March 12, 2013 Forecast Discussion

000
FXUS61 KALY 121036
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
636 AM EDT TUE MAR 12 2013

.SYNOPSIS…
A COLD FRONT WILL SLOWLY MOVE EASTWARD ACROSS EASTERN
NEW YORK AND WESTERN NEW ENGLAND TODAY…AS A WAVE OF LOW PRESSURE
RIDES NORTHWARD ALONG IT. THESE FEATURES WILL BRING PERIODS OF RAIN
AND GUSTY WINDS TO THE REGION TODAY…WITH SOME LOCALLY HEAVY
RAINFALL POSSIBLE. IN THE WAKE OF THE COLD FRONTAL PASSAGE…PRECIPITATION
WILL TAPER OFF THIS EVENING…WITH COLDER AIR GRADUALLY MOVING
INTO THE REGION FOR WEDNESDAY INTO THURSDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
…FLOOD WATCH IN EFFECT THROUGH 8 AM EDT WED FOR THE SOUTHERN
ADIRONDACKS/WESTERN MOHAWK VALLEY/EASTERN CATSKILLS AND SCHOHARIE
VALLEY/TACONICS AND WESTERN NEW ENGLAND…

AS OF 635 AM EDT…LIGHT TO MODERATE RAIN PERSISTS ACROSS THE
SOUTHERN ADIRONDACKS AND WESTERN MOHAWK VALLEY…WITH ADDITIONAL
PATCHES OF LIGHT/MODERATE RAIN ACROSS THE SE CATSKILLS AND MID
HUDSON VALLEY REGION. WE EXPECT THE RAIN TO GRADUALLY BECOME MORE
WIDESPREAD…ESP LATER THIS MORNING INTO THE AFTERNOON HOURS…AND
MAY BECOME HEAVY AT TIMES AS A WAVE OF LOW PRESSURE RIDES
NORTHWARD FROM THE CENTRAL APPALACHIANS ALONG THE COLD FRONT TO
OUR WEST. PWAT/S ARE EXPECTED TO REACH AROUND ONE INCH…ALONG
WITH FAIRLY STRONG SOUTHERLY 925-850 WINDS. AN UPPER LEVEL JET
MAX…CURRENTLY OVER THE CENTRAL APPALACHIANS…IS FORECAST TO
CONTINUE TRANSLATING NORTH NORTHEAST TODAY…MOVING ACROSS OUR
REGION AROUND MIDDAY…AND INTO NORTHERN NEW ENGLAND BY MID TO
LATE AFTERNOON. INITIALLY…OUR REGION WILL BE IN THE FAVORABLE
LEFT EXIT REGION LATER THIS MORNING INTO THE EARLY AFTERNOON FOR
INCREASED ASCENT AND RAINFALL. THE RIGHT ENTRANCE REGION
ASSOCIATED WITH THIS JET MAX IS THEN EXPECTED TO AFFECT SOUTHEAST
PORTIONS OF THE FORECAST AREA WITH ENHANCED RAINFALL LATER THIS
AFTERNOON. RAINFALL AMTS OF 0.75-1.5 INCHES ARE EXPECTED
TODAY…WITH ISOLATED HIGHER AMTS POSSIBLE ACROSS PORTIONS OF NW
CT…WESTERN MA AND SOUTHERN VT…AND ALSO ACROSS A SMALL PORTION
OF THE SOUTHERN ADIRONDACKS. THIS LOCALLY HEAVY RAINFALL…IN
COMBINATION WITH SIGNIFICANT SNOWMELT ACROSS HIGHER ELEVATIONS MAY
LEAD TO AT LEAST SOME MINOR FLOODING OF SMALL STREAMS…AND
POSSIBLY LARGER STEM TRIBUTARIES WITHIN THE WATCH AREA LATER TODAY
AND TONIGHT.

