February 13, 2014 Forecast Discussion

000
FXUS61 KALY 132342
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
642 PM EST THU FEB 13 2014

.SYNOPSIS…
A NOR`EASTER WILL MOVE NORTHEAST OF LONG ISLAND BY EARLY
THIS EVENING…AND INTO THE GULF OF MAINE BY TOMORROW MORNING. THIS
POWERFUL STORM WILL BRING A SIGNIFICANT SNOWFALL TO EASTERN NEW YORK
AND WESTERN NEW ENGLAND. THE SNOW WILL TAPER TO SCATTERED SNOW
SHOWERS AND FLURRIES BY LATE MORNING…BUT BRISK CONDITIONS AND
SEASONABLE TEMPERATURES WILL PERSIST INTO THE AFTERNOON. ANOTHER
DISTURBANCE WILL BRING MAINLY LIGHT SNOW TO THE REGION TO OPEN THE
WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/…
…THE ENTIRE FORECAST CONTINUES TO BE UNDER A WINTER STORM
WARNING…

AS OF 642 PM EST…HERKIMER AND HAMILTON COUNTIES HAVE A WINTER
STORM WARNING UNTIL NOONTIME TOMORROW.

WINTER STORM WARNINGS CONTINUE UNTIL 10 AM EST FRIDAY FOR ALL OF
WESTERN NEW ENGLAND…THE MOHAWK VALLEY…GREATER CAPITAL
REGION…EASTERN CATSKILLS…HELDERBERGS…MID HUDSON VALLEY…
TACONICS…LAKE GEORGE SARATOGA REGION…

A LULL IN THE PCPN CONTINUES OVER NW CT…THE MID HUDSON
VALLEY…AND PARTS OF THE SOUTHEAST CATSKILLS WITH THE MAIN BATCH
OF WARM ADVECTION PCPN AND THE RESIDUAL BANDS/BANDLETS LOCATED FROM
THE CAPITAL REGION NORTH AND WEST. SOME IMPRESSIVE SNOW TOTALS
HAVE COME IN THUS FAR…PLEASE SEE OUR LATEST PUBLIC INFORMATION
STATEMENT.

THE NOR`EASTER IS ABOUT 100-125 MILES SOUTH OF LONG ISLAND THIS
HOUR AND HAS LOWERED TO 986 HPA BASED ON THE RUC AND MSAS
ANALYSES…AND THE BEST PRESSURE FALLS ON THE ORDER OF 8-10+ HPA/3
HRS ARE NOW IN THE GULF OF MAINE. THE LATEST GFS/NAM/ECMWF
GUIDANCE HAS THE IMPRESSIVE CYCLONE TRACKING A LITTLE BIT CLOSER
TO THE COAST. THIS SHIFT HAVING THE CYCLONE MOVE OVER RI AND ERN
MA WILL ALLOW THE HEAVY SNOWBAND ON THE NW SIDE OF THE SYSTEM
TO IMPACT THE ENTIRE FORECAST AREA…AS FAR WEST AS THE WRN MOHAWK
VALLEY AND THE SRN DACKS NOW.

THE WATER VAPOR LOOP THIS EVENING SHOWS A DISTINCT DRY SLOT
MOVING ALONG THE EAST COAST INTO NJ AND PARTS OF WRN NEW ENGLAND.
THIS HAS ALLOWED THE PCPN TO LIGHTEN IN INTENSITY WITH SOME SLEET
AND FREEZING RAIN OVER THE MID HUDSON VALLEY…SRN TACONICS SRN-
CNTRL BERKS AND NW CT. THE MID LEVEL DRYING IS EXPECTED TO RESULT
IN A POSSIBLE LOSS OF ICE NUCLEI IN THE CLOUDS…RESULTING IN THE
MIXED PRECIP ACROSS THESE AREAS FOR A SHORT-PERIOD OF TIME.
HOWEVER…THE PCPN IS STARTING TO FILL BACK IN AHEAD OF THE
COMPACT CLOSED CIRCULATION OVER ERN VA THE DELMARVA. THE H500
CLOSED UPPER LEVEL LOW CENTERED OVER NC/VA HAS BECOME NEGATIVELY TILTED
EMBEDDED IN THE LONG WAVE TROUGH. THIS CLOSED LOW WILL CAPTURE THE
SFC CYCLONE…AND ALLOW VERY HEAVY SNOWFALL TO RETURN BTWN 9 PM
AND MIDNIGHT ACROSS THE ENTIRE AREA. OUR CONFIDENCE IS VERY HIGH FOR A
NORTH TO SOUTH OR SLIGHTLY N/NW TO S/SE ORIENTED MESOSCALE
SNOWBAND TO HIT MOST OF ERN NY AND WRN NEW ENGLAND. THE LATEST
HRRR-3KM COLUMNAR BASE REF PRODUCT SHOWS POTENTIAL EMBEDDED
CONVECTIVE ELEMENTS COALESCING INTO AN INTENSE BAND FOR THE
OVERNIGHT PERIOD. IT APPEARS WILL HIT THE HUDSON RIVER VALLEY
EASTWARD INTO NEW ENGLAND.

