January 20, 2012 Forecast Discussion

000
FXUS61 KALY 201112
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
612 AM EST FRI JAN 20 2012

.SYNOPSIS…
HIGH PRESSURE WILL CREST ACROSS NEW YORK AND NEW ENGLAND INTO THIS
EVENING. WEAK LOW PRESSURE WILL TRACK FROM THE TENNESSEE VALLEY
TONIGHT TO OFF THE NEW JERSEY COAST MIDDAY SATURDAY…RESULTING
IN SOME LIGHT TO MODERATE SNOW ESPECIALLY SOUTH OF ALBANY. HIGH
PRESSURE WILL BUILD INTO THE NORTHEAST AND QUEBEC FOR THE REST OF
THE WEEKEND SLIDING OFFSHORE SUNDAY NIGHT. SUNDAY NIGHT AND MONDAY
IT`S RETURN SOUTHERLY FLOW WILL PUSH MOISTURE AND MILDER AIR INTO
THE REGION AS A POWERFUL STORM MOVES FROM THE UPPER GREAT LAKES TO
NEAR JAMES BAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
MOST OF THE SNOW SHOWER ACTIVITY HAS ENDED SO LET THE WINTER
WEATHER ADVISORY EXPIRE. BASED ON OBSERVATIONS AND TRENDS…A FEW
MINOR ADJUSTMENTS TO TEMPERATURES AND PROBABILITIES OF
PRECIPITATION THROUGH THE DAY…NOT MUCH ELSE.

PREV AFD BELOW…

BAND OF SNOW SHOWERS ASSOCIATED WITH THE COLD FRONT TRACKING THROUGH
EASTERN NY WILL TRACK THROUGH SOUTHERN VT AND THE BERKSHIRES BY 6
AM. THE BAND OF SNOW SHOWERS LOOKS TO TRACK JUST NORTH OF THE MID
HUDSON VALLEY AND NW CT. LAKE EFFECT SNOW BAND NOSING BARELY INTO
THE WESTERN MOHAWK VALLEY AND SOUTHWESTERN ADIRONDACKS…WILL
DIMINISH IN COVERAGE THROUGH THE MORNING…BUT WILL CONTINUE THE
ADVISORY UNTIL THE BAND GETS DISRUPTED LATER THIS MORNING. ANY
ADDITIONAL SNOW WOULD BE LESS THAN AN INCH. CLEARING WILL TAKE PLACE
THROUGH THE MORNING AND WINDS FROM THE NORTHWEST WILL PICK UP. DEEP
COLD ADVECTION WILL TAKE PLACE THROUGH THE DAY. TEMPERATURES WILL
NOT RISE MUCH FROM MORNING LOWS…AND WILL LIKELY REMAIN NEARLY
STEADY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/…
GEM/GFS/NAM FAIRLY CONSISTENT WITH CURRENT FCST THINKING WITH
NEXT SYSTEM. WEAK AND OPEN SFC WAVE MOVES NE FM TN VLY TO NJ COAST
MIDDAY SAT…WITH PERIOD OF ISENTROPIC LIFT PRODUCED PCPN WITH
ONSET JUST PRIOR TO DAYBREAK SAT AND ENDING EARLY EVENING ACROSS
FCA.

GEM/GFS/NAM PRODUCE QPF AMOUNTS FM TRACE/0.10 NORTH TO 0.3 TO 0.45
SOUTH. LATEST SREF PLUMES (21UTC) RANGE FROM NOTHING AT ALB TO 0.6
LIQ. OOUTC GEFS ARE FAIRLY TIGHT AT 0.1 TO 0.2. WILL GET THE
BLENDER TOOL OUT…BLEND ALL 3 MODELS WITH CURRENT QPF FCST. GIVEN
H850 TEMPS NEVER GET MUCH ABE -6 TO -14C WHICH WILL FAVOR MORE
FLUFFIER TYPES OF ICE CRYSTAL FORMATION SNOW:LIQ RATIOS OF 13-14
NORTH AND 11-12 SOUTH AS USED PVSLY LOOK GOOD.

ONLY MODEST CHANGES FM CURRENT FCST. BY MID AFTN SAT SFC LOW WILL
BE WELL OFF NJ…WAA/ISENTROPIC LIFT WILL ABRUPTLY END AND 500HPA
TROF WILL BE EXITING RGN. CLEARING WILL COME IN QUICKLY AS SFC
HIGH BUILDS INTO E GRTLKS. WITH CLEARING AND FRESH SNOW SHOULD BE
A CHILLY NIGHT.

AS 500HA RIDGE SHARPENS ALONG THE E SEABOARD HIGH PRESSURE WILL
SHIFT NE REST OF WEEKEND…WITH SOME PATCHY MID LEVEL WAA CLOUDS
LATE SAT EARLY SUN NORTH.

