Area Forecast Discussion
Issued by NWS Albany, NY

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000
FXUS61 KALY 212343
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
643 PM EST SUN DEC 21 2014

.SYNOPSIS...
HIGH PRESSURE OVER THE NORTHEAST AND QUEBEC WILL KEEP A MOIST LOW
LEVEL FLOW OVER THE REGION...WITH LOTS OF CLOUDS INTO MID WEEK.
THERE WILL BE SOME SPOTTY PRECIPITATION TONIGHT AND A BETTER CHANCE
FOR LIGHT MIXED PRECIPITATION MONDAY NIGHT AND TUESDAY. WEDNESDAY
A STORM WILL ORGANIZE IN THE TENNESSEE VALLEY AND INTENSIFY RAPIDLY
AS IT MOVES NORTH TO THE OTTAWA VALLEY. IT WILL BRING A PERIOD OF
LOCALLY HEAVY RAIN AND STRONG WINDS WEDNESDAY INTO WEDNESDAY
NIGHT.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
MASSIVE INVERSION FM 925HPA TO 850HPA COMBINED WITH LLVL EASTERLY
FLOW AND WEAK UVM WITH 500HPA TROF OVER RGN WILL INSURE ITS MOSTLY
CLOUDY WITH LOWERING CLOUDS OVERNIGHT.  SOME SPOTTY PCPN PARTICULAR
ON THE EAST FACING SLOPES OF THE LITCHFIELD HILLS/BERKS AND
TACONICS OVERNIGHT IS EXPECTED ALSO. THE REMAINDER OF THE FA WILL
BE DRY WITH MAINLY CLOUDY SKIES OVERNIGHT AND LOWS IN THE MID
TEENS TO MID 20S.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
ON MONDAY...MOSTLY CLOUDY CONDITIONS WILL CONTINUE AS MOISTURE
STARTS TO LIFT NORTHWARD FROM THE MID ATLANTIC REGION ON MONDAY
AHEAD OF A SURFACE LOW LIFTING NORTHEASTWARD ALONG THE EASTERN
SEABOARD. WHILE IT WILL BE DRY...CLOUDS WILL BE FAIRLY WIDESPREAD
WITH HIGHS ON MONDAY IN THE 30S.

ON MONDAY NIGHT MOISTURE STARTS TO OVERSPREAD THE FORECAST AREA AS
THE LOW PRESSURE SYSTEM IS LOCATED OFF THE DELMARVA PENINSULA WITH
A TROUGH OF LOW PRESSURE ALONG THE SOUTHERN NEW ENGLAND COAST.
WEAK ISENTROPIC LIFT IS EXPECTED ACROSS THE FA WITH A PLETHORA OF
PCPN TYPES MONDAY NIGHT ACROSS THE SOUTHERN HALF OF THE FA WITH
MAINLY SNOW ACROSS THE NORTHERN HALF OF THE FA. PCPN SHOULD START
AS SNOW IN ALL AREAS BEFORE THE TRANSITION OCCURS DURING THE
SECOND HALF OF THE NIGHT ACROSS THE SOUTHERN HALF OF THE FA AND
EVENTUALLY THE NORTHERN HALF OF THE FA BY MORNING. PARTIAL THICKNESS
VALUES AND MODEL SOUNDINGS SUPPORT SOME LIGHT FREEZING RAIN AND
SLEET MIXING IN. LOWS MONDAY NIGHT WILL BE TRICKY WITH NOT MUCH
OF A DROP FROM DAYTIME HIGHS ON MONDAY. EXPECT LOWS MONDAY NIGHT
TO BE IN THE MID 20S TO LOWER 30S.

ON TUESDAY...FREEZING RAIN WILL LINGER INTO EARLY TUESDAY MORNING
ACROSS THE NORTHERN HALF OF THE AREA WITH ALL RAIN FROM MID
MORNING TUESDAY ON ACROSS THE FA. HIGHS ON TUESDAY ARE EXPECTED TO
BE IN THE UPPER 30S TO MID 40S.

