February 21, 2013 Forecast Discussion

000
FXUS61 KALY 211144
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
645 AM EST THU FEB 21 2013

.SYNOPSIS…
AN UPPER LEVEL LOW OVER THE NORTHEAST WILL CONTINUE TO PROVIDE COLD
AND BLUSTERY WEATHER THROUGH TODAY. HIGH PRESSURE WILL BUILD INTO
THE REGION THURSDAY NIGHT INTO FRIDAY…RESULTING IN TRANQUIL
CONDITIONS WITH LIGHTER WIND AND MODERATING TEMPERATURES. A
DEVELOPING COASTAL STORM MAY BRING ACCUMULATING SNOWFALL TO THE
REGION FOR THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
AS OF 640 AM…A BAND OF LAKE EFFECT SNOW HAD BEEN WORKING THROUGH
THE MOHAWK VALLEY…BUT AS THE SURFACE TO 10,000 AGL MEAN FLOW HAS
TURNED MORE OF A 310 VECTOR…THE BANDS WERE MIGRATING SOUTH OF
ALBANY TOWARD THE CATSKILLS. WE EXPECT THIS TREND TO CONTINUE…AND
EVENTUALLY THE BANDS WILL VEER OUT OF REGION.

STILL MIGHT HAVE SOME UPSLOPE SNOW SHOWERS EAST OF THE HUDSON VALLEY
AS WELL AS THE ADIRONDACKS BUT THESE SHOULD BE LIGHT AND SCATTERED.

ANY SNOWFALL ACCUMULATIONS WITH ANY OF THESE SNOW SHOWERS WILL RANGE
FROM A COATING TO A COUPLE OF INCHES.

VALLEY AREAS LOOK DRY WITH NOTHING MORE THAN A FEW FLURRIES AND
INCREASING SUNSHINE.

A NORTHWEST WIND WILL CONTINUE…10 TO 20 MPH…GUSTING TO 30 MPH IN
SECTIONS.

TEMPERATURES ALOFT WILL REMAIN QUITE LOW…ONLY WARMING TO ABOUT
-10C BY LATE IN THE DAY. BELIEVE HIGH TEMPERATURES WILL REMAIN
MAINLY AT OR BELOW FREEZING…BUT NOT AS COLD AS THE METS FORECAST.
WENT WITH A BLEND OF THE COLDER METS/WARMER MAVS WHICH TRANSLATED TO
HIGH TEMPERATURES NEAR FREEZING IN THE MID HUDSON VALLEY/LOWER
LITCHFIELD COUNTY…UPPER 20S GREATER CAPITAL REGION…TEENS TO MID
20S ELSEWHERE. AGAIN THE WIND WILL MAKE THESE VALUES FEEL ABOUT 10
DEGREES COLDER.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/…
AS HIGH PRESSURE BOTH AT THE SURFACE AND ALOFT BUILDS INTO THE
REGION THURSDAY NIGHT…THE WIND WILL FINALLY RELAX. LOW
TEMPERATURES WILL BE COLDEST ACROSS AREAS WHICH HAVE SIGNIFICANT
SNOW DEPTH WITH GOOD RADIATIONAL COOLING CONDITIONS BUT OVERALL THIS
SHOULD BE THE COLDEST NIGHT OF THE NEXT SEVERAL.

A STRENGTHENING LATE FEBRUARY SUN ANGLE COMBINING WITH RISING
HEIGHTS/WARMING TEMPERATURES ALOFT WILL COAX SURFACE TEMPERATURES
INTO THE 30S ACROSS OUR ENTIRE REGION…MAYBE TOUCH 40 A FEW OF THE
WARMER VALLEY LOCATIONS. THE WIND WILL BE LIGHT AND VARIABLE
EARLY…BECOMING SOUTH OR SOUTHEASTERLY 5 TO 10 MPH FRIDAY
AFTERNOON.

