February 18, 2012 Forecast Discussion

000
FXUS61 KALY 181324
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
824 AM EST SAT FEB 18 2012

.SYNOPSIS…
HIGH PRESSURE WILL BRIEFLY BUILD IN FROM THE MID
ATLANTIC REGION THIS MORNING. A CLIPPER LOW WILL MOVE ACROSS THE
REGION THIS AFTERNOON INTO EARLY THIS EVENING WITH SOME LIGHT SNOW.
HIGH PRESSURE WILL USHER IN SEASONABLY COLD AND DRY WEATHER FROM
SOUTHEASTERN CANADA AND THE GREAT LAKES REGION SUNDAY INTO THE
PRESIDENTS DAY HOLIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
AS OF 815 AM EST…DID SOME MINOR ADJUSTMENTS TO CLOUDS AND POPS
BASED ON SATELLITE AND RADAR TRENDS. LITTLE MORE SUNSHINE THIS
MORNING THAN EARLIER FORECAST INDICATED. BAND OF MOD-HEAVY SNOW
MOVING THROUGH FINGER LAKES PRODUCED 1 INCH IN 1 HOUR AT BUFFALO
AND ROCHESTER.

THE LATEST RUC/SFC ANALYSIS HAS HIGH PRESSURE OVER THE MID ATLANTIC
REGION BRIEFLY BUILDING NORTHWARD OVER NY AND WRN NEW ENGLAND THIS
MORNING. A CLIPPER LOW OVER MICHIGAN THIS MORNING WILL APPROACH THE
FCST AREA THIS AFTERNOON IN THE ZONAL FLOW ALOFT. THE SHORT-WAVE IS
NICELY DEPICTED IN THE WATER VAPOR LOOP THIS MORNING OVER THE
W-CNTRL GREAT LAKES REGION. SOME LIGHT SNOW OR SNOW SHOWERS WILL
OVERSPREAD LOCATIONS WEST OF THE HUDSON RIVER VALLEY IN THE EARLY TO
MID AFTERNOON…THEN WILL QUICKLY SPREAD EASTWARD BY THE LATE
PM/EARLY PM FROM THE HUDSON RIVER VALLEY EAST. THE NAM IS VERY
AGGRESSIVE WITH STRONG UPWARD VERTICAL MOTION GENERATED BY THE
ISENTROPIC LIFT ON THE 295K SFC. THIS NAM MODEL CYCLE WAS A BIT HIGH
ON THE QPF FROM THE MOHAWK VALLEY/NRN CATSKILLS/CAPITAL REGION SOUTH
COMPARED TO PREVIOUS RUNS. THE GFS IMPLIES WEAKER ISENTROPIC
LIFT…BUT STRONGER DIFFERENTIAL CYCLONIC VORTICITY IN THE H850-500
LAYER FOR A BURST OF SNOW FROM THE CAPITAL REGION SOUTH AND WEST
TOWARDS THE ERN CATSKILLS. AGAIN…THIS IS BASED ON A CLIPPER TRACK
ALONG OR JUST SOUTH OF THE I-90 CORRIDOR.

MODEL SOUNDINGS/CRITICAL THICKNESS PROFILES INDICATE MAINLY A SNOW
PTYPE…EXCEPT OVER THE HUDSON RIVER VALLEY FROM KALB SOUTH…WHERE
IT WILL BE BRIEFLY RAIN BEFORE THE COLUMN COOLS TO THE WET BULB
TEMPS. THE UPPER SHORT-WAVE TROUGH IS FAIRLY DYNAMIC…THAT THE
DYNAMIC COOLING SHOULD CHANGE THE PRECIP TO ALL SNOW AFTER DARK.
WE ARE EXPECTING TEMPS IN THE LOWER TO M40S FROM THE CAPITAL
DISTRICT SOUTH INTO THE MID HUDSON VALLEY…AND NW CT. EXPECT MID
AND U30S ELSEWHERE…EXCEPT OVER THE HIGH PEAKS IN THE SRN
DACKS…AND SRN GREENS WHERE U20S TO L30S WILL BE COMMON.

TOTAL SNOWFALL ACCUMULATIONS WILL GENERALLY BE AN INCH OR LESS
BEFORE NIGHTFALL…EXCEPT OVER THE WRN MOHAWK VALLEY…NRN
CATSKILLS…SCHOHARIE VALLEY WHERE 1-2" COULD OCCUR BEFORE 00Z.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/…
TONIGHT…THE FAST MOVING CLIPPER MOVES EAST OF THE REGION BEFORE
MIDNIGHT WITH THE SNOW SHOWERS/LIGHT SNOW QUICKLY ENDING. THE
TOTAL SNOW ACCUMULATIONS WILL GENERALLY BE AN INCH OR LESS ACROSS
THE REGION WITH 1 TO 3 INCHES OVER PORTIONS OF THE
BERKSHIRES…WRN DACKS…W-CNTRL MOHAWK VALLEY…ERN
CATSKILLS…AND THE SCHOHARIE VALLEY. COLD AIR ADVECTION OCCURS IN
THE WAKE OF THE CLIPPER WITH HIGH PRESSURE BUILDING IN NORTH OF
LAKE HURON AND JAMES BAY. MEANWHILE…A SOUTHERN STREAM SYSTEM LOOKS
LIKE IT WILL STAY WELL SOUTH OF THE REGION…OVER THE SOUTHEASTERN
STATES AND SHIFTING INTO THE MID ATLANTIC REGION WITH THE SPLIT
UPPER LEVEL FLOW…NOT PHASING…AND THE NRN STREAM TROUGH STEERS
THE STORM OUT TO SEA. EXPECT THE SKIES TO GRADUALLY CLEAR SATURDAY
NIGHT WITH LOWS 20-25F IN THE VALLEYS…AND MID AND UPPER TEENS
OVER THE MTNS.

