February 3, 2013 Forecast Discussion

000
FXUS61 KALY 032001
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
301 PM EST SUN FEB 3 2013

.SYNOPSIS…
ANOTHER CLIPPER LOW WILL APPROACH THE REGION TODAY WITH SOME SNOW
SHOWERS IN THE AFTERNOON INTO THE EVENING. SOME LAKE EFFECT
SNOWFALL WILL IMPACT THE WESTERN ADIRONDACKS AND THE MOHAWK VALLEY
ON MONDAY. BLUSTERY AND COLD CONDITIONS ARE EXPECTED TO OPEN THE
WEEK…BEFORE HIGH PRESSURE BUILDS IN MONDAY NIGHT INTO TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/…
H2O VAPOR IMAGERY SHOWS A NEARLY NEGATIVE TILTED TROUGH WITH THE
BEST UPPER JET SUPPORT WELL OFF THE MIDDLE ATLANTIC COAST PER THE
SCATTEROMETER WINDS. OVERALL DYNAMICS AND SURFACE CONVERGENCE ACROSS
OUR REGION ARE RATHER WEAK WITH QG FORCING REVEALING THE MAX
POTENTIAL FOR SNOW WILL BE DURING THE EVENING HOURS ACROSS EASTERN
NY AND THROUGH THE EARLY MORNING HOURS MONDAY ACROSS THE NORTHERN
BERKS AND SOUTHERN GREENS. SO WILL PLACE THE HIGHER POPS AOA 03Z
MONDAY FOR THE ENTIRE REGION. THE LATEST RAP/RUC/HRRR POINT TOWARD
THE HIGHER TERRAIN A LITTLE MORE FAVORED THAN THE VALLEYS AND AS
WITH THE PREVIOUS FORECAST…WE WILL PLACE HIGH SCT-CHC TO LIKELY
POPS FOR THE DACKS AND CATSKILLS. THEN WE SHIFT OUR ATTENTION TO
LAKE EFFECT DEVELOPMENT DOWNWIND OF LAKE ONTARIO. IN
FACT…UPSTREAM LAKE CONNECTIONS WILL LIKELY FURTHER ENHANCE THE
LAKE EFFECT AS THOSE H850 TEMPS DROP TOWARD TOWARD THE NEGATIVE
TEENS CELSIUS AND EVEN COLDER FURTHER UPSTREAM. PER OUR LOCAL
HIRESWRF…NCEP RAP/RUC/NAM…THE LOW LEVEL CONVERGENT SIGNATURES
INCREASE RATHER QUICKLY TOWARD MIDNIGHT WITH A WEST-NORTHWEST
TRAJECTORY. FORECAST INVERSION HEIGHTS ARE EXPECTED TO BE BETWEEN
8K-10K FEET WITH FAIRLY STEEP LOW LEVEL LAPSE RATES. LAKE INDUCED
CAPES CLIMB TOWARD THE MID 100 J/KG RANGE AS LOCAL CSTAR RESEARCH
SUGGEST INLAND PENETRATION OF THE LAKE EFFECT SNOW WILL MAKE IT
INTO SOUTHERN HERKIMER COUNTY DURING THE OVERNIGHT PERIOD. AFTER
CLOSE COORDINATION WITH OUR NEIGHBORING OFFICES…WE WILL HOIST A
LAKE EFFECT SNOW ADVISORY FOR SOUTHERN HERKIMER COUNTY AT THIS TIME.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/…
SURFACE PRESSURE GRADIENT TIGHTENS UP THROUGH THE DAY MONDAY TO
RESULT IN A RATHER BRISK DAY. BUFKIT MOMENTUM TRANSFER OF THE
HIGHER MOMENTUM WINDS ALOFT SUGGEST WE WILL TAP INTO THE MID 20KT
RANGE THROUGH THE DAY…COULD BE SLIGHTLY HIGHER AS CHANNEL FLOW
DOWN THE MOHAWK IS EXPECTED.

