484
FXUS61 KALY 201755
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1255 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 TONIGHT/
KEY MESSAGE:
- SLIPPERY TRAVEL THIS AFTERNOON THROUGH TONIGHT FROM LIGHT
SNOW. HIGH CONFIDENCE (GREATER THAN 80%) THAT TOTAL AMOUNTS
WILL REMAIN UNDER ADVISORY CRITERIA (4").
- INCREASED SNOWFALL AMOUNTS TO 1 TO 2 INCHES FOR LITCHFIELD
COUNTY, CT THROUGH 7 PM TODAY. SLIPPERY TRAVEL LIKELY FOR THE
P.M COMMUTE.
DISCUSSION:
AS OF 12PM, WE INCREASED SNOWFALL AMOUNTS FOR LITCHFIELD COUNTY
IN COLLABORATION WITH OKX/BOX/WPC AS THE INCOMING COASTAL LOW
TRACKS CLOSE ENOUGH TO THE COAST THAT PART OF ITS QPF SHIELD
SHOULD GRAZES PARTS OF LITCHFIELD RESULTING IN A PERIOD OF
STEADY SNOWFALL THIS AFTERNOON (INCLUDING P.M COMMUTE). WITH
PROBABILISTIC GUIDANCE SUGGESTING GREATER THAN 30% CHANCE FOR
MORE THAN 0.10" OF QPF THROUGH 00 UTC AND GIVEN LATEST IR/RADAR
TRENDS, WE FELT CONFIDENT ENOUGH TO INCREASE QPF/SNOWFALL
AMOUNTS TO 1 - 2 INCHES THROUGH 00 UTC FOR NW CT.
PREVIOUS DISCUSSION, LATEST GOES16 WATER VAPOR IMAGERY SHOWS
THE PARENT TROUGH TRACKING THROUGH WESTERN PA WITH A SECONDARY
COASTAL LOW DEEPENING OFF THE MID-ATLANTIC COAST. THE APPROACHING
TROUGH WILL CONTINUE TO SUPPORT A PERIOD OF SUFFICIENT WARM AIR
ADVECTION THIS AFTERNOON WHICH HAS RESULTED IN LIGHT FLUFFY
SNOW DEVELOPING ACROSS MUCH OF EASTERN NY AND WESTERN NEW
ENGLAND. GIVEN THAT WEAK FORCING REMAINS BELOW THE DGZ, SNOWFALL
RATES WILL REMAIN WELL BELOW 1" AND OUR SNOWFLAKES WILL BE QUITE
SMALL. COATING UP TO AROUND 1" OF SNOW IS EXPECTED BY 00 UTC
WHICH CAN RESULT IN SOME SLIPPERY TRAVEL FOR TODAY'S 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 THROUGH SUNDAY NIGHT/
KEY MESSAGE:
-BELOW NORMAL TEMPERATURES EXPECTED THIS WEEKEND WITH FRIGID
OVERNIGHT LOWS ON BOTH SATURDAY AND SUNDAY NIGHT.
DISCUSSION:
SOME ADDITIONAL LIGHT SNOW MAY LINGER INTO SATURDAY MORNING,
ESPECIALLY WITHIN THE CAPITAL REGION, WHERE HUDSON-MOHAWK
CONVERGENCE COULD ALLOW FOR SNOWFALL TO CONTINUE FOR A FEW
HOURS. OTHERWISE, PRECIP WILL BE WINDING DOWN TOWARDS MIDDAY, AS
THE TROUGH AXIS SHIFTS EASTWARD AND FAST DEVELOPING COASTAL LOW
LIFTS INTO ATLANTIC CANADA. NORTHWEST FLOW IN PLACE WILL ALLOW
FOR SOME LAKE EFFECT SNOW SHOWERS ACROSS CENTRAL NY, BUT MOST OF
THIS ACTIVITY WILL STAY WEST OF THE AREA, WITH JUST SOME
ADDITIONAL LIGHT SNOW SHOWERS OR FLURRIES IMPACTING WESTERN
AREAS. SOME BREAKS IN THE CLOUDS WILL START TO OCCUR BY LATE
MORNING OR AFTERNOON AND NORTHWEST WINDS WILL START TO PICK UP
AND BECOME GUSTY, AS THE PRESSURE GRADIENT INCREASES BETWEEN THE
DEPARTING STORM AND HIGH PRESSURE NORTH OF THE GREAT LAKES. HIGH
TEMPS WILL ONLY TOP OUT IN THE TEENS AND 20S AND IT WILL FEEL
EVEN COLDER WITH GUSTY WINDS, WHICH MAY EXCEED 25 MPH AT TIMES.
