December 10, 2013

000
FXUS61 KALY 101127
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
627 AM EST TUE DEC 10 2013

.SYNOPSIS…
AN AREA OF LOW PRESSURE WILL MOVE OFF THE MID ATLANTIC COAST
TODAY AND WILL PASS WELL SOUTH OF LONG ISLAND. SNOW ASSOCIATED
WITH THIS LOW WILL SPREAD FAR ENOUGH NORTHWARD TO IMPACT AREAS TO
THE SOUTH AND EAST OF THE CAPITAL DISTRICT…MAINLY FROM MID
MORNING INTO THE EARLY AFTERNOON. IN ADDITION…CONDITIONS WILL
BECOME FAVORABLE FOR LAKE EFFECT SNOWS TO IMPACT PORTIONS OF THE
ADIRONDACKS TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. ALSO…IT WILL
TURN COLDER ACROSS THE REGION.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
AS OF 6 AM EST…SNOW IS STARTING TO BREAK OUT ACRS EASTERN PA AND
WILL BE HEADING FOR THE SOUTHEAST THIRD OF OUR FA THIS MORNING.

FOR TODAY…A WAVE OF LOW PRESSURE WILL TRACK ALONG A STALLED FRONTAL
BOUNDARY MOVING OFF THE MID ATLANTIC COAST TODAY AS NORTHERN
STREAM ENERGY INTERACTS WITH SOUTHERN STREAM ENERGY. THE MODELS
AND ENSEMBLE GUIDANCE SHOW LITTLE SPREAD AND PASS THE SURFACE LOW
ABOUT 230 MILES SOUTH OF MONTAUK POINT EARLY TUESDAY AFTERNOON.
THE MODELS ARE ALSO IN AGREEMENT SHOWING MID LEVEL FRONTOGENETIC
FORCING OCCURRING JUST TO THE SOUTH OF OUR FORECAST AREA ACROSS
THE NEW YORK METROPOLITAN AREA AND LONG ISLAND ALONG WITH UPPER
LEVEL DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A STRONG 180+
KNOT JET. EXPECTING A LIGHT ACCUMULATION OF SNOW…1 TO 4 INCHES…TO
THE SOUTH AND EAST OF THE CAPITAL DISTRICT WITH THE SNOW OCCURRING
MAINLY FROM MID MORNING INTO THE EARLY AFTERNOON. MAX TEMPS WILL
RANGE FROM THE LOW 20S OVER THE ADIRONDACKS TO THE MID 30S IN THE
HUDSON VALLEY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/…
A LAKE EFFECT SNOW WARNING HAS BEEN ISSUED FOR NORTHERN HERKIMER
AND HAMILTON COUNTIES FROM THIS EVENING THROUGH LATE WEDNESDAY
NIGHT.

TONIGHT THROUGH WEDNESDAY NIGHT…CONDITIONS WILL BECOME FAVORABLE
FOR LAKE EFFECT SNOWS. AN INTENSE LAKE EFFECT SNOW BAND WILL
DEVELOP EAST OF LAKE ONTARIO TONIGHT AND CONTINUE THROUGH
WEDNESDAY NIGHT. THE CSTAR INLAND LAKE EFFECT INLAND EXTENT
PROGRAM INDICATES THAT THE BANDS MAY EXTEND 110 TO 130 KM INLAND
FROM LAKE ONTARIO. THERE IS ALSO A MULTI LAKE CONNECTION WITH
BANDS OFF OF LAKE SUPERIOR AND LAKE HURON SPECIFICALLY GEORGIAN
BAY. THE LAKE ONTARIO WATERS ARE STILL RELATIVELY WARM BASED ON
GLERL THE SURFACE WATER TEMPERATURE IS 48 DEGREES FAHRENHEIT AND
850 MB TEMPERATURES ARE FORECAST TO DROP TO AROUND -18 DEGREES
CELSIUS DURING THIS TIME FRAME. SO LAKE EFFECT SNOWS WILL PICK UP
IN INTENSITY TONIGHT INTO WEDNESDAY MORNING AS THE COLDER AIR
CONTINUES TO ADVECT INTO THE REGION ACROSS THE LAKES AND CONTINUE
RIGHT THROUGH AT LEAST WEDNESDAY EVENING. TOTAL SNOWFALL
ACCUMULATIONS ARE EXPECTED TO REACH 12 TO 24 INCHES ACROSS
NORTHERN HERKIMER COUNTY AND 8 TO 16 INCHES ACROSS HAMILTON COUNTY
WITH THE GREATEST ACCUMULATIONS ACROSS THE NORTHERN PORTION OF THE
COUNTY. AS COLDER AIR CONTINUES TO MOVE INTO THE REGION IT WILL
GET PROGRESSIVELY COLDER. OUTSIDE OF THE LAKE EFFECT THERE MAY BE
SNOW SHOWERS AND SQUALLS WITH THE POTENTIAL FOR A WINDEX TYPE
EVENT AHEAD OF THE ARCTIC COLD FRONT WHICH WILL BE CROSSING THE
REGION WEDNESDAY INTO WEDNESDAY EVENING. EXPECT LOWS TONIGHT IN
THE UPPER SINGLE DIGITS TO MID TEENS WITH HIGHS ON WEDNESDAY IN
THE MID 20S TO AROUND 30 AND LOWS WEDNESDAY NIGHT IN THE SINGLE
DIGITS TO LOWER TEENS.

