November 16, 2014 Forecast Discussion

000
FXUS61 KALY 161413
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
913 AM EST SUN NOV 16 2014

.SYNOPSIS…
TODAY WILL BE DRY AND CLOUDY. A STORM SYSTEM ORIGINATING IN THE
DEEP SOUTH WILL MOVE NORTHEASTWARD TOWARD THE REGION TONIGHT INTO
MONDAY…CROSSING THE REGION MONDAY AFTERNOON AND NIGHT. THIS
SYSTEM WILL BRING WIDESPREAD PRECIPITATION TO THE AREA LATE
TONIGHT THROUGH MONDAY EVENING. INITIALLY THE PRECIPITATION SHOULD
START OUT AS SNOW…THEN A CHANGEOVER TO MIXED PRECIPITATION AND
EVENTUALLY RAIN IS EXPECTED ACROSS MOST OF THE LOCAL AREA BY MONDAY
AFTERNOON. A CHANGEOVER BACK TO MIXED PRECIPITATION AND SNOW IS
EXPECTED MONDAY NIGHT.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
WIDESPREAD CLOUDS AND SOME FLURRIES ACROSS THE REGION…WITH MORE
SNOW SHOWER TYPE PRECIPITATION WITH POTENTIAL LIGHT ACCUMULATIONS
IN THE SOUTHERN ADIRONDACKS THROUGH THIS AFTERNOON. SO…SOME
MINOR ADJUSTMENTS TO THE FORECAST TO LOWER MAX TEMPERATURES AND
PUT SOME FLURRIES AND SPRINKLES INTO THE FORECAST.

