December 27, 2013 Forecast Discussion

000
FXUS61 KALY 280016
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
716 PM EST FRI DEC 27 2013

.SYNOPSIS…
MILD DAY IS ON TAP FOR SATURDAY. A WARM FRONT WILL ACROSS THE REGION
OVERNIGHT AND HIGH PRESSURE WILL BUILD IN ON SATURDAY. THE HIGH
WILL QUICKLY MOVED OUT OF THE REGION AS A STORM WILL TRACK UP THE
EASTERN COAST SUNDAY. RAIN WILL OVERSPREAD MUCH OF THE AREA IN THE
AFTERNOON WITH THE RAIN CHANGING TO SNOW DURING THE EVENING. COLDER
AIR WILL RETURN TO CLOSE OUT THE YEAR AFTER THE PASSAGE OF A STRONG
COLD FRONT MONDAY.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/…
LOWER LEVEL CLOUDS ARE HANGING TOUGH ACROSS MUCH OF THE FORECAST
AREA. THEY EXTEND WESTWARD ACROSS CENTRAL NEW YORK ITO WESTERN NEW
YORK. PLUS A HIGHER CLOUD DECK IN MOVING IN. HAVE ADJUSTED TEMPERATURES
FOR THE OVERNIGHT. A WARM FRONT WILL CROSS THE REGION. TEMPERATURES
WILL FALL SOME BUT THEN WILL LEVEL OFF THEN EVEN RISE LATER
TONIGHT. MAINLY LOOKING A DRY WEATHER.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/…
HIGH PRESSURE WILL CREST TO OUR SOUTH ON SATURDAY…BRINGING A BRIEF
MODERATION IN TEMPERATURES AS THE WIND FLOW BECOME SOUTHWESTERLY.
THERE WILL BE SOME SUNSHINE…MAINLY SOUTH OF THE CAPITAL
DISTRICT…MORE IN THE WAY OF CLOUDS NORTH AS THESE PLACES WILL BE
NEAR A WEAK STATIONARY BOUNDARY. OUTSIDE A FEW POSSIBLE FLURRIES
ACROSS THE ADIRONDACKS…IT WILL BE DRY.

LOOK FOR HIGHS INTO THE 30S ACROSS THE ADIRONDACK PARK AND SOUTHERN
GREENS…40-45 ALBANY SOUTHWARD…MILDEST IN THE MID HUDSON VALLEY.
A SOUTH TO SOUTHWEST BREEZE WILL BE 5 TO 15 MPH.

TRANQUIL CONDITIONS WILL PERSIST INTO SATURDAY NIGHT. INITIALLY IT
LOOKS TO BE PARTLY CLOUDY…BUT HIGH CLOUDS WILL INCREASE LATE AT
NIGHT. DEVIATED A LITTLE FROM MACHINE GUIDANCE TEMPERATURES (LOOKED
TOO COLD SOUTH AND A LITTLE WARM NORTH). OVERALL…LOWS ARE
FORECASTED TO BE MAINLY IN THE 20S…WITH SOME TEENS TO THE NORTH.

A SOUTHERLY BREEZE 5 TO 10 MPH WILL BECOME LIGHT OVERNIGHT.

LOW PRESSURE DOWN IN THE GULF CONTINUED TO SLOWLY GET ITS ACT
TOGETHER…STILL MORE OF A MID LEVEL FEATURE ACROSS WESTERN TEXAS.
IT WILL DEEPEN MORE AS IT TRACKS ALONG AN INCREASING BAROCLINIC
ZONE. BY SUNDAY MORNING…IT WILL OVER THE SOUTHEAST WITH WHAT COULD
QUITE A BIT OF MOISTURE. THE GEFS KEEP THE ONE INCH PWAT CONTOUR
LOOKS TO STAY SOUTH AND EAST OF THE REGION…BUT WE WILL STILL GET
INTO 20-3 STANDARD DEVIATION ABOVE NORMAL PWAT AIR OF NEARLY HALF AN
INCH. THE NAM GUIDANCE WAS WETTER WITH THE ONE INCH PWAT INTO AREAS
SOUTH AND EAST OF ALBANY. HOWEVER IT WAS ALSO WARMER AS WELL.

THE BEST H850 AND H925 SOUTHERLY WINDS ALSO ARE FORECAST TO REMAIN
OFFSHORE SUNDAY NIGHT ON THE GEFS BUT HUG THE COAST ON THE NAM
MODELS.

OUR THINKING IS THAT LOW PRESSURE WILL LIKELY TRACK JUST TO THE EAST
OF THE "BENCHMARK" (40/70) POINT TO THE SOUTHEAST OF CAPE COD. WITH
SUCH A TRACK…WE FAVOR THE SLIGHTLY COLDER SOLUTION. (BTW…THE
EUROPEAN AND EVEN CANADIAN FAVOR THIS TRACK AS WELL). RAIN…(MIXED
WITH SLEET AND SNOW) WILL OVERSPREAD THE REGION SOUTH TO NORTH
STARTING LATE SUNDAY MORNING…REACHING THE CAPITAL REGION BY MID
AFTERNOON…AND SOUTHERN VERMONT BY EVENING. IT WILL BE A FAST MOVER
(OPEN WAVE…NO CLOSED STRUCTURE). THE 300-PV TRACES STILL INDICATED
NO PHASING WITH THE NORTHERN STREAM. THE PRECIPITATION WILL BE
HEAVIEST TO THE SOUTHEAST.

