117
FXUS61 KALY 211952
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
252 PM EST SUN DEC 21 2025
WHAT HAS CHANGED
AS OF 2:45 PM, WINTER WEATHER ADVISORY FOR LAKE EFFECT SNOW WAS
ISSUED FOR SOUTHERN HERKIMER COUNTY IN COLLABORATION WITH WFO
BGM BASED ON A REPORT OF 5" IN NORTH CENTRAL ONEIDA COUNTY.
DESPITE THIS HEADLINE ISSUANCE, PREVIOUS FORECAST THINKING
REMAINS LARGELY UNCHANGED, AS WE WILL CONTINUE TO MESSAGE THE
POTENTIAL FOR UP TO 4-5" OF SNOW WHERE THE LAKE EFFECT BAND
REMAINS MOST PERSISTENT. THIS WILL LIKELY BE JUST NORTH OF THE
THRUWAY. OTHERWISE, PREVIOUS FORECAST REMAINS ON TRACK WITH MORE
DETAILS BELOW...
PREVIOUS (1"30 PM EST)...MINOR ADJUSTMENTS MADE TO POPS AND
SNOWFALL AMOUNTS THROUGH THIS EVENING WITH THE LAKE EFFECT SNOW.
INCREASING CONFIDENCE FOR MOST AREAS TO SEE LIGHT SNOW
ACCUMULATIONS LATE MONDAY NIGHT AND/OR TUESDAY AS GUIDANCE IS
COMING INTO BETTER AGREEMENT ON THE TRACK OF THIS CLIPPER
SYSTEM. WILL ALSO BEGIN MENTIONING POTENTIAL FOR GUSTY (BUT SUB-
ADVISORY-LEVEL) WINDS BEHIND THIS CLIPPER SYSTEM TUESDAY NIGHT
INTO WEDNESDAY.
KEY MESSAGES
1. IN THE WAKE OF A COLD FRONTAL PASSAGE, REGION-WIDE WIND GUSTS UP
TO 35-40 MPH ARE EXPECTED THIS AFTERNOON AND EVENING, WITH UP TO 2-
4" OF LAKE EFFECT SNOW IN THE SOUTHWESTERN ADIRONDACKS AND WESTERN
MOHAWK VALLEY.
2. THERE IS MODERATE TO HIGH CONFIDENCE IN THE POTENTIAL FOR A LIGHT
TO LOCALLY 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 WITH INCREASING CHANCES FOR
PRECIPITATION FRIDAY INTO SATURDAY, ALTHOUGH CONFIDENCE IS VERY LOW
IN PRECIPITATION TYPE AND AMOUNTS RIGHT NOW.
DISCUSSION
KEY MESSAGE 1...
CURRENT SFC ANALYSIS AS OF 1:30 PM EST SHOWS A 1002 MB LOW
LOCATED OVER FAR SOUTHEASTERN QUEBEC, WITH ITS TRAILING COLD
FRONT NOW TRACKING THROUGH THE MID HUDSON VALLEY AND WESTERN CT.
THERE IS VERY LITTLE MOISTURE AHEAD OF THIS FRONT, SO EARLIER
SNOW SHOWERS HAVE DIMINISHED AS THE FRONT CONTINUES ITS
SOUTHEASTWARD TREK.