HOWEVER…THE MAIN ATTENTION WILL BE THE ONGOING LAKE EFFECT SNOW
DOWNWIND OF LAKE ONTARIO. WITH NEAR IDEAL UPSTREAM LAKE
CONNECTIONS AND DEEP MOISTURE BELOW 10K FEET ALONG WITH MODERATE
TO EXTREME INSTABILITY /GLERL LAKE TEMPS OVER ONTARIO REMAIN INTO
THE LOWER 40S/ WILL POINT TOWARD A MODERATE TO HEAVY LAKE EFFECT
SNOW EVENT. AS MENTIONED…LOCAL CSTAR RESEARCH OF INLAND
EXTENT…SUGGESTS THE BAND WILL MAKE INTO ALL OF SOUTHERN HERKIMER
COUNTY. AS THE BOUNDARY LAYER FLOW LINES UP CLOSE TO THE MOHAWK
RIVER…POTENTIAL FOR A FEW OF THESE SNOW SHOWERS/SQUALLS TO MAKE
INTO THE CAPITAL REGION. SO WE WILL KEEP CHC-SCT POPS AND THE
LIKELY POPS ACROSS SOUTHERN HERKIMER COUNTY. QUESTION WILL BE THE
SUN IMPACTS ON THE LAKE BANDS AS WE COULD SEE A MULTI-BAND EVOLVE
THROUGH THE DAY. THE BAND WILL LIKELY STAY CONSOLIDATED TO KEEP
THE ADVISORY GOING THROUGH THE DAY. FOR THE REMAINDER OF THE
CWA…A BRISK DAY WITH CHANCE FOR SNOW SHOWERS/FLURRIES. HIGHS
WILL RANGE FROM TEENS ACROSS THE DACKS AND NEAR 30F FOR THE MID
HUDSON VALLEY AND SOUTHERN LITCHFIELD COUNTY.

SURFACE HIGH BUILDS IN FROM THE UPPER GREAT LAKES REGION AND
ACROSS LAKE ONTARIO MONDAY EVENING. THIS SHOULD GREATLY DIMINISH
LAKE EFFECT POTENTIAL ALONG WITH PARTIAL CLEARING SKIES. COULD BE
QUITE COLD ACROSS THE NORTHERN ZONES MONDAY NIGHT AS ANY PARTIAL
CLEARING WITH SUB -20C H850 TEMPS WILL SET THE STAGE FOR OVERNIGHT
LOWS DROPPING BELOW 0F. MEANWHILE…A FAST MOVING CLIPPER SYSTEM
IS FORECAST TO WEAKEN ACROSS THE UPPER MISSISSIPPI RIVER VALLEY
AND ACROSS OR JUST SOUTH OF THE MASON-DIXON LINE MONDAY NIGHT.
MAINLY CLOUDS EARLY ON SOUTH OF I90 WITH THE AFOREMENTIONED
CLEARING EVOLVING DURING THE OVERNIGHT PERIOD.

TUESDAY…HIGH PRESSURE IS EXPECTED TO REMAIN IN CONTROL FOR A
TRANQUIL DAY. HOWEVER…TEMPERATURES WILL BE RATHER CHILLY AS
THOSE H850 TEMPS REMAIN INTO THE MID NEGATIVE TEENS TO NEAR -20C.
FURTHER UPSTREAM…YET ANOTHER CLIPPER WILL BE APPROACHING. THIS
WILL SET AN INCREASE IN HIGH AND MID LEVEL CLOUDS THROUGH THE
AFTERNOON AND BECOMING CLOUDY TOWARD SUNSET.

TUESDAY NIGHT…ANOTHER CHANCE FOR A PERIOD OF LIGHT SNOW AND/OR
FLURRIES AS THE GLOBAL MODELS ARE MORE MOIST THAN THE NAM. AT THIS
TIME…SEEMS ACCUMULATIONS WILL BE AN INCH OR LESS AS LOWER LEVELS
REMAIN RATHER DRY WITH QPF VALUES REMAIN A TENTH OF AN INCH OR
LESS.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/…
AT THE START OF THE EXTENDED PERIOD…A CLIPPER SYSTEM WILL BE
MOVING ACROSS THE REGION. TEMPS CONTINUE TO BE COLD ENOUGH FOR ALL
SNOW WITH THIS FEATURE. WITH THIS BEING A MOISTURE STARVED NORTHERN
STREAM SYSTEM…QPF WILL BE LIMITED…WITH JUST AN INCH OF SNOW OR
SO…AND MAINLY ACROSS THE HIGH TERRAIN. PRECIP LOOKS TO MAINLY
COME ACROSS DURING THE MORNING HOURS…AS THE SYSTEM WILL BE EAST OF
THE REGION BY WED AFTN. MAX TEMPS ON WED WILL RANGE FROM THE MID 20S
TO MID 30S.