VERY COLD TEMPS ARE EXPECTED ON SATURDAY NIGHT. WHILE NORTHWEST
WINDS WILL DIMINISH SLIGHTLY, THEY STILL WILL BE A LITTLE BREEZY
ON SATURDAY NIGHT WITH WINDS OF AROUND 10 MPH AND GUSTS UP TO
20 MPH AT TIMES. SKIES WILL BE CLEARING OUT AS HIGH PRESSURE
GETS CLOSER TO THE AREA. LOWS WILL BE IN THE SINGLE DIGITS FOR
MOST, WITH HIGH CONFIDENCE (GREATER THAN 75%) FOR BELOW ZERO
READINGS ACROSS THE ADIRONDACKS (ACCORDING TO THE LATEST NBM).
WIND CHILL VALUES MAY COME CLOSE TO COLD ADVISORY CRITERIA IN
HIGH TERRAIN AREAS FOR LATE SATURDAY NIGHT.
ON SUNDAY INTO SUNDAY NIGHT, DRY WEATHER IS EXPECTED AS HIGH
PRESSURE BUILDS DIRECTLY OVER THE AREA. THIS SHOULD FOR WINDS TO
DIMINISH AND BECOME LIGHTER WITH PLENTY OF CLEAR SKIES.
HOWEVER, TEMPS WILL REMAIN VERY COLD, AS 850 HPA TEMPS FALL TO
-12 TO -18 C. HIGHS LOOK TO ONLY REACH THE TEENS FOR MOST AREAS
ON SUNDAY. HAVE LEANED TOWARDS THE LOWER END OF THE BLENDED
GUIDANCE FOR SUNDAY NIGHT CONSIDERING THE GOOD RADIATIONAL
COOLING SETUP AND FRESH SNOWPACK, WITH LOWS NEAR ZERO IN THE
CAPITAL REGION AND MID HUDSON VALLEY, WITH BELOW ZERO TEMPS IN
THE OUTLYING AREAS AND HIGHER TERRAIN.
LONG TERM /MONDAY THROUGH THURSDAY/
KEY MESSAGES:
- CONFIDENCE IS INCREASING IN A WIDESPREAD LIGHT SNOWFALL ACROSS THE
REGION ON MONDAY NIGHT INTO TUESDAY.
- FORECAST HAS TRENDED DRIER FOR CHRISTMAS DAY THROUGH THE END OF
THE WEEK, BUT FORECAST CONFIDENCE REMAINS LOW THIS FAR OUT.
DISCUSSION:
LONG TERM PERIOD WILL START OFF QUITE COLD MONDAY MORNING WITH
TEMPERATURES BELOW 0F FOR MANY HIGH TERRAIN AREAS. HIGH PRESSURE AND
UPPER RIDGING OVERHEAD WILL KEEP US DRY THROUGH THE DAY MONDAY, BUT
AS THESE FEATURES SLIDE OFF TO THE EAST, OUR LOW-LEVEL FLOW TURNS
SOUTHWESTERLY AND ALLOWS FOR WARM ADVECTION INTO THE REGION AHEAD OF
AN APPROACHING UPPER SHORTWAVE AND ASSOCIATED SURFACE LOW THAT WILL
MOVE IN FROM THE GREAT LAKES REGION MONDAY NIGHT. WHILE DAYTIME
HIGHS WILL BE WARMER THAN SUNDAY, DAYTIME HIGHS WILL STILL BE
SEVERAL DEGREES BELOW NORMAL WITH TEMPERATURES RANGING FROM THE 10S
IN THE HIGH TERRAIN TO 20S IN THE VALLEYS.
MONDAY NIGHT THROUGH TUESDAY...DETERMINISTIC AND ENSEMBLE GUIDANCE
CONTINUE TO COME INTO BETTER AGREEMENT ON THE POTENTIAL FOR A LIGHT
SNOWFALL EVENT MONDAY NIGHT AND TUESDAY. THE AFOREMENTIONED UPPER
SHORTWAVE AND SURFACE LOW ARE EXPECTED TO WEAKEN AS THEY TRACK
THROUGH UPSTATE NY INTO NEW ENGLAND, BUT UPPER DYNAMICS AND
INCREASING MOISTURE SHOULD ALLOW FOR MOST AREAS TO SQUEEZE OUT SOME
LIGHT PRECIP. NBM PROBS FOR MEASURABLE PRECIP HAVE INCREASED
CONSIDERABLY FROM LAST NIGHT, AND ARE NOW >60% REGION-WIDE FOR
MONDAY NIGHT THROUGH TUESDAY TIMEFRAME. THERMAL PROFILES FAVOR
MAINLY SNOW, EVEN IN THE VALLEYS, BUT PRECIP WILL LIKELY BE LIGHT.
