February 27, 2012 Forecast Discussion

000
FXUS61 KALY 272107
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
407 PM EST MON FEB 27 2012

.SYNOPSIS…
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A FAST MOVING CLIPPER SYSTEM WILL BRING A FEW RAIN AND
SNOW SHOWERS TO THE REGION TONIGHT…MAINLY FOR NORTHERN PARTS OF
THE AREA. HIGH PRESSURE WILL BRIEFLY BUILD IN FROM THE GREAT LAKES
REGION WITH SEASONABLY COLD AND DRY AIR FOR TUESDAY. A COMPLEX LOW
PRESSURE SYSTEM WILL APPROACH FROM THE UPPER MISSISSIPPI VALLEY AND
WESTERN GREAT LAKES REGION FOR THE MID WEEK WITH SOME SNOW…RAIN…
AND MIXED PRECIPITATION.
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&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/…
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A CLIPPER SYSTEM WILL SLIDE ACROSS THE ST. LAWRENCE
VALLEY/NORTHERN NEW ENGLAND THIS EVENING. THIS SYSTEM…EVIDENT ON
THE LATEST WATER VAPOR IMAGERY AS A SWIFT MOVING SHORTWAVE ACROSS
THE GREAT LAKES…WILL DRAG A COLD FRONT THROUGH OUR AREA.
MOISTURE IS QUITE LIMITED WITH THIS SYSTEM…AND PRECIP WILL
MAINLY BE CONFINED TO THE HIGHER TERRAIN OF THE ADIRONDACKS AND
SOUTHERN GREEN MOUNTAINS THIS EVENING INTO EARLY TONIGHT. TEMPS
IN THE HIGHER TERRAIN THIS EVENING ARE MUCH COOLER THAN THE
VALLEYS…SO P-TYPE IS LOOKING GENERALLY SNOW SHOWERS…ALTHOUGH
ANY SHOWER THAT MAKES IT INTO THE VALLEY AREAS WILL BE IN THE FORM
OF RAIN BEFORE TEMPS CAN COOL OFF TO BELOW FREEZING. SOME UPSLOPE
FLOW/LAKE ENHANCEMENT MAY HELP SQUEEZE OUT A LITTLE EXTRA PRECIP FOR
WESTERN FACING SLOPES OF THE HIGHER TERRAIN…ALTHOUGH SNOWFALL
AMOUNTS GENERALLY LOOK ONLY ABOUT AN INCH OR TWO AT MOST. TEMPS
WILL DROP OFF BEHIND THE BOUNDARY LATER TONIGHT…WITH MIN TEMPS
RANGING FROM THE UPPER TEENS IN THE SOUTHERN ADIRONDACKS TO NEAR
30 IN THE MID HUDSON VALLEY.
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&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/…

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…COMPLEX WINTER STORM TO IMPACT THE REGION WEDNESDAY INTO THURSDAY…

HIGH PRESSURE WILL CONTROL THE REGION FOR TUESDAY INTO TUESDAY
NIGHT. MAX TEMPS ON TUESDAY WILL BE COOLER THAN RECENT DAYS…WITH
ONLY UPPER 30S TO LOW 40S FOR VALLEY AREAS…AND 20S TO LOW 30S
FOR THE HIGH TERRAIN. THERE SHOULD BE A GOOD DEAL OF SUNSHINE FOR
TUESDAY AFTN…AND THIS WILL PROMOTE GOOD DAYTIME MIXING. A FEW
WIND GUSTS MAY APPROACH 25 KTS FOR TUESDAY AFTN.

MID AND HIGH LEVEL CLOUDS WILL BEGIN TO INCREASE ON TUESDAY NIGHT.
WITH THE WIND DYING DOWN BY EVENING…THE CLOUDS SHOULD REMAIN THIN LONG
ENOUGH FOR TEMPS TO DROP NICELY EARLY IN THE NIGHT FOR MINS TO
BOTTOM OUT BETWEEN THE SINGLE DIGITS IN THE ADIRONDACKS TO THE MID
20S FOR SOUTHERN AREAS.

