January 23, 2015 Forecast Discussion

000
FXUS61 KALY 240012
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
712 PM EST FRI JAN 23 2015

.SYNOPSIS…
A LOW PRESSURE SYSTEM ALONG THE GULF COAST STATES WILL RAPIDLY
STRENGTHEN INTO A NOR`EASTER AS IT TRACKS NORTHEASTWARD OFF THE
NORTH CAROLINA COAST TONIGHT…TO SOUTH OF LONG ISLAND AND SOUTHERN
NEW ENGLAND ON SATURDAY. THIS STORM IS EXPECTED TO BRING A LIGHT TO
MODERATE SNOWFALL FOR AREAS FROM MAINLY THE CAPITAL DISTRICT SOUTH
AND EAST…WITH HEAVY SNOW OVER LITCHFIELD COUNTY. ANOTHER STORM
SYSTEM IS EXPECTED TO PASS SOUTH OF THE REGION EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/…
AS OF 630 PM EST… NO CHANGES TO CURRENT HEADLINES AT THIS TIME.
THE STRATUS DECK ACROSS PORTIONS OF THE DACKS HAS DISSIPATED WITH
A CANOPY OF HIGH THIN SCT-BKN CI/CS SOUTH OF I90 EVOLVING. LATEST
3HR ISALLOBARIC PRESSURE DROPS WERE STILL INLAND INTO CENTRAL NC.
THERE WAS DEEP CONVECTION ACROSS THE SUNSHINE STATE AS MEAN UPPER
TROUGH WAS APPROACHING THE LOWER MISSISSIPPI RIVER AND WESTERN
OHIO RIVER VALLEYS. CONCERN REMAINS THAT DOWNSTREAM RIDGING MAY
AMPLIFY A LITTLE MORE AS 18Z NAM/GFS AND HOURLY RAP WAS JUST TO
THE LEFT OF THE PREVIOUS GUIDANCE. THIS HAS RESULTED TOO IN HIGHER
QPF VALUES FROM ALBANY AND POINTS SOUTH AND EAST. IF THESE TRENDS
CONTINUE…WE MAY HAVE SOME FURTHER ADJUSTMENTS TO HEADLINES.
OTHERWISE…CLOUDS WILL INCREASE AS TEMPERATURES LOOK GOOD.

PREV DISC..
UPGRADE TO A WINTER STORM WARNING FOR LITCHFIELD
COUNTY…WITH WINTER WEATHER ADVISORIES EXPANDED TO EASTERN
COLUMBIA…NORTHERN BERKSHIRE AND EASTERN WINDHAM COUNTY. WINTER
WEATHER ADVISORY CONTINUES FOR EASTERN ULSTER…DUTCHESS AND
SOUTHERN BERKSHIRE COUNTY.

AS OF 430 PM EST…SKIES HAVE BECOME MAINLY CLEAR ACROSS MUCH THE
REGION EXCEPT FOR SOME LINGERING CLOUDS OVER THE WESTERN
ADIRONDACKS. HOWEVER…CLOUDS WILL START TO INCREASE AGAIN THIS
EVENING AND ESPECIALLY OVERNIGHT AS A DEEPENING CYCLONE TRACKS
NORTHEASTWARD FROM THE GULF COAST STATES TO THE CAROLINAS.

SNOW WILL GRADUALLY OVERSPREAD THE REGION FROM SOUTH TO NORTH
OVERNIGHT…AS THIS SYSTEM QUICKLY STRENGTHENS AS IT HEADS
NORTHEASTWARD OFF THE DELMARVA. IT SHOULD REMAIN DRY THROUGH
MIDNIGHT…WITH SNOW BECOMING LIKELY ACROSS THE SOUTHERN THIRD OF
THE AREA BEFORE SUNRISE AS ISENTROPIC LIFT ON THE 290-295K SURFACE
INCREASES.

