AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
649 AM EST WED JAN 11 2012
.SYNOPSIS…
HIGH PRESSURE WILL CONTROL OUR WEATHER THROUGH TODAY WITH DRY AND
RELATIVELY MILD CONDITIONS. A STORM SYSTEM WILL MOVE FROM THE
MISSISSIPPI VALLEY THROUGH THE MID ATLANTIC REGION TOWARD CAPE
COD…BRINGING A WINTRY MIX OF PRECIPITATION TO THE REGION LATE
TONIGHT INTO THURSDAY. A SECOND STORM SYSTEM IS EXPECTED TO BRING
ANOTHER WINTRY MIX OF PRECIPITATION TO OUR AREA LATER THURSDAY
NIGHT WHICH WILL CHANGE TO SNOW ON FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/…
AS OF 645 AM EST…SKIES WERE MAINLY CLEAR SOUTH OF THE MOHAWK
VALLEY AND ACROSS THE LITCHFIELD HILLS WITH MORE CLOUDS FARTHER
NORTH. TEMPERATURES ACROSS THE REGION WERE GENERALLY IN THE 20S
EXCEPT FOR PARTS OF THE WESTERN ADIRONDACKS WHERE TEMPS WERE IN
THE MID TO UPPER TEENS. HAVE NOT CHANGED MOST OTHER GRIDS…OTHER
THAN TO MAKE ADJUSTMENTS TO BETTER FIT CURRENT TRENDS.
AS OF 445 AM EST…MOSTLY CLOUDY SKIES REMAINED ACROSS FAR
NORTHERN PORTION OF FA WITH SKIES HAVING CLEARED FARTHER SOUTH.
TEMPERATURES HAVE FALLEN INTO THE 20S IN MOST AREAS AND ARE
EXPECTED TO FALL SEVERAL MORE DEGREES BEFORE DAYBREAK.
TODAY IS EXPECTED TO BE DRY WITH GENERALLY PARTLY TO MOSTLY SUNNY
CONDITIONS AS A RIDGE OF HIGH PRESSURE MOVES OVER THE REGION THIS
MORNING AND THEN SLIDES OFF THE EASTERN SEABOARD LATE TODAY. SKIES
ARE EXPECTED TO BE PARTLY TO MOSTLY SUNNY WITH HIGHS RANGING FROM
THE UPPER 20S TO LOWER 30S NORTHWEST TO THE LOWER 40S SOUTHEAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/…
TONIGHT AND THURSDAY REPRESENT AN EXTREMELY CHALLENGING FORECAST
AS SEVERAL FACTORS WILL DETERMINE NOT ONLY THE AMOUNT OF QPF…BUT
PTYPE AS WELL. IT REMAINS TO BE SEEN HOW QUICKLY THE COLUMN CAN BE
COOLED ONCE PCPN STARTS AND IF THE NORTHERLY AGEOSTROPHIC FLOW IS
STRONG ENOUGH TO BRING WHAT COLD AIR IS IN PLACE SOUTHWARD DOWN
THE HUDSON VALLEY. THERE IS ALSO THE POSSIBILITY THAT SOME
DOWNSLOPING WILL TAKE PLACE IN THE HUDSON VALLEY AS THE LOW LEVEL
WINDS BECOME EASTERLY AND THIS MAY DECREASE THE QPF AND ALSO KEEP
TEMPS IN AT LEAST PARTS OF THE HUDSON VALLEY FROM GOING BELOW
FREEZING.
HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE ENTIRE FA WITH THE
ADVISORY RUNNING FROM MIDNIGHT TONIGHT THROUGH NOON THURSDAY IN ALL
AREAS EXCEPT ACROSS THE SOUTHERN ADIRONDACKS WHERE THE PCPN WILL
START LATER AND ALSO WHERE WITH MORE COLD AIR IN PLACE THE MIXED PCPN
WILL LAST LONGER. THE ADVISORY FOR THE SOUTHERN ADIRONDACKS WILL RUN
FROM 4 AM TONIGHT THROUGH THURSDAY AFTERNOON. IT NOW APPEARS THAT A
WINTRY MIX OF PCPN WILL OCCUR ACROSS OUR AREA LATE WEDNESDAY NIGHT
INTO THURSDAY. THE DRY WEATHER WILL LINGER INTO WEDNESDAY EVENING
BEFORE PCPN STARTS TO OVERSPREAD THE REGION FROM SOUTHWEST TO
NORTHEAST MAINLY DURING THE SECOND HALF OF THE NIGHT. PARTIAL
THICKNESS VALUES AND BUFKIT MODEL SOUNDINGS SUPPORT PTYPE BEING
STARTING AS SNOW AND TRANSITIONING TO MAINLY A WINTRY MIX SOUTH LATE
WEDNESDAY NIGHT SOUTH WITH MAINLY SNOW NORTH. THE SOUTHERN AREAS ARE
EXPECTED TO TRANSITION TO RAIN ON THURSDAY WHILE NORTHERN ARES
TRANSITION TO A WINTRY MIX. SREF 03Z PTYPE PROBABILITIES SUPPORT A
RATHER QUICK TRANSITION FROM SNOW TO MIXED PCPN LATE TONIGHT IN MOST
AREAS EXCEPT ACROSS FAR NORTHERN SECTIONS OF FA WHERE THE SNOW WILL
LINGER LONGER AND THEN ON THURSDAY A QUICK TRANSITION TO RAIN SOUTH
WITH SLEET AND FREEZING RAIN LINGERING INTO THE AFTERNOON ACROSS THE
SOUTHERN ADIRONDACKS. THE PLUME DIAGRAM FOR KALB OFF THE 03Z SREF
AND 00Z GEFS ALSO SUPPORT A WINTRY MIX WITH MANY ENSEMBLE MEMBERS
INDICATING FREEZING RAIN LATE TONIGHT. THE MODELS CONTINUE TO
INDICATE THAT THE NORTHERN AND SOUTHERN STREAM SYSTEMS MAKING UP
THIS COMPLEX STORM SYSTEM WILL NOT PHASE WITH OUR AREA IN THE MIDDLE
OF TWO AREAS OF LOW PRESSURE. MODELS ARE IN GOOD AGREEMENT ON THE
TRACK OF THE SOUTHERN STEAM SYSTEM WHICH IS EXPECTED TO TRACK OVER
OR NEAR THE EASTERN TIP OF LONG ISLAND EARLY THURSDAY AFTERNOON AND
THEN PASS NEAR OR OVER CAPE COD LATE THURSDAY AFTERNOON WHILE THE
NORTHERN STREAM SYSTEM DRIFTS FROM THE CENTRAL GREAT LAKES TOWARDS
THE EASTERN GREAT LAKES.
QPF AMOUNTS WITH THIS COMPLEX SYSTEM STILL REMAIN HIGHLY UNCERTAIN
AND GENERALLY WENT WITH A BLEND OF THE MODELS AS WELL AS HPC
GUIDANCE. EXPECT TOTAL QPF FROM WEDNESDAY NIGHT THROUGH THURSDAY
OF AROUND TWO THIRDS OF AN INCH ACROSS FAR NORTHWEST PORTION OF
FA WITH MOST AREAS HAVING AROUND THREE QUARTERS TO SEVEN EIGHTS OF
AN INCH AND SOUTHEAST PORTION OF FA SEEING QPF AMOUNTS SLIGHTLY
OVER AN INCH. AT THIS TIME IT IS DIFFICULT TO BREAK DOWN EXACT
SNOWFALL AND FREEZING RAIN TOTALS…HOWEVER MOUNTAIN AREAS ARE
EXPECTED TO HAVE 2 TO 6 INCHES OF SNOW WITH LESS IN THE VALLEYS
WITH ICE ACCRETION OF A TENTH TO TWO TENTHS OF AN INCH POSSIBLE IN
MANY AREAS. EXPECT LOWS TONIGHT TO RANGE FROM THE UPPER TEENS AND LOW
20S NORTHWEST TO LOWER 30S SOUTHEAST WITH HIGHS ON THURSDAY
RANGING FROM THE LOWER AND MID 30S NORTHWEST TO LOWER 40S
SOUTHEAST.