ONCE THE SFC HIGH IS OFFSHORE SUN NT WAA WILL TAKE HOLD. WEAK
COASTAL FRONT COULD SET UP FM ACK-ACY-HAT. WITH INCRG SE INFLOW
MOISTURE WILL INCR..LOW CLOUDS WILL SPREAD IN WITH SPOTTY
PCPN..MAINLY DZ AT FIRST. SUNDAY NIGHT TEMPS WILL HOLD STEADY OR
RISE. BULK OF PCPN WILL BE RN BUT MAY START AS LT WINTRY MIX. NEW
PLUMES DIMINISH THIS TREAT FM PVS RUNS. TIMING OF CLOUDS AND
MIXING WILL BE KEY IN THIS TIMING.

MONDAY WILL BE A WINDY MILD DAY AS RAPIDLY DEEPENING STORM MOVES
NE FM UPR GRTLKS INTO W QB. SCT -SHRA TILL FRONT MOVES THROUGH WITH
KATA TYPE CDFNT SHARP CONVECTIVE LINE BACKED BY STRONG 500HPA
SHORT WV.

THIS SYSTEM IS OFFSHORE BY EVENING WITH STRONG CAA AND 500HPA
TROF OVER RGN.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/…
GFS/ECMWF IN REASONABLE AGREEMENT DURING THE FIRST 2 DAYS.
ALTERNATING FAST 500HPA FLOW PATTERN CONTINUES DURING THIS PERIOD.
TUESDAY 500HPA TROF AND SECONDARY CDFNT MOVE THROUGH THE NE USA.
WITH EMBEDDED SHORT WAVE AND CAA IN ITS WAKE…VRBL CLOUDS AND
SOME LAKE RES PONCE…PARTICULARLY N.

BY WED 500HPA RIDGE HAS REBUILT ALONG EASTERN SEABOARD WITH A LARGE
SFC HIGH OVER THE EAST. THIS BREAKS DOWN THURSDAY AS 500HPA TROF
BUCKLES IN FLOW OVER MID WEST. SOUTHERN STREAM MOISTURE REMAINS FM
NJ TO TX WITH CUTOFF OVER TX THREATENING TO EJECT. FOR NOW THE
ECMWF SUGGESTS A MAINLY WEAK N STREAM SYSTEM INCR CLOUDS THU AND
RAISES CHC POPS FOR -SHSN. THE GFS 6 DAYS OUT PHASES THESE
BRANCHES WITH ANOTHER POWERFUL STORM LIFTING NE THROUGH THE MID
WEST TO END THE PERIOD WITH MAINLY RN.

DURING WHAT SHOULD BE THE COLDEST WEEK OF THE YEAR BASED ON
CLIMO…TEMPS WILL BE NEAR OR A FEW DEGREES ABV NORMAL. WHILE
TUESDAY WILL BE BREEZY AND CHILLY THE REST OF THE PERIOD WINDS
WILL BE RATHER LIGHT.

&&

.AVIATION /11Z FRIDAY THROUGH TUESDAY/…
COLD FRONT NOW CROSSING CENTRAL NY…AND A BAND OF SNOW SHOWERS WILL
TRACK ACROSS KALB AND KGFL TROUGH ABOUT 07Z WITH A BRIEF PERIOD OF
IFR POSSIBLE. THE MAIN BAND SHOULD TRACK JUST NORTH OF KPOU…BUT
ACKNOWLEDGING VCSH THERE. VFR CEILINGS AND VISIBILITIES SHOULD
PREVAIL THE REST OF THE MORNING AND THE REST OF THE TAF PERIOD INTO
EVENING.

SOUTH WINDS AT 10 KT OR LESS WILL BECOME NORTHWEST AROUND 10 KT BY
AROUND 09Z WHEN THE FRONT TRACKS THROUGH. THERE COULD BE SOME
INITIAL GUSTS AT KALB…BUT FOR SUCH A BRIEF TIME…JUST PUTTING
TEMPO FOR GUSTS FOR A FEW HOURS. ONCE DAYTIME MIXING
OCCURS…AFTER ABOUT 15Z…NORTHWEST WINDS WILL STRENGTHEN TO
AROUND 10 KT WITH SOME GUSTS NEAR 20 KT AT KALB. WINDS WILL
DIMINISH TO LIGHT DURING THE EVENING.

OUTLOOK…
FRI NIGHT-SAT…IFR/MVFR. -SN LIKELY.
SUN…VFR…NO SIG WX.
SUN NIGHT-MON…MVFR/IFR. CHC -RA/-SN/-PL/-FZRA.
TUE…VFR. NO SIG WX.

&&

.HYDROLOGY…
NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH
NEXT THURSDAY. ANY PRECIPITATION WHICH FALLS THROUGH THE WEEKEND
WILL BE SNOW. MONDAY MAY BRING SOME LIGHT MIXED PRECIPITATION
EARLY AND 0.25 TO 0.50 OF RAIN SHOWERS DURING THE AFTERNOON.

ICE FORMATION ON BODIES OF WATER IS EXPECTED TO INCREASE AGAIN
THROUGH THE WEEKEND AS COLD AIR WILL BE IN PLACE ACROSS THE
REGION. TEMPS WILL BEGIN RISING LATE SUNDAY AND MONDAY…ONLY
COOLING TO NEAR OR SLIGHTLY ABOVE NORMALS NEXT WEEK.

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…NAS

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