January 16, 2012 Forecast Discussion

000
FXUS61 KALY 161120
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
620 AM EST MON JAN 16 2012

.SYNOPSIS…
AN ARCTIC HIGH PRESSURE SYSTEM WILL MOVE OFF THE EAST
COAST TODAY…AS A LOW PRESSURE SYSTEM APPROACHES FROM THE WEST.
THIS WILL ALLOW CLOUDS TO INCREASE THIS AFTERNOON…WITH LIGHT SNOW
DEVELOPING THIS EVENING…CHANGING TO A WINTRY MIX LATER TONIGHT
INTO TUESDAY MORNING. THE PRECIPITATION WILL THEN CHANGE TO RAIN
TUESDAY AFTERNOON…BEFORE ENDING AS SNOW SHOWERS TUESDAY NIGHT.
WINDY AND COLDER CONDITIONS WILL RETURN FOR LATE TUESDAY NIGHT INTO
WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
AS OF 625 AM EST…JUST SOME MINOR TWEAKS TO HOURLY
TEMPS/DEWPOINTS ACCORDING TO RECENT OBS. MESONET OBS INDICATE
TEMPS IN THE -15 TO -20 RANGE ACROSS PORTIONS OF THE SOUTHERN
ADIRONDACKS…AND -5 TO -10 ACROSS THE SOUTHERN GREENS AND
BERKSHIRES. ELSEWHERE…TEMPS GENERALLY HOLDING BETWEEN -5 AND +5.

PREVIOUS DISCUSSION FOLLOWS…

AS OF 445 AM EST…CLEAR SKIES AND NEARLY CALM WINDS HAVE ALLOWED
TEMPS TO DROP INTO THE +5 TO -5 F RANGE ACROSS THE HUDSON AND
MOHAWK RIVER VALLEYS…WITH -5 TO -10 DEGREES ACROSS HIGHER
ELEVATIONS ACROSS WESTERN NEW ENGLAND…AND -10 TO -15 DEGREES
ACROSS THE WESTERN ADIRONDACKS. TEMPERATURES ACROSS THE WESTERN
ADIRONDACKS MAY RISE A COUPLE OF DEGREES BY DAYBREAK AS SOME MID
LEVEL CLOUDS APPROACH. ELSEWHERE…TEMPS MAY STILL FALL ANOTHER
2-4 DEGREES THROUGH SUNRISE.

A SUNNY START TO THE DAY WILL GIVE WAY TO INCREASING HIGH AND MID
LEVEL CLOUDS…AS WARM ADVECTION ALOFT DEVELOPS….AND SOME HIGH
LEVEL MOISTURE FROM A SHEARING SHORTWAVE ACROSS THE SOUTHEAST
STATES COMBINES WITH THE PASSAGE OF A SHORTWAVE NORTH OF THE GREAT
LAKES.

SOUTH TO SOUTHEAST WINDS WILL INCREASE THIS AFTERNOON…AS THE LOW
LEVEL PRESSURE GRADIENT TIGHTENS BETWEEN THE STRONG DEPARTING HIGH
TO OUR EAST…AND LOWERING PRESSURES ACROSS THE GREAT LAKES/OHIO
VALLEY REGION. THE S/SE WINDS WILL INCREASE FURTHER WITHIN THE
HUDSON RIVER VALLEY…WHERE SOME GUSTS OF 25-30 MPH WILL BE
POSSIBLE THIS AFTERNOON…ESP WITHIN THE IMMEDIATE CAPITAL REGION.

SOME SUNSHINE AND OVERALL WARM ADVECTION SHOULD ALLOW TEMPS TO
REACH 25-30 IN MUCH OF THE HUDSON AND MOHAWK RIVER VALLEYS
TODAY…WITH MAINLY LOWER/MID 20S ACROSS HIGHER ELEVATIONS. SOME
OF THE WARMEST TEMPS…REACHING IN THE LOWER 30S…MAY ACTUALLY
OCCUR WITHIN THE SOUTHERN GREENS AND NORTHERN BERKSHIRES…WHERE
SOME DOWNSLOPE COMPONENT TO THE WIND ALLOWS FOR SLIGHTLY WARMER
TEMPS.