PREV AFD BELOW…

MOISTURE AHEAD OF A PRE-FRONTAL TROUGH HAS CAUSED AN AREA OF SNOW
TO BLOSSOM OVER THE FINGER LAKES REGION WHICH IS TRACKING
NORTHEAST TOWARD THE WESTERN ADIRONDACKS. HAVE THUS UPPED POPS
ACROSS THIS AREA FOR THIS MORNING AND CALLED FOR AN INCH OR SO OF
SNOW ACCUMULATION. OTHERWISE…A RIDGE OF HIGH PRESSURE WILL MOVE
OFF THE EASTERN SEABOARD THIS MORNING SETTING UP A RETURN
SOUTHWESTERLY FLOW OF AIR WHICH WILL BOOST TEMPS SLIGHTLY TODAY
FROM THOSE ON SATURDAY AFTER A CHILLY START THIS MORNING. HIGHS
THIS AFTERNOON ARE EXPECTED TO RANGE FROM THE MID 30S NORTHWEST TO
THE MID 40S SOUTHEAST DESPITE A GREAT DEAL OF CLOUD COVER.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/…
TONIGHT THROUGH MONDAY NIGHT…HAVE ISSUED A WINTER WEATHER
ADVISORY FOR OUR ENTIRE FA FROM 1 AM TONIGHT UNTIL 7 AM TUESDAY
MORNING AS OUR ATTENTION TURNS TO A LOW PRESSURE SYSTEM WHICH
WILL BE LIFTING QUICKLY NORTHEAST FROM THE SOUTHEAST STATES MONDAY
MORNING INTO THE CANADIAN MARITIMES BY TUESDAY MORNING. WHILE THE
FORECAST AREA CAN EXPECT SOME SNOW FROM THIS SYSTEM THE TRACK OF
THE SYSTEM IS NOT IDEAL FOR A HEAVY SNOW EVENT AND IN FACT LOOKS
MORE LIKE A WINTRY MIX WITH THE VARIOUS MODELS INDICATING DOUBLE
LOW PRESSURE SYSTEMS WHICH TRACK BOTH TO OUR NORTHEAST AND
NORTHWEST WHICH WILL PREVENT ANY EXTENSIVE COOL COLUMN FROM
FORMING IN THE ATMOSPHERE. THERE STILL EXISTS CONSIDERABLE MODEL
DISCREPANCIES WITH THE TRACK OF THE SURFACE LOWS…HOWEVER BASED
ON PARTIAL THICKNESS VALUES AND MODEL SOUNDINGS IT IS BECOMING
INCREASINGLY MORE APPARENT THAT SLEET AND FREEZING RAIN WILL BE
PART OF THE EVENT AS WELL…THUS NECESSITATING ISSUANCE OF A
WINTER WEATHER ADVISORY. HAVE GENERALLY GONE CLOSER TO GFS
SOLUTION WHICH PROVIDES ENOUGH COLD AIR TO KEEP NORTHWEST PORTION
OF FA MAINLY SNOW…BUT MISSES THE BENCH MARK OF THE EASTERN TIP
OF LONG ISLAND FOR A HEAVY SNOWFALL ACROSS THE BULK OF THE FA. THE
SREF PROBABILISTIC PCPN TYPE GRAPHICS SHOW MOST AREAS WITH RAIN AT
18Z MONDAY EXCEPT ACROSS FAR NORTHWEST PORTION OF FA IN ADDITION
THEY HINT AT CHANCE POPS FOR FREEZING RAIN ACROSS THE
CATSKILLS…ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. THE GEFS
PLUME DIAGRAM FOR KALB HAS MOST MEMBERS WITH RAINFALL FOR MUCH OF
THE EVENT. IN ADDITION TO THE SPEED AT WHICH THE LOW IS EXPECTED
TO MOVE IT REMAINS A RELATIVELY WEAK SYSTEM WITH A CENTRAL
PRESSURE OF AROUND 998 MB WHEN IT REACHES THE NORTHEAST US.
BASICALLY ALL THE SYSTEM HAS GOING FOR IT IS A SURGE OF MOISTURE
FROM THE GULF AND ATLANTIC WITH ISENTROPIC LIFT OUT AHEAD OF IT.
HAVE GENERALLY GONE WITH STORM TOTAL SNOWFALL AMOUNTS RANGING FROM
LESS THAN A TENTH OF AN INCH ACROSS EXTREME SOUTHEAST LITCHFIELD
COUNTY TO AROUND 4 INCHES ACROSS THE WESTERN ADIRONDACKS AND A
TENTH OR TWO OF ICE ACCRETION IN MOST AREAS. TOTAL QPF AMOUNTS RANGE
FROM AROUND HALF AN INCH NORTHWEST TO AN INCH OR SO IN THE
BERKSHIRES. WITH THE SPEED OF THE SYSTEM…THE BULK OF THE PCPN
WILL FALL DURING MONDAY WITH THE GREATEST SNOW ACCUMULATION DURING
LATE TONIGHT AND MONDAY MORNING. EXPECT LOWS TONIGHT IN THE 20S TO
AROUND 30 WITH HIGHS ON MONDAY IN THE MID 30S TO LOWER 40S AND
LOWS MONDAY NIGHT IN THE 20S.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/…
MUCH OF THE LONG TERM PORTION OF THE FORECAST WILL BE FEATURED BY
WELL BELOW NORMAL TEMPS…AND LAKE EFFECT SNOW POTENTIAL. A SURGE OF
ARCTIC AIR WILL OVERSPREAD THE REGION FROM THE WEST IN THE WAKE OF
MONDAY/S STORM SYSTEM. A TIGHT PRESSURE GRADIENT BETWEEN THE
DEPARTING LOW TO THE NORTH AND EAST…AND HIGH PRESSURE BUILDING IN
FROM THE SOUTHWEST/WEST WILL BRING WINDY CONDITIONS…ALONG WITH
UNSEASONABLY COLD TEMPS. LAKE EFFECT SNOW BANDS DOWNWIND OF LAKE
ONTARIO…AND PERHAPS ERIE WILL BE AFFECTING THE REGION TUE-TUE
NT…BEFORE DIMINISHING WED. ANOTHER CLIPPER TYPE SYSTEM MAY ENHANCE
SNOW SHOWER CHANCES ACROSS NORTHERN AREAS WED NT-THU NT…WITH
ANOTHER POSSIBLE REINFORCING SHALLOW COLD AIR MASS FOLLOWING IN ITS
WAKE FOR LATE FRI INTO SAT.

