 2024
GENERALLY LIGHT SNOWSHOWERS ARE IMPACTING MANY AREAS AS THE
POCKET OF COLDER AIR, COMBINED WITH A DISTURBANCE CLIPPING SW
AREAS, AID IN INCREASED LIFT. THUS FAR NO IMPACTS HAVE BEEN
REPORTED WITH SOME SPOTS LIKELY SEEING A DUSTING OR MAYBE TENTH
OF SNOW. THE EXCEPTION MAY BE CLOSER TO LK MI WHERE SOMEWHAT
HEAVIER SHOWERS EXISTED AS LAKE ENHANCEMENT WAS HELPING. QPF
AMOUNTS FROM KBEH HAVE NOT BEEN OVERLY IMPRESSIVE SO FAR, WITH
MDOT PLOW AND STATIONARY CAMERAS SHOWING MAYBE A FEW TENTHS TO
LOCALLY AN INCH.
THE UPPER LEVEL LOW IS SLOWLY WORKING ACROSS CENTRAL LOWER MI
WITH THE SFC LOW MOVING ACROSS THE EASTERN UP OF MI. MODELS HAVE
BEEN PRETTY PRONOUNCED ON COVERAGE, INTENSITY AND QPF POTENTIAL
AS THE LOW DROPS SOUTH DOWN THE HEART OF LAKE MI TODAY, REACHING
NW AREAS LATER THIS MORNING (16Z OR SO) AND THEN EXISTING THE
SOUTH NEAR 00Z FRI. CONCERNED THAT QPF MAY BE WAY OVERDONE GIVEN
A CLOSE LOOK AT OBSERVATIONS IN THE UP WHERE THE HEAVIEST
PRECIP IS SUPPOSED TO EXIST PER THE MODELS. THE SFC LOW WILL BE
SLOWLY WEAKENING AS IT DROPS SOUTH, BUT STILL HAVE A FAIR AMOUNT
OF ENERGY AND MOISTURE ACCOMPANYING IT. THE BIGGEST CHANGES FOR
NOW WAS TO LIMIT THE EASTERN EDGE OF THE HIGHEST POPS AS THE
BULK OF THE PRECIP LOOKS TO REMAIN ALONG/WEST OF INDIANA 15. QPF
AMOUNTS WERE LOWERED SOME, BUT NOT SUBSTANTIALLY FOR NOW,
YIELDING SLIGHTLY LOWER ACCUMULATIONS WEST (STILL IN THE 1 TO
MAYBE 2 INCH RANGE). MODEL TRENDS HAVE ALSO SHOWED SOMEWHAT
HIGHER AFTERNOON TEMPS WITH EVEN A DEGREE OR 2 WARMER IMPACTING
THE OVERALL ACCUMULATION. AS THE AREA OF PRECIP COMES THROUGH,
EXPECT REDUCED VISIBILITY AND IN AREAS THAT SEE SNOWFALL,
ACCUMULATIONS WOULD OCCUR ON GRASSY AND ELEVATED AREAS. ROAD
TEMPERATURE FORECASTS SUGGEST READINGS IN THE 40S DURING THE
PEAK OF THE EVENT, MEANING ROADS SHOULD BE WET. WHILE IT WILL BE
BREEZY TODAY THE SFC LOW TRACK WILL PUSH THE STRONGEST PRESSURE
GRADIENT WEST OF THE AREA (WHERE WIND ADVISORIES HAVE BEEN
ISSUED ACROSS IL). STRONGEST WINDS FOR OUR AREA WILL BE BOTH
AHEAD OF AND BEHIND THE LOW, WITH GUSTS OF 35 TO MAYBE 40 MPH IN
THE WEST.
SIGNIFICANT CHANGES MADE FOR TONIGHT TO TREND MUCH DRIER AND
ALSO COLDER AS SUBSIDENCE ARRIVES IN THE WAKE OF THE LOW AND
MAYBE EVEN SOME BREAKS OR THINNING OF THE CLOUDS. LOWS WILL BE
IN THE UPPER 20S NE TO NEAR FREEZING WEST, SO ANY WET ROADS
COULD FREEZE IN SPOTS (ALTHOUGH SUSPECT MINIMAL IF ANY IMPACTS).
LAKE EFFECT SHOWERS WILL BE POSSIBLE ON FRIDAY AS ANOTHER
DISTURBANCE DROPS SOUTH. THERMAL PROFILES SUPPORT ALL RAIN WITH
OVERALL INTENSITY LIKELY NOT VERY HIGH AS DELTA TS ARE CLOSER TO
12 TO 14 C (ENOUGH FOR LAKE EFFECT, BUT NOT IDEAL FOR HEAVIER
PRECIP). IN ADDITION, INVERSION HEIGHTS WILL BE LOWER (7 TO
8KFT).
WITH FOCUS ON THE NEXT 24 TO 36 HOURS, LITTLE WAS MODIFIED IN
THE EXTENDED PERIOD (SAT-THU) WITH THE WEEKEND LIKELY DRY AND
WARMER (ABOVE NORMAL), FOLLOWED BY A NORTHERN STREAM WAVE THAT
MAY BRING SOME RAIN OR SNOW CHANCES MID TO LATE WEEK.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1200 PM EST THU NOV 21 2024
SYNOPTIC SNOW, NOW INTO KSBN, SHOULD REACH KFWA BY APPROXIMATELY
19Z. HEAVIER WIND-DRIVEN SNOW WITH 1/4 TO 1/2 MILE VISBYS SHOULD
MAINLY BYPASS THE TERMINALS, THOUGH A PERIOD OF LIFR TO IFR
RESTRICTIONS REMAIN LIKELY THIS AFTERNOON AS THE SNOW MOVES
THROUGH. MINOR ACCUMS ON MAINLY GRASSY/ELEVATED SURFACES MAINLY
EXPECTED. THIS VORT MAX AND ASSOCIATED SFC REFLECTION SINK SOUTH
OF THE AREA BY 23-00Z WITH QUICK IMPROVEMENT AND LIGHTER NW
WINDS INTO TONIGHT. THE LAKE PLUME DOES PIVOT BACK INTO NORTHERN
IN LATE TONIGHT INTO FRIDAY WITH MVFR CIGS AND SCATTERED LAKE
EFFECT RAIN SHOWERS AT MAINLY KSBN.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...GALE WARNING UNTIL 1 AM EST FRIDAY FOR LMZ043-046.
UPDATE...MARSILI
DISCUSSION...FISHER
AVIATION...STEINWEDEL
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