FXUS61 KALY 260210
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
910 PM EST FRI DEC 25 2009
.SYNOPSIS...
A FRONT ASSOCIATED WITH A STORM SYSTEM OVER THE UPPER MIDWEST WILL
APPROACH FROM THE SOUTHWEST OVERNIGHT AND SATURDAY...BRINGING A
WINTRY MIX TO THE REGION...BEFORE CHANGING TO PLAIN RAIN SATURDAY
NIGHT. PRECIPITATION SHOULD END BY SUNDAY MORNING...BEFORE THE
WEAKENING REMNANT OF THE UPPER MIDWEST STORM SYSTEM BRINGS SNOW
SHOWERS TO THE REGION SUNDAY NIGHT AND MONDAY...WITH MUCH COLDER
AIR RETURNING TO THE REGION BY MONDAY NIGHT AND TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
THE LATEST RUC/RADAR/SFC MSAS/LAPSS ANALYSES SHOWS THERMAL
ADVECTION PCPN MOVING IN AHEAD OF AN OCCLUDED FRONT TIED TO THE
POTENT STORM SYSTEM OVER THE UPPER MIDWEST...AND IN ADVANCE OF A
SECONDARY SFC WAVE DEVELOPING OVER THE MID ATLANTIC REGION. THE
OVER RUNNING SCENARIO HAS SET UP DUE TO THE COLD AIR DAMMING
INVOKED BY THE SFC ANTICYCLONE SLIDING EASTWARD OVER S-CNTRL
QUEBEC.
THE PCPN WAS SLOWING MOVING INTO LOCATIONS SOUTH AND WEST OF THE
CAPITAL REGION AS OF 845 PM EST. WE HAVE SEEN SOME -FZRA/-SN
REPORTED FROM KMGJ/KSWF. KPOU HAS RISEN TO 36F...BUT WE BELIEVE
THEY WILL WET BULB DOWN TO OR BELOW FREEZING. A BRIEF PEIOD OF MIXED
PCPN IS LIKELY THERE INTO THE EARLY MORNING HOURS. HOWEVER...AS
ONE GOES NORTHWARD MORE COLD AIR IS IN PLACE FOR A PERIOD OF SNOW
AND SLEET. THE 00Z KALB SOUNDING SHOWS A 2-3C WARM NOSE AT H825.
IT IS DRY IN THE LAYER...AND WITH SATURATION SHOULD COOL DOWN. WE
WILL CONTINUE MENTION OF AN INCH OR SO OF SNOW AND SLEET IN THE
CAPITAL REGION. WE MENTIONED -IP/-FZRA TO START AT KPOU BEFORE GOING
TO -FZRA/-RA BTWN 09Z-12Z. FURTHER NORTH...WE INCREASED THE SNOW
AMOUNTS TO A COUPLE OF INCHES FOR THE SOUTHERN ADIRONDACK REGION
AFTER MIDNIGHT WITH THE RELATIVELY DEEP COLD AIR THAT WILL SLOWLY
ERODE ALOFT. ALL AND ALL...PREVIOUS FORECAST PRETTY MUCH ON TRACK.
...PORTION OF PREVIOUS NEAR TERM FORECAST DISCUSSION...