BY WEDNESDAY MORNING…SURFACE LOW PRESSURE WILL REMAIN WELL TO
OUR WEST ACROSS THE UPPER MIDWEST/WESTERN GREAT LAKES.
HOWEVER…STRONG WARM ADVECTION/ISENTROPIC LIFT AHEAD OF THIS
SYSTEM ACROSS THE UPPER OHIO VALLEY/MID ATLANTIC WILL SPREAD
TOWARDS OUR AREA FOR THE MORNING HOURS. THE HIGH PRESSURE THAT
PROVIDED THE NICE WEATHER FOR TUESDAY WILL BE SITUATED ACROSS
NORTHERN NEW ENGLAND/SOUTHEASTERN CANADA…AND THE FLOW AROUND
THIS HIGH SHOULD HELP KEEP SOME DEEP COLD AIR IN PLACE OVER THE
REGION. THE RESULT WILL BE A PERIOD OF PRECIPITATION ACROSS OUR
AREA. AT THIS POINT…ALL THE MODELS AGREE THAT THIS PRECIP SHOULD
BE IN THE FORM OF SNOWFALL. ALTHOUGH WE WILL BE FIGHTING LATE
FEBRUARY SUN /VERY LATE FEBRUARY CONSIDERING IN MOST YEARS THIS
LEAP YEAR DATE IS ALREADY MARCH/…SOME SNOWFALL SHOULD STILL
ACCUMULATE DURING THE DAYTIME HOURS…WITH SEVERAL INCHES POSSIBLE
BY THE LATE AFTN. IT/S NOT CLEAR EXACTLY HOW FAR NORTH THE BEST
WARM ADVECTION PRECIP WILL MAKE IT. THIS WAS AN ISSUE WITH THE
STORM LAST FRIDAY…AS PRECIP SLID EASTWARD ACROSS SOUTHERN
AREAS…LEAVING LITTLE TO NO PRECIP FOR THE CAPITAL REGION ON
NORTHWARD. IN THIS GO AROUND…THERE SEEMS TO BE BETTER MODEL
SUPPORT /ESP THE 12 UTC ECMWF/GGEM/UKMET/ THAT AT LEAST SOME
PRECIP MAKES IT TOWARDS OUR NORTHERN ZONES FOR A FEW INCHES OF
SNOW TO ACCUMULATE. MAX TEMPS LOOKS TO RANGE FROM THE UPPER 20S IN
THE DACKS TO LOWER TO MIDDLE 30S FOR VALLEY AREAS.

BY EVENING…THE WARM AIR WILL BE TRYING TO MOVE IN ALOFT…ESP
AROUND THE 800 HPA LAYER. THE 12 UTC GFS HAS BEEN SHOWING THIS
WARM LAYER MOVING IN ALOFT…WITH DECREASING AMOUNTS OF PRECIP FOR
THE OVERNIGHT HOURS. MEANWHILE…THE ECMWF/NAM KEEP PRECIP AROUND
FOR MUCH OF THE NIGHT…AS A SECONDARY LOW PRESSURE AREA
DEVELOPING OFF THE JERSEY SHORE ALLOW FOR CONTINUED ROUNDS OF
PRECIPITATION OVERNIGHT. AT THE POINT…WE HAVE SIDED WITH THE
LATEST ECMWF/NAM. HOWEVER…EVEN WITH THESE SCENARIOS…SOME
WARMER AIR MAY ALLOW FOR MIXING WITH SLEET/FREEZING RAIN AND EVEN
PLAIN RAIN FOR AREAS FROM THE CAPITAL REGION SOUTHWARD. THE COLD
AIR LOOKS TO REMAIN BEST ENTRENCHED ACROSS THE SOUTHEASTERN
ADIRONDACKS/LAKE GEORGE AREA/SOUTHERN VT. THE CAPITAL REGION WILL
BE ON THE BORDERLINE. DURING THE OVERNIGHT HOURS…TEMPS LOOKS TO
REMAIN STEADY IN MOST AREAS…OR EVEN RISE A DEGREE OR TWO…ESP
ACROSS SOUTHERN AREAS.

BY THURSDAY…TEMPS ALOFT WILL BE CRASHING AS THE UPPER LOW MOVES
FROM THE GREAT LAKES TOWARDS THE NORTHEAST. THIS LOOKS TO CONTINUE
A PERIOD OF PRECIP FOR DURING THE DAY THURSDAY. THE MODELS
DISAGREE ON JUST HOW MUCH ADDITIONAL PRECIP OCCURS AND WHAT FORM
IT WILL BE IN. THE GGEM/ECMWF SHEAR OUT THE UPPER LOW AND SLIDE IT
OUR NORTH…KEEPING ADDITIONAL PRECIP MINIMAL. MEANWHILE…THE 12
UTC GFS…WHICH HAD THE LULL IN THE PRECIP FOR WED NIGHT…RAMPS
IN BACK UP WITH THE UPPER LOW BOWLING ACROSS OUR AREA.
HOWEVER…BOUNDARY LAYER TEMPS COULD BE AN ISSUE IN VALLEY
AREAS…ESPECIALLY TO THE SOUTH OF ALBANY. FOR NOW…HAVE GONE
WITH RAIN OR SNOW BASED ON THE DIURNAL TEMP CURVE…BUT ADDITIONAL
SNOWFALL IS POSSIBLE…ESP FOR THE HIGHER TERRAIN AND NORTHERN
AREAS.