BASED ON CSTAR RESEARCH WITH SUNYA THESE MESOSCALE SNOWBANDS ARE
VERY LIKELY WITH THE H700 CLOSED CIRCULATION MOVING FROM ERN
PA/NJ/DELMARVA REGION AT 00Z TO ERN NY AND WRN NEW ENGLAND BY
06Z/FRI. ON THE NW SIDE OF THE CLOSED LOW IS WHERE A SIGNIFICANT
PIVOTING MESOSCALE SNOWBAND IS LIKELY TO SET UP. ALSO…THE LEFT
FRONT QUAD OR LEFT EXIT REGION REGION OF 130-140+ KT JET STREAK
WILL BE MOVING ACROSS WRN NEW ENGLAND WITH STRONG OMEGA/UPWARD
VERTICAL MOTION OVER A LARGE PORTION OF THE REGION.

A QUICK CHECK OF CROSS-SECTIONS DOWN THE HUDSON RIVER VALLEY FROM THE
NAM AND GFS TONIGHT SHOW STRONG UPWARD VERTICAL VELOCITIES WITH
STEEPLY SLOPED FGEN BENEATH NEGATIVE EPV /AT 400-500 HPA/ BTWN 00Z-
06Z WITHIN THE DEFORMATION ZONE TO THE SYSTEM…AND THE OPTIMAL DENDRITIC
GROWTH ZONE /-10C TO -16C/ INTERSECTS THIS AREA OF STRONG FGEN AND OMEGA
DURING THIS TIME FRAME. SOME HOURLY SNOWFALL RATES OF 1 TO 3
INCHES LOOK LIKELY. THE STRONG MESOSCALE BANDING IN ASSOCIATION
WITH THE MID AND UPPER LEVEL LOW MAY ALSO ALLOW FOR A FEW RUMBLES
OF THUNDER IN THE HEAVIER SNOW /THUNDER SNOW !/. SOME CG LTG
STRIKES CONTINUE OVER THE DELMARVA REGION EARLY THIS EVENING.

THE GFS/NAM/ECMWF SHOWS A LARGE AMOUNT OF ATLANTIC MOISTURE BEING
UTILIZED FOR THE NIGHT TIME PERIOD. PWAT ANOMALIES ARE 1 TO 2 STANDARD
DEVIATIONS ABOVE NORMAL. TONIGHT…ADDITIONAL SNOWFALL AMOUNTS OF 6
TO 12 INCHES WILL BE LIKELY WITH LOCALLY HIGHER AMOUNTS /PERHAPS
IN EXCESS OF A FOOT OVER THE ERN CATSKILL/BERKSHIRES/SRN GREENS/…ON
TOP OF WHAT HAS ALREADY FALLEN.

OVERALL…THE TOTAL SNOWFALL ACCUMULATIONS HAVE BEEN INCREASED
WITH 14 TO 18 INCHES FROM THE CAPITAL REGION…SOUTHERN
VERMONT…AND THE NRN CATSKILLS SOUTH AND EAST EXCEPT FOR SRN
LITCHFIELD…WHERE 10-14 INCHES IS LIKELY. THE MIXED PCPN MAY KEEP
THE SNOW AMOUNTS LOWER IN PARTS OF NW CT TO 14-18 INCHES. SNOW TOTALS OF
18-24" FOR THE SRN GREENS…PART OF THE BERKSHIRES…AND THE ERN
CATSKILLS.

