FXUS61 KALY 042137
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
437 PM EST FRI DEC 4 2009
.SYNOPSIS...
HIGH PRESSURE WILL PRODUCE FAIR AND COLD WEATHER TONIGHT.
LOW PRESSURE WILL MOVE NORTHEAST FROM NEAR THE MID ATLANTIC COAST
TOMORROW PRODUCING SOME ACCUMULATING SNOWFALL PRIMARILY FROM THE
MOHAWK RIVER VALLEY...GREATER CAPITAL REGION...AND SOUTHERN VERMONT
SOUTH AND EAST. THE CYCLONE MOVES EAST OF NOVA SCOTIA BY SUNDAY
MORNING...AS HIGH PRESSURE RIDGES IN FROM THE TENNESSEE VALLEY TO
CLOSE THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 3 PM EDT...THE FCST AREA HAS ENJOYED A FAIR AND DRY DAY WITH
SOUTHWEST FLOW ALOFT AND SFC HIGH PRESSURE RIDGING IN FROM MIDWEST
AND THE OH VALLEY. A FEW SNOW SHOWERS AND FLURRIES GRAZED EXTREME
NRN HERKIMER COUNTY FROM A 240-250 DEGREE LAKE TRAJECTORY. ALL AN
ALL...MIXED CLOUDS AND SOME SUN SHINE DOMINATED WITH TEMPS AROUND
5 DEGREES OR SO ABOVE NORMAL.
THE WATER VAPOR LOOP WITH H500 HEIGHTS OVERLAYED FROM THE GFS
DEPICTS A LONGWAVE TROUGH EAST OF THE ROCKY MTNS WITH MULTIPLE
SHORT WAVES MIGRATING THROUGH THE BASE OF THE TROUGH. ONE SHORT
WAVE AND ITS ASSOCIATED SFC LOW IS MOVING THROUGH THE NRN GULF.
THIS DISTURBANCE IS RESPONSIBLE FOR SNOWFALL OCCURRING NEAR HOUSTON
TX. LOW PRESSURE WILL MOVE ALONG THE JET STREAM TONIGHT...AND
REDEVELOP OFF THE COAST OF SC/NC BY 12Z SATURDAY. THIS STORM
SYSTEM WILL LIKELY PRODUCE THE FIRST ACCUMULATING SNOWFALL FOR
MOST THE REGION LATE TOMORROW AFTERNOON INTO THE EVENING PERIOD.
THE OVERNIGHT PERIOD LOOKS TO BE VERY QUIET WITH INITIALLY A
PARTIAL CLEARING...AND LIGHT TO CALM WINDS. SOME RADIATIONAL
COOLING WILL OCCUR. HOWEVER...MID AND HIGH CLOUDS WILL INCREASE
WITH THE WARM AIR ADVECTION ALOFT. EXPECT LOWS TO BE IN THE TEENS
AND LOWER 20S NORTH AND WEST OF THE CAPITAL REGION...AND MID 20S
TO LOWER 30S SOUTH AND EAST.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
SATURDAY INTO SATURDAY NIGHT...THE DETERMINISTIC MODELS SUCH AS THE
GFS...NAM...AND ECMWF HAVE TRENDED A LITTLE FURTHER NORTH WITH THE
QPF FROM THE COASTAL/OCEAN LOW MOVING NORTHEAST OFF THE MID
ATLANTIC COAST. THIS STORM ACCORDING TO THE 12Z GLOBAL ENSEMBLE
MEAN APPEARS IT WILL MOVE FAR ENOUGH SOUTH AND EAST OF LONG ISLAND
TO GIVE THE ALY FCST AREA A LIGHT TO MODERATE PCPN EVENT. THE
TRACK OF THE LOW KEEPS US IN THE DEFORMATION ZONE OF THE WAVE WITH
MOISTURE OVER RUNNING THE COLD DOME. THE BOUNDARY LAYER WILL NEED
A LITTLE TIME TO COOL SOUTH OF KALB INITIALLY IN THE LATE
MORNING/EARLY PM. WE SHOULD SEE SOME VIRGA BEFORE SATURATION
OCCURS. THE BEST H850-700 FGEN OCCURS DOWN NEAR AND SOUTH OF LONG
ISLAND. THE STRONGEST SYNOPTIC QG OMEGA LIFT IS SITUATED SOUTH OF
THE FCST AREA...BUT CLOSE TO NW CT. IT IS INTERESTING HOW MUCH QPF
THE GUIDANCE IS FORECASTING NOW...WITH THE BETTER DYNAMICS OFF THE
COAST. TYPICALLY DEFORMATION SNOW IS LIGHT TO MODEST AT BEST.