PRECIPITATION ASSOCIATED WITH THE LEADING EDGE OF MID LEVEL WARM
ADVECTION HAS ALREADY REACHED PORTIONS OF SOUTH CENTRAL
NYS/NORTHERN PA...BUT HAS BEEN SHOWING SOME SIGNS OF
WEAKENING/DRYING UPON ENTERING THE DEEP MID LEVEL DRY LAYER. THIS
FIRST BAND COULD PRODUCE SOME LIGHT SNOW ACROSS SOUTHERN/WESTERN
AREAS AFTER SUNSET...AND POSSIBLY REACHING THE CAPITAL REGION
BETWEEN 8-11 PM...ESP AS PRECIP FALLS INTO LINGERING STRATUS
DECK...LEADING TO SOME SEEDER-FEEDER PRECIP PROCESSES. A MORE
ROBUST AREA OF PRECIP...IN ASSOCIATION WITH STRONGER LOW/MID LEVEL
MOISTURE ADVECTION AND UPPER LEVEL DYNAMICS IS BLOSSOMING FROM
SOUTH CENTRAL PA INTO EASTERN VA/NC...AND THIS SHOULD GRADUALLY
EXPAND NORTH NORTHEAST TONIGHT...REACHING THE SW PORTIONS OF THE
REGION AROUND MIDNIGHT...AND AREAS FROM THE CAPITAL REGION AND
POINTS N/E AFTER MIDNIGHT...POSSIBLY HOLDING OFF ACROSS SE VT
UNTIL DAYBREAK. GIVEN FAIRLY COLD FORECAST SOUNDING TEMPERATURE
PROFILES...WE EXPECT MOST PRECIP TO BEGIN AS SNOW. IN FACT...A
QUICK COATING TO ONE INCH COULD OCCUR IN MANY VALLEY LOCALES
INCLUDING THE CAPITAL REGION WELL AFTER MIDNIGHT AS SOMEWHAT
HEAVIER PRECIP DEVELOPS...WITH SOME AREAS...MAINLY ACROSS THE
EASTERN CATSKILLS/SCHOHARIE VALLEY POSSIBLY RECEIVING 2-4 INCHES
OF SNOWFALL.
AS WE APPROACH DAYBREAK...A TRANSITION TO SLEET/FREEZING RAIN IS
EXPECTED TO OCCUR ACROSS THE MID HUDSON VALLEY...NW CT...AND THE
SCHOHARIE VALLEY...EXTENDING NNW INTO THE WESTERN MOHAWK VALLEY AND
SW DACKS...WHILE SLEET MIXES WITH SNOW FURTHER N AND E INTO THE
CAPITAL REGION.
FOR MIN TEMPS...HAVE GENERALLY FOLLOWED CLOSE TO...OR EVEN A TAD
ABOVE THE WARMER MET MOS...GIVEN THE LOW CLOUDS IN PLACE ACROSS
VALLEY REGIONS...AND HIGHER LEVEL CLOUDS RAPIDLY INCREASING
ELSEWHERE. DID INDICATE COLDER MINS ACROSS PORTIONS OF SOUTHERN VT
AND THE NORTHERN BERKS...WHERE ENOUGH TRANSPARENCY IN THE HIGH
CLOUDS MAY ALLOW TEMPS TO DROP SEVERAL DEGREES THIS EVENING...BEFORE
BECOME STEADY OR EVEN RISE AFTER MIDNIGHT.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
SATURDAY/SAT NT...A WINTRY MIX OF SNOW/SLEET/FREEZING RAIN SHOULD BE
ONGOING AT OR JUST AFTER DAYBREAK FROM THE CAPITAL REGION S AND
W...WITH MAINLY FREEZING RAIN/SLEET ACROSS THE MID HUDSON VALLEY AND
NW CT/SOUTHERN BERKS...AND MAINLY SNOW ACROSS SOUTHERN VT INTO THE
LAKE GEORGE/SARATOGA REGION AND AREAS JUST N OF THE MOHAWK RIVER.
THE PRECIP SHOULD TRANSITION TO MAINLY FREEZING RAIN/FREEZING
DRIZZLE BY MID MORNING...WITH PLAIN RAIN/DRIZZLE ACROSS THE MID
HUDSON VALLEY. GIVEN A STRONG LOW LEVEL N/NNE AGEOSTROPHIC WIND
COMPONENT OF 40-50 KT WITHIN THE 1000-900 MB LAYER...HAVE INDICATED
MAX TEMPS COLDER THAN MOST MOS GUIDANCE. THIS WILL KEEP POCKETS OF
FREEZING RAIN INTO AT LEAST THE EVENING ACROSS THE HIGHER ELEVATIONS
WITHIN THE EASTERN CATSKILLS...AND NORTHERN PORTIONS OF THE HUDSON
RIVER VALLEY/LAKE GEORGE REGION...AS WELL AS HIGHER ELEVATIONS
WITHIN EASTERN BENNINGTON CO/WESTERN WINDHAM CO. IN THESE
REGIONS...ICE ACCRETION OF UP TO...OR SLIGHTLY IN EXCESS OF ONE
THIRD OF AN INCH COULD OCCUR BY EVENING. FORTUNATELY...PRECIP
INTENSITY SHOULD REMAIN GENERALLY LIGHT...WITH SOME BREAKS IN THE
STEADY PRECIP POSSIBLE FROM LATE MORNING INTO MID AFTERNOON AS THE
STRONGER UPPER LEVEL DYNAMICS/MOISTURE ADVECTION HOLD OFF UNTIL LATE
AFTERNOON AFTER THE INITIAL BURST IN THE MORNING. E/SE WINDS WILL
ALSO INCREASE ACROSS HIGHER ELEVATIONS OF THE TACONICS/SOUTHERN
GREENS/BERKS...ESP TOWARD AND AFTER SUNSET...WELL INTO THE OVERNIGHT
HOURS. GIVEN WIND SPEEDS POTENTIALLY REACHING 45-55 KT AT 925
MB...HAVE HOISTED WIND ADVISORIES FOR THE AFOREMENTIONED
REGIONS...WHERE WINDS OF THIS DIRECTION TEND TO
FUNNEL/ENHANCE...WITH POSSIBLE GUSTS REACHING 45-55 MPH.