DYNAMICAL COOLING OF MELTING SNOWFLAKES SHOULD ALLOW RAIN OR MIXED
PRECIPITATION TO CHANGE ALL SNOW AROUND DARK ACROSS MOST AREAS (IF
NOT A LITTLE SOONER OVER THE MOUNTAINS). WE ARE THINKING AT LEAST
LIGHT SNOWFALL ACCUMULATIONS IN THE VALLEYS…POSSIBLY MODERATE OVER
THE MOUNTAINS. HOWEVER…THE EXACT TRACK AND ULTIMATE THERMAL
PROFILE WILL PLAY A HUGE ROLE IN DETERMINING EXACT SNOWFALL
ACCUMULATIONS WHICH ARE HIGHLY UNCERTAIN AT THIS TIME.

WE UNDERCUT THE MACHINE GUIDANCE FOR HIGHS ON SUNDAY…AS THE CLOUDS
LOOK TO ROLL IN BY DAYBREAK…AND IF THE STORM TRACKS TO THE
SOUTHEAST…OUR WIND WILL LIKELY HOLD FROM THE NORTH OR NORTHEAST
(AT LEAST IN THE VALLEYS) PROVIDING OF DRAINAGE WIND OF ADDITIONAL
LOW LEVEL COLD AIR DAMMING. LOOK FOR HIGHS IN THE 30S ON
SUNDAY…MAINLY ABOVE FREEZING…EXCEPT SOME OF THE HIGHEST
ELEVATIONS TO THE NORTH AND WEST OF ALBANY WHICH WILL BE CLOSER TO
30.

COLDER AIR WORKS IN BEHIND THE STORM LATE SUNDAY DROPPING
TEMPERATURES WELL DOWN INTO THE 20S INSURING ANY SLUSHY SNOW OR WET
ROADS COULD TURN ICY.

MONDAY AS THE STORM DEPARTS…AN ARCTIC FRONT WILL QUICKLY FOLLOW ON
ITS HEELS. THIS FRONT LOOKS TO MOVE DURING THE MORNING DRIVING SOME
OF THE COLDEST YEAR OF THE SEASON OUR WAY. THE COLDEST AIR WILL BE
REALIZED MONDAY NIGHT INTO THE LATTER PORTION OF THE WEEK. (SEE THE
EXTENDED PORTION OF THE DISCUSSION FOR MORE ABOUT THE COLD).

WE ARE CONCERNED THAT A BURST OF SNOW SQUALLS COULD ACCOMPANY THIS
FRONT ALTHOUGH THE 12Z MODEL GUIDANCE DID NOT SUPPORT THIS IDEA JUST
YET. FOR NOW…WENT WITH SLIGHT POPS FROM ALBANY SOUTHWARD…CHANCES
FURTHER NORTH…ESPECIALLY ACROSS THE ADIRONDACKS WHERE LAKE
MOISTURE WOULD HELP INCREASE THE CHANCE OF CONVECTIVE SNOW
SHOWERS.

HIGHS MONDAY WILL BE 30-35 FROM ALBANY SOUTHWARD…TEENS ACROSS THE
ADIRONDACKS…20S ELSEWHERE. THESE HIGHS MIGHT HAPPEN DURING THE
MORNING…FALLING MORE DURING THE AFTERNOON.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/…
THE LATEST 12 MODELS GUIDANCE AND MOS DATA ARE IN GOOD AGREEMENT FOR
THE EXTENDED PERIOD. WITH SLIGHT VARIATIONS OF THE MAGNITUDE OF THE
COLD AIR THAT WILL FILL INTO THE REGION AT THE BEGINNING OF THE
EXTENDED PERIOD…OVERALL TEMPERATURES WILL BE WELL BELOW AVERAGE AT
THIS TIME AS A BROAD UPPER LEVEL 500 HPA POSITIVE TILTED TROUGH
BRINGS A PERSISTENT NORTH TO NORTHWESTERLY FLOW ACROSS THE ENTIRE
REGION. AS OF LATEST INTERPRETATION OF THE DATA…THE COLDEST
SECTION OF THE EXTENDED PERIOD LOOKS TO BE ON WEDNESDAY NIGHT INTO
THURSDAY AS THE COLDEST AIR WITH ORIGINS NEAR THE 483 DECAMETER
POLAR VORTEX OVER CENTRAL QUEBEC WILL BRING T850 TEMPS RANGING FROM
-20C TO -30C AND T925 TEMPS FROM -15 TO -20C BEFORE SLIGHT
MODERATION OF TEMPERATURES OCCUR AT THE END OF THE EXTENDED PERIOD.
THE ECMWF SUPPORTS COLDER MEMBERS WHILE THE GFS MODEL SUPPORTS
WARMER MEMBERS OF THESE RANGES. HIGH TEMPERATURES THROUGH THE
EXTENDED PERIOD WILL RANGE FROM THE SINGLE DIGITS IN THE ADIRONDACKS
TO MID AND UPPER TEENS NORTH AND WEST OF THE IMMEDIATE CAPITAL
REGION TO LOWER AND MID 20S SOUTH AND EAST OF THE IMMEDIATE CAPITAL
REGION. LOW TEMPERATURES WILL BE WELL BELOW ZERO IN THE ADIRONDACKS
TO NEAR ZERO NORTH OF THE IMMEDIATE CAPITAL REGION AND SINGLE DIGITS
TO LOW TEENS FOR THE REST OF THE REGION.