THE EASTERN CATSKILLS...MID HUDSON VALLEY...BERKSHIRES...TACONICS...AND
NW CT HAVE THE BEST CHANCE FOR QPF AMOUNTS APPROACHING A QUARTER
TO HALF AN INCH BASED ON THE NAM AND GFS...THOUGH THE 18Z NAM HAS
COME DOWN ON THE QPF. THE CANADIAN GUIDANCE IS LEANER ON THE QPF
WITH MAYBE A QUARTER OF AN INCH WELL SOUTH OF THE CAPITAL
REGION...AND AROUND A TENTH IN THE CAPITAL DISTRICT...WITH LESS
THAN A TENTH NORTH AND WEST. WE WENT CLOSE TO THE HPC QPF FOR THE
EVENT WHICH FAVORED THE 09Z SREF...ECMWF...AND CANADIAN GUIDANCE.
WE BELIEVE THE ONSET OF PCPN WILL BE GRADUAL FROM SOUTH TO
NORTH...WITH LIGHT SNOW MOVING INTO THE CAPITAL REGION AROUND THE
MID TO LATE PM. IT WILL BE A RAIN/SNOW MIX INITIALLY NEAR
KPOU...BEFORE A COMPLETE CHANGEOVER TO SNOW STICKING TO THE GROUND.
WE ARE NOT CONFIDENT ABOUT ANY HEADLINES RIGHT NOW. IT MAYBE A
BORDERLINE WINTER WX ADVISORY SITUATION FOR LOCATION SOUTH AND
EAST OF THE CAPITAL REGION. WE WILL CONTINUE THE UNCERTAINTIES IN
THE HWO PRODUCT. WE WILL ALSO ALLOW A FEW MORE MODEL RUNS FROM THE
GFS AND NAM FOR CONTINUITY FOR THE NORTHWARD TRACK OF THE QPF WITH
THE OCEANIC CYCLONE. THE BEST MESOSCALE BANDING POTENTIAL FOR
THIS STORM LOOKS LIKE IT BE OVER THE OCEAN...OR JUST OFF THE COAST.
HERE IS OUR SNOW ACCUMULATION BREAKDOWN FOR NOW...
NW CT...SRN TACONICS...SRN BERKS: 2-4"
ERN CATSKILLS...MID HUDSON VALLEY...SRN VT: 1-3"
MOHAWK VALLEY...CAPITAL REGION...AROUND AN INCH OR SO
LAKE GEORGE REGION...SRN DACKS...AN INCH OR LESS
THE SNOW MAY LINGER TOWARDS MIDNIGHT...AS THE H850 CIRCULATION
MOVES EAST OF CAPE COD...AND PROGRESSES NORTHEAST TOWARDS NOVA
SCOTIA. SOME COLD AIR ADVECTION OCCURS TOWARDS 12Z SUNDAY...WITH
H850 TEMPS FALLING NEAR CLIMO VALUES OF -10C. MIN TEMPS WILL
GENERALLY BE IN THE 20S.
IN THE WAKE OF THE STORM SYSTEM...SUNDAY LOOKS BETTER WITH
ANTICYCLONIC FLOW ALOFT AND AT THE SFC WITH MAINLY DRY WEATHER. THERE
COULD BE A LITTLE LAKE EFFECT SNOW SHOWER ACTIVITY SUNDAY
AFTERNOON FOR THE WRN ADIRONDACKS. THE MOISTURE FETCH AND
INSTABILITY DON/T LOOK GOOD WITH THE INVERSION HEIGHTS LOWERING.
FRESH SNOW COVER WITH H850 VALUES -5C TO -10C SHOULD KEEP MAX
TEMPS IN THE 30S.
SUNDAY NIGHT INTO MONDAY...HIGH PRESSURE RETREATS OFF THE MID
ATLANTIC COAST WITH A CLIPPER LOW AND ITS ASSOCIATED COLD FRONT
BRINGING SOME SNOW SHOWERS IN FOR MONDAY AFTERNOON. TEMPS COULD
PLUMMET INTO THE TEENS AND L20S MON MORNING WITH THE SNOW
COVER...MOSTLY CLEAR SKIES...AND LIGHT TO CALM WINDS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
MOS GUIDANCE. A COLD FRONT BRINGS A CHANCE OF SNOW SHOWERS TO THE
ENTIRE REGION MONDAY NIGHT. NORTHWEST WINDS BEHIND THE FRONT WILL
CONTINUE THE CHANCE FOR SNOW SHOWERS IN THE WESTERN ADIRONDACKS ON
TUESDAY.
IT LOOKS AS THOUGH A MAJOR WINTER STORM WILL BEGIN TO TAKE SHAPE
OVER THE SOUTHWESTERN U.S. WHICH WILL AFFECT OUR REGION AT MID-WEEK.
