439
FXUS61 KALY 211736
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1236 PM EST SUN DEC 21 2025
WHAT HAS CHANGED
SNOWFALL AMOUNTS FOR THE LAKE EFFECT SNOW THIS AFTERNOON INTO
THIS EVENING HAVE INCREASED WITH THE WESTERN MOHAWK NOW
PREDICTED TO RECEIVE 2 TO 4 INCHES OF SNOW (ISOLATED 4-5"
AMOUNTS MAINLY NORTH OF THE NY THRUWAY). THE LAKE EFFECT BAND
IS NOW EXPECTED TO EXTEND AS FAR EAST SARATOGA COUNTY INTO
SOUTHERN VERMONT THIS AFTERNOON INTO THE EARLY EVENING LEADING
TO LIGHT SNOW ACCUMULATIONS.
KEY MESSAGES
1. A BAND OF LAKE EFFECT SNOW DEVELOPING OFF LAKE ONTARIO THIS
AFTERNOON WILL LIKELY EXTEND INTO THE WESTERN MOHAWK VALLEY AND
SOUTHWEST ADIRONDACKS LEADING TO 2 TO 4" OF SNOW. GUSTY
NORTHWEST WINDS REACHING 30-35MPH ALSO DEVELOP REGIONWIDE TODAY
INTO THIS EVENING AND THE COMBINATION OF FALLING SNOW AND
STRONG GUSTY WINDS CAN LEAD TO LOW VISIBILITY AND DIFFICULT
TRAVEL.
2. THERE IS MODERATE CONFIDENCE FOR THE POTENTIAL FOR A LIGHT
TO MODERATE SNOWFALL LATE MONDAY NIGHT THROUGH TUESDAY, WHICH
COULD IMPACT BOTH THE MORNING AND EVENING COMMUTES AS WELL AS
ANY PRE-HOLIDAY TRAVEL.
3. TEMPERATURES CONTINUE TO TREND NEAR TO SLIGHTLY ABOVE NORMAL
FOR THE SECOND HALF OF THE WEEK AND WHILE THERE IS LOW TO
MODERATE CONFIDENCE IN ADDITIONAL CHANCE FOR PRECIPITATION FOR
THE END OF THE WEEK (MAINLY AFTER CHRISTMAS), FORECAST
CONFIDENCE IN OVERALL TIMING AND AMOUNTS REMAINS LOW.
DISCUSSION
KEY MESSAGE 1...
A MOISTURE STARVED COLD FRONT WILL CONTINUE TRACKING EASTWARD
EARLY THIS MORNING INTO EASTERN NY AND WESTERN NEW ENGLAND RESULTING
IN LIGHT SNOW SHOWERS MAINLY IN THE MOHAWK VALLEY AND SOUTHERN
ADIRONDACKS WHERE SNOW AMOUNTS RANGE FROM COATINGS TO 1 INCH.