TUESDAY NIGHT A STORM SYSTEM WILL MOVE INTO THE EASTERN GREAT
LAKES WITH AN INCREASING SOUTHERLY FLOW AHEAD OF IT. AS THE LOW
APPROACHES IT WILL LIFT A WARM FRONT INTO SOUTHERN PENNSYLVANIA
AND THE MID ATLANTIC REGION. IT WILL BE WARM ENOUGH TUESDAY NIGHT
SUCH THAT ALL OF THE PRECIPITATION WHICH WILL BE MAINLY LIGHT WILL
FALL IN THE FORM OF RAIN. EXPECT LOWS TUESDAY NIGHT TO BE IN THE
30S TO LOWER 40S.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE EXTENDED FORECAST LOOKS WET AND MILD TO START FOR CHRISTMAS
EVE...AND THEN BLUSTERY AND COLDER CONDITIONS RETURN FOR CHRISTMAS
INTO THE WEEKEND WITH PERHAPS SOME UNSETTLED WEATHER TO CLOSE THE
HOLIDAY WEEKEND.

AS PREVIOUS DISCUSSIONS HAVE MENTIONED THE PAST SEVERAL DAYS...A
POTENTIAL MULTI-HAZARD EVENT IS POSSIBLE WED INTO THU WITH A STRONG
LOW PRESSURE SYSTEM MOVING WELL WEST OF THE REGION FROM THE TN
VALLEY INTO THE GREAT LAKES REGION AND SE CANADA.  THIS SYSTEM WILL
BRING MILDER WX ACROSS ERN NY AND WRN NEW ENGLAND WITH ABOVE NORMAL
TEMPS...AND A SURGE OF GULF MOISTURE.  ALSO STRONG S TO SW WINDS
AHEAD OF THE DEEPENING AND INTENSIFYING SFC CYCLONE ARE EXPECTED WED
INTO WED PM...AND A BAND OF VERY HEAVY RAINFALL WILL OCCUR WITH THE
PASSAGE OF THE COLD FRONT.  THE ABOVE NORMAL TEMPS COUPLED WITH 1 TO
2 INCHES OF RAINFALL IN 24 HRS OR LESS...AND SNOW MELT COULD PRODUCE
SOME MINOR HYDRO ISSUES.  ALSO THE STRONG GUSTY WINDS AHEAD OF THE
CYCLONE AND ITS ASSOCIATED COLD FRONT...AND IN THE WAKE OF THE FRONT
WITH THE CYCLONE DEEPENING TO 970 HPA OR LOWER OVER WRN QUEBEC COULD
ALLOW FOR SOME STRONG W/NW WINDS ACROSS THE REGION ON CHRISTMAS.

WED-WED NIGHT...INITIAL BURST OF RAINFALL DURING THE DAY ON WED WILL
BE WITH THE ISENTROPIC LIFT ON THE 285/290K SFC.  THE WARM FRONT
SHOULD LIFT QUICKLY NORTH DURING THE AFTERNOON.  AN ANOMALOUS
SOUTHERLY LLJ JET OF 40-60 KTS AT H850 WILL ADVECT IN ANOMALOUS PWAT
VALUES OF 3 TO 5 STD DEVS ABOVE NORMAL ACCORDING TO THE LATEST
GEFS.  THE +V-WIND ANOMALIES /SOUTHERLIES/ ARE 2 TO 3 STD DEVS ABOVE
NORMAL.  THE HEAVIEST RAINFALL LOOKS LIKE IT WILL BE IN THE LATE
AFTERNOON INTO THE OVERNIGHT PERIOD.  H850 TEMPS RISE TO +10C TO
+12C IN THE WARM SECTOR.  THE NARROW COLD FRONT RAINBAND LOOKS LIKE
IT WILL SWING THROUGH ON THE GFS/ECMWF/CAN GGEM BTWN
06Z-12Z/THU...AS THE CYCLONE DEEPENS AND INTENSIFIES AS IT MOVES
N/NE TOWARDS JAMES BAY.  HIGH TEMPS ON CHRISTMAS EVE WILL BE IN THE
MID TO U50S FROM THE CAPITAL REGION SOUTH AND EAST /NEARLY 20
DEGREES ABOVE NORMAL/...AND M40S TO L50S TO THE NORTH AND WEST.  AS
COLDER AIR FILTERS IN WED NIGHT...EXPECT SOME OF THE RAIN TO
TRANSITION TO SNOW OVER THE HIGH PEAKS OF THE SRN DACKS.  PERHAPS AN
INCH OR SO OF WET SNOW IS POSSIBLE.  LOWS CHRISTMAS MORNING WILL BE
IN THE MID TO U30S WEST OF THE HUDSON RIVER VALLEY...AND LOWER TO
MID 40S FROM THE HUDSON RIVER VALLEY EAST.