THURSDAY NIGHT AND FRIDAY…THE SECOND STORM SYSTEM IS EXPECTED
TO MOVE INTO THE EASTERN GREAT LAKES THURSDAY NIGHT AND PASS
THROUGH THE SAINT LAWRENCE VALLEY INTO THE CANADIAN MARITIMES ON
FRIDAY. THIS STORM ALSO LOOKS AS THOUGH IT WILL BRING A WINTRY MIX
OF PRECIPITATION TO THE AREA LATER THURSDAY NIGHT WITH THE
PRECIPITATION TRANSITIONING TO SNOW ON FRIDAY AS COLDER AIR WRAPS
AROUND THE BACK ON SYSTEM INTO OUR REGION. QPF AMOUNTS WITH THIS
SYSTEM ARE ALSO RATHER UNCERTAIN…HOWEVER AT THIS TIME THEY LOOK
TO BE LIGHTER THAN WITH THE FIRST SYSTEM GENERALLY RANGING FROM A
TENTH TO A QUARTER OF AN INCH SOUTHEAST TO AROUND TWO THIRDS OF AN
INCH NORTHWEST. THERE IS ALSO A POSSIBILITY THAT AN ADVISORY WILL
NEED TO BE ISSUED WITH THIS SYSTEM ESPECIALLY FOR NORTHERN AREAS.
EXPECT LOWS THURSDAY NIGHT TO RANGE FROM THE MID 20S NORTHWEST TO
LOW TO MID 30S SOUTHEAST WITH HIGHS ON FRIDAY RANGING FROM THE
UPPER 20S TO LOWER 30S NORTHWEST TO UPPER 30S TO LOWER 40S SOUTHEAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/…
WE TRANSITION BACK TOWARD A TYPICAL MID JANUARY WINTER PATTERN AS WE
WATCH ONE STORM DEPART AT THE START OF THIS LONG TERM PORTION OF THE
FORECAST. THE BALANCE OF THIS WEEKEND WE WILL BE UNDER THE
INFLUENCE OF A CHILLY CYCLONIC FLOW WITH A COUPLE OF SHORT WAVES
MIGRATING ON ACROSS THE REGION. LAKE ONTARIO CONTRIBUTION IS
EXPECTED TO BE MORE PROBLEMATIC FRIDAY NIGHT INTO EARLY SATURDAY
MORNING WITH FAVORABLE INVERSION LEVELS AND NEARLY PARALLEL BOUNDARY
LAYER WINDS /IE MINIMAL SHEAR/ FOR THE DACKS AND WESTERN MOHAWK
VALLEY. THRU THE REMAINDER OF SATURDAY MORNING…THOSE INVERSION
LEVELS ARE EXPECTED TO LOWER ALONG WITH AN INCREASING ANTICYCLONIC
SURFACE FLOW AS A SURFACE HIGH FROM CENTRAL CANADA ATTEMPTS TO WEDGE
INTO THE GREAT LAKES REGION AND NORTHEAST. HOWEVER…AS THAT LAST
SHORT WAVE APPROACHES OVERNIGHT SATURDAY INTO SUNDAY MORNING…THE
GFS REMAINS THE MOST AGGRESSIVE WHILE THE OTHER GLOBAL MODELS ARE
MORE FLAT AND PROGRESSIVE WITHIN THE CONFLUENT FLOW…SO WE WILL
LEAN AWAY FROM THE GFS AND LIMIT TO A SLIGHT CHANCE POPS ON SUNDAY.
THEN THE START OF NEXT WEEK…LARGE SCALE SURFACE HIGH AND BUILDING
HEIGHTS WILL RESULT IN A TRANQUIL AND SEASONABLE CONDITIONS FOR THE
ENTIRE REGION. UPSTREAM…ANOTHER STRONG PIECE OF PACIFIC ENERGY
COMES OUT INTO THE CENTRAL AND NORTHERN PLAINS WITH FRONTOGENESIS
EXPECTED MONDAY NIGHT INTO TUESDAY. THIS WILL PROVIDE OUR NEXT
CHANCE FOR PRECIPITATION ON TUESDAY.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/…
VFR CONDITIONS THROUGH THE DAYLIGHT HOURS WITH A MIXTURE OF SCT-BKN
AC DECK AND AN INCREASE IN CI/CS THROUGH THE AFTERNOON.
TONIGHT…THE STORM APPROACHES FROM THE SOUTHEAST CONUS WITH
DETERIORATING CONDITIONS FROM SOUTH TO NORTH. ONSET OF THE PRECIP
WOULD BE IN THE FORM OF SNOW WITH KPOU EXPECTED TO WARM UP TO MAINLY
RAIN AFTER MIDNIGHT.