SLIGHT CHC POPS ARE INDICATED ACROSS FAR WESTERN AREAS AROUND OR
AFTER SUNSET…TO ACCOUNT FOR THE POSSIBILITY THAT SOME SPOTTY
LIGHT SNOW DEVELOPS WITHIN INTENSIFYING WARM ADVECTION.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/…
TONIGHT…MID LEVEL ISENTROPIC LIFT WILL INTENSIFY ACROSS THE
REGION THIS EVENING THROUGH THE OVERNIGHT HOURS. THIS SHOULD
PRODUCE PERIODS OF MAINLY LIGHT PRECIPITATION…ALTHOUGH A FEW
BRIEF BURSTS OF MODERATE INTENSITY ARE POSSIBLE. THROUGH
MIDNIGHT…MOST PRECPITATION SHOULD BE IN THE FORM OF SNOW.
THEREAFTER…AS WARMING OCCURS AROUND 800-850 MB…SOME SLEET AND
FREEZING RAIN WILL GRADUALLY MIX IN FROM SOUTH TO NORTH. IT
APPEARS THAT P-TYPE MAY VERY WELL DEPEND ON THE EXACT INTENSITY OF
PRECIPITATION OVERNIGHT…WITH HEAVIER PRECIP ELEMENTS PRODUCING
MAINLY SNOW OR SLEET…THEN WHEN INTENSITY DECREASES AND CLOUD
DEPTH BECOMES MORE SHALLOW…FREEZING RAIN OCCURS. OVERALL QPF
APPEARS LIGHT…GENERALLY AROUND OR JUST OVER ONE TENTH OF AN
INCH. THIS SHOULD PRODUCE SNOWFALL AMOUNTS OF AROUND AN INCH IN
MOST AREAS…EXCEPT FOR LOCALLY HIGHER AMOUNTS…OF 1-3 INCHES
ACROSS THE BERKSHIRES…AND FROM THE NORTHERN PORTIONS OF THE
MOHAWK VALLEY INTO THE LAKE GEORGE/SARATOGA REGION. ICE ACCRETION
SHOULD GENERALLY REMAIN UNDER ONE TENTH OF AN INCH.
HOWEVER…SINCE GROUND/ROAD SURFACES WILL BE SO COLD COMING OUT OF
THIS BRIEF BITTER STRETCH…THAT ICY CONDITIONS COULD DEVELOP QUITE
FAST…PRODUCING TREACHEROUS TRAVEL CONDITIONS LATE TONIGHT.

TUESDAY…A LIGHT WINTRY MIX OF SNOW/SLEET/FREEZING RAIN SHOULD
CONTINUE THROUGH MID MORNING FOR AREAS SOUTH OF THE MOHAWK
RIVER…AND UNTIL EARLY AFTERNOON TO THE NORTH. WARMER AIR WILL
EVENTUALLY WORK NORTHWARD UP THE HUDSON RIVER VALLEY IN THE
MORNING…REACHING THE MID HUDSON VALLEY SHORTLY AFTER
DAYBREAK…AND CLOSER TO THE CAPITAL REGION AND BERKSHIRES BY MID
MORNING. FURTHER N…THE LOW LEVEL COLD AIR MAY BE MORE DIFFICULT
TO DISLODGE…ESP ACROSS SOME DEEPER VALLEY REGIONS WITHIN THE
SOUTHERN ADIRONDACKS…SOUTHERN VT…AS WELL AS THE LAKE
GEORGE/GLENS FALLS AREA. AGAIN…EXPECT TREACHEROUS TRAVEL
CONDITIONS FOR THE MORNING COMMUTE IN MOST AREAS…AND PLAN AHEAD
ACCORDINGLY. THE PRECIPITATION SHOULD TRANSITION TO RAIN SHOWERS
DURING TUESDAY AFTERNOON AS THE BOUNDARY LAYER WARMS IN TANDEM
WITH WARMING ALOFT. FOR MAX TEMPS…GENERALLY EXPECT QUITE A
SOUTH/NORTH THERMAL CONTRAST…WITH MAXES ONLY REACHING THE MID TO
POSSIBLY UPPER 30S ACROSS THE SOUTHERN ADIRONDACKS…LAKE GEORGE
REGION…AND NORTHERN PORTIONS OF THE MOHAWK VALLEY EXTENDING INTO
HIGHER ELEVATIONS OF SOUTHERN VT…WITH MAXES REACHING AROUND 40
CLOSE TO THE CAPITAL REGION…AND 40-45 WITHIN THE HUDSON VALLEY
SOUTH OF THE CAPITAL REGION. EVEN WARMER TEMPS COULD OCCUR WITHIN
THE MID HUDSON VALLEY SHOULD ANY BREAKS IN THE CLOUDS DEVELOP.