CHRISTMAS-CHRISTMAS NIGHT...LOW PRESSURE CONTINUES TO DEEPEN OVER
WRN QUEBEC NEAR JAMES BAY.  SIGNIFICANT MSLP PRESSURE RISES WILL BE
OCCURRING OVER THE FCST AREA WITH THE PASSAGE OF A SECONDARY COLD
FRONT AND THE UPPER TROUGH AXIS.  BLUSTERY W/NW WINDS OF 15 TO 30
MPH WITH SOME GUSTS TO 35-45 MPH WILL BE POSSIBLE DUE TO THE DEEPER
MIXING AND A STRONG LOW-LEVEL PRESSURE GRADIENT.  A WIND HEADLINE
MAY BE NEEDED HERE FOR PARTS OF THE FCST AREA.  SOME WESTERLY
UPSLOPE SNOW SHOWERS WILL BE COMMON OVER THE WRN DACKS...AND WRN
GREENS.  HIGHS WILL RANGE FROM THE M30S TO U40S FROM NW TO SE OVER
THE FCST AREA.  THE SNOW SHOWERS WILL TAPER OFF CHRISTMAS NIGHT WITH
SLIGHT TO LOW CHC POPS WEST OF THE TRI CITIES.  LIGHT SNOW ACCUMS
ARE POSSIBLE OVER THE WRN DACKS AND SRN GREENS. LOWS WILL BE IN THE
MID 20S TO L30S.

FRI-SAT...HIGH PRESSURE BRIEFLY RIDGES IN FROM THE SOUTH WITH THE
MID LEVEL FLOW W/SW ALOFT.  A CLIPPER TYPE LOW APPROACHES FROM THE
GREAT LAKES REGION AND SRN ONTARIO ON FRIDAY.  THIS SYSTEM LIFTS
N/NE INTO QUEBEC WITH SOME SCT SNOW SHOWERS AHEAD OF THE BOUNDARY
MAINLY NORTH AND WEST OF THE CAPITAL DISTRICT FRI NIGHT INTO
SATURDAY.  SOME ISOLD RAIN/SNOW SHOWERS MAY GET INTO THE CAPITAL
REGION AND BERKSHIRES DURING THE DAY ON SATURDAY.  HIGH WILL BE IN
THE M30S TO M40S WITH LOWS IN THE MID 20S TO L30S.  HIGHS ON
SATURDAY WILL BE A LITTLE COLDER WITH THE COLD FRONTAL PASSAGE WITH
HIGHS IN THE L30S TO U30S OVER THE HIGHER TERRAIN...AND U30S TO L40S
IN THE VALLEYS.

