Tuesday March 6, 2012

000
FXUS61 KALY 070331
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1030 PM EST TUE MAR 6 2012

.SYNOPSIS…
HIGH PRESSURE WILL BUILD EAST OF THE REGION TONIGHT AND INFLUENCE
OUR WEATHER THROUGH WEDNESDAY NIGHT. A COLD FRONT WILL APPROACH THE
REGION FROM THE SAINT LAWRENCE VALLEY AND GREAT LAKES
THURSDAY…TRACKING THROUGH THE REGION THURSDAY NIGHT. HIGH
PRESSURE WILL BUILD INTO THE REGION FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/…
CLOUDS ARE QUICKLY PASSING BY TO THE EAST WITH RADAR REFLECTIVITIES
RAPIDLY DECREASING DUE TO THE DRIER AIR IN PLACE. TEMPERATURES
REMAIN A BIT ELEVATED THAN PREVIOUS FORECAST WITH THE LATEST LAMP
GUIDANCE ALSO A LITTLE HIGHER. SO DID NUDGE TEMPS UP
SLIGHTLY…OTHERWISE…NO OTHER CHANGES.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/…
WARM ADVECTION INCREASES AS DOES THE BOUNDARY LAYER FLOW. MOSTLY
SUNNY SKY WITH THE INCREASING SUN ANGLE THIS TIME OF YEAR WILL
HELP WITH THE MIXING…AND WITH THE MELTING OF ANY SNOW THAT IS
LEFT FROM THE STORM LAST WEEK. HIGHS WEDNESDAY IN THE 50S TO NEAR
60…THEN EVEN WARMER THURSDAY WITH BREEZY SOUTHWEST WINDS. HIGHS
THURSDAY IN THE LOWER TO MID 60S…BUT 50S IN THE SOUTHERN
ADIRONDACKS.

CLOUDS SHOULD ADVANCE FROM THE GREAT LAKES AND ST LAWRENCE VALLEY
THROUGH THE DAY THURSDAY…WITH FILTERED SUN THROUGH HIGH CLOUDS
THURSDAY MORNING…AND THICKENING CLOUDS THURSDAY AFTERNOON. SOME
SHOWER ACTIVITY COULD ADVANCE TO THE WESTERN MOHAWK VALLEY AND
SOUTHERN ADIRONDACKS BY THURSDAY AFTERNOON. SHOWERS AFFECT THE
ENTIRE REGION ASSOCIATED WITH THE COLD FRONT THURSDAY NIGHT…
THEN MOVES EAST FRIDAY MORNING. BOUNDARY LAYER TEMPERATURES COOL
OFF ENOUGH THAT SOME LAKE EFFECT ACTIVITY SHOULD GET STARTED BY
FRIDAY MORNING AND SOME CLOUDINESS COULD SPREAD ACROSS THE REGION
FRIDAY. TEMPERATURES WILL RISE A FEW DEGREES THROUGH THE DAY
FRIDAY AND HOLD STEADY MUCH OF THE DAY AS COLD ADVECTION
STRENGTHENS. SO…HIGHS IN THE MID TO UPPER 40S…SOME MID 30S TO
LOWER 40S SOUTHERN ADIRONDACKS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/…
THE EXTENDED FORECAST OPENS WITH AN UPPER LEVEL TROUGH LIFTING N/NE
OF THE FORECAST AREA. THERE WILL BE SOME ISOLD SNOW SHOWERS
DIMINISHING NORTH AND WEST OF THE CAPITAL REGION. A FRIGID POCKET
OF COLD AIR AT H850 WILL MOVE OVER THE REGION WITH BETTER AGREEMENT
BTWN THE GFS AND ECMWF WITH TEMPS IN THE -15C TO -19C NORTH AND WEST
OF KALB
/COLDER TEMPS ON THE GFS SLIGHTLY/ AND -10C TO -15C SOUTH AND EAST.
LOWS SATURDAY MORNING WILL BE IN THE TEENS OVER THE MTNS /SOME
SINGLE DIGITS OVER THE SRN DACKS/ AND LOWER TO M20S OVER THE VALLEYS.

SATURDAY TO SUNDAY…GOOD AGREEMENT BETWEEN THE GFS/CAN
GGEM/ECMWF/GLOBAL ENSEMBLES THAT A DOME OF CANADIAN HIGH PRESSURE
WILL BUILD IN OVER NY AND NEW ENGLAND SATURDAY AFTERNOON WITH
SUNNY…COOL AND DRY WEATHER. TEMPS WILL BE SEASONABLE ON SATURDAY
THEN MODERATE BACK ABOVE NORMAL ON SUNDAY…AS THE ANTICYCLONE
DRIFTS OFF THE SRN NEW ENGLAND COAST WITH A SOUTHERLY RETURN FLOW OF
MILDER AIR. MAX TEMPS SHOULD CLOSE THE WEEKEND IN THE LOWER TO M50S
IN THE VALLEYS AND OVER THE HILLS…AND MID TO U40S OVER THE MTNS.