TUE NT/WED…AS AN INTENSIFYING LOW TRACKS ACROSS NORTHERN NEW
ENGLAND…A COLD FRONT WILL SWEEP ACROSS THE REGION DURING THE
LATE EVENING HOURS. RAIN SHOWERS WILL PRECEDE THIS FRONTAL
BOUNDARY…WITH PRECIPITATION CHANGING BACK TO SNOW ACROSS THE
SOUTHERN ADIRONDACKS FIRST…AND POSSIBLY INTO THE WESTERN MOHAWK
VALLEY AND LAKE GEORGE REGION BY MIDNIGHT. BEHIND THE
FRONT…STRONG WEST TO NORTHWEST WINDS WILL DEVELOP WITHIN A
TIGHTENING LOW LEVEL PRESSURE GRADIENT. THERE IS SOME POTENTIAL
FOR WIND GUSTS TO APPROACH 50 MPH LATE TUE NT…ESP WITHIN THE
MOHAWK RIVER VALLEY/CAPITAL REGION…AS WELL AS THE NE CATSKILLS
INTO THE BERKSHIRES. WE WILL HIGHLIGHT THIS POTENTIAL IN THE
HWOALY. THESE STRONG WINDS WILL PERSIST INTO WED MORNING…BEFORE
GRADUALLY EASING LATE WED. IN ADDITION…GIVEN WIND TRAJECTORIES
FROM THE GREAT LAKES…SOME OROGRAPHIC/UPSLOPE SNOWFALL WILL
DEVELOP ACROSS THE WESTERN ADIRONDACKS LATE TUE NT…AND INTO THE
SOUTHERN GREENS/BERKSHIRES AND TACONICS BY WED MORNING. THERE IS
THE POTENTIAL FOR ADVISORY LEVEL SNOWFALL ACCUMS IN THESE
REGIONS. THE ONE NOTABLE FEATURE DIFFERENT FROM THE LOCALLY HEAVY
UPSLOPE SNOWS FROM FRIDAY IS THAT THE MAIN UPPER LEVEL LOW WILL BE
TRANSLATING NORTH OF THE REGION…WITH MUCH LESS DEFORMATION
ACROSS THE REGION. IN ADDITION…THE MID LEVELS WILL BE MUCH DRIER
IN COMPARISON TO LAST FRIDAY…WHEN A DEEPER MOIST COLUMN COMBINED
WITH INSTABILITY AND INTERACTED WITH THE TERRAIN IN THIS REGION.
SO…WE ARE NOT AT THIS TIME EXPECTING A REPEAT PERFORMANCE OF
LAST FRIDAY. HOWEVER…LOCALIZED MODERATE SNOWFALL AMOUNTS WILL
STILL BE POSSIBLE…AND WILL ADDRESS IN THE HWOALY. AS FOR
TEMPS…FOR TUE NT…HAVE GONE ABOVE BOTH THE MAV AND MET
MOS…DUE TO THE EXPECTATION FOR PERSISTENT WIND…AND CLOUDS. ON
WED…MAXES WILL LIKELY OCCUR IN THE MORNING…BEFORE TEMPS FALL
THROUGHOUT THE DAY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/…
QUICK BROAD CYCLONIC FLOW WILL DOMINATE ACROSS EASTERN NORTH AMERICA
THROUGH THE PERIOD. WEAK HIGH PRESSURE BUILDS INTO THE REGION
WEDNESDAY NIGHT…BUT THE NEXT SYSTEM WILL APPROACH FROM THE GREAT
LAKES THURSDAY. EVEN WITH THE INCREASING WARM ADVECTION…BOUNDARY
LAYER TEMPERATURES SHOULD NOT WARM SO MUCH AS TO SUPPORT MIXED
PRECIPITATION. LOWS WEDNESDAY NIGHT IN THE TEENS TO SINGLE
NUMBERS…SOME BELOW ZERO IN THE SOUTHERN ADIRONDACKS. HIGHS
THURSDAY WITH INCREASING HIGH CLOUDS IN THE 20S TO LOWER 30S.

QUICK NORTHERN STREAM UPPER IMPULSE TRACKS THROUGH THE REGION
THURSDAY NIGHT INTO EARLY FRIDAY WITH RELATIVELY LITTLE MOISTURE.
SOME LAKE EFFECT MOISTURE AND UPPER DYNAMICS COULD RESULT IN SOME
LIGHT ACCUMULATING SNOW ACROSS THE REGION…ESPECIALLY IN HIGHER
TERRAIN. ANY PRECIPITATION SHOULD MOVE OUT FRIDAY DURING THE DAY AS
ANOTHER BRIEF SHOT OF COLD AIR ARRIVES. HIGHS FRIDAY IN THE 20S TO
LOWER 30S…SOME UPPER TEENS IN THE SOUTHERN ADIRONDACKS.

