February 4, 2014 Forecast Discussion

000
FXUS61 KALY 042101
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
401 PM EST TUE FEB 4 2014

.SYNOPSIS…
A STORM TRACKING JUST TO OUR SOUTH WILL BRING A SNOWSTORM TO THE
REGION LATE TONIGHT INTO WEDNESDAY. HIGH PRESSURE WITH GENERALLY
DRY BUT COLD WEATHER WILL BUILD IN FOR THE REST OF THE WORK WEEK.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/…
…WINTER STORM WARNING CONTINUES TONIGHT AND TOMORROW…

CLOUDS ARE THICKENING AND LOWERING AND SHOULD LIMIT THE COOLING OF
TEMPERATURES THIS EVENING…BEFORE THE SNOW STARTS OVERNIGHT. LOWS
IN THE 20S…WITH TEENS IN THE NORTH. SNOW SHOULD SPREAD OVER THE
ENTIRE REGION THROUGH THE NIGHT…AND SOME HIGHER ELEVATIONS OF
THE CATSKILLS…HELDERBERGS AND BERKSHIRES COULD SEE UP TO 6
INCHES BY DAYBREAK…WITH 2 OR MORE INCHES IN MANY OTHER AREAS.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/…
…WINTER STORM WARNING CONTINUES TONIGHT AND TOMORROW…

FEW CHANGES TO PREVIOUS THINKING IN TERMS OF THE FORCING
MECHANISMS AND MOISTURE ASSOCIATED WITH THE SYSTEM TOMORROW…
ENDING TOMORROW EVENING. THE STRONG FORCING SHOULD SUPPORT AREAS
OR BANDS OF SNOW WITH AN INCH OF SNOW PER OUR OR MORE AT TIMES.

SOME OF THE FEATURES THAT COULD CONTRIBUTE TO LOCAL EFFECTS
BETWEEN HIGHER TERRAIN AND VALLEYS…ARE EAST WINDS AT 925 HPA OFF
THE BERKSHIRES AND TACONICS POTENTIALLY CAUSING DOWNSLOPE FLOW AND
REDUCED SNOWFALL AMOUNTS IN THE HUDSON VALLEY. SOUTH TO SOUTHWEST
FLOW AT 850 HPA AND HIGHER SHOULD ENHANCE SNOWFALL AMOUNTS IN THE
EASTERN CATSKILLS…BERKSHIRES AND SOUTHERN GREEN MOUNTAINS.

FINALLY…THERE ARE INDICATIONS THAT THE STRONG WARM ADVECION
COULD BRING A PERIOD OF SLEET TO THE MID HUDSON VALLEY AND NW CT.
BASED ON CURRENT SATELLITE…RADAR AND LIGHTNING TRENDS…WILL
HAVE TO WATCH HOW/IF THE CONVECTION IN THE SOUTHERN U.S.
CONTRIBUTES TO DOWNSTREAM UPPER RIDGING…AND AN EVEN MORE
NORTHWARD STORM TRACK…BRING A PERIOD OF SLEET FURTHER NORTH INTO
THE TACONICS AND SOUTHERN BERKSHIRES. WILL LET THE NEXT SET OF
GUIDANCE THIS EVENING DETERMINE OF SLEET NEEDS TO BE ADDED FURTHER
NORTH THAN THE MID HUDSON VALLEY AND NW CT. STILL…EVEN IN AREAS
WHERE A MIX OCCURS…THERE SHOULD BE ENOUGH COMBINED SNOW AND
SLEET FOR A SIGNIFICANT IMPACT TO TRAVEL WITH 4 TO 8 INCHES OF
COMBINED SNOW AND SLEET…MAYBE EVEN A FEW FREEZING RAIN SPRINKLES.

THE REST OF THE REGION…EXPECTING ALL SNOW…SHOULD SEE GENERALLY
8 TO 12 INCHES WITH AROUND 15 INCHES IN SOME HIGHER ELEVATIONS.
SNOW AMOUNTS IN THE SOUTHERN ADIRONDACKS TO LAKE GEORGE AREA COULD
BE MORE IN THE 5 TO 10 OR 6 TO 12 INCH RANGE…NORTH OF THE BEST
FORCING AND MOISTURE…BUT SLIGHTLY HIGHER LIQUID TO SNOW RATIOS.
SNOW INTENSITY SHOULD DECREASE DURING THE AFTERNOON…AND SOME
LINGERING SNOW SHOWER ACTIVITY COULD LINGER INTO THE
EVENING…AMAYBE SOME HUDSON/MOHAWK CONVERGENCE. HIGHS TOMORROW
IN THE 20S TO LOWER 30S.

