April 20, 2012 Forecast Discussion

000
FXUS61 KALY 201421
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1021 AM EDT FRI APR 20 2012

.SYNOPSIS…
MUCH NEEDED RAINFALL THIS WEEKEND INTO EARLY NEXT WEEK…UNTIL THEN
ANOTHER WARM AND DRY DAY TODAY. A COLD FRONTAL BOUNDARY WILL MOVE
GRADUALLY EASTWARD ACROSS THE AREA SATURDAY. AN AREA OF LOW PRESSURE
WILL APPROACH FROM THE SOUTH ON SUNDAY AND IS EXPECTED TO MOVE INTO
THE REGION ON MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/…
— Changed Discussion —
AS OF 10 AM…QUASI-STATIONARY FRONTAL BOUNDARY WAS DRAPED ACROSS
THE ST LAWRENCE VALLEY WITH A NARROW BAND OF CI/CS ACROSS THE
HUDSON RIVER VALLEY. PER THE 12Z SOUNDING…SEEMS OUR CURRENT HIGH
TEMPERATURE FORECAST IS ON TARGET WITH MAINLY 70S FOR THE
REGION…60S FOR THE HIGHER TERRAIN. SOUTHERN WINDS SHOULD ALSO
INCREASE WITH POTENTIAL FOR SOME FUNNELING ALONG THE HUDSON RIVER
VALLEY BUT PER THE 12Z SOUNDING…MIXING LAYER HEIGHTS TAP INTO
LOWER 20KTS RANGE.

TEMPERATURES WILL FALL WELL SHORT OF THE RECORD HIGHS FOR THE DATE:
ALBANY: 93 DEGREES 1941 (RECORDS DATE BACK TO 1874)
GLENS FALLS: 83 DEGREES 1954 (RECORDS DATE BACK TO 1949)
POUGHKEEPSIE: 86 DEGREES 2005 (RECORDS DATE BACK TO 1949)
— End Changed Discussion —

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/…
— Changed Discussion —
MUCH NEED RAINFALL OVER THE WEEKEND. THE MODELS ARE IN BETTER
AGREEMENT THIS MORNING THAN THE LAST COUPLE…HOWEVER QPF AMOUNTS
CONTINUE TO BE QUITE VARIABLE.

THE FRONTAL BOUNDARY IS EXPECTED TO STALL ALONG THE EAST COAST BY
SATURDAY EVENING. THERE ARE TIMING AND STRENGTHEN DIFFERENCES AS A
STRONG AREA OF LOW PRESSURE MOVES NORTHWARD ALONG THE BOUNDARY
ALONG THE SOUTHEAST COAST INTO THE MID ATLANTIC REGION SATURDAY
NIGHT THROUGH SUNDAY NIGHT. THE GFS ENSEMBLE SPREAD LESSENS AS THE
LOW MOVES INTO THE MID ATLANTIC REGION SUNDAY NIGHT.

SHOWERS WILL BECOME LIKELY ACROSS THE FORECAST AREA ON SATURDAY AS
THE DAY PROGRESSES AND THE BOUNDARY GRADUALLY MOVES THROUGH. DO
HAVE A CHANCE OF THUNDER SATURDAY AFTERNOON INTO EARLY EVENING FOR
THE SCHOHARIE VALLEY…EASTERN CATSKILLS…THE SOUTHERN PORTIONS
OF THE CAPITAL DISTRICT…HUDSON RIVER VALLEY…THE BERKSHIRES AND
LITCHFIELD COUNTY AS MODELS INDICATE INSTABILITY ALONG/AHEAD OF
THE BOUNDARY. HAVE POPS DECREASED TO CHANCE FOR MUCH OF SUNDAY
WITH THE BOUNDARY TO OUR EAST AND THE APPROACHING LOW WELL TO OUR
SOUTH. HOWEVER CHANCES FOR RAIN RAPIDLY INCREASE SUNDAY NIGHT AS
THE LOW APPROACHES AND A STRONG LOW LEVEL MOVES INTO THE REGION.
THERE IS THE CHANCE FOR SOME LIGHT SNOW ACCUMULATIONS LATE SUNDAY
NIGHT INTO EARLY MONDAY MORNING ACROSS A PORTION OF THE SOUTHERN
ADIRONDACKS.

HAVE USED GUIDANCE FROM THE HYDROMETEOROLOGICAL PREDICTION CENTER
FOR THE QPF AMOUNTS. AT THIS TIME LOOKING WIDESPREAD 1 TO 4 INCHES
ACROSS THE FORECAST AREA FROM SATURDAY THROUGH SUNDAY NIGHT.
PRECIPITATION DEFICITS FOR THE YEAR ACROSS EAST CENTRAL NEW YORK
AND WESTERN NEW ENGLAND ARE RUNNING 5 TO 10 INCHES.
— End Changed Discussion —