SUNDAY…THE LOW AND MID LEVEL FLOW BECOMES ANTICYCLONIC WITH ANY
LAKE EFFECT OVER CNTRL NY IN THE NW FLOW. THE RH PROFILES ARE VERY
DRY WITH PLENTY OF STRONG SUBSIDENCE FROM THE BROAD ANTICYCLONE TO
THE NORTH AND WEST. SOME MID AND HIGH CLOUDS ASSOCIATED WITH THE
STORM MOVING OVER THE MID ATLANTIC STATES MAY REACH THE SOUTHERN
ZONES. HIGHS WILL TREND TOWARDS SEASONABLE READINGS WITH MID AND
UPPER 30S IN THE VALLEY /EXCEPT OVER THE MID HUDSON VALLEY AND NW
CT/ WHERE SOME LOWER 40S WILL BE POSSIBLE…AND U20S TO M30S OVER
THE MTNS. THESE VALUES WERE CLOSER TO THE METMOS VALUES.

SUNDAY NIGHT THROUGH MONDAY NIGHT…QUIET WEATHER CONTINUES WITH
THE SFC ANTICYCLONE RIDGING IN OVER NY AND NEW ENGLAND OVERNIGHT
INTO MONDAY MORNING WITH DECENT RADIATIONAL COOLING IF THE WINDS
GO CALM. THE UPPER LEVEL RIDGE AXIS MOVES OVER THE REGION LATE
MONDAY PM TO MONDAY NIGHT…WITH HEIGHTS AND H850 TEMPS ON THE
RISE FOR TUESDAY. TEMPS WILL BE NEAR NORMAL FOR THE STRETCH…WITH
LOTS OF SUNSHINE FOR THE PRESIDENTS DAY HOLIDAY.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/…
UNCERTAINTY IN THE FORECAST GROWS WITH TIME. THE MODEL GUIDANCE IS
IN GENERAL AGREEMENT IN REGARDS TO THE LONGWAVE PATTERN…WITH A
STRENGTHENING RIDGE OFFSHORE THE WEST COAST AND TROUGHING ACROSS
MUCH OF THE CONUS. HOWEVER…THIS IS NOT TRANSLATING TO AGREEMENT
WITH THE PLACEMENT…MOVEMENT AND/OR STRENGTHEN OF SURFACE
FEATURES/SYSTEMS. THE HYDROMETEOROLOGICAL PREDICTION CENTER HAS
FAVORED THE ENSEMBLE GUIDANCE FOR MUCH OF THE PERIOD. THIS IS DUE TO
THE FACT THAT THE OPERATIONAL RUNS OF THE GFS…ECMWF AND UKMET ARE
ALL MORE PROGRESSIVE THAN THE ENSEMBLE GUIDANCE WHICH IS SLOWER
MOVING SYSTEMS FROM THE MIDWEST EASTWARD MID WEEK ONWARD. AT THIS
TIME LOOKS LIKE UNSETTLED WEATHER WITH ABOVE NORMAL TEMPERATURES.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/…
WILL HAVE SOME WEAK SURFACE RIDGING AHEAD OF OUR NEXT LOW PRESSURE
SYSTEM. THIS CLIPPER SYSTEM WILL BRING SOME LIGHT PRECIPITATION
TO MUCH OF THE FORECAST AREA LATE IN THE DAY INTO THE EVENING HOURS.
THE BEST CHANCES FOR PRECIPITATION WILL BE AT KALB WITH A RAIN/SNOW
MIX CHANGING TO SNOW BEFORE ENDING. A PERIOD OF LIGHT SNOW IS ALSO
EXPECTED AT KGFL EARLY THIS EVENING. DON`T HAVE ENOUGH CONFIDENCE TO
PLACE PRECIPITATION IN KPOU TAF. AT THIS TIME…ONLY EXPECTED MVFR
CONDITIONS…BUT CAN`T RULE OUT IFR VISIBILITY WITH SNOW. OTHERWISE
VFR CONDITIONS ARE EXPECTED BEFORE AND AFTER THE PRECIPITATION.

WINDS WILL BE WESTERLY AND MAINLY LIGHT SHIFTING MORE TO THE NORTH
WITH THIS EVENING IN THE WAKE OF THE CLIPPER`S COLD FRONTAL BOUNDARY.

OUTLOOK…
SUN-TUE…VFR…NO SIG WX.
TUE NIGHT-WED…VFR/MVFR. CHC -SHRA/-SHSN.

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE EXPECTED INTO THE MIDDLE OF NEXT WEEK. SOME
HYDRO GAGES MAY SHOW ICE EFFECTS FROM THE MOHAWK VALLEY NORTHWARD
IN THE ALBANY HYDRO SERVICE AREA.

THE CLIPPER LOW WILL BRING LIGHT QPF OF ONE TO TWO TENTHS OF AN
INCH. SOME LOCATIONS WILL GET A FEW INCHES OF SNOWFALL. DRY
WEATHER WILL PREVAIL SUNDAY THROUGH MOST OF TUESDAY.

AS A REMINDER….THE WINTER SPRING FLOOD POTENTIAL OUTLOOK HAS
BEEN ISSUED FOR EASTERN NEW YORK AND WESTERN NEW ENGLAND. PLEASE
REFER TO ALBESFALY /FGUS71 KALY/ FOR FURTHER DETAILS.

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…WASULA/SND
SHORT TERM…WASULA
LONG TERM…IAA
AVIATION…IAA
HYDROLOGY…WASULA

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