OTHERWISE...MOST TEMPS SHOULD RISE ABOVE FREEZING ACROSS THE REGION
ONCE MOD PRECIP DEVELOPS SAT NT...WITH PERIODS OF RAIN EXPECTED. IN
FACT...SOME ELEVATED INSTABILITY HAS BEEN NOTED IN THE NAM12...WITH
850 LI/S REACHING 0 TO -1 ACROSS EASTERN AREAS SAT EVE. THUS...A FEW
RUMBLES OF THUNDER CAN NOT BE RULED OUT IN THESE AREAS...BUT DUE TO
OVERALL LOW CHC...HAVE KEPT OUT MENTION AT THIS TIME. RAIN SHOULD
TAPER OFF IN INTENSITY FROM SW TO NE PRIOR TO DAYBREAK SUNDAY.
SUN...ANY LINGERING PRECIP SHOULD END QUICKLY SUN MORNING...WITH A
BREAK IN PRECIP EXPECTED DURING MUCH OF THE DAY. THERE IS AT LEAST A
POSSIBILTY OF SOME BREAKS IN THE CLOUDS TO DEVELOP WITHIN VALLEY
REGION...ESP SUN MORNING...BEFORE COOLING MID LEVELS ALLOW CLOUDS TO
REDEVELOP FROM THE CAPITAL REGION N AND W DURING THE MID/LATE
AFTERNOON. HOWEVER...SHOULD LOW LEVEL MOISTURE REMAIN MORE
ABUNDANT...AS THE NAM12 IMPLIES...LOW CLOUDS MAY PERSIST. SO...GIVEN
THE UNCERTAINTY...HAVE GENERALLY LEANED TOWARD MORE CLOUDS ACROSS
EASTERN AREAS...WHERE UPSLOPE W WINDS SHOULD ALLOW CLOUDS TO BE MORE
PREVALENT...WITH P SUNNY CONDITIONS WITHIN THE VALLEYS. MAX TEMPS
SHOULD REACH THE LOWER 40S WITHIN THE VALLEYS...AND 30S FOR HIGHER
ELEVATIONS...ALTHOUGH MAXES MAY OCCUR DURING THE LATE MORNING BEFORE
SLOWLY FALLING IN THE AFTERNOON WITH INTENSIFYING COLD ADVECTION.
SUN NT...POTENTIALLY INTERESTING SCENARIO DEVELOPING FOR LATE SUN
NT...AS REMNENT UPPER LEVEL LOW ASSOCIATED WITH CURRENT MIDWESTERN
SYSTEM PASSES NEAR OR SOUTH OF THE REGION. DEPENDING ON ITS
TRACK...A PORTION OF OUR REGION MAY LIE WITHIN A FAVORABLY
DEFORMATION REGION LATE AT NIGHT OR MON MORNING...ACCOMPANIED BY A
BURST OF SNOW. THIS COULD LEAD TO SOME QUICK...ALBEIT REALTIVELY
MINOR ACCUMS. THIS WILL NEED TO BE WATCHED...ESP SINCE TIMING COULD
OCCUR TOWARD OR DURING THE MON MORNING RUSH HOUR.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
WENT WITH MOS GUIDANCE...WHICH HELPS US FIT OUR GEOGRAPHICAL PUZZLE
PIECE WELL FOR TEMPS. A COLD FRONT WILL SLIDE TOWARD THE REGION
FROM SOUTH CENTRAL CANADA AT THE BEGINNING OF THE PERIOD. THIS WILL
BRING US A GOOD CHANCE OF SNOW SHOWERS...ALONG WITH STRONG WINDS AND
MUCH COLDER TEMPERATURES...AS ASSOCIATED LOW PRESSURE DEEPENS AROUND
NEWFOUNDLAND.
