FXUS61 KALY 081145
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
645 AM EST TUE DEC 8 2009
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL SLIDE EAST ACROSS THE REGION
TODAY...PROVIDING GENERALLY FAIR WEATHER AND SEASONABLY COLD
TEMPERATURES. A DEVELOPING LOW PRESSURE SYSTEM WILL TRACK FROM THE
SOUTHERN PLAINS INTO THE EAST CENTRAL GREAT LAKES TONIGHT AND
WEDNESDAY...BRINGING SNOW TO THE REGION LATE TONIGHT...AND A WINTRY
MIX WEDNESDAY MORNING BEFORE CHANGING TO RAIN BY AFTERNOON. WINDY
AND MUCH COLDER CONDITIONS WILL FOLLOW IN THE WAKE OF THIS STORM FOR
THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 530 AM EST...WE WILL ISSUE A MINOR UPDATE TO ACCOUNT FOR SNOW
SHOWERS/FLURRIES ACROSS THE SOUTHERN TACONICS...HEADING TOWARD NW
CT. WE EXPECT THESE TO REACH AT LEAST NORTHERN LITCHFIELD COUNTY
OVER THE NEXT 2 HOURS...POSSIBLY PRODUCING A COATING TO A FEW TENTHS
OF AN INCH ACCUM,
PREVIOUS DISCUSSION FOLLOWS...
AS OF 430 AM EST...A PLUME OF LAKE EFECT SNOW SHOWERS/FLURRIES
EXTENDS ESE DOWN THE MOHAWK VALLEY...INTO WESTERN PORTIONS OF THE
CAPITAL REGION. WE EXPECT THIS BAND TO PERSIST THROUGH SUNRISE...AND
PERHAPS A COUPLE OF HOURS THEREAFTER...BEFORE GRADUALLY DISSIPATING
WITH A LOWERING INVERSION LEVEL. HOWEVER...A DUSTING TO UP TO AN
INCH COULD OCCUR WITHIN THIS BAND THIS MORNING...WITH THE HIGHER
AMOUNTS ACROSS THE WESTERN MOHAWK VALLEY. SOME SNOW SHOWERS/FLURRIES
WILL LIKELY MIGRATE PERIODICALLY INTO THE CAPITAL REGION AS WELL
THROUGH MID MORNING...AND INTO THE WESTERN BERKSHIRES AS
WELL...WHERE A COATING TO LESS THAN AN INCH COULD ALSO OCCUR.
OTHERWISE...SOME LOWER CLOUDS WILL LIKELY LINGER INTO THE EARLY
AFTERNOON FOR AREAS FROM THE CAPITAL REGION N AND E...AS LAKE
MOISTURE BECOMES TRAPPED BENEATH THE AFOREMENTIONED LOWERING
INVERSION. IN FACT...SOME AREAS THAT INITIALLY RECEIVE SUNSHINE THIS
MORNING ACROSS NORTHERN PORTIONS OF THE HUDSON VALLEY MAY CLOUD UP
ONCE AGAIN BY MID MORNING ONCE MIXING COMMENCES.
GIVEN THAT WE EXPECT MORE CLOUDS...WE HAVE INDICATED MAXES COLDER
THAN A MAV/MET MOS BLEND...WITH MAINLY MID/UPPER 30S WITHIN THE
VALLEYS...AND UPPER 20S/LOWER 30S ACROSS HIGHER ELEVATIONS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
A WINTER STORM WATCH HAS BEEN ISSUED FOR THE SOUTHERN
ADIRONDACKS...AS WELL AS FOR ELEVATIONS ABOVE 1000 FEET WITHIN
SOUTHERN VT AND THE NORTHERN BERKSHIRES FROM MIDNIGHT TONIGHT UNTIL
7 PM EST WED. IN THIS REGION...CONFIDENCE IS HIGH ENOUGH TO WARRANT
A WATCH...WHERE SNOWFALL ACCUMS OF 5-10 INCHES IS POSSIBLE. IN
ADDITION...A WINTER WEATHER ADVISORY HAS BEEN ISSUED FOR THE EASTERN
CATSKILLS...FOR THE SAME TIME PERIOD...WHERE 4-8 INCHES OF SNOWFALL
IS POSSIBLE...IN ADDITION TO THE CHANCE OF PATCHY FREEZING RAIN.
