FXUS61 KALY 270524
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1225 AM EST FRI NOV 27 2009
.SYNOPSIS...
A COMPLEX STORM SYSTEM WILL IMPACT THE NORTHEAST TONIGHT
INTO SATURDAY WITH UNSETTLED WEATHER INCLUDING RAIN...AND SOME
SNOW...ESPECIALLY ACROSS THE HIGHER ELEVATIONS...AND BLUSTERY WINDS.
THE STORM WILL MOVE INTO THE CANADIAN MARITIMES SATURDAY NIGHT INTO
SUNDAY...WITH HIGH PRESSURE BUILDING IN FROM THE SOUTHEAST WITH
DIMINISHING WINDS AND TRANQUIL WEATHER.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A QUICK UPDATE AS TEMPERATURES IN THE HUDSON VALLEY HAVE DROPPED
THRU THE OVERNIGHT LOWS. THEREFORE HAVE UPDATED THE LAST HOUR OR
TWO AND FLATLINED THEM FOR THE REST OF THE NITE AS THE TEMPS WERE
ON OR ONLY ONE DEGREE OFF THE DEWPOINTS AND MANY SITES IN THE
HUDSON VALLEY HAVE HAD SOME OFF AND ON FOG.
AFTER A PLEASANT THANKSGIVING DAY...LOOKS LIKE THINGS WILL
DETERIORATE TONIGHT AS LATEST RADAR IMAGES SHOW PRECIP WAS SLOWLY
EDGING ITS WAY INTO THE MOHAWK VALLEY. ALSO...WITH THE CLEAR SKIES
IN THE HUDSON VALLEY...TEMPERATURES HAVE PLUNGED TO THE MID 30S IN
THE HUDSON VALLEY FROM GLENS FALLS TO POUGHKEEPSIE. A NUMBER OF
NON-METAR SITES ACROSS OUR FORECAST AREA WERE IN THE UPPER 30S AS
WELL. THE RUC-13 HAD A REASONABLY GOOD HANDLE...AT LEAST FOR STARTERS
...ON THE TEMPERATURE AND TRENDS BUT EVEN IT WAS TOO WARM FOR ALBANY
AND POUGHKEEPSIE...SO DID ANOTHER UPDATE TO THE GRIDS FOR THE
OVERNIGHT PERIOD. HAVE ALSO INCREASED THE POP FROM LIKELY TO
CATEGORICAL OVER THE ADIRONDACKS FOR TONIGHT BASED ON RADAR
TRENDS AND FOR CONSISTENCY. THE COOLER TEMPS THUS SEGWAY INTO P-TYPE
ISSUES AND HAVE UPDATED WX/SNOW GRIDS USING MOSTLY THE RAIN/SNOW/SFC
TOOL WITH A VERY CONSERVATIVE 32 FOR ALL SNOW AND 36 FOR UPPER END
OF MIX...AND A FAIRLY DENSE (7 AND 8 TO 1) SNOW RATIO. THESE GIVE
THE ADIRONDACKS UP TO AN INCH OVERNIGHT...AND UP TO ANOTHER INCH FOR
FRIDAY MORNING BEFORE THINGS WARM UP ENOUGH TO MIX AND THEN TURN IT
BACK TO RAIN. A QUICK LOOK AT THE 00Z ALY OBSERVED SOUNDING SHOWS
BOTH A TEMPERATURE INVERSION AND DRYING AROUND 760 HPA...WITH A NEAR
ADIABATIC LAPSE RATE DOWN TO 920 HPA...THEN NEARLY ISOTHERMAL TO THE
SURFACE AT THE TIME OF LAUNCH. SINCE THEN IT HAS COOLED HERE TO 39.
IT LOOKS LIKE THINGS MAY BE COOL ENOUGH ALOFT AT LEAST ATTM TO NOT
HAVE TO WORRY ABOUT FZRA ISSUES...BUT WILL MAY TO TAKE ANOTHER LOOK
AT THIS LATER THIS EVE OR TONIGHT. WE ARE LOOKING AT LOWS AT 32 IN A
NUMBER OF SPOTS IN THE ADIRONDACKS...AND 33 TO 36 DEGREES ACROSS
MUCH OF THE ADIRONDACKS...CATSKILLS...AND HIGHER ELEVS OF SOUTHERN
VT. WE STILL HAVE POPS GOING TO CATEGORICAL ACROSS THE ENTIRE REGION
BY MIDNIGHT. SNOW AMTS UP TO 1 INCH ARE MOSTLY ACROSS HAMILTON AND
NORTHEASTERN HERKIMER CO...ALONG WITH A VERY SMALL AREA IN GREENE
CO...WITH LIGHT DUSTING AMTS POSSIBLE OVER THE REST OF THE
ADIRONDACKS AND NORTHERN CATSKILLS INCLUDING THE HILLTOWN AREA OF
EASTERN SCHOHARIE/WESTERN ALBANY COUNTIES.