IN THE WAKE OF THE BOUNDARY, WINDS SHIFT TO THE WEST AND BECOME
QUITE GUSTY AS COLD AIR ADVECTION INTENSIFIES RESULTING IN DEEP
BOUNDARY LAYER MIXING. EXPECTING MAX WIND GUSTS TO RANGE 30 TO
35MPH REGIONWIDE WITH PROBABILISTIC GUIDANCE SHOWING A 50 TO
70% CHANCE FOR GUSTS TO EXCEED 35MPH IN THE MOHAWK VALLEY,
GREATER CAPITAL DISTRICT, THE TACONICS AND WESTERN MA. THE
STRONG COLD AIR ADVECTION, WESTERLY FLOW, AND BROAD TROUGHING
EXTENDING FROM THE GREAT LAKES INTO THE NORTHEAST LOOKS TO
SUPPORT A MULTI-LAKE CONNECTION WITH HIGH RES GUIDANCE IN GOOD
AGREEMENT SHOWING A SINGLE LAKE EFFECT BAND DEVELOPING OFF LAKE
ONTARIO AND EXTENDING INTO THE WESTERN MOHAWK VALLEY BY 15 - 17
UTC TODAY. FORECAST SOUNDINGS SHOW A WELL MIXED BOUNDARY LAYER
EXTENDING UP TO 800HPA WITH STRONG FORCING IN THE LOW-LEVELS
INTERSECTING THE DGZ ALONG WITH CONDITIONAL LAKE INDUCED
INSTABILITY FOR THE AFTERNOON HOURS. AS THE BAND BECOMES
BETTER ORGANIZED, THE HREF EVEN SHOWS 20-30% PROBABILITY VALUES
FOR HOURLY SNOWFALL RATES TO EXCEED 1". MODERATE SNOWFALL RATES
COMBINED WITH THE GUSTY WINDS WILL LEAD TO LOWER VISIBILITY AND
POTENTIAL DIFFICULT TRAVEL WITHIN THIS BAND. THE GUSTY WESTERLY
(270-280 DEGREE) WINDS WILL INITIALLY DIRECT THE BAND INTO
SOUTHERN HERKIMER COUNTY (MAINLY NORTH OF THE NY THRUWAY) WITH
THE BAND PERSISTING FOR A FEW HOURS EARLY THIS AFTERNOON BEFORE
WINDS VEER MORE TO THE NORTHWEST. THIS WILL SHIFT THE BAND
SOUTHWARD BY 21 - 00 UTC WHEN IT REACHES THE NY THRUWAY AND
AREAS SOUTH. BLENDED IN MORE OF THE RGEM FOR QPF AMOUNTS WHICH
HANDLES LAKE EFFECT WELL AND THE LATEST FORECAST SNOWFALL
AMOUNTS HAVE INCREASED A BIT TO 2 TO 4 INCHES WITH ISOLATED 4-5"
JUST NORTH OF THE NY THRUWAY IN SOUTHERN HERKIMER COUNTY. HELD
OFF ON A WINTER WEATHER ADVISORY GIVEN THE LIMITED COVERAGE OF
4"+ OF SNOW. AS THE STRONG WESTERLY WINDS VEER TO 270-290
DEGREES LATE THIS AFTERNOON INTO THE EARLY EVENING HOURS, THERE
IS INCREASING AGREEMENT AMONG THE HIGH RES GUIDANCE THAT THE
LAKE EFFECT BAND EXTENDS EASTWARD AND REACHES INTO
SARATOGA/WASHINGTON COUNTY AND EVEN INTO SOUTHERN VT. HOWEVER,
THIS LOOKS BRIEF AS THE WINDS CONTINUE VEERING THIS EVENING AND
THE MULTI-LAKE CONNECTION WEAKENS SO ONLY EXPECTING COATING UP
TO 1 INCH OF SNOW.
LAKE EFFECT SNOW DIMINISHES THIS EVENING AS WINDS BECOME MORE
NORTHWESTERLY AND WE LOSE THE FAVORABLE FETCH OFF LAKE ONTARIO.
ANY SNOW SHOWERS BECOME DIRECTED INTO CENTRAL NY.
KEY MESSAGE 2...
WE CONTINUE TO CLOSELY MONITOR A RATHER COMPACT AND VIGOROUS
SHORTWAVE AND ASSOCIATED DEVELOPING CLIPPER FOR LATE MONDAY
NIGHT INTO TUESDAY. THERE REMAINS MORE SPREAD IN THE GUIDANCE
THAN WE WOULD LIKE TO SEE AT THIS LEAD TIME REGARDING THE
OVERALL TRACK OF THE SFC LOW. THE ENSEMBLE MEMBER PRESSURE
CLUSTERS FROM THE GEFS CONTINUES TO SUGGEST THE SFC LOW
TRACKS ACROSS THE SOUTHERN HALF OF NY TOWARDS SOUTHERN NEW
ENGLAND WHILE THE PRESSURE CLUSTERS FROM THE EPS SHOWS THE SFC
LOW TRACKING WELL TO THE NORTH THROUGH ONTARIO INTO QUEBEC.