FORECAST MODELS…INCLUDING THE 12Z GFS/ECMWF/NAM HAVE ALL SHIFTED
THE TRACK OF THE CYCLONE NORTH AND WEST FROM PREVIOUS FORECASTS.
THIS TREND STARTED WITH LAST NIGHT/S 00Z ECMWF RUN…AND HAS
CONTINUED TODAY. A POSSIBLE REASON FOR THE SHIFT IS ASSOCIATED WITH
WIDESPREAD CONVECTION DEVELOPING OVER THE FLORIDA PANHANDLE AND
EXPANDING SOUTHWARD INTO THE GULF OF MEXICO. THIS CONVECTION IS
LIKELY TO INCREASE DOWNSTREAM RIDGING ALONG THE EASTERN
SEABOARD…WHICH IN TURN COULD CAUSE THE STORM TO TRACK CLOSER TO
THE COAST. WE HAVE ADJUSTED WINTER HEADLINES AND SNOWFALL AMOUNTS
ACCORDINGLY TO ACCOUNT FOR THIS EXPECTED SHIFT.

THIS STORM WILL STRENGTHEN CONSIDERABLY AS IT DEEPENS CLOSE TO 24 MB
IN 24 HOURS FROM 06Z SATURDAY AROUND 996MB JUST OFF THE DELMARVA TO
06Z SUNDAY AROUND 963MB OVER NEW BRUNSWICK. FRONTOGENESIS ON THE
NORTHWEST PERIPHERY OF THE SYSTEM WILL LEAD TO BANDING…ALTHOUGH AT
THIS TIME IT APPEARS MOST OF THE STRONGEST FORCING AND HEAVIEST
SNOWFALL RATES WILL BE INTO CENTRAL/SOUTHERN NEW ENGLAND.
HOWEVER…SOME OF THIS BANDING IS EXPECTED TO REACH INTO LITCHFIELD
COUNTY…WHERE SNOWFALL RATES COULD APPROACH ONE INCH PER HOUR AT
TIMES YIELDING STORM TOTALS OF AROUND 5-9 INCHES. THERMAL PROFILES
HAVE TRENDED COLDER AS WELL…SO WILL JUST MENTION SOME SLEET
POSSIBLY MIXING IN ACROSS SOUTHERN LITCHFIELD FROM MID MORNING TO
EARLY AFTERNOON SATURDAY.

TO THE NORTH AND WEST THERE WILL BE ENOUGH QPF WITHOUT BANDING TO
RESULT IN ADVISORY LEVEL SNOWS FOR SOUTHERN PARTS OF THE MID HUDSON
VALLEY…CENTRAL AND SOUTHERN TACONICS…BERKSHIRES AND EASTERN
WINDHAM COUNTY. ALSO INCREASED POPS AND SNOW AMOUNTS FOR 1-3 INCHES
FROM THE CAPITAL DISTRICT SOUTHEASTWARD TO THE ADVISORY AREA. AREAS
TO THE NORTH AND WEST OF THE CAPITAL DISTRICT SHOULD SEE LITTLE IF
ANY SNOW. HOWEVER…IF THE STORM TRACK SHIFTS FARTHER NORTH AND WEST
AMOUNTS WOULD INCREASE.

WE WILL CONTINUE TO MONITOR MODEL TRENDS FOR SUBSEQUENT CHANGES…AS
THE STORM IS STILL IN THE DEVELOPMENTAL STAGES WITH ONGOING
CONVECTION AND MAY END UP SHIFTING THE TRACK FURTHER.

SNOW SHOULD TAPER OFF FROM NORTHWEST TO SOUTHEAST SATURDAY
AFTERNOON. IT WILL LIKELY SNOW THROUGH MUCH OF THE AFTERNOON HOURS
FROM THE MID HUDSON VALLEY AND TACONICS TO WESTERN NEW ENGLAND.

SNOW SHOWERS WILL INCREASE IN COVERAGE ACROSS THE WESTERN
ADIRONDACKS LATE SATURDAY ASSOCIATED WITH A COLD FRONT APPROACHING
FROM THE GREAT LAKES. ANY ACCUMULATIONS THERE WILL BE LIGHT.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/…
THE SHORT TERM PERIOD OF THE FORECAST LOOKS TO FEATURE MUCH QUIETER
WEATHER. THE AFOREMENTIONED COLD FRONT WILL SWEEP FROM NORTHWEST TO
SOUTHEAST ACROSS THE REGION SATURDAY NIGHT WITH GENERALLY ISOLATED
TO PERHAPS SCATTERED SNOW SHOWERS. SNOW SHOWERS WILL BE LIKELY
ACROSS THE WESTERN ADIRONDACKS WHERE AN INCH OR TWO MAY
ACCUMULATE…AS THERE WILL BE SOME LAKE ENHANCED/UPSLOPE MOISTURE
THERE.