THE WRN-CNTRL MOHAWK VALLEY…LAKE GEORGE SARATOGA REGION…AND
THE SRN DACKS ARE EXPECTED TO HAVE 8 TO 14 INCHES.

BLOWING AND DRIFTING SNOW WILL BE A PROBLEM OVERNIGHT AS THE LOW
DEEPENS AND INTENSIFIES TO AROUND 975 HPA IN THE GULF OF MAINE BY
DAY BREAK. N TO NW WINDS OF 10 TO 20 MPH WITH SOME GUSTS TO 30 TO 35
MPH WILL BE COMMON. SOME OF THE GUSTS MAY NOT MIX TO THE SFC
TONIGHT DUE TO A STRONG LOW-LEVEL INVERSION…AND THE HEAVY PCPN.

SNOW TO LIQUID RATIOS OF 10-13:1 HAVE BEEN USED FOR THE ENTIRE
EVENT FOR MOST OF THE AREA. THE WETTER SNOW WILL LIKELY BE IN THE
SOUTHEAST EXTREME OF THE FCST AREA WHERE THE PCPN WILL MIX FOR A
BRIEF PERIOD. SNOW TO LIQUID RATIOS OF 6-8:1 WERE USED EARLY
TONIGHT TO ACCOUNT FOR SLEET AND FREEZING RAIN. IT SHOULD BE NOTED
ANY ICE ACCUMULATION SHOULD BE VERY LIGHT FOR THE MID HUDSON
VALLEY/SRN BERKS/SRN TACONICS/NW CT WITH A COATING TO A TENTH OF
AN INCH.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/…
TOMORROW…THE NOR`EASTER MOVES NORTHEAST OF THE GULF OF MAINE
TOWARDS NOVA SCOTIA BY THE EARLY PM WITH DEFORMATION SNOW AND SNOW
SHOWERS DIMINISHING BY NOONTIME. THE WARNING GOES FOR HERKIMER AND
HAMILTON COUNTIES…AS MOISTURE DOWNWIND OF LAKE ONTARIO MAY BE
UTILIZED. ADDITIONAL SNOWFALL AMOUNTS WILL RANGE FROM A HALF AN
INCH TO AN INCH. SOME WESTERLY UPSLOPE SNOW SHOWERS WILL LINGER
ALONG THE SPINE OF THE SRN GREEN MTNS. WEAK UPPER LEVEL RIDGING
BUILDS IN FOR THE AFTERNOON…AND H850 TEMPS WILL ACTUALLY BE NEAR
NORMAL IN THE -6C TO -8C RANGE. MAX TEMPS WILL BE NEAR NORMAL WITH
POSSIBLY A FEW BREAKS OF SUN IN THE AFTERNOON. HIGHS WILL
GENERALLY BE IN THE LOWER TO M30S ACROSS MOST OF THE
REGION…POSSIBLY SOME U30S IN THE MID HUDSON VALLEY…AND MID AND
UPPER 20S OVER THE MTNS.

FRIDAY NIGHT…ANOTHER SRN STREAM SYSTEM MOVES TOWARDS THE MID
ATLANTIC REGION…WITH A NRN STREAM UPPER LEVEL TROUGH APPROACHING
FROM THE GREAT LAKES REGION AND SE ONTARIO. IT APPEARS THESE
SHORT-WAVES WILL NOT PHASE TOGETHER UNTIL NEAR THE DELMARVA
REGION…AS THE LONGWAVE TROUGH TURNS NEGATIVE. SOME LIGHT SNOW
MAY SPREAD INTO THE REGION TOWARDS DAYBREAK. SOME CHC POPS HAVE
BEEN ADDED TO FORECAST. LOWS WILL GENERALLY BE IN THE TEENS AND L20S.