GRADUAL CLEARING TOMORROW NIGHT…WITH SOME AREAS POSSIBLY NOT
SEEING CLEARING UNTIL TOWARD DAYBREAK. LOWS TOMORROW NIGHT AROUND
10…BUT NEAR ZERO IN THE SOUTHERN ADIRONDACKS. SNOW PACK COULD
HELP TEMPERATURES GET COLDER IF CLEARING OCCURS EARLIER.

LAKE EFFECT SNOW SHOWERS POTENTIALLY EXTEND INTO THE SOUTHERN
ADIRONDACKS THURSDAY INTO FRIDAY…WITH ADDITIONAL LIGHT AMOUNTS.
EVERYWHERE ELSE LOOKS DRY…WITH HIGHS THURSDAY AND FRIDAY IN THE
20S…WITH TEENS IN NORTHERN AREAS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/…
THE POTENTIAL STILL EXISTS FOR ANOTHER SIGNIFICANT WINTER STORM TO
IMPACT THE REGION LATE THIS WEEKEND INTO THE BEGINNING OF NEXT WEEK.

AT THE START OF THE LONG TERM PERIOD…HIGH PRESSURE WILL BE
BUILDING ACROSS THE REGION FRIDAY NIGHT AND FOR MOST OF THE DAY
SATURDAY…BRINGING DRY WEATHER AND PARTLY CLOUDY TO MOSTLY CLOUDY
SKIES. THERE MAY BE SOME LAKE EFFECT SNOW SHOWERS ACROSS EXTREME
NORTHWESTERN PORTIONS OF THE FORECAST AREA LATE FRIDAY NIGHT…AND
HAVE INDICATED SLIGHT CHANCE POPS FOR THIS AREA TO ACCOUNT FOR THIS.

THE FORECAST THEN SHIFTS TO ENERGY TAKING SHAPE ACROSS THE CENTRAL
PORTION OF THE CONUS FRIDAY INTO SATURDAY. A PIECE…OR PIECES OF
POTENT PACIFIC ENERGY WILL BE EJECTING OUT OF THE SOUTHWEST CONUS
AND INTERACTING WITH SOUTHERN STREAM ENERGY. AT THE SAME TIME…THE
CONTINUED UPPER-LEVEL RIDGING ACROSS THE NORTHERN PACIFIC RESULTING
FROM A POSITIVE PNA TELECONNECTION PATTERN WILL ALLOW THE POLAR JET
TO DIVE SOUTHWARDS…INTERACTING WITH THE SOUTHERN STREAM.

WHILE IT IS STILL TOO EARLY TO TELL HOW THIS PACIFIC ENERGY WILL
ULTIMATELY EVOLVE…PV TRACES MAY BE ABLE TO OFFER SOME CLUES.
NEARLY ALL OF THE 12Z LONG RANGE GUIDANCE DEPICTS A NORTHERN STREAM
PV ANOMALY INTERACTING IN SOME WAY WITH A SOUTHERN STREAM PV ANOMALY
AS A SHARP UPPER-LEVEL TROUGH DEVELOPS OVER THE CENTRAL PLAINS.
WHILE THE MODELS ARE IN AGREEMENT WITH THIS UPPER-LEVEL TROUGH
DEVELOPING…WHAT HAPPENS AFTERWORDS CONTINUES TO REMAIN MURKY.

AS THIS UPPER-LEVEL TROUGH MOVES EASTWARD SATURDAY NIGHT…CURRENT
PV TRACES SUGGEST THE POTENTIAL FOR COASTAL LOW DEVELOPMENT IN THE
GULF STREAM AS THE NORTHERN AND SOUTHERN STREAM PV ANOMALIES BEGIN
TO PHASE ACROSS THE MID-TENNESSEE VALLEY INTO A CLASSIC TREBLE CLEF
SIGNATURE. THE 12Z GFS AND SEVERAL OF ITS ENSEMBLE MEMBERS INDICATE
PHASING OF THE PV ANOMALIES…RESULTING IN A MILLER TYPE A EVOLUTION
OF THE COASTAL LOW…AS IT RACES UP THE COAST SUNDAY INTO MONDAY AND
RAPIDLY DEEPENS AS A TROPOPAUSE FOLD UNFOLDS ALOFT. IF THIS SCENARIO
WERE TO OCCUR…ANOTHER SIGNIFICANT SNOWFALL ACROSS THE REGION WOULD
BE LIKELY LATE SUNDAY THROUGH MONDAY.