WEATHER CONDITIONS SHOULD BE RELATIVELY QUIET THROUGHOUT THE
EXTENDED PERIOD WHERE LAKE EFFECT SNOW SHOWERS SHOULD DIMINISH AS WE
GET CLOSER TO THURSDAY AS A COLD CANADIAN HIGH PRESSURE ANCHORS INTO
THE REGION WITH LARGE UPPER LEVEL SUBSIDENCE IS OVER THE REGION.
SOME MODELS SHOWS A POTENTIAL COASTAL LOW GRAZING OUR SOUTHERN AREAS
AS WE GO INTO THE DAY ON FRIDAY. OTHER MODELS TAKE THAT SAME LOW
PRESSURE SYSTEM WELL OUT TO SEA. THIS IS THE RESULT OF UPPER LEVEL
DYNAMICS INTERACTING IN THE SOUTHEASTERN UNITED STATES…WHICH GETS
DEFLECTED BY THE LARGE UPPER LEVEL TROUGH AXIS IN THE NORTHEAST
HEADING INTO FRIDAY NIGHT. SLIGHT CHANCE TO CHANCE POPS ARE IN THE
FORECAST FOR THURSDAY THROUGH THE END OF THE EXTENDED PERIOD TO
REFLECT A BLEND OF UNCERTAINTIES AT THIS TIME.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/…
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD…00Z/SUNDAY. LOWER
LEVEL CLOUDS ARE HANGING TOUGH ACROSS MUCH OF THE FORECAST AREA.
THEY EXTEND WESTWARD ACROSS CENTRAL NEW YORK INTO WESTERN NEW
YORK. PLUS A HIGHER CLOUD DECK IN MOVING IN. CLOUD COVER WILL BE
MORE SCATTERED AT KPOU. SO HAVE REMOVED MENTION OF ANY FOG FROM
TAFS. A WARM FRONT WILL CROSS THE REGION. A BREAK IN THE CLOUD
COVER IS EXPECTED ONCE THE WARM FRONT PASSES AND HIGHER PRESSURE
BUILDING IN ON SATURDAY.

LIGHT SOUTH-SOUTHWEST TO WEST WINDS OVERNIGHT INCREASING TO 8 TO
20 KNOTS SATURDAY. GUSTS IN THE TEENS ARE EXPECTED AT KALB AND
KPSF FOR THE AFTERNOON HOURS.

OUTLOOK…
SAT NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
SUN: HIGH OPERATIONAL IMPACT. AFTN RA. CHC PL KGFL.
SUN NIGHT: HIGH OPERATIONAL IMPACT. RA TO SN.
MON: LOW OPERATIONAL IMPACT. SLIGHT CHANCE SHSN.
MON NIGHT-TUE NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
WED/NEW YEARS DAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE -SHSN.

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE EXPECTED THROUGH NEW YEARS.

TEMPERATURES WILL MODERATE TO SEASONABLE TO SLIGHTLY ABOVE NORMAL
LEVELS THROUGH THE WEEKEND. LATE SUNDAY A STORM WILL IMPACT THE
REGION. IT WILL BEGIN AS RAIN…BUT TURN TO SNOW. THE HIGHEST QPF
WILL BE SOUTH AND EAST OF ALBANY. OVER AN INCH OF RAIN COULD FALL TO
THE SOUTHEAST OF ALBANY…WHICH WOULD PRODUCE SOME MINOR WITHIN BANK
RISES ON MAINLY THE HOUSATONIC BASIN. ELSEWHERE LIGHT RAINFALL
AMOUNTS WITH RAIN CHANGING TO SNOW.

TEMPERATURES WILL TURN SHARPLY COOLER NEXT WEEK…AND ICE
FORMATION WILL RESUME IN EARNEST. OTHERWISE STREAM FLOWS WILL
RECEDE ACROSS THE REGION.

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…IAA/HWJIV
NEAR TERM…IAA/HWJIV
SHORT TERM…HWJIV
LONG TERM…LFM
AVIATION…IAA
HYDROLOGY…HWJIV

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