IN THE WAKE OF THE STORM…HIGH PRESSURE WILL NOSE DOWN FROM
SOUTHERN CANADA. THIS LOOKS TO BE A STRONG HIGH /1030 TO 1035 MB/
AND WITH CLEAR SKIES…LIGHT WINDS…AND POSSIBLY SOME SNOW ON
GROUND /ESP ACROSS THE HIGH TERRAIN/…GOOD RADIATIONAL COOLING IS
EXPECTED. WE ARE CURRENTLY FORECASTING MINS FROM JUST BELOW ZERO
ACROSS THE ADIRONDACKS TO THE TEENS ACROSS THE MID HUDSON VALLEY/NW
CT. HOWEVER…THERE IS POTENTIAL FOR TEMPS TO BE COLDER…ESP IF WE
GET A FEW INCHES OF SNOW ON THE GROUND IN THE VALLEYS BETWEEN NOW
AND WED AFTN.

THE DRY WEATHER FOR WED NIGHT INTO THURSDAY MORNING WILL BE
SHORT-LIVED…AS ANOTHER SYSTEM WILL BEGIN TO APPROACH THE REGION.
HOWEVER…THE MODELS ARE IN DISAGREEMENT ABOUT EXACTLY WHAT HAPPENS
FROM THIS POINT ON. THE 12Z GFS AND GGEM SHOW A NORTHERN STREAM
CLIPPER APPROACHING FOR THURSDAY AFTN INTO THURSDAY NIGHT.
MEANWHILE…THE 12Z ECMWF /FOLLOWING THE TREND IT STARTED WITH ITS
00Z RUN/ SHOWS THIS CLIPPER A LITTLE SLOWER AND IT PHASES IT WITH A
SOUTHERN STREAM SYSTEM TO MAKE A RAPIDLY DEEPENING LOW OFF THE MID
ATLANTIC COAST. WITH THIS SCENARIO…WE WOULD HAVE MUCH MORE
PRECIP…AND MUCH OF IT IN THE FORM OF SNOW /SOME MIX TO RAIN FOR
THE SOUTHERN THIRD OF THE REGION/ FOR THURSDAY NIGHT INTO FRIDAY. IN
EITHER SCENARIO…THERE IS THE THREAT FOR SOME PRECIP…SO WILL GO
WITH CHC POPS FOR THURSDAY NIGHT INTO FRIDAY AND CONTINUE TO MONITOR
MODEL TRENDS. TEMPS LOOK TO AVERAGE NEAR TO SLIGHTLY ABOVE NORMAL
FOR THURSDAY NIGHT INTO FRIDAY DUE TO THE CLOUDS/POSSIBILITY OF
PRECIP.

DRY WEATHER WILL RETURN FOR THE WEEKEND WITH HIGH PRESSURE BUILDING
IN. WHILE TEMPS MAY AVERAGE NEAR NORMAL FOR SATURDAY /ESP IF WE GET
SOME SNOW ON THE GROUND/…THE TREND IS FOR TEMPS TO GRADUALLY
WARM…AS RIDGING LOOKS TO ESTABLISH ITSELF ALONG THE EASTERN
SEABOARD FOR LATE IN THE WEEKEND AND INTO EARLY NEXT WEEK.