MEANWHILE…THE 12Z ECMWF/GGEM INDICATES THE SOUTHERN STREAM PV
ANOMALY WILL MOVE SLIGHTLY FASTER THAN ITS NORTHERN STREAM
COUNTERPART…STILL CAUSING SURFACE LOW DEVELOPMENT…BUT A TRACK
THAT MOVES IT OUT TO SEA AS IT FAILS TO GET CAPTURED BY THE
UPPER-LEVEL TROUGH. IF THIS SCENARIO WERE TO PLAY OUT…MUCH IF NOT
ALL OF THE REGION WOULD SEE ONLY LIGHT SNOW ACCOMPANYING THE
UPPER-LEVEL TROUGH PASSAGE.

DUE TO THE LARGE DIFFERENCES AMONGST THE MODEL GUIDANCE…WILL GO
WITH HIGH CHANCE POPS FOR SNOW DURING THE LATE SUNDAY INTO MONDAY
TIMEFRAME…WITH THE ULTIMATE EVOLUTION OF THIS SYSTEM DEPENDING ON
HOW THE NORTHERN AND SOUTHERN STREAM PV ANOMALIES INTERACT ACROSS
THE CENTRAL CONUS…WHICH REMAINS UNCERTAIN AT THIS TIME.

REGARDLESS OF WHICH SCENARIO OCCURS…HIGH PRESSURE WILL BUILD
ACROSS THE REGION FOR THE MIDDLE OF NEXT WEEK RESULTING IN DRY
WEATHER. HIGH TEMPERATURES THROUGHOUT THE LONG TERM PERIOD WILL
GENERALLY RANGE FROM THE TEENS TO UPPER 20S. LOW TEMPERATURES WILL
GENERALLY RANGE FROM NEAR OR SLIGHTLY BELOW ZERO ACROSS THE SOUTHERN
ADIRONDACKS TO SINGLE DIGITS AND TEENS ACROSS THE REST OF THE
FORECAST AREA.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/…
HIGH PRESSURE WILL MOVE EAST OFF THE NEW ENGLAND COAST TONIGHT.
A COMPLEX STORM SYSTEM WILL APPROACH THE OHIO VALLEY AND THE MID
ATLANTIC REGION OVERNIGHT. THE STORM WILL REDEVELOP NEAR THE NJ
COAST TOWARDS DAYBREAK…AND QUICKLY MOVE NORTHEAST OF THE GULF OF
MAINE BY EARLY EVENING.

VFR CONDITIONS WILL CONTINUE PRIOR TO 06Z/WED FOR KALB/KGFL/KPOU/KPSF
WITH CLOUDS THICKENING AND LOWERING. THE WARM ADVECTION SNOWFALL
AHEAD OF THE STORM SYSTEM WILL OVERSPREAD THE REGION FROM THE S/SW
TO THE N/NE BETWEEN 06Z-09Z/WED. CONDITIONS WILL INITIALLY LOWER
TO MVFR/IFR LEVELS. THE SNOW IS EXPECTED TO INCREASE IN INTENSITY
BTWN 09Z-12Z/WED WITH CONDITIONS IN TERMS OF VSBYS/CIGS LOWERING TO
IFR/VLIFR LEVELS. THESE FLIGHT CONDITIONS WILL PERSIST THROUGH MUCH
OF WEDNESDAY MORNING WITH SOME SLEET LIKELY MIXING IN AT KPOU
TOWARDS 14Z/WED.

THE WINDS WILL BE LIGHT AND VARIABLE AT 5 KTS OR LESS THE REST OF
THE AFTERNOON…AND WILL BE CALM EARLY THIS EVENING. THE WINDS ARE
EXPECTED TO VARY FROM THE NORTH TO NORTHEAST AT 7 KTS OR LESS
DURING THE MID TO LATE MORNING.

OUTLOOK…
WEDNESDAY: MODERATE OPERATIONAL IMPACT. SNOW
WEDNESDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHSN.
THURSDAY TO SATURDAY: NO SIG WX. NO OPERATIONAL IMPACT.
SATURDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SN.
SUNDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.

&&

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

OUR REGION WILL HAVE A SNOWSTORM LATE TONIGHT THROUGH WEDNESDAY.

DRY AND COLD WEATHER RETURNS BY THURSDAY AND FRIDAY.

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 FROM MIDNIGHT TONIGHT TO 6 PM EST
WEDNESDAY FOR CTZ001-013.
NY…WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST
WEDNESDAY FOR NYZ032-033-038>043-047>054-058>061-063>066-
082>084.
MA…WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST
WEDNESDAY FOR MAZ001-025.
VT…WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST
WEDNESDAY FOR VTZ013>015.

&&

$$
SYNOPSIS…NAS
NEAR TERM…NAS
SHORT TERM…NAS
LONG TERM…IRL
AVIATION…WASULA
HYDROLOGY…HWJIV/NAS

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