DESPITE THE DIFFERENCE IN THE SFC LOW TRACK, THERE IS A GENERAL
CONSENSUS THAT AN INITIAL PERIOD OF ISENTROPIC LIFT SUPPORTS AN
ORGANIZED PRECIPITATION SHIELD THAT TRACKS FROM THE OHIO VALLEY
NORTHEASTWARD TUESDAY MORNING WITH THERMAL PROFILES SUPPORTING
ALL SNOW. THE DIFFERENCE IN THE STORM TRACK ARE LEADING TO
DIFFERENCES IN THE TIME OF ARRIVAL OF THE SNOW AND ITS INTENSITY
AS A FURTHER NORTH STORM TRACK LOOKS TO DELAY THE SNOW UNTIL
TUES A.M AND SUGGESTS LOWER SNOWFALL AMOUNTS WHILE THE FURTHER
SOUTH TRACK LOOKS TO SUPPORT STRONGER FORCING/HIGHER SNOWFALL
AMOUNTS AND AN EARLIER ARRIVAL TIME STARTING MONDAY NIGHT. THE
TIMING AND SNOW INTENSITY DIFFERENCE WILL BE IMPORTANT FOR
POTENTIAL IMPACTS TO THE TUESDAY A.M COMMUTE AS AN EARLIER
ARRIVAL TIME AND HIGHER SNOWFALL INTENSITY WOULD LEAD TO MORE
DIFFICULT TRAVEL CONDITIONS. OUR FORECAST SIDES WITH THE EARLIER
ARRIVAL TIME AND THEREFORE SHOWS A WIDESPREAD 1 TO 2 INCHES BY
12 UTC TUES WITH AN ADDITIONAL 1 TO 2 INCHES BY 18 UTC. BY
TUESDAY AFTERNOON, THE STRONGEST LIFT ESCAPES TO OUR EAST AND
SNOWFALL WEAKENS WITH SFC TEMPERATURES WARMING SLIGHTLY ABOVE
FREEZING IN VALLEY AREAS. THIS CAN LEAD TO A RAIN/SNOW IN THE
MID-HUDSON VALLEY BUT WET-BULBING EFFECTS LOOK TO KEEP ANY
ADDITIONAL SHOWERS AS MAINLY LIGHT SNOW. LATEST NBM
PROBABILISTIC GUIDANCE SHOWS A 20 TO 40% CHANCE TO EXCEED 4
INCHES ACROSS THE REGION WITH THE HIGHEST PROBABILITIES 40-50%
IN THE SOUTHERN ADIRONDACKS AND WESTERN MA/SOUTHERN VT WHERE
SOUTHWEST FLOW ALOFT LEADS TO UPSLOPE ENHANCEMENTS. THESE AREAS
THEREFORE HAVE THE HIGHEST POTENTIAL FOR WINTER WEATHER
ADVISORIES WHILE OTHER AREAS MAY FALL SHY OF THE 4" THRESHOLD
(3" IN MA/CT).
KEY MESSAGE 3...
HIGH PRESSURE BUILDS OVER THE NORTHEAST JUST IN TIME FOR CHRISTMAS
EVE GIVING US MAINLY QUIET WEATHER. THEN, LARGE SCALE RIDGING
BUILDING ACROSS THE SOUTHERN TIER OF THE CONUS STARTS TO EXPAND
TOWARDS THE NORTHEAST CHRISTMAS DAY INTO THE END OF THE WEEK.