TONIGHT/WEDNESDAY...STRONG MID LEVEL ISENTROPIC LIFT...IN ADDITION
TO DYNAMICAL SUPPORT WITHIN THE COUPLED UPPER LEVEL JET REGION
SHOULD FAVOR A BAND OF MODERATE TO HEAVY SNOW TO DEVELOP FROM SW TO
NE AFTER MIDNIGHT. HOWEVER...AS MID LEVELS WARM...THE SNOW IS
EXPECTED TO TRANSITION TO SLEET DURING WED MORNING FROM S TO N.
BEFORE THIS OCCURS...HIGHER ELEVATIONS WITHIN THE CATSKILLS MAY
RECEIVE 4-8 INCHES OF SNOWFALL...THUS JUSTIFYING THE ADVISORIES.
HOWEVER...WITHIN THE VALLEYS...CONFIDENCE IS STILL SOMEWHAT LOW
REGARDING ULTIMATE SNOWFALL AMOUNTS...AS SLEET MAY MIX IN AFTER
ABOUT 2-3 HOURS OF SNOW...ESP ACROSS THE MID HUDSON VALLEY AND
SOUTHERN LITCHFIELD CO CT. THUS...WE HAVE NOT ISSUED ADVISORIES JUST
YET FOR THESE AREAS. FURTHER N/E...WHERE WATCHES HAVE BEEN
POSTED...ENOUGH DEEP COLD AIR SHOULD ALLOW FOR MOD-HVY SNOW TO OCCUR
FOR SEVERAL HOURS...POSSIBLY REACHING WARNING LEVELS. THIS WILL BE
ESPECIALLY TRUE FOR THE HIGHEST ELEVATIONS...MAINLY ABOVE 1000
FT...WITHIN THE WESTERN NEW ENGLAND WATCH AREAS. STRONG E/SE
DOWNSLOPING WINDS SHOULD LIMIT SNOWFALL AMTS ACROSS WESTERN PORTIONS
OF BENNINGTON CO...AND LOWER ELEVATIONS WITHIN NORTHERN BERKSHIRE
CO...WHERE BOUNDARY LAYER TEMPS MAY ACTUALLY WARM ABOVE FREEZING BY
OR JUST AFTER DAYBREAK. THUS...THE WATCH FOR THE NEW ENGLAND AREA IS
CONFINED TO THE HIGHER ELEVATIONS. IT SHOULD BE STRESSED THAT WITH
OR WITHOUT AN ADVISORY...THE MORNING COMMUTE WILL LIKELY BE MESSY
GIVEN THE TIMING OF THE MOD-HVY PRECIP AND TRANSITION...AS WELL AS
SINCE THIS IS THE FIRST SUCH EVENT OF THE SEASON. PRECIP SHOULD
GRADUALLY CHANGE TO RAIN FROM S TO N...INCREASING IN ELEVATION
DURING WED AFTERNOON...WITH THE EXCEPTION OF THE SOUTHERN
ADIRONDACKS AND HIGHER TERRAIN OF SOUTHERN VT...WHERE SNOW WILL
GRADUALLY CHANGE OVER TO SLEET.
AS FOR FREEZING RAIN POTENTIAL...IT APPEARS TO MAINLY BE FOR HIGHER
ELEVATIONS AS WELL...MAINLY ABOVE 1000 FT...GIVEN THE MOIST
ADIABATIC LOW LEVEL THERMAL PROFILE...FROM MID/LATE WED MORNING INTO
THE EARLY/MID AFTERNOON. IT SHOULD BE NOTED THAT THE NAM12 HINTS AT
COLD AIR LINGERING LONGER ACROSS THE REGION...FOR ELEVATIONS BETWEEN
800-1800 FT...WHICH COULD ALLOW FOR FREEZING RAIN TO BE MORE
WIDESPREAD AND PERSISTENT THAN CURRENTLY INDICATED. LATER FORECASTS
MAY NEED TO BE TWEAKED SHOULD FUTURE TRENDS REMAIN CONSISTENT.