BEHIND THE FRONT, HOWEVER, A COLD ADVECTION REGIME OVER THE GREAT
LAKES IS ALLOWING FOR A BAND OF LAKE EFFECT SNOW OFF OF LAKE
ONTARIO. WITH LAKE TEMPERATURES OF AROUND +6C AND 850 MB
TEMPERATURES DROPPING TO AROUND -14C THIS AFTERNOON, THERE WILL BE
SUFFICIENT LAKE-INDUCED INSTABILITY FOR THE BAND TO EXTEND WELL
INLAND, ESPECIALLY GIVEN THE EXPECTED MULTI-LAKE CONNECTION, 30-40KT
WINDS AT 850MB, AND INVERSION HEIGHTS AROUND 750 MB. WITH LOW-LEVEL
FLOW TRAJECTORIES CURRENTLY OUT OF THE WEST, THE BAND IS
PUSHING INTO THE SOUTHERN ADKS, NORTH OF THE THRUWAY. SNOW
SHOWERS WITH THIS BAND EXTEND ALL THE WAY INTO SOUTHERN VT AND
THE NORTHERN BERKSHIRES. AS WE HEAD THROUGH THE AFTERNOON, LOW-
LEVEL FLOW TRAJECTORIES VEER TO AROUND 290 DEGREES, WHICH WILL
HELP PUSH THE BAND FURTHER SOUTH INTO THE MOHAWK VALLEY, WHICH
IS WHEN SNOW WILL LIKELY MOVE OVER THE THRUWAY. AS THIS HAPPENS,
THE CAPITAL DISTRICT COULD GET IN ON SOME OF THE SNOW SHOWERS
AS WELL. AS WE HEAD INTO TONIGHT (AFTER 03Z), THE LOW-LEVEL FLOW
CONTINUES TO VEER MORE TO THE NW. THIS WILL HELP PUSH THE BAND
FURTHER SOUTH OF OUR CWA, WHILE LOWERING INVERSION HEIGHTS,
WEAKENING WINDS, AND MORE DIRECTIONAL SHEAR DUE TO HIGH PRESSURE
BUILDING INTO THE GREAT LAKES WILL ALL HELP TO REDUCE THE
INLAND EXTENT OF THE BAND AS WELL. WITHIN THE BAND ITSELF,
SNOWFALL RATES OF UP TO AROUND 1" PER HOUR AND GUSTY WINDS
LEADING TO BLOWING SNOW AND REDUCED VISIBILITY WILL MAKE FOR
DIFFICULT TRAVEL CONDITIONS THIS AFTERNOON AND EVENING.
BY THE TIME SNOW STOPS, UP TO 3-5"" OF SNOW WILL BE POSSIBLE IN
THE SOUTHWESTERN ADKS AND MOHAWK VALLEY. WHILE RESIDENCE TIME
FOR THE BAND OVER ANY ONE LOCATION WILL BE RELATIVELY SHORT, THE
WE ULTIMATELY DECIDED TO ISSUE AN ADVISORY AS OF 2:45 PM EST PER
COLLABORATION WITH WFO BGM BASED ON REPORTS THEY HAVE RECEIVED
IN ONEIDA COUNTY SO FAR AND THE FACT THAT THE BAND LOOKS QUITE
IMPRESSIVE ON RADAR. LOWER SNOWFALL AMOUNTS ARE EXPECTED
ELSEWHERE, WITH PORTIONS OF THE SOUTHERN GREENS, NORTHERN
BERKSHIRES, CAPITAL DISTRICT SOUTH OF SARATOGA SPRINGS, AND
NORTHERN CATSKILLS SEEING A COATING UP TO A HALF INCH OR SO OF
SNOW. LATE TONIGHT OR TOMORROW MORNING, THE BAND MAY DRIFT BACK
NORTH WITH RENEWED SNOW SHOWER ACTIVITY OVER THE WESTERN ADKS AS
A WARM FRONT LIFTING NORTHWARDS THROUGH THE REGION ALLOWS WINDS
TO BACK MORE TO THE WEST. HOWEVER, ANY ADDITIONAL ACCUMULATIONS
WILL BE MINOR WITH WARMING 850 MB TEMPS AND LESS INSTABILITY
COMPARED TO TODAY. THE REST OF THE REGION SHOULD REMAIN DRY
TONIGHT AND TOMORROW WITH HIGH PRESSURE AND SUBSIDENCE BUILDING
OVER THE REGION.
WITH A TIGHT PRESSURE GRADIENT BETWEEN THE SFC LOW TO OUR NORTHEAST
AND SFC HIGH BUILDING INTO THE GREAT LAKES, WINDS ATOP THE BOUNDARY
LAYER WILL BE AT 35-45KT THIS AFTERNOON AND EARLY EVENING.