COLDER AIR WILL START TO FILTER IN LATE SATURDAY NIGHT INTO
SUNDAY…WITH THE COLDEST TEMPS OVER THE ADIRONDACKS. JUST A SLIGHT
CHANCE OF A FEW SNOW SHOWERS WEST OF ALBANY EARLY SUNDAY…OTHERWISE
DRY CONDITIONS WILL PREVAIL WITH TEMPERATURES SLIGHTLY BELOW NORMAL
AS ARCTIC HIGH PRESSURE STARTS TO BUILD IN FROM SOUTHEAST CANADA. A
VERY COLD NIGHT LOOKS TO BE IN STORE AS THE ARCTIC HIGH BUILD MOVES
INTO SOUTHERN QUEBEC…WITH NORTHERLY FLOW USHERING IN VERY COLD
AIR. MIN TEMPS EXPECTED TO BE IN THE SINGLE DIGITS TO BELOW ZERO
ACROSS MUCH OF THE AREA…BUT POSSIBLY WELL BELOW ZERO OVER THE
ADIRONDACKS.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/…
RATHER TRANQUIL PERIOD OF WEATHER EXPECTED FOR THE FIRST HALF OF THE
WEEK WITH AN INCREASE IN ACTIVE WEATHER TOWARD THE END OF THE
EXTENDED PERIOD.

MONDAY…
RECENT TRENDS HAVE BEEN A LITTLE FURTHER SOUTH WITH THE SHORT WAVE
ROUNDING THE BASE OF THE TROUGH. RECENT ENSEMBLE GUIDANCE SUGGEST
THIS WAVE WILL TRACK CLOSER TO THE I70 CORRIDOR THAN THE I80
CORRIDOR. THE PREVIOUS EXTENDED FORECAST HANDLED THIS VERY WELL
WITH VERY LITTLE CHANGES TO THE POPS/WX. THE 1025MB SURFACE HIGH
NORTH OF THE GREAT LAKES REGION WILL KEEP THE NORTHERN 2/3RDS OF THE
CWFA RATHER DRY WITH SOME PARTIAL SUNSHINE EXPECTED. AS H850
TEMPERATURES WILL AVERAGE -10C/-12C…SURFACE TEMPERATURES WILL
AVERAGE 5-10 DEGREES BELOW NORMAL.

MONDAY NIGHT…
CONSENSUS FAVORS A MORE PROGRESSIVE UPPER PATTERN AS SUGGESTED BY
THE ECMWF/GGEM AS THE GFS IS A LITTLE DEEPER WITH THE UPPER PATTERN
THEREFORE SLOWER WITH THE EXIT OF THIS WAVE. PER WPC GUIDANCE…WE
WILL KEEP OUR SOUTHERN COUNTIES DRY WITH A GRADUAL DECREASE IN CLOUD
COVER FROM NORTH TO SOUTH. AS SURFACE GRADIENT IS EXPECTED TO
REMAIN RATHER LIGHT AND A CLEARING TREND EXPECTED…OVERNIGHT LOWS
WILL BE RATHER CHILLY WITH BELOW ZERO READINGS EXPECTED INTO THE
TERRAIN AND SINGLE DIGITS ELSEWHERE.

TUESDAY-WEDNESDAY…
AN ELONGATED NORTH-SOUTH SURFACE RIDGE AND RISING HEIGHTS ALOFT WILL
RESULT A IN PERIOD OF TRANQUIL WEATHER AND A SLOW RETURN TO
SEASONABLE TEMPERATURES FOR THE END OF JANUARY. PARTLY CLOUDY TO
MOSTLY CLEAR SKIES ARE EXPECTED AS THE H850 TEMPS MODERATE INTO THE
NEGATIVE SINGLE DIGITS.