PREVIOUS NEAR TERM DISCUSSION...ISSUED AT 430 PM...FOLLOWS.
HAPPY THANKSGIVING TO ALL...WITH MILD WEATHER AND EVEN SOME SUN
ACROSS THE FCST AREA LATE THIS AFTERNOON WITH WEAK HIGH PRESSURE
MOVING OFF THE MAINE COAST. THE WATER VAPOR LOOP WITH H500 HEIGHTS
OVERLAYED FROM THE NAM80 DEPICTS A PROGRESSIVE UPPER LEVEL TROUGH
OVER THE MS RIVER VALLEY...AND EAST OF THE ROCKIES. SHORT WAVE
ENERGY IS MOVING THROUGH THE BASE OF TROUGH WITH A COASTAL/OCEAN
LOW FORMING OFF THE MID ATLANTIC COAST. THE CLOSED/CUTOFF LOW TO
THE HIGH AMPLITUDE LONGWAVE TROUGH IS MOVING ACROSS MI. THE UPPER
TROUGH WILL BECOME NEGATIVELY TILTED OVER THE NEXT 12 HOURS OR SO
...AND WILL TRY TO CAPTURE THE COASTAL LOW.
THE PHASING BETWEEN THE UPSTREAM SHORT WAVE ENERGY AND THE COASTAL
LOW APPEARS IT WILL OCCUR A LITTLE TOO LATE WITH THE LATEST TRENDS
OF THE DETERMINISTIC MODELS AND THE ENSEMBLES TO IMPACT THE FCST
WITH HVY PCPN /RAIN AND SNOW/...AS THE WARM CONVEYOR BELT WILL BE
CUTOFF...WITH ERN NEW ENGLAND IMPACTED THE MOST IN TERMS OF QPF.
HOWEVER...A VERY INTENSE CYCLONE WILL MATERIALIZE BY FRIDAY
AFTERNOON IN THE GULF OF MAINE. STRONG GUSTY WINDS MAY BECOME
PROBLEMATIC FRI NIGHT INTO SATURDAY...WHICH WILL BE DISCUSSED IN
MORE DETAIL IN THE SHORT TERM.
OVERNIGHT...SOME -RA WILL MOVE IN FROM THE SOUTH AND WEST DUE TO
THE UPPER LOW APPROACHING FROM THE WEST. THE CYCLONIC VORTICITY
ADVECTION AND WEAK ISENTROPIC LIFT WILL FOCUS THE LIGHT RAIN. SOME
MOISTURE WILL ALSO BE CREEPING UP FROM THE COASTAL WAVE. WE MAY
END UP IN THE VOID OR NULL ZONE FOR A WHILE...IN TERMS OF THE PCPN
EVOLVING. WE INCREASED THE POPS TO CATEGORICAL VALUES AFTER
MIDNIGHT. MIN TEMPS WILL BE OF THE WET BULB VARIETY WITH MINS IN
THE MID 30S TO L40S.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
TOMORROW...RAPID CYCLOGENESIS OCCURS WITH THE COASTAL LOW PASSING
EAST OF CAPE COD AND INTO THE GULF OF MAINE. THE LOW DEEPENS AND
INTENSIFIES TO 975-980 HPA. MOST OF THE FCST AREA GETS INTO THE
STRONG DEFORMATION ZONE OF THE CYCLONE. THE H850 TEMPS COOL DOWN
BELOW ZERO QUICKLY IN THE MORNING...BUT IT IS UNCERTAIN HOW COLD
THE BOUNDARY LAYER TEMPS WILL GET. WE ARE EXPECTING SOME WET SNOW
OVER THE ADIRONDACKS PRIOR TO NOONTIME DUE TO THE STRONG
DYNAMICAL LIFT...AND LATENT HEAT OF FUSION /MELTING EFFECTS COOLING
DOWN THE COLUMN DUE TO THE MODERATE TO HVY PCPN/. HOWEVER...THIS
WILL LIKELY AMOUNT TO AN INCH OR TWO. ELSEWHERE...WE ARE
EXPECTING PERIODS OF RAIN FOCUSED BY THE LOW-MID LEVEL DEFORMATION
ZONE. THE H850-700 PARTIAL THICKNESSES ARE BELOW 1540 METERS
DURING THE DAY...BUT THE 1000-850 VALUES ARE STILL ABOVE 1310
METERS. THEREFORE...THE PREDOMINANT PTYPE DURING THE DAY WILL BE
RAIN. WE FOLLOWED A GFS/GEFS/ECMWF SCENARIO HERE AND THROUGHOUT.
