330
FXUS61 KALY 202124
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
424 PM EST FRI DEC 20 2024
SYNOPSIS
LIGHT SNOW THIS AFTERNOON INTO TOMORROW MORNING RESULTING IN
SLIPPERY TRAVEL, INCLUDING TODAY'S EVENING COMMUTE. AFTER SNOW
ENDS TOMORROW MORNING, WINDS TURN BREEZY WITH CLEARING SKIES AND
TEMPERATURES TURNING COLD. COLD TEMPERATURES PERSIST THROUGH
MONDAY BEFORE OUR NEXT LIGHT SNOW EVENT ARRIVES MONDAY NIGHT
INTO CHRISTMAS EVE.
NEAR TERM /THROUGH SATURDAY/
KEY MESSAGE:
- SLIPPERY TRAVEL THIS AFTERNOON THROUGH EARLY EVENING FROM
LIGHT SNOW. MOTORISTS ARE ENCOURAGED TO EXERCISE CAUTION WHILE
DRIVING AND ALLOW ADDITIONAL TIME TO ARRIVE AT THEIR
DESTINATION. SNOW TURNS LIGHTER THIS EVENING AND MAY BRIEFLY
END OVERNIGHT.
- SNOW WILL LIKELY TURN BRIEFLY STEADY FOR THE PRE-DAWN HOURS
INTO SATURDAY MORNING (4AM TO 10AM) PRODUCING A QUICK 1 TO 2
INCHES FOR THE CAPITAL DISTRICT. SLIPPERY TRAVEL IS ONCE AGAIN
EXPECTED.
DISCUSSION:
LATEST GOES16 WATER VAPOR IMAGERY SHOWS THE PARENT TROUGH
TRACKING THROUGH PA WITH A COASTAL LOW DEEPENING OFF THE MID-
ATLANTIC COAST. LATEST RAP ANALYSIS SHOWS ITS CENTRAL PRESSURE
NOW SUB-1000HPA. THE APPROACHING TROUGH SUPPORTED SUFFICIENT
WARM AIR ADVECTION THIS AFTERNOON WHICH RESULTED IN LIGHT SNOW
ACROSS MUCH OF EASTERN NY AND WESTERN NEW ENGLAND. GIVEN THAT
WEAK FORCING HAS REMAINED BELOW THE DGZ, SNOWFALL RATES HAVE
BEEN WELL BELOW 1" AND SNOWFLAKES HAVE BEEN QUITE SMALL YET
ACCUMULATED EFFICIENTLY DUE TO COLD TEMPERATURES IN THE 20S.
UP TO AROUND 1" OF SNOW IS EXPECTED BY 00 UTC AND WE HAVE
RECEIVED REPORTS OF NUMEROUS ACCIDENTS DUE TO SLIPPERY ROAD
CONDITIONS. WE ISSUED A SPECIAL WEATHER STATEMENT THROUGH 7PM TO
ENCOURAGE MOTORISTS TO DRIVE CAUTIOUSLY THROUGH THE P.M
COMMUTE. AS THE TROUGH EXITS OFF SHORE THIS EVENING (00 - 03
UTC), WARM AIR ADVECTION WEAKENS AND SNOW LIKELY TURNS
INTERMITTENT AND EVEN STOPS AT TIMES, ESPECIALLY EAST OF THE
HUDSON. AREAS AT AND ABOVE 1000 FEET, ESPECIALLY IN THE
NORTHERN/EASTERN CATSKILLS SHOULD SEE SNOW PERSIST THANKS TO
UPSLOPE ENHANCEMENTS. OTHERWISE, TEMPERATURES STAY COLD TONIGHT
IN THE TEENS AND 20S.
AS A SECONDARY UPPER LEVEL TROUGH APPROACHES FROM WESTERN NY
LATE TONIGHT (09-10UTC), A MOHAWK HUDSON CONVERGENCE (MHC)
SIGNAL IDENTIFIED IN CSTAR RESEARCH DEVELOPS RESULTING IN A
SECOND PERIOD OF SNOW OVER THE CAPITAL DISTRICT THROUGH ABOUT
14-16 UTC. THIS WILL LIKELY PRODUCE A QUICK 1-2 INCHES OF
LIGHT/FLUFFY SNOW (SLRS 14-16:1) WITH SNOWFALL RATES BRIEFLY
REACHING 0.5" PER HOUR AS THE THERMAL PROFILES COOL BEHIND THE
ARCTIC FRONT AND FORCING INTERSECTS THE DGZ. SNOW ENDS BY
MIDDAY WITH NORTHWEST WINDS BEHIND OUR COLD FRONT USHERING IN
MUCH CHILLIER AIR. TOTAL SNOWFALL AMOUNTS RANGE 1 TO 3 INCHES
WITH THE HIGHEST AMOUNTS IN THE NORTHERN/EASTERN CATSKILLS AND
SCHOHARIE COUNTY WHERE AMOUNTS RANGE 3-4 INCHES. THERE IS 40 TO
70% CONFIDENCE FOR MUCH OF THE REGION TO RECEIVE AT LEAST 2
INCHES OF SNOW BUT UNDER 10% FOR GREATER THAN 4 INCHES. SOME
UPSLOPE ENHANCEMENTS BRING LIGHT SNOW FOR THE SOUTHERN GREENS
AND NORTHERN TACONICS THROUGH TOMORROW AFTERNOON.