WITH DECENT BL MIXING, WE ARE EXPECTING GUSTS OF UP TO 35-40 MPH
TO GET MIXED DOWN TO THE SURFACE, WITH THE STRONGEST WINDS IN
THE TYPICAL W/NW CHANNELED FLOW AREAS OF THE MOHAWK VALLEY,
CAPITAL DISTRICT, AND BERKSHIRES. WE ENDED UP INCREASING WIND
GUSTS BY 5-10 KT FROM THE NBM IN COLLABORATION WITH NEIGHBORING
OFFICES. WHILE THESE GUSTS ARE EXPECTED TO REMAIN BELOW
ADVISORY CRITERIA, A FEW INSTANCES OF DOWNED TREES/LIMBS LEADING
TO POWER OUTAGES CAN'T BE RULED OUT, AS WELL AS BLOWING AND
DRIFTING OF ANY NEW LAKE EFFECT SNOW THAT FALLS THIS AFTERNOON
AND EVENING. WINDS AND GUSTS SHOULD DIMINISH OVERNIGHT WITH THE
SFC HIGH BUILDING IN FROM THE WEST.
KEY MESSAGE 2...
LATE MONDAY NIGHT OR TUESDAY MORNING, AN UPPER SHORTWAVE AND
ASSOCIATED SFC LOW EMBEDDED WITHIN FAST NW FLOW ALOFT WILL TRACK
INTO SOUTHERN CANADA. AS THE SYSTEM'S WARM FRONT LIFTS NORTHWARDS
THROUGH THE REGION, WARM ADVECTION AND ISENTROPIC LIFT WILL RESULT
IN SNOW OVERSPREADING THE REGION FROM SOUTHWEST TO NORTHEAST LATE
MONDAY NIGHT OR EARLY TUESDAY AM. THERE REMAINS SOME UNCERTAINTY IN
THE EXACT TIMING, BUT OVERALL GUIDANCE HAS COME TO A BETTER
CONSENSUS ON THE STORM TRACK. THEREFORE, CONFIDENCE IS
INCREASING IN A MID-LEVEL FGEN BAND AND ADDITIONAL FORCING FROM
RIGHT ENTRANCE REGION OF THE UPPER JET HELPING KEEP PRECIP
MAINLY SNOW THROUGH AT LEAST 18Z, EVEN WITH SFC TEMPERATURES
WARMING TO NEAR FREEZING FOR VALLEY AREAS. HOWEVER, IN THE
AFTERNOON OR EVENING, A MID-LEVEL DRY SLOT WILL PUNCH INTO THE
REGION, AND THE LOSS OF CLOUD ICE AND BETTER FORCING MOVING OFF
THE E/NE MAY ALLOW FOR A MIX WITH OR CHANGE OVER TO
RAIN/DRIZZLE, ESPECIALLY FOR VALLEY AREAS. CONFIDENCE IS
INCREASING FOR A GENERAL 1-3" FOR MOST AREAS, AND UP TO 4-6" FOR
SOME HIGH TERRAIN AREAS, ESPECIALLY THE ADKS. WINTER WEATHER
ADVISORIES WILL LIKELY BE NEEDED FOR THE ADKS, AND POSSIBLY
OTHER HIGH TERRAIN AREAS FOR THIS TIMEFRAME. WHILE LOWER
ELEVATION WILL LIKELY SEE SUB-ADVISORY LEVEL SNOWFALL AMOUNTS,
THE TUESDAY AM COMMUTE AND POSSIBLY THE EVENING COMMUTE COULD
STILL BE SLICK, AS WELL AS FOR ANY PRE-HOLIDAY TRAVEL DURING
THE DAY TUESDAY.