THE QPF IS MUCH LOWER WITH A DRY SLOT IMPACTING THE HUDSON RIVER
VALLEY VIA THE GFS/NAM.
THE WINDS WILL SHIFT TO THE W/NW DURING THE AFTERNOON AND WILL
INCREASE BY THE EARLY EVENING...AS THE LOW LEVEL HORIZONTAL
PRESSURE GRADIENT INCREASES BETWEEN THE CYCLONE...AND HIGH
PRESSURE NEAR THE LOWER MS RIVER VALLEY. THE PCPN WILL START TO
TRANSITION TO SNOW AT ALL LOCATIONS AT 1500 FT AGL AND GREATER BY
00Z. TEMPS WILL SLIGHTLY FALL...OR BE STEADY THROUGHOUT THE
DAY...WITH PEAK READINGS IN THE M30S TO M40S.
FRIDAY NIGHT...WE HAVE WAITED TO ISSUE A POSSIBLE WIND ADVISORY
HERE...SINCE THEY ARE NOT ISSUED BEYOND THE FIRST TWO PERIODS.
THANKS FOR THE COLLABORATION WITH THE NEIGHBORING OFFICES. THE LOW
LEVEL WIND FIELDS STRENGTHEN WITH H925 WINDS VIA THE GFS OF 35-45
KTS. THE NAM IS A LITTLE WEAKER WITH 30-40 KTS. THE H850 WINDS ARE
45-60 KTS AS THE LOW BEGINS TO OCCLUDE NEAR THE MAINE COAST. THE
BEST MOMENTUM TRANSFER AT NIGHT OFF THE GFS/NAM BUFKIT SOUNDINGS
WOULD BE 35-40 KTS FROM 2.5 KFT AGL. FOR NOW...WE HAVE GUSTS
MENTIONED TO 39 KTS /45 MPH/ JUST SHY OF MARGINAL WIND ADVISORY
CRITERIA. THE SITUATION IS SOMEWHAT SIMILAR TO CASES IN THE
CURRENT COOL SEASON HIGH WIND STUDY IN CSTAR...BUT THE SYSTEM
LOCATION...AND MORE IMPORTANTLY THE TIMING OF THE MIXING OF THE
STRONG WINDS TO SFC IS NOT IDEAL.
IN TERMS OF THE SNOWFALL...WE CONCUR WITH THE HPC GRAPHICS...AND
HAVE 1-3 INCHES OCCURRING OVER THE SRN ADIRONDACKS...SRN
GREENS...AND BERKSHIRES OVERNIGHT.
AN INCH OR SO OVER THE HELDERBERGS...ERN CATSKILLS...AND TACONICS.
THE CAPITAL REGION...LAKE GEORGE REGION...MOHAWK RIVER
VALLEY...MAY RECEIVE A COATING TO POSSIBLY AN INCH. TOTAL SNOW
ACCUMULATIONS OVER THE SRN GREENS AND DACKS WILL BE IN THE 2-4
INCH RANGE.
SATURDAY...WIND WILL BE THE MAIN CONCERN. BLUSTERY CONDITIONS WILL
CONTINUE...AND BETTER MIXING MAY OCCUR FROM 2-3 KFT AGL...WITH WIND
GUSTS MARGINALLY APPROACHING ADVISORY CRITERIA OF 46-57 MPH. THE
WIND FIELDS START TO WEAKEN BY 18Z WITH THE STACKED OCCLUDED
CYCLONE MEANDERING OVER THE GULF OF ST LAWRENCE. THE BETTER CHANCE
OF VERY STRONG WINDS MAY BE EAST OF THE REGION OVER ERN NEW
ENGLAND. SCT UPSLOPE SNOW SHOWERS WILL LIKELY CONTINUE THROUGH THE
MORNING AND DIMINISH BY THE AFTERNOON WITH THE LOW-LEVEL FLOW MORE
NW...AND THE H500 CIRCULATION WELL NE OF THE REGION. IT WILL BE A
CHILLY DAY WITH MAX TEMPS IN THE MID 30S TO L40S IN THE MTNS...AND
L40S TO MID40S IN THE VALLEYS.