IT THEN TURNS BREEZY TOMORROW AFTERNOON WITH NORTHWEST WINDS
BECOMING SUSTAINED 10-15KTS AND GUSTS UP TO 20-25KTS. WITH
TEMPERATURES ONLY IN THE 20S, THE WINDS WILL MAKE IT FEEL EVEN
CHILLIER IN THE SINGLE DIGITS AND TEENS. GIVEN HOW LIGHT/FLUFFY
THE FRESH SNOW WILL BE, SOME BLOWING SNOW IS NOT RULED OUT.
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/
KEY MESSAGE:
- HIGH CONFIDENCE (GREATER THAN 75%) FOR COLD TEMPERATURES THIS
WEEKEND WITH FRIGID OVERNIGHT LOWS BOTH SATURDAY AND SUNDAY
NIGHT. THE COMBINATION OF COLD TEMPERATURES AND LIGHT WINDS
SATURDAY WILL LEAD TO WIND CHILL OR "FEEL-LIKE" TEMPERATURES
RANGING FROM -20C TO 0C.
DISCUSSION:
CLEARING SKIES AND NORTHWEST WINDS USHERING IN 850HPA ISOTHERMS
2 TO 2.5 STANDARD DEVIATIONS BELOW NORMAL PER THE NAEFS (-15C
TO -18C) WILL PROMOTE VERY COLD OVERNIGHT LOWS SAT NIGHT. WITH
THE PRESSURE GRADIENT BETWEEN THE INCOMING HIGH AND EXITING COLD
FRONT REMAINING TIGHT ENOUGH, NORTHWEST WINDS REMAIN SUSTAINED
5 - 15KTS. THE COMBINATION OF A CONTINUED BREEZE PLUS PLUMMETING
TEMPERATURES INTO THE SINGLE DIGITS AND EVEN SUB-ZERO IN THE
SOUTHERN ADIRONDACKS, SOUTHERN VT, AND NORTHERN CATSKILLS WILL
SUPPORT WIND CHILL VALUES OR "FEEL-LIKE" TEMPERATURES BETWEEN 0
AND -20C. SOME ZONES IN THE NORTHERN CATSKILLS, HELDERBERGS,
TACONICS AND BERKSHIRE COUNTY MAY APPROACH COLD WEATHER ADVISORY
CRITERIA AND WE WILL CONTINUE TO MONITOR TRENDS.
OUR 1035-1040 HPA CANADIAN HIGH BUILDS DIRECTLY OVERHEAD SUNDAY
SUPPORTING CLEAR/SUNNY SKIES. WINDS WILL BE DECREASING THROUGH
THE DAY AS THE PRESSURE GRADIENT WEAKENS BUT STILL EXPECTING A
SLIGHT NORTHWEST BREEZE (SUSTAINED WINDS 5-9KTS). WITH THE CORE
OF OUR CHILLY AIR MASS IN PLACE, DAYTIME TEMPERATURES WILL
REMAIN VERY COLD AS 850 HPA TEMPERATURES ONLY RANGE -12 TO -18C.
THIS WILL RESULT IN TEMPERATURES ONLY CLIMBING INTO THE TEENS
AND SINGLE DIGITS. CLEAR SKIES, DECREASING WINDS, AND A FRESH
SNOW PACK SUNDAY NIGHT WILL SUPPORT IDEAL RADIATIONAL COOLING
CONDITIONS. PROBABILISTIC GUIDANCE SHOWS GREATER THAN 70% CHANCE
FOR TEMPERATURES SUN NIGHT TO FALL BELOW 10 DEGREES ACROSS EASTERN
NY AND WESTERN NEW ENGLAND AND EVEN 30 TO 40% FOR TEMPERATURES
TO FALL BELOW 5 DEGREES IN THE HUDSON VALLEY. THUS, SUN NIGHT
WILL LIKELY BE THE COLDEST NIGHT OF THE SEASON AS WE EXPECT
OVERNIGHT LOWS TO FALL TOWARDS 0 IN THE VALLEY WITH -10 TO 0 FOR
AREAS AT AND ABOVE 1000FT. SOME ZONES IN THE NORTHERN/EASTERN
CATSKILLS, TACONICS, AND BERKSHIRES ARE CLOSE TO COLD WEATHER
ADVISORY (-15F TO -24F) AND WILL BE CONTINUE TO EVALUATE
TRENDS.