&&

.LONG TERM /MONDAY THROUGH THURSDAY/…
THE LONG TERM OPENS WITH A COASTAL LOW NEAR NJ AND LONG ISLAND. THE
GFS/ECMWF/CAN GGEM/GEFS MEAN AND HPC GRAPHICS SLIGHTLY DISAGREE ON
THE EXACT POSITION OF THE CYCLONE AT 1200 UTC/MON…BUT THE MAJORITY
HAVE THE ALY FCST AREA IN THE NW QUADRANT OF THE LOW WITH PERIODS OF
MAINLY RAIN WITH A S/SE FETCH OF ATLANTIC MOISTURE. THE GFS/ECMWF
HAVE THE UPPER TROUGH BECOME NEGATIVELY TILTED AND CAPTURE THE LOW
OVER PA AND CNTRL NY BY THE AFTERNOON. THERE COULD BE A DECENT DRY
SLOT THAT WORKS INTO THE REGION BY THE LATE PM/EARLY EVENING. WE
INCREASED POPS TO LIKELY WITH THE STRONG QG FORCING FROM THE LIFT
GENERATED BY THE COASTAL WAVE. THE CLOSED UPPER LEVEL H500
CONTINUES TO SPIN OVER W-CNTRL PA AND NY…AND WE LOWERED POPS TO
CHANCE VALUES BY MONDAY NIGHT. IN THE DAMP AIR MASS…HIGH TEMPS
WILL BE IN THE LOWER TO MID 50S OVER THE VALLEYS…WITH MAINLY 40S
OVER THE MTNS. THERE COULD BE SOME WET SNOW OVER THE SRN
DACKS…AND GREEN MTNS MONDAY MORNING WITH A LIGHT ACCUMULATION.
LOWS MONDAY NIGHT WILL GENERALLY BE IN THE 30S WITH A FEW U20S OVER
THE HIGH PEAKS.

TUESDAY THROUGH WEDNESDAY…THE STACKED SYSTEM CONTINUE TO CHURN
OVER WRN NY AND INTO ONTARIO AND WRN QUEBEC. A BROAD UPPER LEVEL
TROUGH REMAINS OVER THE EAST COAST. MULTIPLE SHORT-WAVES PINWHEEL
AROUND THE CUTOFF WITH CHANCES OF SHOWERS TUESDAY…AND SLIGHT TO
LOW CHANCES TUE NIGHT INTO WEDNESDAY. THE FORMER H500 CUTOFF OPENS
ON WED OVER QUEBEC…AND BEGINS TO LOSE ITS INFLUENCE ON THE
NORTHEAST BY THE MID WEEK WITH IMPROVING CONDITIONS FOR A SHORT
TIME. HIGHS WILL GENERALLY BE IN THE 50S IN THE VALLEYS…AND 40S
OVER THE MTNS BOTH DAYS WITH LOWS GENERALLY IN THE 30S.

WEDNESDAY NIGHT INTO THURSDAY…A QUICK MOVING SYSTEM APPROACHES
FROM THE MIDWEST AND THE LOWER GREAT LAKES REGION WEDNESDAY NIGHT.
THE MEDIUM RANGE DETERMINISTIC AND ENSEMBLE GUIDANCE CONTINUES TO
SHOW A LOT OF SPREAD AND UNCERTAINTY ON THE TIMING OF THIS
FEATURE…AND THE TRACK. THE ECMWF WOULD BRING SOME LIGHT SNOW FROM
ALBANY SOUTH…WED NIGHT/THU MORNING. THE GFS WOULD HAVE DRY WX WITH
HIGH PRESSURE BUILDING IN FROM GEORGIAN BAY THURSDAY MORNING…AND
THIS UPSTREAM SYSTEM DIVING SOUTH OF UPSTATE NY. HPC IS LEANING
TOWARDS A FRONTAL PASSAGE WITH A CLIPPER LIKE LOW MOVING ACROSS SRN
QUEBEC. WE OPTED TO PUT A SLIGHT CHC OF RAIN/SNOW SHOWERS IN THE
GRIDS FOR NOW…AND LEANED TOWARDS A GFS/HPC SCENARIO /A WARMER
SOLUTION/ WITH LOWS IN THE 40-45F RANGE IN THE VALLEYS…AND 30S
OVER THE MTNS/SRN VT. MAX TEMPS ON THU WOULD RANGE FROM 60-65F IN
THE VALLEY LOCATIONS…AND 50S OVER THE MTNS.

OVERALL…TEMPS WILL AVERAGE NEAR NORMAL…WITH PCPN NORMAL TO ABOVE
NORMAL.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/…
— Changed Discussion —
HIGH PRESSURE WILL CONTINUE TO MOVE EAST OF THE GULF OF MAINE
TODAY…AS A COLD FRONT APPROACHING FROM THE SAINT LAWRENCE RIVER
VALLEY WILL BECOME STATIONARY. A WAVE OF LOW PRESSURE MOVING ALONG
THE BOUNDARY FROM THE ERN GREAT LAKES REGION TONIGHT…WILL INCREASE
THE LOW LEVEL MOISTURE OVER THE REGION WITH THE BETTER CHANCE OF
SHOWERS ON SATURDAY.