ALL IN ALL…SOME AREAS MAY PICK UP MODERATE TO HEAVY SNOW
ACCUMULATIONS WHEN ALL IS SAID AND DONE…MAINLY FOR THE HIGH
TERRAIN WHERE LESS MIXING WILL OCCUR. HOWEVER…THIS IS A LOW
CONFIDENCE FORECAST…AS MANY TIMES STORMS LIKE THIS HAVE LARGE
DRY SLOTS /KNOWN TO SOME AS RIP OFF ZONES/…WHICH SHUT PRECIP OFF
AFTER AN INITIAL SHOT OF WARM ADVECTION. IN ADDITION…ANY MIXING
WILL SIGNIFICANTLY AFFECT SNOWFALL TOTALS…AND THE 12 UTC GEFS
AND 15 UTC SREF PLUMES SHOWS PLENTY OF VARIETY REGARDING QPF
AMOUNTS AND P-TYPE. JUST HOW MUCH ADDITIONAL PRECIP IN THE FORM OF
SNOW THAT CAN BACK INTO OUR AREA WITH THE DEVELOPING SECONDARY LOW
WILL DICTATE JUST HOW MUCH SNOWFALL WE RECEIVE…AND ULTIMATELY
WHAT TYPE OF HEADLINES WE DECIDE TO GO WITH.
— End Changed Discussion —

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/…
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THURSDAY NIGHT…WE BEGIN WITH THE DEPARTING SYSTEM OFF THE NEW
ENGLAND COAST BEING REPLACED WITH A BROAD ANTICYCLONIC FLOW THAT IS
EXPECTED TO EXTEND ACROSS THE OHIO AND TENNESSEE VALLEYS. THIS
RIDGE BUILDS EASTWARD OVERNIGHT THURSDAY WITH DIMINISHING POPS AND
CLOUD COVER.

FRIDAY…THIS RIDGE IS EXPECTED TO SLIDE ACROSS THE CWA AND INTO NEW
ENGLAND TOWARD SUNSET. THIS SHOULD KEEP OUR WEATHER TRANQUIL WITH
850MB TEMPS REBOUNDING TOWARD 0C. ALONG WITH EARLY MARCH PARTIAL
SUNSHINE EXPECTED…THIS SHOULD EQUATE TOWARD TEMPERATURES CLIMBING
TOWARD THE 40S FOR THE REGION. HOWEVER…WITH EXPECTATIONS OF SNOW
COVER…WE WILL KEEP THOSE HIGH TEMPS INTO THE 30S AND LOWER 40S.

FRIDAY NIGHT…TRENDS CONTINUE TO FAVOR A RAPIDLY DEEPENING STORM
OVER THE MISSISSIPPI RIVER VALLEY AND TRACKING TOWARD THE CENTRAL
GREAT LAKES REGION. THIS WILL PLACE OUR REGION UNDER AN INCREASING
SOUTHERLY FLOW AND MOISTURE TRANSPORT FROM THE GULF OF MEXICO. THE
CHANCE FOR SHOWERS IS EXPECTED TO INCREASE OVERNIGHT. AS PER THE
HPC EXTENDED DISC…WE DO PREFER THE SLOWER ARRIVAL TIME GIVEN THE
DEEPENING NATURE OF THIS STORM. WITH THAT SAID…PRECIP TYPE ISSUES
ARE EXPECTED ONCE AGAIN. A LARGE PART TO THIS WILL BE JUST HOW FAR
TEMPS FALL FRIDAY EVENING BEFORE THE ONSET OF CLOUDS AND ASSOCIATION
WARMING TEMPERATURES. FOR NOW…WE WILL PLACE A RAIN/SNOW MIXTURE
THAT COULD TRANSITION TO MAINLY RAIN BY SUNRISE SATURDAY MORNING.