WHILE WINDS WILL GENERALLY BE LIGHT THROUGH THE DAY…THE WINDS
ALOFT ARE EXPECTED TO INCREASE TONIGHT. THE POTENTIAL FOR LLWS
SEEMS TO INCREASE AND LATER FORECASTS WILL RE-EVALUATE FOR FUTURE
INCLUSIONS.
OUTLOOK…
THU…IFR/MVFR. MIXED PRECIPITATION/RAIN TAPERING OFF DURING THE
AFTERNOON.
THU NT…MVFR/IFR. RAIN OR MIXED PRECIPITATION ENDING AS SNOW.
FRI-FRI NT…MAINLY MVFR. SNOW SHOWERS LIKELY.
SAT…VFR. CHC MVFR DUE TO LAKE EFFECT -SHSN.
&&
.HYDROLOGY…
A COMPLEX STORM SYSTEM WILL APPROACH THE REGION LATE WEDNESDAY
INTO THURSDAY. A LOW PRESSURE SYSTEM IS EXPECTED TO TRACK VERY
CLOSE TO LONG ISLAND ON THURSDAY AFTERNOON WHILE A SECOND AREA OF
LOW PRESSURE REMAINS IN THE GREAT LAKES REGION. A WINTRY MIX OF
PCPN IS EXPECTED ACROSS SOUTHERN AREAS LATE WEDNESDAY NIGHT WITH
MOSTLY SNOW NORTH. THE PRECIPITATION IS THEN EXPECTED TO
TRANSITION TO MAINLY RAIN SOUTH DURING THE DAY ON THURSDAY WITH
THE SNOW TRANSITIONING TO A WINTRY MIX OF PCPN NORTH. QPF AMOUNTS
STILL REMAIN SOMEWHAT UNCERTAIN…HOWEVER A CONSENSUS OF THE MODEL
GUIDANCE WOULD HAVE AMOUNTS RANGING FROM TWO THIRDS OF AN INCH
NORTHWEST TO SLIGHTLY OVER AN INCH SOUTHEAST FROM WEDNESDAY NIGHT
THROUGH THURSDAY.
THE SECOND STORM SYSTEM IS EXPECTED TO MOVE INTO THE EASTERN GREAT
LAKES THURSDAY NIGHT AND PASS THROUGH THE SAINT LAWRENCE VALLEY
INTO THE CANADIAN MARITIMES ON FRIDAY. THIS STORM ALSO LOOKS AS
THOUGH IT WILL BRING A WINTRY MIX OF PRECIPITATION TO THE AREA
LATER THURSDAY NIGHT WITH THE PRECIPITATION TRANSITIONING TO SNOW
ON FRIDAY AS COLDER AIR WRAPS AROUND THE BACK ON SYSTEM INTO OUR
REGION. QPF AMOUNTS WITH THIS SYSTEM ARE ALSO RATHER
UNCERTAIN…HOWEVER AT THIS TIME THEY LOOK TO BE LIGHTER THAN WITH
THE FIRST SYSTEM GENERALLY RANGING FROM A TENTH TO A QUARTER OF AN
INCH SOUTHEAST TO AROUND TWO THIRDS OF AN INCH NORTHWEST.
MILDER TEMPERATURES DURING THE MID WEEK PERIOD ARE EXPECTED TO
SLOW THE RATE OF ICE FORMATION AND THICKENING WHICH IS EXPECTED TO
INCREASE AGAIN THIS WEEKEND WHEN MUCH COLDER AIR MOVES BACK INTO
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…WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
THURSDAY FOR CTZ001-013.
NY…WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
THURSDAY FOR NYZ038>041-043-047>054-058>061-063>066-
082>084.
WINTER WEATHER ADVISORY FROM 4 AM TO 6 PM EST THURSDAY FOR
NYZ032-033-042.
MA…WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
THURSDAY FOR MAZ001-025.
VT…WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
THURSDAY FOR VTZ013>015.
&&
$$
SYNOPSIS…11
NEAR TERM…11
SHORT TERM…11
LONG TERM…BGM
AVIATION…BGM
HYDROLOGY…11