HERE ARE SOME MORE SPECIFICS…

TUE-TUE NT…AS MENTIONED…COLD AND WINDY…WITH LAKE EFFECT SNOW
POTENTIAL AS H700 TEMPS IN THE -22 TO -26 C RANGE PASS OVER THE
LAKES. MOST MODELS SUGGEST A GENERAL WEST TO WEST/SOUTHWEST LOW
LEVEL WIND TRAJECTORY ACROSS THE LAKES…ALONG WITH PERIODS OF SHEAR
AND AN AFTERNOON SHORTWAVE PASSAGE WHICH COULD OCCASIONALLY DISRUPT
THE BANDS. OUR CSTAR LAKE EFFECT SNOWBAND INLAND EXTENT PROGRAM
SUGGESTS THAT…DESPITE SIGNIFICANT INSTABILITY…THE WIND SHEAR AND
LACK OF AN AMPLE MULTI-LAKE CONNECTION MAY LIMIT THE POTENTIAL FOR
PURE SINGLE LAKE EFFECT SNOWBANDS. HOWEVER…A FAIRLY MOIST LAYER
WITHIN THE H850-H700 LAYER MAY COUNTERACT THIS. SO…SOME MIXED
SIGNALS REGARDING OVERALL INTENSITY AND DURATION OF LAKE EFFECT
SNOWBAND POTENTIAL…BUT AT THIS TIME…IT APPEARS THAT AT THE VERY
LEAST…SOME LAKE EFFECT SNOWBANDS SHOULD EXTEND INTO THE WESTERN
ADIRONDACKS/NORTHERN HERKIMER AND HAMILTON COS/ WHERE LOCALLY HEAVY
SNOWFALL AMTS COULD OCCUR. ADDITIONALLY…GIVEN THE LOW LEVEL
INSTABILITY ACCENTUATED BY THE EXTREME LAKE-H700 TEMP
DIFFERENTIAL…SOME SNOW SHOWERS AND/OR SNOWBANDS COULD FORM OFF
LAKE ERIE AND EXTEND INTO PORTIONS OF THE MOHAWK VALLEY/CAPITAL
REGION AND/OR SARATOGA REGION AND SOUTHERN VT AS WELL…AS SUGGESTED
BY THE 00Z/16 NAM. MAX TEMPS SHOULD ONLY REACH THE TEENS AND 20S
ACROSS HIGHER ELEVATIONS…WITH UPPER 20S TO MID 30S ACROSS VALLEY
REGIONS. TUE NT/WED AM MINS SHOULD FALL INTO THE TEENS TO LOWER 20S
IN MOST VALLEYS…WITH SINGLE DIGITS AND LOWER TEENS ACROSS HIGHER
ELEVATIONS. WIND CHILLS WILL LIKELY FALL INTO THE SINGLE DIGITS AND
TEENS LATE TUE INTO TUE NT…WITH SOME SUBZERO VALUES POSSIBLE
ACROSS PORTIONS OF THE SOUTHERN ADIRONDACKS.

WED-THU…AS THE INITIAL ARCTIC SURGE AND ASSOCIATED MID LEVEL COLD
POOL LIFT NORTHEAST OF THE REGION…A CLIPPER TYPE LOW IS EXPECTED
TO APPROACH FROM THE GREAT LAKES REGION LATE WED OR EARLY THU. A
BRIEF PERIOD OF SHORTWAVE RIDGING MAY ALLOW FOR DECREASED AREAL
COVERAGE OF LAKE EFFECT SNOWSHOWERS LATE WED MORNING.
HOWEVER…ISENTROPIC LIFT ASSOCIATED WITH THE CLIPPER SYSTEM COULD
ALLOW FOR LIGHT SNOW OR SNOW SHOWERS TO REDEVELOP ACROSS PORTIONS OF
THE SOUTHERN ADIRONDACKS LATE WED AFTERNOON INTO EARLY THU. TEMPS
WED SHOULD REACH THE TEENS AND 20S ACROSS HIGHER ELEVATIONS…AND
20S TO LOWER 30S IN VALLEYS. WED NT/THU AM MINS SHOULD FALL INTO THE
TEENS ACROSS HIGHER ELEVATIONS…AND 20S IN VALLEYS. ON THU…SOME
SLIGHTLY MILDER TEMPS MAY OCCUR AS LOW LEVEL WINDS BRIEFLY BACK INTO
THE SOUTHWEST…WITH 35-40 IN VALLEYS…AND 20S TO LOWER 30S ACROSS
HIGHER ELEVATIONS.