VFR CONDITIONS ARE EXPECTED AT THE KGFL/KALB/KPOU TAF SITES PRIOR
TO 00Z/SAT. MID AND HIGH CLOUDS WILL INCREASE FROM KALB NORTH
DURING THE DAY. SOME OF THE CIRRUS WILL APPROACH KPOU TOWARDS
00Z/SAT.

THE INCREASE OF LOW-LEVEL MOISTURE IN THE LOW LEVELS COUPLED WITH A
SOUTHERLY FLOW IN THE HUDSON RIVER VALLEY…WILL ALLOW SOME MVFR
STRATUS TO FORM AFTER MIDNIGHT…AND DRIFT UP THE VALLEY. FOR
NOW…WE HAVE FOLLOWED THE NAM/GFS SOUNDING PROFILES WITH CIGS IN
THE 2-2.5 KFT AGL RANGE. CONFIDENCE HAS NOT INCREASED FOR IFR
STRATUS YET. LATER TAF ISSUANCE MAY HAVE TO ADD SOME IFR CIGS
TOWARDS 12Z/SAT.

THE SURFACE WINDS WILL INCREASE TO 10 TO 14 KTS DURING THE LATE
MORNING AND AFTERNOON…WITH GUSTS OF 18 TO 22 KTS. THE STRONGER
GUSTS WILL BE AT KALB DUE TO THE FUNNELING EFFECT UP THE HUDSON
VALLEY. AFTER 00Z/SAT…THE WINDS WILL BE FROM THE SOUTH AT LESS
THAN 10 KTS.

.OUTLOOK…
SAT…MVFR/IFR. -SHRA LIKELY. ISOLD -TSRA FROM KALB SOUTH.
SAT NIGHT…MVFR/IFR. SHRAS LIKELY.
SUN-MON…VFR/MVFR…CHC IFR IN RAIN.
MON NIGHT-TUE…VFR…SLIGHT CHC/CHC -SHRAS.
— End Changed Discussion —

&&

.FIRE WEATHER…
— Changed Discussion —
SO THE METEOROLOGICAL CONDITIONS WILL FALL JUST SHORT OF RED FLAG
CRITERIA TODAY. MINIMUMS RELATIVE HUMIDITY VALUES ARE EXPECTED TO
BE IN THE LOW 30S THIS AFTERNOON. SOUTHERLY WINDS WILL FUNNEL UP
THE HUDSON RIVER VALLEY WITH GUSTS UP TO 25 MPH IN THE GREAT
CAPITAL DISTRICT…SO HAVE CANCELLED THE FIRE WEATHER WATCH.
MINIMUMS RELATIVE HUMIDITY VALUES ARE EXPECTED TO BE MAINLY IN THE
LOW 30S ACROSS THE AREA THIS AFTERNOON. SOUTHERLY WINDS WILL
FUNNEL UP THE HUDSON RIVER VALLEY WITH GUSTS UP TO 25 MPH IN THE
GREATER CAPITAL DISTRICT.

TONIGHT THE RELATIVE HUMIDITY SHOULD RECOVER TO 80 TO NEAR 100
PERCENT RANGE…WITH MINIMUMS VALUES IN THE 40 TO 60 PERCENT RANGE
ON SATURDAY WITH SHOWERS BECOMING LIKELY ACROSS THE AREA AS THE
DAY PROGRESSES.

RAIN PROBABILITIES INCREASE THROUGH THE WEEKEND AND INTO EARLY
NEXT WEEK.
— End Changed Discussion —

&&

.HYDROLOGY…
MUCH NEEDED RAINFALL THIS WEEKEND INTO EARLY NEXT WEEK…UNTIL THEN
ANOTHER WARM AND DRY DAY TODAY. A COLD FRONTAL BOUNDARY WILL MOVE
GRADUALLY EASTWARD ACROSS THE AREA SATURDAY. AN AREA OF LOW PRESSURE
WILL APPROACH FROM THE SOUTH ON SUNDAY AND IS EXPECTED TO MOVE INTO
THE REGION ON MONDAY.

HAVE USED GUIDANCE FROM THE HYDROMETEOROLOGICAL PREDICTION CENTER
FOR THE QPF AMOUNTS. AT THIS TIME LOOKING AT WIDESPREAD 1 TO 4
INCHES ACROSS THE FORECAST AREA FROM SATURDAY THROUGH SUNDAY
NIGHT. EXPECTING THE HIGHEST PRECIPITATION AMOUNTS ACROSS THE
DRIEST AREAS…THE SOUTHERN PORTION THE FORECAST AREA WITH
AMOUNTS DECREASES AS YOU HEAD NORTHWEST ACROSS THE FORECAST AREA.
PRECIPITATION DEFICITS FOR THE YEAR ACROSS EAST CENTRAL NEW YORK
AND WESTERN NEW ENGLAND ARE RUNNING 5 TO 10 INCHES.

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…IAA/BGM
NEAR TERM…IAA/BGM
SHORT TERM…IAA/BGM
LONG TERM…WASULA
AVIATION…WASULA
FIRE WEATHER…IAA/BGM
HYDROLOGY…IAA

FOR THE LATEST UPDATES…PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License