HIGH PRESSURE AND THE RIDGE ALOFT WILL SLOWLY MOVE EAST FRIDAY
NIGHT. A SOUTHERLY FLOW WILL GRADUALLY INCREASE MOISTURE ACROSS THE
REGION. ISENTROPIC LIFT WILL INCREASE AND THEREFORE SO WILL
EVENTUALLY THE CHANCE FOR LIGHT SNOW TO BREAK UP…MAINLY TOWARD
DAYBREAK WEST OF THE HUDSON VALLEY.

ON SATURDAY…AN INCREASING SOUTHERLY FLOW WILL BRING A BETTER
CHANCE OF LIGHT SNOW OR MIXED SNOW AND RAIN ACROSS THE REGION.

MEANWHILE…AN UPPER LEVEL DISTURBANCE WILL BE APPROACHING FROM THE
GREAT LAKES IN THE NORTHERN STREAM AND INITIALLY A WEAK LOW PRESSURE
AREA IN THE SOUTHERN STREAM. EARLIER MODELS RUN HAS SOME SORT OF
PHASE INTERACTIONS OF THE TWO SOURCES OF ENERGY…YIELDING IN A
POTENTIALLY HEAVY SNOW EVENT ACROSS OUR REGION.

HOWEVER…THE 00Z GFS/CANADIAN GEM AND ESPECIALLY ECMWF HAVE BACKED
OFF THE QPF AS THEY KEEP THE SOUTHERN STREAM AN OPEN WAVE AND
TRACKING A LITTLE FURTHER FROM THE COAST OF CAPE COD SUNDAY MORNING.
EVEN THE 06Z NAM BACKED OFF THE ROBUST QPF OF ITS EARLIEST 00Z RUN
ALSO TRACKING THE STORM OFF THE EASTERN SEABOARD. THE AVERAGE OF
THESE AND THE 00Z GFS ENSEMBLES GAVE OUR REGION AROUND HALF AN INCH.

IT WILL BE INTERESTING TO SEE WHAT THE 06Z GFS HAS IN STORE. EVEN IF
DOES THE SAME TREND…WE WILL HAVE TO MONITOR TRENDS AND WILL
CONTINUE TO MENTION A POSSIBLE SIGNIFICANT SNOWFALL IN OUR HAZARDOUS
OUTLOOK.

THE THERMAL PROFILES WOULD INDICATE MOSTLY SNOWFALL WITH THIS SYSTEM
SATURDAY NIGHT INTO SUNDAY. HOWEVER…IF THE PRECIPITATION WERE TO
BE LIGHT AS THE ECMWF INDICATED…IT MIGHT EVEN FALL PARTIALLY AS
RAIN…ESPECIALLY SOUTH AND EAST OF ALBANY.

SO THERE ARE STILL A LOT UNCERTAINTIES WITH THIS UPCOMING SYSTEM. WE
ARE HOWEVER CONFIDENT SOME PRECIPITATION WILL FALL SATURDAY NIGHT SO
WE RAMPED UP POPS TO CATEGORICAL (75-80 POPS). THE BIG QUESTION NOW
IS HOW MUCH WILL FALL. ARE BEST BEST NOW ARE MODERATE
AMOUNTS…POSSIBLY HEAVIER ESPECIALLY IN OUR SOUTH AND EASTERN
ZONES. WE ARE CONCERNED THIS WILL BE A WET HEAVY SNOW…ESPECIALLY
IN THE VALLEYS.