THU NT-FRI…MOST MODELS SUGGEST THAT A COLD FRONT ASSOCIATED WITH
THE AFOREMENTIONED CLIPPER SYSTEM MOVES THROUGH THE
REGION…ALLOWING FOR A REINFORCING SURGE OF COLDER AIR FROM THE
NORTHWEST. HOWEVER…THERE ARE SOME SLIGHT TIMING DIFFERENCES
REGARDING THE PASSAGE OF THIS FRONT…AND ALSO IF SOME MID LEVEL
MOISTURE FROM THE SOUTHWEST BECOMES ENTRAINED INTO THE FRONTAL
BOUNDARY AND/OR A WEAK WAVE DEVELOPS ALONG THE FRONT…AS SUGGESTED
BY THE 00Z/16 ECMWF…WHICH WOULD ALLOW FOR PERHAPS A PERIOD OF
LIGHT SNOW OR SNOW SHOWERS TO OCCUR. HAVE INDICATED SLIGHT CHC TO
CHC POPS ACROSS MOST OF THE REGION…HIGHEST ACROSS NORTHERN AREAS
WHERE ADDED LAKE MOISTURE SHOULD ENHANCE SNOW SHOWER CHANCES.
HOWEVER…SHOULD THE ECMWF PROVE CORRECT…THEN SOME OF THE BEST
CHANCES FOR LIGHT SNOW OR SNOW SHOWERS MAY ACTUALLY BE ACROSS
CENTRAL AND SOUTHERN AREAS DURING FRI. OTHERWISE…THU NT/FRI AM
MINS SHOULD FALL INTO THE 20S IN VALLEYS AND TEENS ACROSS HIGHER
ELEVATIONS…WITH FRI MAXES REACHING 35-40 IN VALLEYS…AND 20S TO
LOWER 30S ACROSS HIGHER TERRAIN.

FRI NT-SAT…HIGH PRESSURE SHOULD BUILD INTO THE REGION FROM THE
WEST/SOUTHWEST. THIS SHOULD ALLOW FOR A GENERAL DECREASING TREND IN
SNOW SHOWERS…ALONG WITH SLIGHTLY MODERATING TEMPS.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/…
HIGH PRESSURE WILL SLIDE OFFSHORE TODAY. LOW PRESSURE DEVELOPING
ALONG THE GULF COAST WILL TRACK NORTHEASTWARD TONIGHT AND MONDAY.

VFR CONDITIONS SHOULD PREVAIL THROUGH TODAY…WITH MAINLY JUST MID
LEVEL CLOUDS IN PLACE. A FEW FLURRIES MAY FALL FROM THESE CLOUDS
AT TIMES…ESP LATE THIS MORNING INTO EARLY AFTERNOON…BUT NO
ACCUMULATIONS ARE EXPECTED.