SATURDAY NIGHT INTO SUNDAY...HIGH PRESSURE WILL NUDGE IN FROM THE
SOUTHEAST WITH THE MID LEVEL FLOW BECOMING FLATTER AND ZONAL AHEAD
OF THE NEXT WEAK DISTURBANCE APPROACHING FROM THE GREAT LAKES
REGION. WE DON/T SEE ANY LAKE EFFECT ISSUES SATURDAY NIGHT...AND
HAVE GONE WITH A RELATIVELY DRY FCST DURING THIS TIME FRAME WITH
JUST A SLIGHT CHANCE OF A SNOW SHOWER OR FLURRY WELL WEST OF THE
HUDSON RIVER VALLEY SAT NIGHT...AND A SLIGHT CHANCE OF SHOWERS ON
SUNDAY WITH AN APPROACHING TROUGH OF LOW PRESSURE...AND A COLD
FRONT. TEMPS MODERATE ABOVE NORMAL TO CLOSE THE HOLIDAY WEEKEND
WITH HIGHS 5-10 DEGREES ABOVE NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
MOS AND ECMWF IN CLOSE AGREEMENT CONCERNING THE FIRST SYSTEM...SO
WENT WITH MOS GUIDANCE. A COLD FRONT BRINGS GOOD CHANCE POPS FOR
THE START OF THE WORK WEEK. PRECIP WILL LIKELY BE MOSTLY RAIN IN
THE VALLEYS AND SOUTHERN LOCATIONS...WITH A MIX OF RAIN OR SNOW
SHOWERS ELSEWHERE. MAXIMUM TEMPERATURES ARE LIMITED BY CLOUD COVER
AHEAD OF THE FRONT...WITH HIGH READINGS EXPECTED TO BE IN ONLY THE
30S IN THE HIGHEST PEAKS...WHERE THE ONSET OF PRECIP WILL ONLY SERVE
TO COOL THE COLUMN OF AIR. THE FRONT PULLS THROUGH LATE MONDAY...
BUT WE KEEP CHC POPS GOING AS A WESTERLY WIND FLOW BEHIND THE FRONT
MAY RESULT IN SOME LAKE-ENHANCED SHOWERS...THOUGH NOTHING OF GREAT
CONSEQUENCE.
AS WINDS QUIET DOWN...POPS MAX OUT AT SLGT CHC FROM TUE NGT INTO WED
NGT. WE WILL HAVE THE GREATEST CHANCE OF SEEING THE STARS TUE
NGT...BUT THEN HIGH CLOUDINESS LIFTS IN AHEAD OF LOW PRESSURE
FORMING OVER THE DEEP SOUTH...EVEN AS WE SIT UNDER AN AREA OF HIGH
PRESSURE. HOWEVER...WHILE SCANT SUNSHINE MEANS LIMITED WARMING ON
WEDNESDAY... THE LACK OF A SOURCE OF COLD AIR MEANS THE POTENTIAL
FOR JUST ANOTHER MIXED EVENT ON THURSDAY AS THIS LOW REACHES THE
MID-ATLANTIC REGION. WHILE BOTH THE GFS AND ECMWF DIFFER IN THE
STORM TRACK /ECMWF KEEPS IT WELL INLAND/ AND TEMPERATURE ASPECT WITH
THIS SYSTEM...HPC SENDS THE LOW OUT TO SEA WELL TO OUR SOUTH...
WHICH...IF ANYTHING...WOULD APPEAR TO LEAN TOWARD THE COLDER
SOLUTION OF THE GFS...WHICH...AGAIN...WOULD BE ONLY COLD ENOUGH TO
GIVE US A MIXED SCENARIO...INSTEAD OF RAIN. THUS...GMOS REPRESENTS
THE BEST COMPROMISE AT THIS TIME.
HIGH TEMPERATURES WON'T SHOW TOO MUCH DAY-TO-DAY VARIATION. TUESDAY
WILL BE SLIGHTLY THE COLDEST DAY...FRESH BEHIND THE COLD FRONT.
