FXUS61 KALY 300915
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
415 AM EST MON NOV 30 2009
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL TRACK ACROSS NORTHERN NEW ENGLAND TODAY.
A COLD FRONT TRAILING FROM THIS LOW WILL MOVE ACROSS THE REGION THIS
MORNING...PRECEDED AND ACCOMPANIED BY RAIN SHOWERS. MUCH COLDER AIR
WILL FOLLOW IN THE WAKE OF THIS FRONT FOR TONIGHT THROUGH WEDNESDAY.
A MORE POTENT STORM SYSTEM SHOULD BRING A SOAKING RAIN TO THE REGION
WEDNESDAY NIGHT INTO THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 4 AM EST...SCATTERED TO NUMEROUS RAIN SHOWERS CONTINUE TO
AFFECT THE SW ADIRONDACKS AND EXTREME WESTERN MOHAWK VALLEY...WITH
SHOWERS TAPERING TO SPRINKLES ACROSS VALLEY REGIONS FURTHER E. AS A
COLD FRONT APPROACHES FROM THE W LATER THIS MORNING...AND UPPER
LEVEL DYNAMICS BECOME MORE FAVORABLE WITH A POTENT JET MAX
APPROACHING FROM THE SW...WE EXPECT THE AREAL COVERAGE OF RAIN
SHOWERS TO INCREASE FROM W TO E...WITH THE GREATEST CONCENTRATION
EXPECTED ACROSS SOUTHERN AREAS...FROM THE SE CATSKILLS INTO THE MID
HUDSON VALLEY...NW CT AND SW MA LATER THIS MORNING INTO AT LEAST THE
EARLY AFTERNOON HOURS...AS THIS REGION SHOULD LIE WITHIN THE LEFT
EXIT REGION OF AFOREMENTIONED JET MAX...WHICH IS MORE FAVORABLE FOR
ASSOCIATED LOW/MID LEVEL ATMOSPHERIC LIFT AND RAINFALL.
ONCE THE FRONT MOVES FURTHER S/E...SUBSIDENCE SHOULD ALLOW FOR SOME
CLEARING ACROSS N/W AREAS LATE THIS AFTERNOON...POSSIBLY REACHING
THE CAPITAL REGION PRIOR TO SUNSET.
AS FOR MAX TEMPS TODAY...VERY TRICKY GIVEN THE INITIAL WARMTH THIS
MORNING...WITH TEMPS ALREADY APPROACHING OR SLIGHTLY EXCEEDING 50.
ONCE THE RAIN DEVELOPS...WET BULBING SHOULD COOL TEMPS A BIT INTO
THE MID/UPPER 40S...WHICH ARE THE FORECAST MAXES AFTER 12Z.
HOWEVER...TEMPS SHOULD FALL DURING THE AFTERNOON AS COLD ADVECTION
INTENSIFIES...FALLING INTO AND THROUGH THE 30S ACROSS HIGHER
ELEVATIONS N AND W OF ALBANY...AND INTO THE LOWER 40S WITHIN THE
CAPITAL REGION AND ADJACENT VALLEY REGIONS. ACROSS SOUTHERN
AREAS...A PERIOD OF STEADIER RAIN SHOULD LIMIT MAXES FROM REACHING
ABOVE THE MID 40S. HOWEVER...SHOULD RAIN END ANY SOONER THAN
CURRENTLY EXPECTED...WARMER MAXES COULD OCCUR.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...|
TONIGHT...MAIN AREA OF PRECIPITATION SHOULD SHIFT S/E OF REGION
SHORTLY AFTER SUNSET. THEREAFTER...A PERIOD OF CLEARING IS EXPECTED
AS A WEAK SHORTWAVE RIDGE BUILDS EASTWARD ACROSS THE REGION.
HOWEVER...SOME UPSLOPE CLOUDS...AND PERHAPS FLURRIES ARE POSSIBLE
ACROSS HIGHER ELEVATIONS OF SOUTHERN VT/WESTERN MA THIS EVENING.