HIGH PRESSURE JUST BEGINS TO SETTLE IN ON TUESDAY...AS NORTHWESTERLY
WINDS WON'T SUBSIDE UNTIL TUESDAY NIGHT. WITH VERY DRY AIR
INFILTRATING THE REGION...HAVE ONLY A SLGT CHC FOR LAKE EFFECT IN
THE FAR WESTERN ADIRONDACKS TUE THRU WED.
A COMPLEX...THOUGH RELATIVELY TIMID SCENARIO EVOLVES FOR MID- TO
LATE-WEEK. A WEAK COASTAL LOW OFF CAPE HATTERAS WILL TRACK
NORTHEAST OUT TO THE SEA ACCORDING TO THE GFS. MEANWHILE...A WEAK
CLIPPER-LIKE SYSTEM WILL TRACK GENERALLY EAST ACROSS THE GREAT
LAKES...POSSIBLY TAPPING SOME MOISTURE FROM THE COASTAL LOW LATE IN
THE GAME. HOWEVER...QPFS ARE VERY LIGHT. GFS THEN LIFTS THIS LOW
NORTH INTO QUEBEC.
A COUPLE OF PRETTY COLD DAYS ARE ON TAP BEHIND THE CANADIAN FRONT...
WITH HIGHS ON TUESDAY IN ONLY THE TEENS AND 20S. DECENT SUNSHINE
WILL HELP TEMPERATURES BOUNCE BACK RATHER SWIFTLY...WITH HIGHS BY
THU AND FRI IN THE MID 20S AND 30S. TUE NIGHT WILL BE COLDEST...
WITH ALMOST ALL LOCATIONS DOWN INTO THE SINGLE DIGITS...MAINLY BELOW
ZERO IN THE ADIRONDACKS. BY THURSDAY NIGHT...MOST LOWS WILL BE DOWN
ONLY INTO THE TEENS.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
A COMPLEX STORM SYSTEM APPROACHING THE NORTHEAST WILL BRING MIXED
PRECIP TONIGHT...TRANSITIONING TO MAINLY RAIN SATURDAY LATE MORNING
AND AFTERNOON.
EXPECT A LONG DURATION OF MVFR/IFR VSBYS/CIGS AT THE ERN NY
TERMINALS TONIGHT INTO SATURDAY AFTERNOON WITH THE PCPN AHEAD OF
OCCLUDED FRONT...AND A SECONDARY AREA OF LOW PRESSURE.
THE ONSET OF PRECIP WILL MOVE S/SW TO THE N/NE STARTING AROUND 02Z
AT KPOU. THE PCPN WILL THEN APPROACH KALB TOWARDS 04Z...AND KGFL
TOWARDS 06Z. THE PCPN WILL START OUT AS -SN AT ALL THE SITES...BUT
QUICKLY TRANSITION TO -FZRA AT KPOU AROUND 04Z...AND -RA BY 09Z.
THE TRANSITION WILL BE SLOWER AT KALB WITH A PERIOD OF SNOW AND
SLEET UNTIL 08Z...BUT -FZRA WILL MIX IN THEREAFTER...AND CONTINUE
UNTIL THE LATE MORNING BEFORE CHANGING TO -DZ/-RA BY 16Z. KGFL WILL
HAVE SOME SNOW TO START...THEN AN EXTENDED PERIOD OF LIGHT
-FZRA/-IP UNTIL THE EARLY AFTERNOON BEFORE CHANGING TO RAIN BY THE
EARLY TO MID AFTERNOON.