THE ECMWF IS WAY TOO FAST WITH THIS SYSTEM...PULLING IT THROUGH NEW
YORK AND SOUTHERN NEW ENGLAND WEDNESDAY EVENING. THE GFS TRACKS IT
INTO THE LOWER GREAT LAKES ON WEDNESDAY...AND UP ACROSS NORTHERN NEW
YORK TO NORTHERN NEW ENGLAND BY THURSDAY. HPC IS A LITTLE FARTHER
NORTH AND WEST...AND A LITTLE FASTER...THAN THE GFS...BUT THIS IS
THE CLOSEST-ALIGNED PAIRING FOR THIS EVENT. THIS COULD BE A SOMEWHAT
LONG-LASTING EVENT...AND IT LOOKS TO BE MIXED. GFS TEMPERATURE
PROFILES SUGGEST ANY SNOW FROM THE CAPITAL REGION ON SOUTH WILL
QUICKLY CHANGE OVER TO RAIN...BUT AS THE STORM INTENSIFIES AND
BEGINS TO PASS THROUGH OUR REGION...SIGNIFICANTLY COLDER AIR INVADES
WEDNESDAY NIGHT...TURNING ALL PRECIPITATION BACK OVER TO ALL SNOW.
TO THE NORTH AND WEST OF THE CAPITAL REGION...SLEET AND FREEZING
RAIN COULD BE THE PREDOMINANT PRECIPITATION TYPE BEFORE IT CHANGES
BACK OVER TO SNOW. THE BULK OF THE QPF LOOKS TO BE COMING IN DURING
THE EARLIER PART OF THE EVENT...SO SNOW SHOULD BECOME LIGHTER RATHER
QUICKLY...AND AMOUNTS SHOULD BE LIMITED.
BEHIND THE SYSTEM...A BROAD PATTERN OF SCATTERED LAKE-ENHANCED
WRAPAROUND SNOW SHOWERS ARE A GOOD POSSIBILITY ON THURSDAY AS STRONG
WESTERLY WINDS ENSUE BEHIND THE COLD FRONTAL PASSAGE. MULTIPLE
BANDING COULD PRODUCE AREAS WITH ADDITIONAL MEASURABLE SNOW...THUS
WE CONTINUE WITH CHC POPS FOR ALL. THE PRESSURE GRADIENT LOOSENS
SOMEWHAT THURSDAY NIGHT...BUT CHC POPS CONTINUE FOR THE LAKE-EFFECT
SNOW BELT REGION OF MAINLY HERKIMER AND HAMILTON COUNTIES.
MEANWHILE...ANOTHER SYSTEM WILL BE PULLING OUT OF THE COLORADO
ROCKIES AND HEADING EASTWARD...POSSIBLY AFFECTING OUR AREA AT THE
END OF THE PERIOD.
&&
.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL CONTINUE THROUGH MOST OF THE TAF PERIOD. SOME
SCT-BKN STRATOCU IS ACROSS THE REGION THIS AFTN ALONG WITH LIGHT SFC
WINDS /LESS THAN 10 KTS/.
MID AND HIGH LEVEL CLOUDS WILL BEGIN TO INCREASE OVERNIGHT AS A
SOUTHERN STREAM SYSTEM MOVES UP THE EASTERN SEABOARD WITH N-NW SFC
WINDS LESS THAN 5 KTS. THIS WILL EVENTUALLY ALLOW FOR A BKN-OVC CIG
OF 3500-5000 FT BY LATE SAT MORNING. SOME LIGHT SNOW AND RAIN WILL
BEGIN TO SPREAD TO AS FAR NORTH AS KPOU BY NEAR MIDDAY SATURDAY.
THIS MAY EVENTUALLY ALLOW FOR MVFR AND POSSIBLY IFR CONDITIONS AT
KPOU FOR SAT AFTN...AND PERHAPS EVEN MVFR CONDITIONS AS FAR AS NORTH
AS KALB BY THE LATE AFTN AS WELL.
OUTLOOK...
SAT PM...CHC MVFR/IFR IN -SN/RA MAINLY FROM KALB SOUTH LATE IN THE
DAY AND SAT NITE.
SUN-TUE...VFR. NO SIG WX.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS ARE EXPECTED OVER THE NEXT 5 DAYS. RIVERS WILL
CONTINUE TO RECEDE FROM THE RAINFALL YESTERDAY WITH THE COLDER
WEATHER. THE MAIN PTYPE WILL BE SNOW FROM THE OCEAN LOW ON SATURDAY
WITH GENERALLY A TENTH TO FOUR TENTHS OF AN INCH OF LIQUID
EQUIVALENT.
THE NEXT CHANCE OF A SIGNIFICANT PCPN EVENT LOOKS TO BE AROUND MID WEEK
WITH MIXED PCPN TO ALL RAIN.
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
SHORT TERM...WASULA
LONG TERM...ELH
AVIATION...FRUGIS
HYDROLOGY...WASULA