LONG TERM /TUESDAY THROUGH FRIDAY/
KEY MESSAGES:
- CONFIDENCE IS INCREASING FOR A WIDESPREAD LIGHT SNOWFALL MONDAY
NIGHT INTO CHRISTMAS EVE BEFORE DRIER WEATHER ARRIVES FOR CHRISTMAS
DAY
DISCUSSION:
A POSITIVELY TILTED UPPER LEVEL TROUGH AND WEAKENING SURFACE LOW
WILL CROSS THE REGION MONDAY NIGHT INTO CHRISTMAS EVE BRINGING A
PERIOD OF SNOW TO THE REGION. THERE STILL REMAINS SOME UNCERTAINTY
WITH THE AMOUNT OF QPF WITH THIS SYSTEM WHICH WOULD IMPACT SNOWFALL
TOTALS. A CURRENT BLEND OF THE GUIDANCE SUGGESTS SNOWFALL AMOUNTS OF
A COATING TO 2 INCHES MAY BE COMMON. SOUTHERLY FLOW MAY RESULT IN
SOME UPSLOPE ENHANCEMENT ACROSS THE FOOTHILLS OF THE SOUTHERN
ADIRONDACKS COULD RECEIVE 3 OR 4 INCHES. WILL CONTINUE TO MONITOR
TRENDS AND FINE TUNE SNOWFALL TOTALS OVER THE COMING DAYS.
IN THE WAKE OF THIS SYSTEM, HIGH PRESSURE CENTERED ACROSS QUEBEC AND
NORTHERN NEW ENGLAND NOSES INTO THE REGION AND LOOKS TO BRING A
PERIOD OF MAINLY DRY WEATHER FOR CHRISTMAS DAY THROUGH THE REMAINDER
OF THE WEEK. HIGHS EACH DAY WILL BE IN THE 30S WITH SOME UPPER 20S
ACROSS THE HIGHER ELEVATIONS. LOWS WILL BE MAINLY IN THE TEENS TO
LOWER 20S.
AVIATION /20Z FRIDAY THROUGH WEDNESDAY/
THROUGH 18Z SATURDAY...SNOW WILL CONTINUE TO DEVELOP ACROSS THE
REGION THIS AFTERNOON, WITH VSBY QUICKLY LOWERING TO IFR LEVELS.
CIGS WILL LIKELY BE MVFR, ALTHOUGH A FEW BRIEF PERIODS OF IFR CIGS
MAY OCCUR, ESPECIALLY AT KPSF. IFR VSBY FROM SNOW WILL LINGER INTO
EARLY THIS EVENING, THEN A BREAK IN THE SNOW IS EXPECTED FROM AROUND
01Z OR 02Z THROUGH AROUND 06Z SAT. THEN LOW LEVEL CONVERGENCE
INCREASES WITH SNOW DEVELOPING AGAIN. MAINLY IFR VSBYS MVFR CIGS
WILL BE FAVORED UNTIL THE SNOW ENDS BY AROUND 13Z-14Z SAT. VFR
CONDITIONS SHOULD THEN QUICKLY RETURN THROUGH THE 18Z SAT. WINDS
WILL BE NORTH-NORTHEAST AROUND 5-9 KT, BECOMING NORTHWEST AT 10-13
KT WITH GUSTS AROUND 20 KT AFTER 12Z SAT.
OUTLOOK...
SATURDAY NIGHT: LOW OPERATIONAL IMPACT. BREEZY. NO SIG WX.
SUNDAY: NO OPERATIONAL IMPACT. NO SIG WX.
SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.
TUESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHSN...SN.
TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHSN.
CHRISTMAS DAY: NO OPERATIONAL IMPACT. NO SIG WX.
ALY WATCHES/WARNINGS/ADVISORIES
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
SYNOPSIS...SPECIALE
NEAR TERM...SPECIALE
SHORT TERM...SPECIALE
LONG TERM...RATHBUN
AVIATION...JPV
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