THEN...AFTER MIDNIGHT...WITH THE APPROACH OF A SHORTWAVE FROM THE
W...SNOW SHOWERS/FLURRIES ARE EXPECTED TO DEVELOP ACROSS THE WESTERN
ADIRONDACKS...AND PERHAPS THE WESTERN MOHAWK VALLEY AND SCHOHARIE
VALLEY TOWARD DAYBREAK. ELSEWHERE...AFTER A PERIOD OF MOSTLY CLEAR
SKIES...CLOUDS SHOULD INCREASE FROM W TO E TOWARD DAYBREAK GIVEN THE
APPROACH OF THE SHORTWAVE. GIVEN THE EXPECTATION FOR A PERIOD OF
CLEARING...AND LIGHT WINDS ASSOCIATED WITH SHORTWAVE RIDGE PASSING
THROUGH...WE HAVE SIDED WITH THE COLDER MET MOS NUMBERS...WHICH ARE
GENERALLY IN THE MID/UPPER 20S...EXCEPT UPPER TEENS TO LOWER 20S
ACROSS NORTHERN AREAS.
TUE...AS A SHORTWAVE AND ASSOCIATED MID LEVEL COLD POOL CROSS THE
REGION...WE EXPECT SKIES TO BECOME MOSTLY CLOUDY...ALONG WITH
SCATTERED TO NUMEROUS SHOWERS OF RAIN AND SNOW ACROSS THE REGION. IN
FACT...SEVERAL INDICATORS HINT AT POSSIBLE WINDEX ACTIVITY...MAINLY
THE APPROACH OF THE TROUGH...COMBINED WITH RH GREATER THAN 50
PERCENT IN THE LOW/MID LEVELS...INCREASING LI/S...AND STEEPENING LOW
LEVEL LAPSE RATES. THIS SHOULD SUPPORT NUMEROUS SNOW SHOWERS ACROSS
THE HIGHER ELEVATIONS OF THE ADIRONDACKS...AND THE WEST FACING
SLOPES OF THE SOUTHERN GREEN MOUNTAINS...WHERE 1-3 INCHES OF SNOW
COULD OCCUR. ELSEWHERE...A SLIGHTLY WARMER BOUNDARY LAYER MAY ALLOW
FOR RAIN AND SNOW SHOWERS...AND WITH A DOWNSLOPING W FLOW...WILL
SCALE BACK POPS INTO THE SLIGHT CHC RANGE. AS FOR MAX TEMPS...HAVE
SIDED CLOSER TO THE COOLER MET MOS...WITH MAINLY LOWER 40S WITHIN
THE VALLEYS...AND 30S ACROSS MOST HIGHER ELEVATIONS.
TUE NT...SCATTERED SNOW SHOWERS WILL REMAIN POSSIBLE ACROSS
FAVORABLE UPSLOPE AREAS OF SOUTHERN VT/WESTERN MA...AND WITHIN THE
SOUTHERN ADIRONDACKS EARLY BEFORE GRADUALLY TAPERING OFF LATE.
HOWEVER...LOW CLOUDS COULD LINGER THROUGHOUT THE NIGHT ACROSS
CENTRAL AND NORTHERN AREAS GIVEN RAPIDLY LOWERING INVERSION LEVELS
AND RESIDUAL LAKE MOISTURE BECOMING TRAPPED UNDERNEATH. WILL
THEREFORE INDICATE MINS A BIT WARMER ACROSS CENTRAL AND NORTHERN
AREAS THAN MON NT/TUE AM...SLIGHTLY CLOSER TO THE MAV MOS IN SOME
AREAS...WITH MINS MAINLY RANGING FROM THE MID 20S ACROSS THE
DACKS...TO THE UPPER 20S TO LOWER 30S ELSEWHERE.