SATURDAY-SATURDAY NIGHT…THE SUBSEQUENT COASTAL WAVE BASED ON THE
GFS/ECMWF/NAM APPEARS IT WILL DEVELOP FAR ENOUGH SOUTH THAT IT
WILL HAVE A MINIMAL IMPACT ON THE REGION. LIGHT SNOW CAN NOT BE
RULED OUT…AND HIGH CHC AND LIKELY POPS WERE ADDED TO THE FCST
AREA FOR SATURDAY. SNOW ACCUMS OF 1 TO 3 INCHES MAY BE POSSIBLE.
THE COASTAL WAVE PASSES WELL EAST OF CAPE COD SATURDAY NIGHT AND
TOWARDS NOVA SCOTIA. SOME LAKE EFFECT AND WESTERLY UPSLOPE SNOW
SHOWERS WILL LINGER AGAIN. AFTER MAX TEMPS IN THE M20S TO L30S…LOWS
WILL FALL BACK INTO THE SINGLE DIGITS AND TEENS /EXCEPT SOME BELOW
ZERO READINGS OVER THE SRN DACKS/…AS A STRONGER SURGE OF COLD
ADVECTION MOVES INTO THE REGION.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/…
THE DEEPENING LOW OVER THE CANADIAN MARITIMES WILL BE FAR ENOUGH
AWAY THAT IT WILL HAVE LITTLE IF ANY IMPACT ON THE FORECAST AREA ON
SUNDAY…BUT A WEAK UPPER LEVEL SYSTEM MAY PRODUCE SOME ISOLATED TO
SCT SNOW SNOW SHOWERS ACROSS AREAS WEST OF THE HUDSON VALLEY ON
SUNDAY. OTHERWISE…HIGH PRESSURE BUILDS IN SUNDAY NIGHT AND MONDAY
WITH FAIR AND DRY BUT VERY COLD WEATHER. HIGHS SUNDAY WILL BE IN THE
MID 20S TO MID 30S. LOWS AROUND ZERO TO AROUND 12 BELOW ZERO SUNDAY
NIGHT. SURFACE WINDS MAY CONTINUE STRONG ENOUGH THROUGH SUNDAY NIGHT
AND EARLY MONDAY MORNING FOR WIND CHILL READINGS TO REACH ADVISORY
LEVELS IN SOME AREAS. HIGHS MONDAY WILL GENERALLY BE IN THE 20S.

A FAST MOVING BUT RELATIVELY MOIST CLIPPER SYSTEM WILL MOVE ACROSS
NY STATE MONDAY NIGHT. HAVE FORECAST LIKELY POPS IN ALL AREAS EXCEPT
THE EXTREME SOUTHERN PART OF THE FORECAST AREA. DESPITE THE SYSTEM
PASSING THROUGH TO THE NORTH OF THE REGION WITH A STRONG SOUTHERLY
FLOW AHEAD OF IT…MODELS GENERALLY SUPPORT SNOW AS THE PCPN TYPE.
LOWS MONDAY NIGHT WILL BE 10 TO 20. THE SYSTEM QUICKLY MOVES OUT
TUESDAY MORNING…BUT CYCLONIC FLOW AROUND IT MAY KEEP SCATTERED
RAIN/SNOW SHOWERS ACROSS THE REGION INTO TUESDAY AFTERNOON. HIGHS
TUESDAY WILL BE IN THE 30S TO LOWER 40S AS THE AIR BEHIND THIS
SYSTEM WILL BE OF PACIFIC ORIGIN.

THE RELATIVELY MILD PACIFIC AIR WILL PERSIST THROUGH THURSDAY WITH
NOTHING MORE THAN A 30 TO 40 PERCENT CHANCE OF MOSTLY RAIN SHOWERS
THURSDAY AS ANOTHER WEAK LOW PRESSURE SYSTEM PASSES BY TO OUR NORTH.
LOWS TUESDAY NIGHT WILL BE IN THE UPPER TEENS TO MID 20S. HIGHS
WEDNESDAY IN THE MID 30S TO LOWER 40S. LOWS WEDNESDAY NIGHT IN THE
20S. HIGHS THURSDAY IN THE UPPER 30S TO MID 40S.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/…
SNOW CONTINUES TO FALL ACROSS THE TERMINALS DUE TO A STRENGTHENING
NOR`EASTER THAT WILL IMPACT THE REGION THROUGH TONIGHT AND INTO
FRIDAY MORNING.