BEYOND FRIDAY…RAPIDLY INCREASING SPREAD SEEN IN GUIDANCE AND
ENSEMBLES AS TO THE TIMING OF NORTHERN STREAM UPPER ENERGY AND UPPER
RIDGING BEHIND IT. A NORTHERN STREAM SYSTEM MAY AFFECT OUR REGION
OVER THE WEEKEND BUT TIMING VERY MUCH IN QUESTION. SO JUST
SUGGESTING GENERIC SLIGHT CHANCES FOR PRECIPITATION WITH VARYING
AMOUNTS OF CLOUDS. TOO MUCH UNCERTAINTY TO GET TOO SPECIFIC ABOUT
PRECIPITATION TIMING AND TYPES.

HOWEVER…GOOD CONSENSUS ON UPPER RIDGING BUILDING INTO EASTERN
NORTH AMERICA ONCE THE NORTHERN STREAM ENERGY EXITS…WITH WARMING
TEMPERATURES. LOWS FRIDAY NIGHT IN THE SINGLE NUMBERS TO AROUND
10…AROUND ZERO OR JUST BELOW ZERO IN THE SOUTHERN ADIRONDACKS.
HIGHS SATURDAY IN THE 30S…SOME UPPER 20S IN THE SOUTHERN
ADIRONDACKS. LOWS SATURDAY NIGHT IN THE 20S TO AROUND 30…SOME
UPPER TEENS IN THE SOUTHERN ADIRONDACKS. HIGHS SUNDAY IN THE
40S…WITH MID TO UPPER 30S IN HIGHER ELEVATIONS.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/…
HIGH PRESSURE WILL CONTROL THE WEATHER ACROSS THE REGION MOST OF THE
DAY…AS IT BUILDS EAST AND OFFSHORE. HIGH CLOUDS WILL SPREAD
ACROSS THE REGION THROUGH THE DAY…AND EVENTUALLY CEILINGS WILL
LOWER TOWARD MVFR LATE THIS EVENING. LIGHT MIXED PRECIPITATION
SHOULD DEVELOP AROUND OR JUST BEFORE MIDNIGHT AT ALL THREE SITES AND
WILL BE INDICATED AFTER 04Z…WITH MVFR VISIBILITIES…AND AGAIN
CEILINGS TRENDING TOWARD MVFR.

WINDS WILL BE LIGHT TO CALM TONIGHT. WINDS WILL RECOVER OUT OF THE
SOUTH AT 7-12 KTS THROUGH THE DAY…AND DIMINISH THIS EVENING TO 6
KTS OF LESS…STILL FROM THE SOUTH.

OUTLOOK…
TUE…MVFR/IFR…PCPN LIKELY…WINTRY MIX CHANGING TO RAIN. TUE
NIGHT…MVFR WITH IFR POSSIBLE…CHANCE OF PCPN. RAIN CHANGING TO
SNOW.
WED…VFR…WINDY. SLIGHT CHC -SHSN.
WED NIGHT…VFR…NO SIG WX.
THU…MAINLY VFR…SLIGHT CHC -SHSN WITH MVFR POSSIBLE.
FRI…VFR. NO SIG WX.

&&

.HYDROLOGY…
NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS OVER THE NEXT
5 DAYS.

LIGHT PRECIPITATION IS EXPECTED TONIGHT INTO TUE EVE…WITH QPF
AMTS GENERALLY REMAINING UNDER ONE QUARTER OF AN INCH…AND AT
LEAST SOME OF THIS WILL BE IN THE FORM OF FROZEN PRECIPITATION.

ICE FORMATION/THICKENING WILL SLOW DOWN OVER THE NEXT TWO DAYS AS
TEMPERATURES MODERATE TO NEAR OR ABOVE SEASONAL LEVELS. ICE
FORMATION SHOULD INCREASE AGAIN WEDNESDAY INTO THURSDAY AS
TEMPERATURES FALL BACK BELOW FREEZING.

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…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST
TUESDAY FOR CTZ001-013.
NY…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST
TUESDAY FOR NYZ047>054-058>061-063>066.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 2 PM EST
TUESDAY FOR NYZ032-033-038>043-082>084.
MA…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST
TUESDAY FOR MAZ001-025.
VT…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 2 PM EST
TUESDAY FOR VTZ013>015.

&&

$$
SYNOPSIS…KL/GJM
NEAR TERM…KL
SHORT TERM…KL
LONG TERM…NAS
AVIATION…NAS
HYDROLOGY…KL/GJM

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