HOWEVER, ADDITIONAL SHORTWAVES TRACKING ALONG ITS NORTHERN
PERIPHERY INCREASES CHANCES FOR PRECIPITATION. AN INITIAL
SHORTWAVE ON CHRISTMAS DAY LOOKS TO TRACK MAINLY TO OUR SOUTH
AND PROBABILITY FOR PRECIPITATION HAS THEREFORE LOWERED TO
SLIGHT CHANCE. EVEN IF PRECIP DOES REACH OUR SOUTHERN AREAS,
TEMPERATURES LOOKS WARM ENOUGH TO FAVOR RAIN. THEN, CHANCES FOR
PRECIPITATION INCREASE FOR THURS NIGHT INTO FRIDAY AS ANOTHER
SHORTWAVE TRACKS THROUGH CANADA; HOWEVER, THE LATEST ENSEMBLE
CLUSTER ANALYSIS SHOWS JUST 35% OF THE MEMBERS FAVOR DEEPENING
HEIGHTS DURING THIS WINDOW WHILE 65% SHOW INCREASING HEIGHTS AND
THEREFORE A DRIER FORECAST. THEREFORE, THE 50TH PERCENTILE 24HR
PRECIP AMOUNTS THROUGH FRI EVENING GENERALLY REMAIN UNDER A
QUARTER INCH WITH PROBABILITY FOR 2" OR MORE OF SNOW UNDER 20%.
WARMER AIR ALOFT NUDGES NORTHEASTWARD DURING THIS PERIOD DUE TO
THE BUILDING RIDGE AND SOUTHWEST FLOW SO SHOULD PRECIPITATION
CHANCES INCREASE, WE WILL HAVE TO MONITOR PRECIPITATION TYPES.
OVERALL FORECAST CONFIDENCE FOR THE END OF THE WEEK REMAINS LOW.
AVIATION /18Z SUNDAY THROUGH FRIDAY/
WE START THE TAF PERIOD WITH VFR CONDITIONS AND PASSING LIGHT
SNOW SHOWERS. THESE LIGHT SNOW SHOWERS COULD BRING BRIEF LIGHT
SNOW FLURRIES TO KALB AND KPSF THROUGH 22Z, SO CONTINUED MENTION
IN TEMPO GROUPS FOR THE SHOWER ACTIVITY. HOWEVER, VISIBILITY
IMPACTS COULD BE NORTH OF THE AIRPORTS SO DID NOT MENTION
CONDITIONS BELOW VFR AS THESE ARE ISOLATED TO SCATTERED QUICK
MOVING LIGHT SNOW SHOWERS IN MORE OF THE VICINITY OF KALB AND
KPSF. OTHERWISE, MVFR CONDITIONS COULD OCCUR OVERNIGHT TONIGHT
AFTER 6Z WITH LOWERING CLOUD CEILINGS WITH CONDITIONS IMPROVING
BACK TO VFR TOWARDS 12Z FOR KALB, KGFL, AND KPSF. KPOU
CONDITIONS ARE FORECASTED TO REMAIN VFR THROUGH THE TAF PERIOD.
GUSTY WEST-NORTHWEST WINDS CONTINUE THROUGH 6Z FOR KALB AND KPSF
RANGING BETWEEN 25 AND 35 KNOTS. GUSTY WINDS DECREASE BEFORE 6Z
FOR KGFL AND KPOU TO LESS THAN 12 KNOTS BETWEEN 00Z AND 06Z. FOR
KALB, WEST-NORTHWEST WIND GUSTS DECREASE TO LESS THAN 12 KNOTS
BETWEEN 5Z AND 7Z. FOR KPSF, WIND GUSTS DECREASE BETWEEN 08Z AND
12Z TO LESS THAN 15 KNOTS.
OUTLOOK...
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. LIKELY SN.
TUESDAY: HIGH OPERATIONAL IMPACT. DEFINITE SN.
TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. BREEZY. CHANCE OF SHSN.
WEDNESDAY: LOW OPERATIONAL IMPACT. BREEZY. NO SIG WX.
WEDNESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
CHRISTMAS DAY: LOW OPERATIONAL IMPACT. NO SIG WX.
THURSDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN.
FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
ALY WATCHES/WARNINGS/ADVISORIES
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
DISCUSSION...31
AVIATION...05
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