BOTH HIGHS AND LOWS WILL AVERAGE VERY CLOSE TO NORMAL. LOW TEMPS
WILL BE SUB-FREEZING EVERYWHERE FROM TUESDAY NIGHT ON...WITH SOME
UPPER TEENS POSSIBLE ON THE MOUNTAINTOPS.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
IFR CONDITIONS THIS MORNING...ESPECIALLY RIGHT ALONG THE HUDSON
RIVER WHERE IDEAL RADIATIONAL FOG HAS RESULTED IN 1/4SM VIS WHICH
WILL CONTINUE FOR THE NEXT FEW HOURS. AS SEEN ON THE RADAR
MOSAIC...REFLECTIVITIES COVERAGE REMAINS OVER CENTRAL NY AND
ADDITIONAL SHOWER ACTIVITY COMING NORTHWARD FROM LONG ISLAND INTO
SOUTHERN NEW ENGLAND. AS THIS STORM EVOLVES OFF THE MID ATLANTIC
COAST...PRECIPITATION WILL INCREASE IN COVERAGE THROUGH THIS FRIDAY
MORNING KEEPING MVFR/IFR CONDITIONS WHICH SHOULD BE MAINLY FROM
CIGS.
WINDS WILL BECOME MORE PROBLEMATIC LATE TODAY INTO TONIGHT WITH AN
INCREASED WEST-NORTHWEST WIND FLOW. WILL INTRODUCE LLWS TONIGHT
WITH SFC WIND GUSTS BETWEEN 20-30 KTS TO START.
OUTLOOK...
FRI OVNGT-SAT NGT...MVFR/IFR...-SHRA CHG TO -SHSNRA. LLWS. WINDY.
SUN...VFR. NO SIG WX.
MON...MVFR/IFR. -RA/-SN.
TUE...VFR/MVFR. CHC -SHRA/-SHSN.
&&
.HYDROLOGY...
A STRONG STORM SYSTEM FORECAST TO DEVELOP ACROSS EASTERN NEW
ENGLAND...WILL BRING PRECIPITATION TO THE REGION FROM LATE TONIGHT
THROUGH SATURDAY MORNING. THERE IS STILL SOME UNCERTAINTY WITH
REGARDS TO THE EVOLUTION OF THE STORM AND ASSOCIATED QPF. MODELS
HAVE COME INTO SOMEWHAT BETTER AGREEMENT. FORECAST QPF AMOUNTS
EXPECTED TO RANGE FROM ONE QUARTER TO AROUND ONE INCH ACROSS THE
HSA. THE HIGHEST AMOUNTS OF 0.50 TO 1.00 INCH ARE EXPECTED TO FALL
ACROSS PORTIONS OF WESTERN NEW ENGLAND. DEPENDING ON WHEN THE COLDER
AIR MOVES IN...SOME OF THE PRECIP MAY FALL AS SNOW...ESPECIALLY
ACROSS THE HIGHER ELEVATIONS LATE FRIDAY INTO FRIDAY NIGHT. AT THIS
TIME IT APPEARS RISES ON AREA RIVERS WILL BE AROUND 1 TO 2 FEET BUT
WILL REMAIN WITHIN THEIR BANKS. THE PRECIPITATION WILL TAPER OFF
SATURDAY MORNING...AS THE STORM PULLS AWAY INTO THE CANADIAN
MARITIMES.
WE HAVE MODELED A NUMBER OF RIVERS SUCH AS THE SMALLER RIVERS OVER
SOUTHERN VERMONT AND WESTERN NEW ENGLAND ALONG WITH THE SOMETIMES
TROUBLESOME EAST CANADA CREEK. SOME OF THEM SHOW RISES OF ONE TO
THREE FEET...BUT NONE GET NEAR FLOOD.
WEAK HIGH PRESSURE BUILDING IN WILL RESULT IN DRY CONDITIONS FROM
SATURDAY AFTERNOON THROUGH MUCH OF SUNDAY. A COLD FRONT PASSAGE WILL
BRING ADDITIONAL SHOWERS WITH MAINLY LIGHT QPF SUNDAY NIGHT THROUGH
MONDAY.
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...WASULA
NEAR TERM...RCK/WASULA
SHORT TERM...WASULA
LONG TERM...ELH
AVIATION...BGM
HYDROLOGY...JPV/RCK
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