THURSDAY…
STRONG PACIFIC SYSTEM MOVING ACROSS THE BRITISH COLUMBIA COAST
EARLIER IN THE WEEK QUICKLY RACES ALONG THE U.S./CANADIAN BORDER AND
AMPLIFIES SOMEWHAT ACROSS THE GREAT LAKES REGION. SCATTERED SNOW
SHOWERS WILL LIKELY ACCOMPANY THIS SYSTEM WITH THE HIGHER POPS NORTH
AND WEST OF ALBANY WITH SLIGHT CHANCE POPS INTO THE MID HUDSON
VALLEY AND NORTHWEST CONNECTICUT. INCREASING CLOUD COVERAGE WITH
NEAR SEASONABLE TEMPERATURES.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/…
VFR CONDITIONS WILL DETERIORATE FROM SOUTH TO NORTH OVERNIGHT AS
THE STORM DEVELOPS AND INTENSIFIES OFF THE MID ATLANTIC COAST ON
SATURDAY. SNOW WILL SPREAD NORTH AND IMPACT KPOU-KPSF FIRST WITH A
DROP TO MVFR AND IFR CONDITIONS AFTER MIDNIGHT. THEN THIS SNOW
WILL SPREAD INTO KALB AROUND SUNRISE WITH MVFR CONDITIONS. FOR
KGFL…EXPECTATIONS ARE FOR VFR CONDITIONS TO PREVAIL AS THIS
LOCATION SHOULD REMAIN TO THE NORTH AND WEST FROM IMPACTS OF THIS
STORM. A PERIOD OF IFR IS EXPECTED SATURDAY MORNING FROM KALB-
KPOU-KPSF WHEN THE STRONGEST IMPACTS ARE EXPECTED.

AS THIS STORM INTENSIFIES TO OUR EAST…THE SNOW WILL TRANSITION
TO SCATTERED MVFR SNOW SHOWERS.

WINDS WILL BE RATHER LIGHT TONIGHT…WITH A TENDENCY TO BECOME
NORTHERLY TO NORTHWESTERLY DURING SATURDAY WITH SPEEDS GENERALLY
10KTS OR LESS.

OUTLOOK…

SATURDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
SUNDAY: NO OPERATIONAL IMPACT. NO SIG WX.
SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
TUESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.

&&

.HYDROLOGY…
NO SIGNIFICANT HYDRO PROBLEMS ARE EXPECTED THROUGH THE NEXT FIVE
DAYS.

A DEVELOPING NOR`EASTER IS EXPECTED TO BRING A LIGHT TO MODERATE TO
SNOWFALL FOR AREAS MAINLY SOUTH AND EAST OF THE CAPITAL DISTRICT
LATE TONIGHT INTO SATURDAY. SOME SNOW SHOWERS WILL BE POSSIBLE
ACROSS THE HIGHER TERRAIN MAINLY WEST OF ALBANY SATURDAY NIGHT.

ICE WILL CONTINUE TO THICKEN ON RIVERS…STREAMS…CREEKS…LAKES
AND OTHER BODIES OF WATER OVER THE NEXT SEVERAL DAYS.

THE EAGLE BRIDGE GAGE ON THE HOOSIC RIVER CONTINUES TO BE HAMPERED
BY ICE EFFECTS AND RECENTLY HAS EXHIBITED A DECREASE IN GAGE
LEVELS /BELOW FLOOD STAGE/.

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 STORM WARNING FROM MIDNIGHT TONIGHT TO 5 PM EST
SATURDAY FOR CTZ001-013.
NY…WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 5 PM EST
SATURDAY FOR NYZ061-064>066.
MA…WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 5 PM EST
SATURDAY FOR MAZ001-025.
VT…WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 5 PM EST
SATURDAY FOR VTZ015.

&&

$$
SYNOPSIS…JPV
NEAR TERM…BGM/JPV
SHORT TERM…JPV
LONG TERM…BGM
AVIATION…LFM/BGM
HYDROLOGY…JPV

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