WED...HIGH PRESSURE RIDGE WILL MOVE E ACROSS THE REGION...AND OFF TO
OUR E BY LATE AFTERNOON. HOWEVER...MID LEVEL WARM ADVECTION WILL
INTENSIFY...IN RESPONSE TO DEEPENING TROUGH TO OUR W. THIS SHOULD
ALLOW AT LEAST HIGH/MID LEVEL CLOUDS TO INCREASE BY AFTERNOON...WITH
ONLY A BRIEF PERIOD OF SUNSHINE EXPECTED FROM MID MORNING INTO EARLY
AFTERNOON. THUS...HAVE INDICATED COOLER MAXES...IN LINE WITH THE MET
MOS...WITH FORECAST MAXES GENERALLY IN THE MID 40S ACROSS
VALLEYS...AND UPPER 30S/LOWER 40S FOR HIGHER TERRAIN. SOME LIGHT
RAIN COULD DEVELOP TOWARD EVENING ACROSS SOUTHERN AREAS...SHOULD THE
AFOREMENTIONED WARM ADVECTION BECOME EVEN STRONGER THAN CURRENTLY
EXPECTED...AND THUS WE HAVE INDICATED SLIGHT CHC POPS FOR THESE
REGIONS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
FOR WEDNESDAY NIGHT INTO THURSDAY...THE DETERMINISTIC LONG RANGE
GUIDANCE /ECMWF...GFS...CANADIAN GGEM/ ALL INDICATE A RATHER POTENT
STORM SYSTEM LIFTING NORTHEAST FROM THE TENNESSEE VALLEY WEDNESDAY
EVENING INTO WESTERN OR CENTRAL NEW YORK THURSDAY MORNING AND INTO
THE CANADIAN MARITIMES THURSDAY EVENING. WHILE THE EXACT TRACK OF
THE SYSTEM REMAINS UNCERTAIN...IT DOES APPEAR THAT SYSTEM WILL TRACK
TO THE WEST OF FA ALLOWING PLENTY OF WARM AIR TO RUSH IN WEDNESDAY
NIGHT INTO THURSDAY MORNING SUCH THAT MOST IF NOT ALL OF THE PCPN
WILL BE IN THE FORM OF RAIN WHICH IS WHAT WE HAVE IN THE GRIDS FOR
WEDNESDAY NIGHT INTO THURSDAY. SOME OF THIS PCPN COULD BE
SIGNIFICANT AS FLOW FROM GULF APPEARS TO BE OPEN WITH ALL MODELS
INDICATING THAT H5 CLOSED LOW OPENS AS IT LIFTS FROM MID MISSISSIPPI
VALLEY WEDNESDAY NIGHT INTO THE EASTERN GREAT LAKES AND WEAKENS AS
AS H5 LOW OVER WESTERN GREAT LAKES BECOMES THE DOMINANT FEATURE. AND
THE ENSEMBLES CONTINUE TO INDICATE A STORM SYSTEM INTERACTING WITH
THE SUBTROPICAL JET STREAM WILL APPROACH FROM THE TN AND OH VALLEYS
WED NIGHT. THE AMOUNT OF GULF MOISTURE THAT IS TAPPED AND THE EXACT
TRACK OF THE INTENSIFYING LOW PRESSURE SYSTEM IS STILL UNCERTAIN AND
THIS COUPLED WITH DAY 4 FOR MAIN ACTIVITY PRECLUDES MENTION IN THE
HWO AT THIS TIME...BUT IT DOES NEED TO BE MONITORED CLOSELY. MREF
PLUME FOR KALB HAS ALL RAIN WITH GENERALLY BTWN 1 AND 2 INCHES OF
QPF WITH A MEAN OF AROUND AN INCH AND A QUARTER. FOR NOW HAVE LIKELY
POPS WEDNESDAY NIGHT INTO THURSDAY MORNING AND THEN TAPER TO CHANCE
POPS THURSDAY AFTERNOON AS DRY SLOT EXPECTED TO MOVE ACROSS FA WITH
LOW LIFTING INTO CANADIAN MARITIMES. HAVE LOWS WEDNESDAY NIGHT IN
THE 30S WITH HIGHS ON THURSDAY IN THE UPPER 30S NORTHWEST TO MID 50S
SOUTHEAST. DID NOT USE A NON DIURNAL TREND THIS FAR OUT ALTHOUGH IT
IS POSSIBLE THAT TEMPS MAY DROP THURSDAY AFTERNOON.
THU NIGHT INTO SAT...IN THE WAKE OF THE SURFACE LOW STRONG COLD AIR
ADVECTION TAKES PLACE WITH FAIRLY STRONG CYCLONIC FLOW AND AS A
RESULT SOME LAKE EFFECT SNOWS ARE POSSIBLE ESPECIALLY ACROSS THE
WESTERN ADIRONDACKS AND NORTHERN PORTIONS OF THE MOHAWK VALLEY. THIS
LOOKS TO BE A FAIRLY PROLONGED LAKE EFFECT EVENT AS LAKE ONTARIO
TEMPS WILL LIKELY STILL BE IN THE MID 40S AND H8 TEMPS LOOK TO DROP
TO AROUND -10 C LATE THURSDAY NIGHT AND REMAIN AROUND -10 C ON
FRIDAY AND DROP -12 OR -13 C ON FRIDAY NIGHT BEFORE RISING SLIGHTLY
ON SATURDAY.