THURSDAY AND THURSDAY NIGHT…IT WILL GET EVEN COLDER IN THE WAKE
OF THE ARCTIC COLD FRONT. HIGHS ON THURSDAY WILL ONLY BE IN THE
MID TEENS TO MID 20S WITH LOWS THURSDAY NIGHT IN THE SINGLE DIGITS
TO AROUND 10 ABOVE. IT MAYBE EVEN COLDER IN AREAS WHERE A DEEPER
SNOW PACK EXISTS. WIND CHILL VALUES COULD APPROACH ADVISORY
CRITERIA ACROSS HIGHER ELEVATIONS THU NT AND HAVE THIS MENTIONED
IN THE HOW.

AS FOR LAKE EFFECT SNOW POTENTIAL…VEERING WINDS SHOULD
FAVOR SNOWBANDS SHIFTING INTO THE SCHOHARIE VALLEY AND EASTERN
CATSKILLS AND AREAS TO THE SOUTH AND WEST…WITH AN OVERALL
DECREASING TREND AS INVERSION HEIGHTS LOWER. ALTHOUGH A MORE
ORGANIZED BAND MAY DEVELOP AGAIN LATE THURSDAY AND THURSDAY
EVENING ACROSS THE WESTERN ADIRONDACKS.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/…
HAVE POPULATED MUCH OF THIS PORTION OF THE DATABASE WITH 00Z/10
HPC.

MODELS SEEM TO BE CONVERGING ON THE IDEA OF A STORM SYSTEM AFFECTING
THE REGION DURING THE SAT-SUN TIME PERIOD. TEMP PROFILES INDICATE
THAT P-TYPE WOULD BE MAINLY SNOW…ALTHOUGH SOME MIXED PRECIP OR
RAIN COULD OCCUR IN ACROSS SOUTHERN AREAS LATE SAT NT OR EARLY SUN.
SIGNIFICANT SNOWFALL AMTS COULD IMPACT AT LEAST PORTIONS OF THE
REGION DURING THIS TIME PERIOD…ALONG WITH A POSSIBLE WINTRY MIX.

IN THE WAKE OF THIS SYSTEM…ANOTHER SURGE OF ARCTIC AIR WILL MOVE
INTO THE REGION…ALONG WITH RESIDUAL SNOW SHOWERS AND POSSIBLE LAKE
EFFECT SNOWFALL.

BELOW NORMAL TEMPS WILL CONTINUE THROUGH THIS PERIOD.

HERE ARE SOME MORE SPECIFICS…

FRI…MODELS HAVE TRENDED TOWARD A PERIOD OF WARM ADVECTION…WELL
AHEAD OF LOW PRESSURE APPROACHING FROM THE WEST. AS LOW LEVEL WINDS
BACK MORE INTO THE SOUTHWEST…SOME LAKE EFFECT SNOW SHOWERS COULD
RETURN TO PORTIONS OF THE WESTERN MOHAWK VALLEY AND
ADIRONDACKS…ALTHOUGH INVERSION HEIGHTS SHOULD REMAIN LOW…SO AT
THIS POINT…IT APPEARS THAT ACCUMS SHOULD BE RELATIVELY MINOR. AS
FOR TEMPS…EXPECT MAXES TO REACH THE LOWER/MID 20S IN VALLEY
AREAS…AND TEENS ACROSS HIGHER ELEVATIONS.

FRI NT-SUN…MODELS ARE CONVERGING AT A HIGHER PROBABILITY OF SNOW
AFFECTING MUCH OF THE REGION DURING A PORTION OF THIS TIME
PERIOD…AS LOW PRESSURE APPROACHES FROM THE GREAT LAKES/OHIO VALLEY
REGION. THE 00Z/10 GEFS GENERALLY INDICATE TWO CENTERS OF CLUSTERING
OF LOW PRESSURE CENTERS…WITH A FEW MEMBERS ACROSS THE GREAT LAKES
REGION…AND SEVERAL ALONG OR JUST OFF THE NORTHERN MID ATLANTIC
COAST. SEVERAL MEMBERS ARE INDICATING A FAIRLY STRONG/DEEP SYSTEM
POTENTIALLY IMPACTING THE REGION…ALTHOUGH SHOULD THE DEEPER CENTER
REMAIN ACROSS THE GREAT LAKES WITH WEAKER REDEVELOPMENT AND/OR TRACK
ALONG THE COAST…A WARM SURGE COULD ALLOW SNOW TO MIX WITH OR
CHANGE TO A WINTRY MIX OR EVEN ALL RAIN ACROSS MUCH OF THE REGION.
THE 00Z/10 ECMWF ALSO HINTS AT A STRONGER STORM SYSTEM…WHICH
TRACKS FURTHER SOUTH…AND INTENSIFIES SOUTH AND EAST OF LONG
ISLAND…WHICH WOULD BRING POTENTIALLY A STEADY SNOWFALL TO A GOOD
PORTION OF THE REGION SAT INTO EARLY SUN…WITH PERHAPS SOME WINTRY
MIX OR RAIN OCCURRING ACROSS SOUTHERN AREAS LATE IN THE EVENT.