WHILE A LULL IN SNOW IS EXPECTED IN THE AFTERNOON AND EVENING, THE
UPPER TROUGH AXIS MOVES THROUGH TUESDAY NIGHT WITH A SFC COLD FRONT,
BOTH OF WHICH WILL PROVIDE RENEWED FORCING FOR ASCENT, AS WILL THE
LEFT EXIT REGION OF AN APPROACHING NW TO SE ORIENTED UPPER JET
STREAK. THE BEST CHANCE FOR ADDITIONAL PRECIP LOOKS TO BE IN THE
ADKS DUE TO LAKE ENHANCEMENT AND IN THE SOUTHERN GREENS DUE TO
UPSLOPE ENHANCEMENT. THESE AREAS COULD SEE UP TO A COUPLE
ADDITIONAL INCHES OF SNOW TUESDAY NIGHT. NOT EXPECTING MUCH
ADDITIONAL PRECIP FOR THE VALLEY AREAS, BUT WITH A SECONDARY SFC
LOW DEVELOPING OFF THE NEW ENGLAND COAST HELPING TO ADVECT
COLDER AIR FROM THE NORTH INTO THE REGION, ANY ADDITIONAL PRECIP
THAT DOES FALL WOULD LIKELY BE IN THE FORM OF SNOW. WINDS ALSO
TURN GUSTY AGAIN BEHIND THIS DEPARTING SYSTEM TUESDAY NIGHT INTO
WEDNESDAY; WE BUMPED UP WIND GUSTS INTO THE 25-35 MPH RANGE IN
COLLABORATION WITH NEIGHBORING OFFICES.
KEY MESSAGE 3...
HIGH PRESSURE AT THE SURFACE AND RIDGING ALOFT BUILD OVER THE REGION
WEDNESDAY INTO THURSDAY, RESULTING IN LARGE-SCALE SUBSIDENCE
AND TRANQUIL WEATHER CONDITIONS. A WEAK UPPER SHORTWAVE IS
EXPECTED TO SLIDE TO THE SOUTHWEST OF OUR REGION ON CHRISTMAS,
BUT SHOULD STAY FAR ENOUGH AWAY THAT OUR AREA REMAINS DRY. A
BETTER CHANCE FOR PRECIPITATION WILL COME FRIDAY INTO EARLY NEXT
WEEKEND AS UPPER TROUGHING AND AN ASSOCIATED SFC LOW OVER
SOUTHERN CANADA OR THE GREAT LAKES MOVE EASTWARDS. THERE IS
STILL SIGNIFICANT UNCERTAINTY IN TIMING, AMOUNT, AND TYPE OF
PRECIP GIVEN UNCERTAINTY IN THE UPPER FLOW EVOLUTION AND THE
POTENTIAL COMPLEX INTERACTION OF THE VARIOUS SHORTWAVES EMBEDDED
WITH THE MEAN FLOW. HOWEVER, WITH HIGH PRESSURE TO THE N/NE,
SOME WINTRY PRECIP MAY BE POSSIBLE, WITH THE BEST CHANCE FOR
NORTHERN ZONES AND HIGH TERRAIN AREAS, WHILE VALLEY AREAS HAVE A
BETTER CHANCE OF SEEING MORE RAIN. WITH RIDGING ALOFT,
TEMPERATURES WEDNESDAY AND CHRISTMAS DAY WILL TREND TOWARDS NEAR
OR EVEN SLIGHTLY ABOVE NORMAL. WHILE WE STUCK NEAR THE NBM FOR
TEMPERATURES FRIDAY AND SATURDAY GIVEN THE HIGH DEGREE OF
UNCERTAINTY, TEMPERATURES TO END THE FORECAST PERIOD WILL
ULTIMATELY BE DETERMINED BY THE TRACK OF THE AFOREMENTIONED SFC
LOW.
AVIATION /19Z 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. CHANCE OF SN.
TUESDAY: HIGH OPERATIONAL IMPACT. DEFINITE RA...SN.
TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. BREEZY. CHANCE OF SN.
WEDNESDAY: LOW OPERATIONAL IMPACT. BREEZY. NO SIG WX.
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
CHRISTMAS DAY: LOW OPERATIONAL IMPACT. NO SIG WX.
THURSDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
FRIDAY: MODERATE OPERATIONAL IMPACT. LIKELY SHRA...SHSN.
ALY WATCHES/WARNINGS/ADVISORIES
CT...NONE.
NY...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NYZ038.
MA...NONE.
VT...NONE.
DISCUSSION...35
AVIATION...05
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