SATURDAY NIGHT INTO SUNDAY...A MEAN UPPER LEVEL TROUGH SET UP OVER
THE GREAT LAKES REGION...NORTHEAST AND EAST COAST.  THE GFS HAS WEAK
IMPULSES IN THE W/NW CYCLONIC FLOW FOCUSING LAKE EFFECT AND W/NW
UPSLOPE SNOWFALL.  THE ECMWF HAS THE LOW-LEVEL BAROCLINIC ZONE
HANGING CLOSE TO THE COAST.  A COASTAL WAVE MOVES ALONG IT SUNDAY
FOR SOME SNOWFALL FOR MOST OF THE REGION.  A LOT OF UNCERTAINTY
STILL EXISTS...SO A LOW CHC OF SNOWFALL WAS USED FOR THE ENTIRE FCST
AREA ON SUNDAY.  TEMPS LOOK SEASONABLE FOR LATE DECEMBER.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
STRATUS DECK REMAINS TRAPPED UNDER MASSIVE INVERSIONS OVER FCA
WITH LITTLE CHANGE LIKELY THROHGH THE TAF PERIOD.  MAINLY MVFR
CIGS AND VSBY WITH WIDESPREAD HIR TRRN OBSCD. GRADUALLY LOWERING
CIGS OVERNIGHT WITH AREAS OF IFR CONDS DVLPG. WK UVM ASSOC WITH
WK 500 HPA CUT OFF OVER RGN...AND LOW LVL ATLC MOISTURE INFLOW
WILL RESULT IN SCT -SHSN/ISOLD ZL OVER W NEW ENG AND SOUTHERN MOST
AREAS OF NYS. CONDS IN THESE AREAS COULD BCM WIDESPREAD IFR
OVERNIGHT.

ON MONDAY...LINGERING PATCHY -SN AND OR ZL WILL DIMINISH EARLY.
OTRW IFR/MVFR CONDITIONS MAY IMPROVE SLIGHTLY DURING THE DAY

WINDS WILL REMAIN LIGHT...FROM THE N TO NE AT LESS THAN 8 KT THROUGH
THE PERIOD.

OUTLOOK...

MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN...FZRA.
TUESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
TUESDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY RA.
WEDNESDAY: HIGH OPERATIONAL IMPACT. DEFINITE RA.
WEDNESDAY NIGHT: HIGH OPERATIONAL IMPACT.BREEZY DEFINITE SHRA...RA.
CHRISTMAS DAY: MODERATE OPERATIONAL IMPACT.WINDY WITH GUSTS TO 34.0 CHANCE OF SHRA.
THURSDAY NIGHT: LOW OPERATIONAL IMPACT.BREEZY  NO SIG WX.
FRIDAY: NO OPERATIONAL IMPACT.  NO SIG WX.

&&

.HYDROLOGY...
NO HYDROLOGIC ISSUES ARE ANTICIPATED THROUGH TUESDAY NIGHT. A
WIDESPREAD RAINFALL IS EXPECTED WEDNESDAY INTO WEDNESDAY NIGHT AS
A LARGE LOW PRESSURE SYSTEM MOVES ACROSS THE REGION. RAINFALL
AMOUNTS OF 1 TO 2 INCHES ARE LIKELY ALONG WITH SIGNIFICANT
SNOWMELT WHICH RAISES THE POTENTIAL FOR MINOR FLOODING AND
SIGNIFICANT WITHIN BANK RISES OF LARGER STEM RIVERS. MMEFS
GUIDANCE SUGGESTS THE BEST CHANCES FOR MINOR FLOODING WOULD BE
FROM THE HUDSON VALLEY THROUGH WESTERN NEW ENGLAND. IT IS TOO
EARLY TO ISSUE ANY FLOOD WATCHES...HOWEVER WILL MENTION IN THE HWO
AT THIS TIME.

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...NONE.
MA...NONE.
VT...NONE.

&&

$$
SYNOPSIS...SNYDER
NEAR TERM...11
SHORT TERM...11/SNYDER
LONG TERM...WASULA
AVIATION...SNYDER
HYDROLOGY...11/NAS






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