THERE COULD BE A LULL IN THE PCPN IN THE AFTERNOON...BEFORE A
STEADIER RAINFALL MOVES IN WITH A SECONDARY AREA OF LOW PRESSURE
AFTER 00Z/SUN. THIS WILL KEEP CIGS/VSBYS AT LOW MVFR/IFR LEVELS.
THE WINDS WILL BE FROM THE E/NE BTWN 4-8 KTS OVERNIGHT INTO TOMORROW
AFTERNOON. SOME LOW LEVEL WIND SHEAR GROUPS MAY NEED TO BE ADDED
TOMORROW AFTERNOON AND EVENING...AS THE LOW LEVEL JET AT 2500 FT AGL
POTENTIALLY STRENGTHENS TO 40-45 KTS.
OUTLOOK...
SAT NGT...MVFR-IFR WITH -RA.
SUN...VFR...MVFR POSSIBLE WITH CHC -SHRA/-SHSN.
MON...VFR...MVFR POSSIBLE WITH CHC -SHSN.
TUE-WED...VFR...NO SIG WX.
&&
.HYDROLOGY...
A WINTRY MIX OF SNOW...SLEET AND FREEZING RAIN IS EXPECTED TO START
LATE THIS EVENING AND TRANSITION TO FREEZING RAIN LATE TONIGHT INTO
SATURDAY MORNING AND THEN EVENTUALLY RAIN SATURDAY AFTERNOON INTO
SATURDAY EVENING. THE TRANSITION TO RAIN WILL BE QUICKER FARTHER
SOUTH...MAINLY ACROSS THE MIDDLE AND LOWER HOUSATONIC BASIN...THE
RONDOUT CREEK...WAPPINGERS CREEK...AND ESOPUS CREEK AND IN THESE
AREAS QPF AMOUNTS MAY LOCALLY EXCEED 1 INCH WHICH MAY RESULT IN
RISES OF SEVERAL FEET. AT THIS TIME IT DOES NOT APPEAR THAT THERE
WILL BE ENOUGH RUNOFF FOR FLOODING.
ACROSS THE REMAINDER OF THE HSA...THE RUNOFF WILL BE LESS AS SOME
SNOW COVER WILL ABSORB SOME OF THE RUNOFF...AND ANY RUNOFF THAT DOES
OCCUR WILL BE LESS DUE TO COLDER TEMPERATURES ON SATURDAY.
AFTER THE SYSTEM WINDS DOWN ON SUNDAY...IT WILL BE MAINLY DRY INTO
EARLY NEXT WEEK. IT WILL TURN COLDER SO THAT PRECIPITATION SHOULD
COME AS SNOW. TEMPERATURES ARE FORECAST TO DROP BELOW FREEZING
SUNDAY NIGHT AND REMAIN BELOW FREEZING IN MOST AREAS THROUGH AT
LEAST THE MIDDLE OF NEXT WEEK.
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...FREEZING RAIN ADVISORY UNTIL NOON EST SATURDAY FOR CTZ001-013.
NY...FREEZING RAIN ADVISORY UNTIL 3 PM EST SATURDAY FOR NYZ038>041-
043-047>054-058-063-083-084.
FREEZING RAIN ADVISORY UNTIL NOON EST SATURDAY FOR NYZ059>061-
064>066.
WIND ADVISORY FROM 6 PM SATURDAY TO 6 AM EST SUNDAY FOR NYZ054-
061-084.
WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR NYZ032-033-
042-082.
MA...FREEZING RAIN ADVISORY UNTIL 3 PM EST SATURDAY FOR MAZ001-025.
WIND ADVISORY FROM 6 PM SATURDAY TO 6 AM EST SUNDAY FOR MAZ001-
025.
VT...WIND ADVISORY FROM 6 PM SATURDAY TO 6 AM EST SUNDAY FOR VTZ013-
014.
WINTER WEATHER ADVISORY UNTIL 6 AM EST SUNDAY FOR VTZ013>015.
&&
$$
SYNOPSIS...KL
NEAR TERM...KL/WASULA
SHORT TERM...KL
LONG TERM...ELH
AVIATION...WASULA
HYDROLOGY...11