LOW TEMPERATURES FRIDAY NIGHT LOOKS TO BE IN THE 20S SO ANYTHING
THAT FALLS SHOULD BE SNOW. ON SATURDAY HOWEVER…HIGH TEMPERATURES
LOOK TO CLIMB INTO THE 30S ABOVE FREEZING EVERYWHERE IN THE
VALLEYS…CLOSER TO FREEZING ACROSS THE MOUNTAIN AREAS. SATURDAY
NIGHT LOWS SHOULD DIP BACK TO DOWN TO THE 20S AROUND 30…SO BELOW
FREEZING EVERYWHERE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/…
SUNDAY-SUNDAY NIGHT…ALTHOUGH MAIN SFC LOW WILL PULL EAST OF THE
REGION…THE REMNANT UPPER LEVEL LOW ACROSS THE GREAT LAKES REGION
WILL GRADUALLY MOVE E/SE ACROSS THE REGION SUNDAY AFTERNOON/EVENING.
FOR AREAS N AND NE OF THE TRACK OF THIS FEATURE…PERIODS OF MAINLY
LIGHT SNOW SHOULD PERSIST…WITH PERHAPS SOME RAIN OCCURRING IN
VALLEY AREAS. ADDITIONAL MINOR ACCUMS WILL BE POSSIBLE…ESP ON
COLDER SURFACES. PRECIPITATION SHOULD TAPER OFF SUNDAY
EVENING…WITH MAINLY DRY CONDITIONS FOR LATE SUNDAY NIGHT. AS FOR
TEMPS…EXPECT SUNDAY MAXES TO REACH 35-40 IN VALLEY AREAS…AND
GENERALLY 30-35 ACROSS HIGHER ELEVATIONS. FOR SUN NT MINS…EXPECT
MAINLY LOWER/MID 20S IN VALLEYS…AND MID/UPPER TEENS ACROSS HIGHER
ELEVATIONS.

MONDAY-MONDAY NIGHT…BRIEF RIDGE OF HIGH PRESSURE SHOULD TRANSLATE
E ACROSS THE REGION DURING THIS TIME PERIOD. THIS SHOULD ALLOW FOR
SOME CLEARING TO OCCUR BY MONDAY AFTERNOON…INTO MONDAY EVENING
BEFORE HIGH AND MID LEVEL CLOUDS INCREASE PRIOR TO DAYBREAK TUE. AS
SOME 00Z/GEFS MEMBERS BRING IN LIGHT PRECIP BY 12Z/TUE…WILL
INDICATE SOME SLIGHT CHC POPS ACROSS SW AREAS LATE MON NT. FOR
TEMPS…EXPECT MONDAY MAXES TO REACH THE MID 30S TO LOWER 40S IN
VALLEYS…AND GENERALLY LOWER/MID 30S ACROSS HIGHER ELEVATIONS. FOR
MON NT/TUE AM…EXPECT MINS TO FALL INTO THE 20S IN VALLEYS…AND
TEENS ACROSS HIGHER ELEVATIONS.

TUE-THU…MODELS CONTINUE TO DEPICT NEXT SYSTEM DEVELOPING ACROSS
THE LOWER MISSISSIPPI VALLEY…WITH ONE PIECE MOVING NORTH…AND A
SECONDARY SYSTEM POSSIBLY DEVELOPING OVER THE SOUTHEAST STATES AND
HEADING NORTH ALONG THE E SLOPES OF THE APPALACHIANS. SHOULD THIS
COME TO FRUITION…SUCH A TRACK OF THE SECONDARY WOULD FAVOR MILDER
AIR MOVING INTO THE REGION FROM THE SOUTHEAST…ALLOWING FOR AN
INITIAL PERIOD OF SNOW OR WINTRY MIX TO CHANGE TO RAIN FOR MUCH OF
THE REGION WITH THE EXCEPTION OF THE WESTERN ADIRONDACKS. FOR
NOW…WILL KEEP MENTION OF SNOW INITIALLY…THEN CHANGING TO A
RAIN/SNOW MIX IN MOST AREAS…EXCEPT FOR RAIN ACROSS SOUTHERN AREAS.
PRECIPITATION MAY LINGER INTO WED…BEFORE BECOMING MORE SHOWERY BY
THU AS THE UPPER LEVEL LOW REMAINS NEARBY. AS FOR TEMPS…EXPECT
DAYTIME MAXES TO MAINLY REACH THE 30S…WITH SOME LOWER 40S POSSIBLE
ACROSS PORTIONS OF THE MID HUDSON VALLEY AND SOUTHERN LITCHFIELD CO
CT. OVERNIGHT MINS SHOULD FALL INTO THE 20S TO LOWER/MID 30S FOR TUE
NT/WED AM…THEN MAINLY 20S FOR THU AM.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/…
SLOW MOVING LOW PRESSURE ACROSS THE CANADIAN MARITIMES WILL MAINTAIN
BREEZY CONDITIONS…ALONG BKN-OVC CONDITIONS ACROSS THE TAF SITES
THROUGH 06Z/FRI. EXPECT CIGS TO OCCASIONALLY DIP INTO THE HIGH END
MVFR RANGE…ESP AT KPSF.