CONFIDENCE REMAINS LOW IN EXACT AMOUNTS THIS FAR OUT, THIS LOOKS
LIKE A SUB-ADVISORY TYPE EVENT WITH PERHAPS UP TO A COUPLE INCHES OF
SNOW POSSIBLE. NEVERTHELESS, WITH INCREASED TRAVEL AROUND CHRISTMAS,
SLIPPERY TRAVEL CONDITIONS ARE POSSIBLE MONDAY NIGHT INTO TUESDAY.
THIS SYSTEM ALSO LOOKS TO COME IN SLIGHTLY EARLIER COMPARED TO THE
PREVIOUS FORECAST, WITH PRECIPITATION POTENTIALLY BEGINNING AS EARLY
AS 06Z TUESDAY FOR AREAS WEST OF I-87. WITH FASTER PROGRESSION OF
THE SYSTEM, WE WILL SEE MORE CLOUDS MONDAY AFTERNOON AND NIGHT, SO
OVERNIGHT LOWS MONDAY WERE BUMPED UP A FEW DEGREES FROM THE PREVIOUS
FORECAST, WITH MOST AREAS IN THE 10S EXCEPT FOR SOME SINGLE DIGITS
IN THE HIGH TERRAIN. HIGHS TUESDAY WILL BE WARMER, WITH 20S FOR THE
TERRAIN TO MID 30S IN THE VALLEYS ESPECIALLY SOUTH OF I-90.
TUESDAY NIGHT THROUGH FRIDAY...SNOW SHOWERS SHOULD TAPER OFF TUESDAY
EVENING, WITH THE REMAINDER OF THE LONG TERM CURRENTLY LOOKING DRIER
COMPARED TO PREVIOUS FORECASTS. THIS COMES WITH A DISCLAIMER THAT
THERE IS STILL LOW FORECAST CONFIDENCE THIS FAR OUT GIVEN THAT THE
UPPER FLOW PATTERN BECOMES VERY CONVOLUTED BY THE MIDDLE OF NEXT
WEEK WITH A SPLIT FLOW REGIME AND SEVERAL SHORTWAVE DISTURBANCES
TRACKING ACROSS NORTH AMERICA. THAT BEING SAID, RECENT TRENDS HAVE
BEEN FOR MORE CONFLUENT FLOW ALOFT AND HIGH PRESSURE AT THE SURFACE
OVER OUR AREA DURING THIS TIMEFRAME. THUS, HAVE BACKED OFF ON POPS
DURING THIS TIME PERIOD FROM WHAT NBM GUIDANCE HAD WITH JUST SOME
SLIGHT CHANCES, MAINLY IN THE HIGH TERRAIN. DAYTIME HIGHS SHOULD BE
CLOSE TO NORMAL, MAINLY IN THE 30S WITH SOME 20S IN THE HIGH
TERRAIN. FOR OVERNIGHT LOWS, WE ARE CURRENTLY FORECASTING MAINLY 10S
(TERRAIN) TO 20S (VALLEYS), BUT IF RECENT TRENDS CONTINUE FOR HIGH
PRESSURE OVERHEAD DURING THIS TIME PERIOD, THEN OVERNIGHT LOWS COULD
END UP SEVERAL DEGREES COOLER THAN THE CURRENT FORECAST. AT THIS
TIME, HOWEVER, CONFIDENCE IS TOO LOW TO DEVIATE SIGNIFICANTLY FROM
THE NBM.
AVIATION /18Z 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: NO OPERATIONAL IMPACT. 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 SHSN.
TUESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHSN.
TUESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
CHRISTMAS DAY: LOW OPERATIONAL IMPACT. NO SIG WX.
ALY WATCHES/WARNINGS/ADVISORIES
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
SYNOPSIS...FRUGIS/SPECIALE
NEAR TERM...FRUGIS/SPECIALE
SHORT TERM...FRUGIS
LONG TERM...MAIN
AVIATION...MAIN
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