E/SE WINDS COULD ALSO APPROACH ADVISORY LEVELS ACROSS HIGHER
ELEVATIONS WITHIN THE SOUTHERN GREEN MOUNTAINS...AND PORTIONS OF THE
BERKSHIRES AND TACONICS. CONFIDENCE STILL LOW ENOUGH AT THIS TIME
RANGE TO PRECLUDE ANY WIND ADVISORY...BUT WILL HIGHLIGHT POTENTIAL
IN HWOALY.
THE PRECIP SHOULD GRADUALLY BECOME MORE SHOWERY BY LATE WED
AFTERNOON...AND AS A STRONG EMBEDDED SHORTWAVE TRACKS ACROSS...AND
THE OCCLUDED FRONT APPROACHES...COULD ALLOW FOR SOME EMBEDDED
RUMBLES OF THUNDER GIVEN THE NAM SHOWALTERS DIPPING INTO SLIGHTLY
NEGATIVE RANGE. THESE SHOWERS SHOULD THEN TAPER OFF WED LATER WED
EVENING...BEFORE OROGRAPHICAL RAIN/SNOW SHOWERS DEVELOP AFTER
MIDNIGHT...WITH ADDITIONAL MINOR ACCUMS POSSIBLE.
THURSDAY...BEHIND THE STORM SYSTEM...THE MAIN IMPACTS TO OUR REGION
WILL BE STRONG WINDS...AND POTENTIAL LAKE EFFECT SNOWFALL. GIVEN THE
TRACK OF THE SFC LOW SO FAR TO THE W...AND THE SECONDAY LOW
REMAINING WEAK AND WELL TO OUR NE...IT APPEARS THAT THE GREATEST
ISALLOBARIC PRESSURE RISES WILL ALSO REMAIN TO OUR N/W. IN
ADDITION...INITIALLY THE WINDS WILL BE MORE FROM THE SW TO
WSW...WHICH DOES NOT FAVOR CHANNELING DOWN THE MOHAWK RIVER VALLEY.
HOWEVER...AS WINDS VEER SLIGHTLY INTO THE W DURING THE
AFTERNOON...AND MIXING DEEPENS...SOME GUSTS COULD APPROACH/SLIGHTLY
EXCEED ADV LEVELS. THUS...WE WILL MENTION THIS POSSIBILITY IN THE
HWOALY. OTHERWISE...LAKE EFFECT/ENHANCED SNOWBANDS ARE EXPECTED TO
DEVELOP...IMPACTING MAINLY NORTHERN HERKIMER CO. THIS WILL NEED TO
BE WATCHED...AS SNOWFALL ACCUMS COULD REACH ADV LEVELS BY LATE
AFTERNOON. AS FOR MAX TEMPS...DEEP MIXING SHOULD ALLOW TEMPS TO
REACH THE MID/UPPER 30S IN THE VALLEYS...WITH MAINLY 20S FOR HIGHER
ELEVATIONS. MAXES WILL LIKELY OCCUR DURING THE LATE MORNING/EARLY
AFTERNOON...WITH TEMPS FALLING DURING THE AFTERNOON HOURS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
BROAD MEAN UPPER TROUGH SETS UP OVER EASTERN NORTH AMERICA...
RESULTING IN BELOW NORMAL TEMPERATURES THROUGH MOST OF THE LONG TERM
PERIOD. MEAN WIND FLOW OFF THE GREAT LAKES THURSDAY NIGHT THROUGH
FRIDAY NIGHT WILL MEAN INTERVALS OF CLOUDINESS ACROSS THE REGION...
AND BEST CHANCE FOR SNOW SHOWERS IN THE ADIRONDACKS. BY SATURDAY...