TONIGHT…LIGHT PRECIPITATION WILL OVERSPREAD THE TAF SITES FROM
SOUTH TO NORTH BETWEEN 05Z-09Z/MON. IT SHOULD BEGIN AS SNOW AT
KGFL/KALB/KPSF…AND SLEET AT KPOU. BETWEEN 09Z-
12Z/MON…PRECIPITATION SHOULD MIX WITH AND CHANGE TO A
SLEET/FREEZING RAIN AT KALB AND KPSF…AND PLAIN RAIN AT
KPOU…WHILE REMAINING ALL SNOW AT KGFL. FLIGHT CONDITIONS SHOULD
DROP INTO THE MVFR RANGE AS THE PRECIP DEVELOPS…WITH A
POSSIBILITY OF SOME IFR…ESP IN AREAS WHERE SNOW FALLS. SNOWFALL
ACCUMULATIONS THROUGH 12Z/MON SHOULD GENERALLY REMAIN UNDER ONE
INCH AT KALB AND KPSF…AND 1-2 INCHES AT KGFL. ALSO…A THIN
COATING OF ICE WILL BE POSSIBLE BY 12Z/MON AT KALB/KPSF AND KPOU.

SOUTH WINDS WILL INCREASE FROM THE S TO SW BY MID MORNING TO 8-12
KT…WITH SOME GUSTS REACHING UP TO 20 KT OR SLIGHTLY HIGHER THIS
AFTERNOON AT KALB DUE TO CHANNELING OF WINDS WITHIN THE HUDSON
RIVER VALLEY. WINDS SHOULD DECREASE SLIGHTLY AFTER SUNSET…GENERALLY
REMAINING IN THE 5-10 KT RANGE…AND TO LESS THAN 5 KT AFTER
08Z/MON.

OUTLOOK…
SUN NIGHT: HIGH OPERATIONAL IMPACT. LIKELY SN…SLEET…FZRA LATE.
MON: HIGH OPERATIONAL IMPACT. DEFINITE RA…SN. SLEET POSSIBLE.
MONDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY RA…SN…FZRA…SLEET.
TUESDAY: MODERATE OPERATIONAL IMPACT.BREEZY CHANCE OF SHSN.
TUESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY NIGHT: SLIGHT CHANCE OF SHSN.
THURSDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.

&&

.HYDROLOGY…
NO HYDROLOGIC PROBLEMS ARE EXPECTED INTO THE MIDDLE OF NEXT WEEK.

HOWEVER…A STORM SYSTEM ORIGINATING IN THE DEEP SOUTH WILL MOVE
NORTHEASTWARD TOWARD THE REGION SUNDAY NIGHT INTO MONDAY AND CROSS
THE REGION MONDAY AFTERNOON AND NIGHT. THIS SYSTEM WILL BRING
WIDESPREAD PRECIPITATION TO THE REGION LATE SUNDAY NIGHT THOUGH
MONDAY EVENING. AT THIS TIME…TOTAL QPF IS EXPECTED TO RANGE FROM
AROUND A HALF OF AN INCH UP TO ABOUT AN INCH. INITIALLY THE
PRECIPITATION SHOULD START OUT AS SNOW…AS WARMER AIR MOVES IN A
TRANSITION TO RAIN IS EXPECTED ACROSS MOST OF THE FORECAST AREA BY
AFTERNOON. A SHORT PERIOD OF SLEET AND FREEZING RAIN IS POSSIBLE
IN THE MORNING. A TRANSITION BACK TO SNOW IS EXPECTED MONDAY NIGHT
AS COLDER AIR IS USHERED BACK INTO THE REGION AS THE STORM MOVES
TO OUR NORTHEAST.

LAKE EFFECT SNOWS ARE EXPECTED DOWNWIND OF LAKE ONTARIO AND LAKE
ERIE IN THE WAKE OF THE STORM AS COLDER AIR POURS INTO THE
REGION.

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 WEATHER ADVISORY FROM 1 AM MONDAY TO 7 AM EST TUESDAY
FOR CTZ001-013.
NY…WINTER WEATHER ADVISORY FROM 1 AM MONDAY TO 7 AM EST TUESDAY
FOR NYZ032-033-038>043-047>054-058>061-063>066-082>084.
MA…WINTER WEATHER ADVISORY FROM 1 AM MONDAY TO 7 AM EST TUESDAY
FOR MAZ001-025.
VT…WINTER WEATHER ADVISORY FROM 1 AM MONDAY TO 7 AM EST TUESDAY
FOR VTZ013>015.

&&

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

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