TAKING A LOOK AT PV ANOMALY TRACES…IT APPEARS THAT THIS POTENTIAL
SYSTEM WILL BE IN ASSOCIATION WITH THREE MAIN PIECES OF
ENERGY…WITH ONE MAIN PIECE EJECTING FROM AN UPPER LEVEL PV ANOMALY
CURRENTLY SOUTH OF THE ALEUTIANS…ALONG WITH ANOTHER PIECE OF
ENERGY DRIVING SOUTHWARD FROM NORTHERN CANADA. THE THIRD PIECE IS
FROM THE SYSTEM CURRENTLY LOCATED SOUTHWEST OF CALIFORNIA. THIS
PIECE OF ENERGY IS FORECAST TO WEAKEN…AND MOVE OUT AHEAD OF THE
OTHER FEATURES…BUT SHOULD IT REMAIN STRONGER FOR A LONGER TIME
PERIOD…IT COULD…IN COMBINATION WITH STRONG WARM/MOISTURE
ADVECTION…ALLOW PRECIP TO DEVELOP QUICKER IN THE REGION…PERHAPS
STARTING FRI NT. AT THIS TIME…DUE TO UNCERTAINTY…HAVE INDICATED
SLIGHT CHC POPS FOR FRI NT…THEN HIGH CHC POPS FOR SNOW SAT INTO
EARLY SUN…WITH A WINTRY MIX AND SOME RAIN INDICATED FOR FAR
SOUTHERN AREAS FOR LATE SAT AND SAT NT.

BEHIND THIS SYSTEM…ARCTIC AIR WILL ONCE AGAIN SURGE INTO THE
REGION…WITH DAYTIME MAX TEMPS MONDAY EXPECTED TO ONLY REACH THE
TEENS AND 20S…WITH OVERNIGHT MINS FALLING INTO THE SINGLE DIGITS
ABOVE AND SLIGHTLY BELOW ZERO FOR SUN NT/MON AM.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/…
A STORM SYSTEM PASSING WELL SOUTH OF THE TAF SITES SHOULD ALLOW
FOR SOME LIGHT SNOW TO DEVELOP SHORTLY AFTER 14Z-15Z/MON…AND
SHOULD LAST UNTIL AT LEAST EARLY AFTERNOON. THIS SHOULD PRODUCE A
PERIOD OF MVFR/IFR CONDITIONS AT KPSF AND KPOU. AT KALB AND KGFL…THE
SNOW SHOULD BE MORE SPOTTY…WITH MAINLY VFR CONDITIONS
PREVAILING…ALTHOUGH A FEW PERIODS OF MVFR VSBY COULD OCCUR AT
KALB. THEN…SCATTERED SNOW SHOWERS ARE EXPECTED TO DEVELOP AT ALL
TAF SITES DURING THE AFTERNOON HOURS…AS COLDER AIR MOVES INTO
THE REGION. CONDITIONS SHOULD GENERALLY BE VFR…BUT MVFR/IFR
CONDITIONS WILL BE POSSIBLE WITHIN ANY SNOW SHOWERS. SNOW SHOWERS
SHOULD DECREASE IN AREAL COVERAGE AFTER 00Z/WED…WITH MAINLY VFR
CONDITIONS EXPECTED TONIGHT.

EXPECT WEST WINDS AT 5-10 KT FOR MUCH OF TODAY INTO TONIGHT.

OUTLOOK…
WED-WED NT: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
THU: MODERATE OPERATIONAL IMPACT. CHANCE OF SHSN.
THU NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
FRI: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
FRI NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SN.
SAT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.
SAT NT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN…SLEET.
SUN: MODERATE OPERATIONAL IMPACT.BREEZY CHANCE OF SHSN.

&&

.HYDROLOGY…
NO HYDRO RELATED CONCERNS ARE EXPECTED THIS WEEK. THE PRECIPITATION
THAT OCCURS WILL BE IN THE FORM OF SNOW…EXCEPT A WINTRY MIX IS
EXPECTED OVER THE WEEKEND.

FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES…INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS…PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.

&&

.ALY WATCHES/WARNINGS/ADVISORIES…
CT…NONE.
NY…LAKE EFFECT SNOW WARNING FROM 6 PM THIS EVENING TO 6 AM EST
THURSDAY FOR NYZ032-033.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…IAA/11
NEAR TERM…IAA/FRUGIS/11
SHORT TERM…IAA/KL/11
LONG TERM…KL
AVIATION…KL
HYDROLOGY…11

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