SATURDAY…AS WE BEGIN THIS FIRST WEEKEND OF MARCH…A POTENT COLD
FRONT APPROACHES. CURRENT GUIDANCE SUGGESTS THE SURFACE LOW BOTTOMS
OUT NEAR 975MB OVER LOWER ONTARIO/QUEBEC. STRONG LOW LEVEL JET WILL
PRECEDE THIS FROPA ALONG WITH A SMALL POTENTIAL FOR THUNDER AS
SHOWLATERS DO DROP BACK TOWARD THE LOWER SINGLE DIGITS. THIS FRONT
WILL QUICKLY PASS THROUGH THE REGION WITH COLD ADVECTION QUICKLY
TAKING PLACE DURING THE AFTERNOON AND EVENING HOURS.

SATURDAY NIGHT INTO SUNDAY…WE WILL FAVOR THE ECMWF AND KEEP POPS
RATHER LOW FOR THE REMAINDER OF THE WEEKEND. THERE REMAINS THE
UPPER TROUGH AS ADDITIONAL UPPER JET SUPPORT IS EXPECTED TO MOVE
INTO THE UPPER PLAINS WHICH ALSO FAVORS A SLOWER SOLUTION OFFERED BY
THE ECMWF. WE WILL GO CLOSE TO HPC GUIDANCE VALUES WITH
TEMPERATURES CLOSE TO OR SLIGHTLY BELOW SEASONABLE VALUES.
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&&

.AVIATION /21Z MONDAY THROUGH SATURDAY/…
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MIDLEVEL CLOUDS HAVE SPREAD ACROSS THE REGION…AND VFR CEILINGS
SHOULD CONTINUE THROUGH TONIGHT. CEILINGS COULD FLIRT WITH MVFR
LATE THIS AFTERNOON AND EVENING IF A BRIEF SHOWER OR SNOW SHOWER
WERE TO OCCUR AT KGFL AND KALB. NOT ENOUGH COVERAGE OF RAIN AND
SNOW SHOWERS TO ACKNOWLEDGE IN TEMPO GROUP SO JUST VCSH AROUND
22Z-02Z.

COLD FRONT TRACKS THROUGH LATER THIS EVENING AND OVERNIGHT AND
CEILINGS SHOULD BREAK UP WITH VFR CONDITIONS CONTINUING THROUGH
TOMORROW MORNING.

SOUTH TO SOUTHWEST WINDS THIS AFTERNOON AT AROUND 10KT WITH SOME
GUSTS TO 20 KT AT KALB AND KPOU. WINDS SHIFT TO NORTH AND NORTHWEST
TONIGHT AT 50 TO 10 KT…THEN INCREASE TO 10 TO 15 KT TOMORROW
MORNING.

OUTLOOK…
TUE…VFR…NO SIG WX.
TUE NGT-THU…VFR/MVFR…CIG…CHC IFR IN -SN/-RA.
THU NGT-FRI…VFR…NO SIG WX.
SAT…CHC MVFR/IFR IN -SHRA/-SHSN.
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&&

.HYDROLOGY…
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NO HYDRO WIDESPREAD HYDRO RELATED PROBLEMS ARE EXPECTED FOR THE
NEXT 5 DAYS ON THE MAIN STEM RIVERS. SOME HYDRO GAGES ARE STILL
BEING IMPACTED BY ICE FROM THE MOHAWK RIVER VALLEY IN THE ALBANY
HYDRO SERVICE AREA NORTHWARD.

A CLIPPER WILL BRING SOME LIGHT SNOW AND RAIN SHOWERS TO THE HSA
TONIGHT. TOTAL QPF WILL GENERALLY BE ONE TENTH OF AN INCH OR
LESS…AND MAINLY CONFINED TO THE HIGHER TERRAIN. THIS SHOULD HAVE
NO IMPACT ON AREA RIVERS AND STREAMS.

A MODERATE TO HEAVY PRECIPITATION EVENT IS LIKELY WEDNESDAY INTO
THURSDAY WITH TOTAL QPF IN THE ONE HALF TO ONE INCH RANGE. A LARGE
PORTION OF THE PRECIPITATION MAY FALL AS SNOW AND SLEET…MIXING
WITH SOME RAIN OR FREEZING RAIN IN THE SOUTHERN REACHES OF THE
HSA.

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.
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&&

.ALY WATCHES/WARNINGS/ADVISORIES…
CT…NONE.
NY…NONE.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…FRUGIS
NEAR TERM…FRUGIS
SHORT TERM…FRUGIS
LONG TERM…BGM
AVIATION…NAS
HYDROLOGY…FRUGIS/WASULA

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