SNOW INTENSITY WILL GENERALLY BE MODERATE TO OCCASIONALLY HEAVY THIS
AFTERNOON…ESPECIALLY FROM KPSF-KPOU. THIS EVENING THERE IS
EXPECTED TO BE AN ADDITIONAL SURGE OF HEAVY SNOWFALL AS THE
NOR`EASTER MOVES NORTHWARD INTO SOUTHERN NEW ENGLAND. FLYING
CONDITIONS ARE EXPECTED TO BE SOLIDLY LIFR/IFR THROUGH THE REST OF
THE AFTERNOON AND MUCH OF THE NIGHT. OCCASIONAL VLIFR VSBYS IN HEAVY
SNOW ARE EXPECTED THIS EVENING ESPECIALLY FROM KALB-KPSF-KPOU AND
POSSIBLY EVEN KGFL. CONDITIONS WILL IMPROVE FROM SOUTH TO NORTH AS
THE STORM PULLS AWAY FROM AROUND 10Z-13Z FRIDAY. VFR CONDITIONS WILL
RETURN BY MID TO LATE FRIDAY MORNING.

NORTHERLY WINDS WILL STRENGTHEN THIS AFTERNOON AND EVENING TO AROUND
10-15 KT WITH GUSTS OF 20-25 KT. WINDS WILL SHIFT TO THE NORTHWEST
TOWARDS DAYBREAK FRIDAY…WITH SPEEDS INCREASING TO 15-20 KT WITH
GUSTS TO 30 KT AT KALB/KPSF FRIDAY MORNING.

OUTLOOK…

FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.
SATURDAY: HIGH OPERATIONAL IMPACT.BREEZY LIKELY SN.
SATURDAY NIGHT: LOW OPERATIONAL IMPACT.BREEZY NO SIG WX.
SUNDAY: NO OPERATIONAL IMPACT. NO SIG WX.
SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
WASHINGTONS BIRTHDAY: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. LIKELY SN.
TUESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA…SN.

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE ANTICIPATED THROUGH THE NEXT FIVE DAYS.

A WIDESPREAD HEAVY SNOWFALL WILL IMPACT THE HYDRO SERVICE AREA
INTO FRIDAY MORNING. SNOWFALL AMOUNTS ARE EXPECTED TO BE HEAVY
ACROSS THE REGION…WITH THE HEAVIEST SNOW FROM THE CAPITAL
DISTRICT…SRN VT…AND NRN CATSKILLS SOUTH AND EAST.

TOTAL LIQUID EQUIVALENT FROM THE STORM SYSTEM WILL RANGE FROM A
WIDESPREAD INCH TO INCH AND AN HALF OVER THE HSA…EXCEPT HALF AN
INCH TO AN INCH OVER THE WRN DACKS AND WRN MOHAWK VALLEY.

ANOTHER DISTURBANCE WILL BRING SOME LIGHT SNOWFALL TO PARTS OF THE
REGION ON SATURDAY WITH LIGHT LAKE EFFECT SNOW SHOWERS SATURDAY
NIGHT INTO SUNDAY.

THE NEXT CHANCE FOR SIGNIFICANT PRECIPITATION LOOKS TO BE MONDAY
NIGHT INTO TUESDAY. THIS LOOKS TO BE INTIALLY A SNOW…POSSIBLY
CHANGING TO A WINTRY MIX EVENT.

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…WINTER STORM WARNING UNTIL 10 AM EST FRIDAY FOR CTZ001-013.
NY…WINTER STORM WARNING UNTIL 10 AM EST FRIDAY FOR NYZ039>043-
047>054-058>061-063>066-082>084.
WINTER STORM WARNING UNTIL NOON EST FRIDAY FOR NYZ032-033-038.
MA…WINTER STORM WARNING UNTIL 10 AM EST FRIDAY FOR MAZ001-025.
VT…WINTER STORM WARNING UNTIL 10 AM EST FRIDAY FOR VTZ013>015.

&&

$$
SYNOPSIS…WASULA
NEAR TERM…WASULA
SHORT TERM…WASULA
LONG TERM…GJM
AVIATION…JPV
HYDROLOGY…HWJIV/WASULA

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