NORMALS FEB 5TH-9TH:
ALBANY: HIGHS LOWER 30S. LOWS MID TEENS.
GLENS FALLS: HIGHS LOWER 30S. LOWS UPPER SINGLE DIGITS.
POUGHKEEPSIE: HIGHS UPPER 30S. LOWS UPPER TEENS.
BENNINGTON: HIGHS LOWER 30S. LOWS MID TEENS.
PITTSFIELD: HIGHS AROUND 30. LOWS MID TEENS.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/…
VFR CONDITIONS ARE IN PLACE EARLY THIS AFTN. SKIES ARE NEARLY CLEAR
ACROSS NORTHERN PARTS OF THE AREA…WITH BKN-OVC MID LEVEL CLOUDS
ACROSS SOUTHERN AREAS. A BRIEF PERIOD OF MVFR CIGS IS POSSIBLE
THROUGH THE AFTN AT KPSF…OTHERWISE ALL SITES SHOULD REMAIN VFR
WITH NO PRECIPITATION THROUGH MID AFTN.

SKIES WILL BECOME BKN-OVC BY LATE THIS AFTN/EARLY THIS EVENING AS A
CLIPPER SYSTEM APPROACHES FROM THE GREAT LAKES REGION. SOME SNOW
SHOWERS OR FLURRIES ARE POSSIBLE WITH THIS SYSTEM…ALTHOUGH
MOISTURE IS LIMITED AND THE BEST CHC APPEARS ACROSS THE HIGH
TERRAIN. FOR NOW…WILL ONLY GO WITH VCSH AT ALL TAF SITES FROM
ABOUT 22Z-23Z UNTIL 08Z-10Z WITH CONTINUED VFR CIGS. WHILE A BRIEF
PERIOD OF MVFR VSBYS CANNOT BE RULED OUT WITHIN ANY SNOW
SHOWER…THE TIMING AND EXTENT IS UNKNOWN AT THIS TIME TO ACCURATELY
FORECAST IN THE TAFS.

BEHIND THIS CLIPPER…SOME LAKE EFFECT SNOW WILL DEVELOP OFF LAKE
ONTARIO. MOST OF THIS ACTIVITY WILL REMAIN TO THE WEST OF THE
REGION…ALTHOUGH IT/S POSSIBLE THAT THE BAND COULD REACH INTO THE
CAPITAL REGION/BERKSHIRES. DUE TO THE UNCERTAINTY…WILL ONLY GO
WITH A VCSH RIGHT NOW FOR KALB/KPSF FOR THE MID TO LATE MORNING
HOURS ON MONDAY.

WINDS ARE EXPECTED TO BE LIGHT AND VARIABLE THIS AFTN INTO THIS
EVENING. BEHIND THE CLIPPER…WESTERLY WINDS WILL INCREASE TO 5-10
KTS. AFTER SUNRISE ON MONDAY…DAYTIME MIXING WILL ALLOW FOR SOME
STRONGER GUSTS WITH WINDS OF 10-15 KTS AND GUSTS OF 20-25 KTS…ESP
FOR KALB/KPSF.

OUTLOOK…
MON NIGHT-TUE…VFR. NO SIG WX.
TUE NIGHT. MAINLY VFR. CHC -SHSN MAINLY AFTER MIDNIGHT.
WED…MAINLY VFR. CHC -SHSN IN THE AM AND SLIGHT CHC IN THE AFTN.
WED NIGHT-THU…VFR. NO SIG WX.
THU NIGHT-FRI. VFR/MVFR/IFR. CHC -SN.

&&

.HYDROLOGY…
HYDRO PROBLEMS ARE NOT ANTICIPATED THE NEXT 5 DAYS WITH COLD TEMPS
AND LIGHT SNOW EVENTS MAINLY IMPACTING THE ALBANY HYDRO SERVICE AREA.

SOME HYDRO GAGES ARE EXPERIENCING ICE EFFECTS AROUND THE HSA. THE
BELOW NORMAL TEMPERATURES WILL ALLOW ICE TO REFORM AND THICKEN ON ALL
BODIES OF WATER THROUGH THE MID WEEK.

FOR SPECIFIC RIVER AND LAKE FORECASTS…PLEASE VISIT THE ADVANCED
HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.

&&

.ALY WATCHES/WARNINGS/ADVISORIES…
CT…NONE.
NY…LAKE EFFECT SNOW ADVISORY FROM 11 PM THIS EVENING TO 7 PM EST
MONDAY FOR NYZ038.
MA…NONE.
VT…NONE.

&&

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

FOR THE LATEST UPDATES…PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY

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