SUNDAY NIGHT INTO MONDAY…A PROGRESSIVE SHORT-WAVE TROUGH
APPROACHES FROM THE SOUTH AND WEST. THE GFS TAKES THIS MID-LEVEL
TROUGH…AND CLOSES IT OFF OVER THE MIDWEST SUNDAY NIGHT…WITH
UPPER LEVEL DIFFLUENCE OVER THE NORTHEAST. THE THERMAL
ADVECTION…AND CYCLONIC VORTICITY WITH THE PROGRESSIVE CLOSED LOW
BRINGS A PERIOD OF SHOWERS OVER THE FORECAST AREA LATE SUNDAY NIGHT
INTO MONDAY…AS THE COMPACT LOW MOVES OVER ERN PA/NJ/SRN NY/SRN NEW
ENGLAND BY THE EARLY EVENING. THE THICKNESSES ARE COLD FOR A PERIOD
OF SNOW SHOWERS OVER THE HIGHER TERRAIN. THE ECMWF KEEPS THE MID
LEVEL TROUGH OPEN…AND SWINGS INTO THROUGH THE CNTRL-ERN GREAT
LAKES REGION WITH AN OCCLUDED FRONTAL BOUNDARY FOCUSING A PERIOD OF
SHOWERS OVER THE REGION. WE PLACED SOME HIGH CHC POPS IN FOR
MONDAY. WE WENT WITH A BLEND OF THE HPC/GFSMOS GUIDANCE FOR MIN AND
MAX TEMPS. ONCE AGAIN…THE THICKNESSES/COLD POOL ARE COLD ENOUGH
ON THE GFS FOR SOME SNOW SHOWERS…ESPECIALLY OVER THE HILLS AND
MTNS. EXPECT LOWS IN THE M30S IN THE VALLEYS…WITH U20S TO L30S
OVER THE MTNS…AND HIGHS IN THE U40S TO L50S IN THE VALLEYS ON
MONDAY…WITH 40S OVER THE MTNS.

MONDAY NIGHT INTO TUESDAY…THE WEATHER CONTINUES TO REMAIN A BIT
UNSETTLED…AS THE ENSEMBLES…AND THE MEDIUM GUIDANCE CONTINUES TO
SHOW THE POTENTIAL FOR A BACKDOOR COLD FRONT TO DROP S/SE FROM THE
ST LAWRENCE RIVER VALLEY WITH HIGH PRESSURE BUILDING IN FROM N-CNTRL
QUEBEC. HPC ALSO FAVORED THIS SCENARIO. WE LEANED CLOSER TO
HPC…ECMWF…AND THE GLOBAL ENSEMBLE MEAN WITH A SLIGHT TO LOW CHC
OF RAIN/SNOW SHOWERS. TEMPS COULD STILL BE ABOVE NORMAL…UNTIL THE
MID LEVEL ZONAL FLOW BUCKLES WITH THE BACKDOOR COLD FRONT.

OVERALL…TEMPS WILL BE ABOVE NORMAL WITH PCPN STILL BELOW NORMAL IN
THE LONG TERM.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/…
VFR CONDITIONS TO PREVAIL THE NEXT 24 HOURS.

HIGH AND MID LEVEL CLOUD COVER WILL MOVE ACROSS THE REGION THIS
EVENING…MAINLY IMPACTING KALB-KGFL. NOT EXPECTING PRECIP TO
REACH THE GROUND AT THESE SITES DUE TO THE DRIER AIR IN PLACE.
LIGHT SOUTHERLY WINDS EXPECTED TONIGHT AND THESE VALUES WILL
INCREASE ON WEDNESDAY WITH SPEEDS BETWEEN 8-14 KTS.

OUTLOOK…
WED-WED NIGHT…VFR. NO SIG WX.
THU-FRI…VFR/MVFR…-SHRA.
SAT-SUN…VFR. NO SIG WX.

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE LIKELY OVER THE NEXT 5 DAYS.

THE NEXT CHANCE FOR PRECIPITATION WILL BE LATE THURSDAY INTO EARLY
FRIDAY WITH A STRONG ANA-TYPE COLD FRONT. (A FRONT THAT LINES UP
WITH THE MEAN FLOW). MUCH OF THIS WILL BE IN THE FORM OF LIQUID
RAIN…BUT AS COLD AIR FILTERS BACK…A CHANGE OVER TO A LITTLE SNOW
IS POSSIBLE ACROSS THE ADIRONDACKS AND SOUTHERN GREENS LATER
THURSDAY NIGHT.

BASIN AVERAGE QPF FROM THIS BOUNDARY LOOKS AS IF IT WILL BE CLOSE TO
A HALF INCH IN NORTHWEST AREAS…WITH MOST OTHER AREAS A QUARTER
INCH OR LESS.

WEDNESDAY INTO THURSDAY…TEMPERATURES WILL WARM INTO THE 40S
TO LOWER 50S NORTH…50S TO LOWER 60S SOUTH. THAT WILL BEGIN SOME
SNOWMELT AND SOME MINOR RUNOFF. THE SHOWERS ON THURSDAY WILL PRODUCE
SOME ADDITIONAL RUNOFF. ONLY WELL WITHIN BANK RISES ARE
ANTICIPATED…WITH THE NWS/RFC EXPERIMENTAL SHORT-TERM
HYDROLOGICAL ENSEMBLES (MMEFS) INDICATING NO RIVERS OR STREAMS IN
OUR HSA LIKELY TO REACH ACTION STAGE LEVELS.

COLDER AIR RETURNS BY FRIDAY…SLOWING DOWN ANY RUNOFF FROM
MELTING SNOW.

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…NAS
NEAR TERM…NAS
SHORT TERM…BGM/NAS
LONG TERM…WASULA
AVIATION…BGM/WASULA
HYDROLOGY…NAS

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

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