AS FOR SNOW CHANCES…IT APPEARS THAT SCATTERED LIGHT SNOW
SHOWERS/FLURRIES WILL REMAIN POSSIBLE AT KGFL/ALB/KPSF THROUGH MUCH
OF THURSDAY MORNING. THERE IS A POSSIBILITY OF SOME LAKE EFFECT
SNOWBANDS DEVELOPING OVER THE NEXT 1-3 HOURS IN THE VICINITY OF THE
MOHAWK VALLEY AND POINTS SOUTH…WHICH COULD IMPACT KALB AND KPSF.
IN GENERAL…VSBYS SHOULD GENERALLY REMAIN VFR. HOWEVER…A FEW
BRIEF REDUCTIONS INTO MVFR/IFR ARE POSSIBLE. SNOW SHOWERS AND
FLURRIES SHOULD DIMINISH IN AREAL COVERAGE LATER THIS AFTERNOON.

BRISK WEST WINDS OF 10-15 KT…WITH GUSTS OF 20-25 KT WILL GRADUALLY
VEER MORE INTO THE NORTHWEST LATER THIS MORNING. SOME GUSTS OF 25-30
KT WILL BE POSSIBLE AT KALB AND KPSF LATE THIS MORNING INTO EARLY
THIS AFTERNOON. NORTHWEST WINDS WILL GRADUALLY DECREASE TO 8-12 KT
AROUND SUNSET…AND MAINLY LESS THAN 8 KT AFTER 03Z/FRI.

OUTLOOK…
THU NT-FRI…VFR. NO SIG WX.
FRI NT…MAINLY VFR. CHC SUB-VFR -SHSN AFTER MIDNIGHT.
SAT-SAT NT…MVFR/IFR. SNOW DEVELOPING. CHC RA/SN AT KPOU SAT PM.
SUN…VFR/MVFR. CHC -SHSN.
MON…VFR. NO SIG WX.

&&

.HYDROLOGY…
NO HYDROLOGY PROBLEMS ARE EXPECTED THROUGH AT LEAST THE NEXT FIVE
DAYS.

LAKE ENHANCED/UPSLOPE SNOWS WILL CONTINUE TO PRODUCE MINOR
ADDITIONAL SNOW ACCUMULATIONS TODAY MAINLY IN THE WESTERN
ADIRONDACKS AND OTHER MOUNTAIN AREAS TODAY. DRY CONDITIONS ARE
EXPECTED ACROSS THE MOST AREAS TODAY…AND ALL AREAS LATER TONIGHT
INTO FRIDAY.

THEN A POSSIBLE COASTAL STORM MAY BRING ACCUMULATING SNOW TO MUCH OF
THE REGION OVER THE WEEKEND…ALTHOUGH SOUTHERN AREAS COULD SEE SOME
RAIN MIXED IN AS WELL. THERE IS STILL UNCERTAINTY IN HOW MUCH
PRECIPITATION OCCURS AND THE PRECIPITATION TYPE DEPENDING ON THE
EXACT TRACK OF THE STORM.

EVEN IF SOME RAIN FALLS ACROSS SOUTHERN AREAS…IT DOES NOT APPEAR
THAT SIGNIFICANT HYDROLOGIC IMPACTS WOULD RESULT DUE TO TEMPERATURES
REMAINING IN THE 30S WITH SNOW POTENTIALLY MIXING IN.

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…HWJIV
NEAR TERM…HWJIV
SHORT TERM…HWJIV
LONG TERM…KL
AVIATION…KL
HYDROLOGY…HWJIV/JPV

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License