WEAK HIGH PRESSURE IS NEARLY CENTERED OVER OUR AREA...AS SOUTHERN
STREAM UPPER ENERGY SQUIRTS JUST SOUTH OF OUR REGION...AND A
NORTHERN STREAM SYSTEM BEGINS TO APPROACH OUT OF CANADA. SOME
ENHANCED SNOW SHOWER ACTIVITY IS POSSIBLE IN THE ADIRONDACKS
ASSOCIATED WITH THE COLD FRONT SATURDAY NIGHT AND SUNDAY.
OTHERWISE...TRACK OF SOUTHERN STREAM SYSTEM SATURDAY AND SUNDAY VERY
MUCH IN QUESTION...AND WILL HAVE TO KEEP AN EYE ON IT IN CASE THERE
ARE TRENDS TO THE NORTH WITH TIME. REGARDLESS...AFTER THE COLD
FRONT TRACKS THROUGH SATURDAY NIGHT OR SUNDAY...MUCH COLDER AIR
POURS IN SUNDAY NIGHT AND MONDAY.
LOWS THURSDAY NIGHT THROUGH SATURDAY NIGHT IN THE TEENS TO LOWER
20S...SOME SINGLE NUMBERS IN THE MOUNTAINS. HIGHS FRIDAY THROUGH
SUNDAY IN THE MID 20S TO LOWER 30S...COLDER IN THE MOUNTAINS. LOWS
SUNDAY NIGHT LOWER TO MID TEENS...WITH HIGHS MONDAY IN THE MID TO
UPPER 20S...AROUND 20 MOUNTAINS...AROUND 30 SOUTHERN AREAS.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
LAKE EFFECT MOISTURE CONTINUES TO PRODUCE A BROKEN TO OVERCAST DECK
AT ABOVE 3000 FEET IN MANY AREAS FROM AROUND KGFL TO KALB. KPOU
REMINS SOUTH OF THE MAIN AREA OF CLOUD COVER. KGFL CONTINUES TO
EXPERIENCE FOG...AND WITH THE LIGHT WINDS AND WEAK WARM
ADVECTION...KGFL WILL SEE IFR FOG THROUGH ABOUT 14Z. AFTER
14Z...ALL SITES SHOULD SEE VFR CONDITIONS. THE LAKE EFFECT
MOISTURE SHOULD MIX OUT THROUGH THE DAY...BUT SOME MID AND HIGH
CLOUDS ABOVE 12000 FEET WILL SPREAD ACROSS THE REGION THIS
AFTERNOON...AND CONTINUE TO THICKEN THROUGH THIS EVENING IN
ADVANCE OF THE NEXT STORM. BY 04Z-06Z...THE CEILING WILL LOWER AND
BETWEEN 07Z-09Z...LIGHT SNOW COULD BEGIN...BRINGING CEILINGS AND
VISIBILITIES TO MVFR LEVELS.
WINDS TODAY WILL BE LIGHT SOUTHWEST TO NORTHWEST...AT 6 KT OR
LESS...THEN DIMINISH TO 3 KT OR LESS THIS EVENING. WINDS WILL
BECOME SOUTHEAST TO NORTHEAST AT LESS THAN 10 KT AFTER MIDNIGHT.
OUTLOOK...
WED...MVFR/IFR. SN/RA LIKELY.
THUR...VFR/MVFR...CHC -SHSN. WINDY.
FRI...VFR. NO SIG WX.
SAT...VFR. NO SIG WX.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS EXPECTED THROUGH EARLY WEDNESDAY AS ANY
PRECIPITATION UP TO THAT TIME WILL COME IN THE FORM OF SNOW AND THUS
HAVE NO DIRECT IMPACT ON THE RIVERS.
ON WEDNESDAY...SNOW MIXING WITH OR CHANGING TO RAIN COULD PRODUCE
SOME HYDRO PROBLEMS...ESPECIALLY FROM ALBANY SOUTH AND EAST WHERE
THE GREATEST AMOUNT OF RAIN IS EXPECTED TO FALL AND TEMPERATURES
WARM UP THE MOST.
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...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST
WEDNESDAY FOR NYZ047-048-051-058-063.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY EVENING
FOR NYZ033-042.
MA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY EVENING
FOR MAZ001.
VT...WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY EVENING
FOR VTZ013>015.
&&
$$
AVIATION...NAS