SATURDAY NIGHT INTO SUNDAY...THE LOW LEVEL FLOW BECOMES ANTICYCLONIC
WHICH SHOULD BRING AN ABRUPT END TO THE LAKE EFFECT ACTIVITY AND
ALLOW TEMPS TO MODERATE AS RIDGING BRIEFLY BUILDS INTO THE REGION
BEFORE ANOTHER SHORT WAVE APPROACHES.
FOR THE PERIOD FROM WEDNESDAY NIGHT THROUGH SUNDAY EXPECT PCPN TO BE
WELL ABOVE NORMAL WITH TEMPS SLIGHTLY BELOW NORMAL.
&&
.AVIATION /09Z MONDAY THROUGH FRIDAY/...
VFR CONDITIONS WILL GRADUALLY GIVE WAY TO MVFR CONDITIONS DURING THE
REMAINDER OF THE OVERNIGHT PERIOD AS SHOWERS OVERSPREAD THE UPPER
HUDSON VALLEY WHICH WILL IMPACT KGFL AND KALB. KPOU IS LIKELY TO
REMAIN VFR DURING THE REMAINDER OF THE OVERNIGHT PERIOD WITH SHOWERS
NOT ARRIVING UNTIL BETWEEN 10Z AND 12Z. TAF SITES LOOK TO GO IFR
AFTER COLD FRONTAL PASSAGE FOR SEVERAL HOURS WHICH IS EXPECTED
AROUND 13Z AT KGFL...14Z AT KALB AND 16Z AT KPOU. THIS WILL BE
FOLLOWED BY IMPROVING CONDITIONS TO VFR AND EVENTUALLY CLEARING
EARLY THIS EVENING AT KGFL AND KALB WITH STRATOCUMULUS VFR CEILINGS
AT KPOU THROUGH THE END OF THE TAF PERIOD AT KPOU.
LIGHT WINDS WILL BECOME SOUTH AT 4 TO 8 KTS AT TAF SITES DURING
THE REMAINDER OF THE OVERNIGHT PERIOD AND THEN SHIFT TO W-SW
AROUND 5 TO 8 KTS WITH COLD FRONTAL PASSAGE BETWEEN 13Z AND 16Z
AND EVENTUALLY NORTHWEST AT 4 TO 8 KTS BETWEEN 16Z AND 22Z.
OUTLOOK...
MON NIGHT-WED...VFR. NO SIG WX.
WED NIGHT-THU...MVFR-IFR. RA LIKELY.
FRI...VFR...CHC -SHRA/-SHSN.
&&
.HYDROLOGY...
NO WIDESPREAD HYDRO PROBLEMS THROUGH WEDNESDAY...WITH JUST LIGHT WPF
AMOUNTS EXPECTED TODAY WITH THE PASSAGE OF A COLD FRONT...WITH TOTAL
QPF RANGING FROM A TENTH TO A THIRD OF AN INCH...HIGHEST ACROSS THE
SOUTHERN ADIRONDACKS.
HIGH PRESSURE WILL YIELD MAINLY DRY WEATHER TUESDAY THROUGH
WEDNESDAY...EXCEPT FOR SOME LIGHT LAKE EFFECT SNOW WHICH WILL BE
MAINLY CONFINED TO THE WESTERN ADIRONDACKS LATE MONDAY NIGHT INTO
TUESDAY EVENING.
A STORM SYSTEM APPROACHING FROM THE OH VALLEY WEDNESDAY NIGHT MAY
BRING A SOAKING RAINFALL TO THE HSA WED NT INTO THU...WITH RAINFALL
AMOUNTS RANGING FROM A HALF AN INCH TO AN INCH AND A HALF.
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...KL
NEAR TERM...KL
SHORT TERM...KL
LONG TERM...11
AVIATION...11
HYDROLOGY...KL/WASULA