SOUTH TO SOUTHEAST WINDS WILL BE STRONG AT TIMES…ESP THIS
MORNING…AS THE WAVE OF LOW PRESSURE ALONG THE FRONT APPROACHES
FROM THE SOUTHWEST. SOME GUSTS COULD REACH 30-40 MPH AT TIMES
WITHIN THE IMMEDIATE HUDSON RIVER VALLEY AND ACROSS PORTIONS OF NW
MA AND SW VT. WE WILL HAVE TO WATCH THIS AREA CLOSELY…AS ANY
BREAKS IN THE CLOUDS COULD INDUCE GREATER MIXING…AND PRODUCE
HIGHER WIND GUSTS INTO THE ADVISORY RANGE.

GIVEN HOW WARM TEMPS ARE ALREADY RUNNING THIS MORNING…WE HAVE
GONE ABOVE A MAV/MET MOS BLEND IN MOST AREAS…WITH LOWER/MID 50S
EXPECTED IN MANY VALLEY AREAS…AND LOWER/MID 40S ACROSS HIGHER
ELEVATIONS ACROSS THE WESTERN ADIRONDACKS. TEMPERATURES WILL
LIKELY REACH MAXES LATE THIS MORNING OR AROUND MIDDAY ACROSS NW
AREAS BEFORE THE FRONT PASSES…AND DURING THE EARLY AFTERNOON
HOURS CLOSER TO THE CAPITAL REGION…WITH FALLING TEMPS EXPECTED
THEREAFTER. THE FRONT IS EXPECTED TO REACH FAR SE AREAS BY LATE
AFTERNOON…SO TEMPS SHOULD EXHIBIT A MORE TYPICAL DIURNAL CURVE
IN THESE AREAS…AND MAY REACH THE UPPER 50S IN SOME AREAS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/…
TONIGHT…AS THE FRONT AND ASSOCIATED WAVE OF LOW PRESSURE MOVE
NORTHEAST OF THE REGION…RAIN AND/OR SHOWERS SHOULD TAPER OFF
THIS EVENING FAIRLY QUICKLY FROM SW TO NE. THERE IS A CHANCE THAT
SOME WET SNOW COULD MIX IN ACROSS THE HIGHEST ELEVATIONS ACROSS
THE WESTERN ADIRONDACKS. AS SUBSIDENCE DEVELOPS IN THE WAKE OF
THIS SYSTEM…SOME BREAKS IN THE CLOUDS WILL LIKELY DEVELOP…AS
FOR TEMPS…TRICKY CALL…AS CURRENT TEMPS ACROSS THE LOWER GREAT
LAKES AND MIDWEST ARE STILL ABOVE FREEZING AS CLOUDS AND SOME WIND
HAS PERSISTED. DEPENDING ON HOW MUCH CLOUD COVER PERSISTS
OVERNIGHT…MIN TEMPS MAY BE WARMER THAN CURRENT MOS SUGGESTS.
HAVE SIDED WITH…OR WENT A BIT ABOVE THE WARMER MAV MOS FOR MINS
BASED ON THIS REASONING…WITH EVEN WARMER MINS POSSIBLE SHOULD
CLOUDS HANG TOUGH. FORECAST MINS ARE GENERALLY IN THE LOWER/MID
30S IN VALLEYS…AND 20S ACROSS HIGHER ELEVATIONS.

WED-WED NT…A STRONG UPPER LEVEL TROUGH WILL TRANSLATE EAST
ACROSS THE REGION LATE WED INTO WED NT. VERY COLD MID LEVEL
TEMPS…WITH 500 MB TEMPS OF -30 TO -35 C…AND 700 MB TEMPS OF
-15 TO -20 C ARE EXPECTED BY LATE WED INTO WED EVENING. THIS WILL
GREATLY STEEPEN LOW LEVEL LAPSE RATES BY LATE WED
AFTERNOON…WHICH…IN COMBINATION WITH INCREASED FORCING AND
ASCENT FROM THE APPROACHING TROUGH AXIS…SHOULD ALLOW RAIN AND
SNOW SHOWERS TO INCREASE IN AREAL COVERAGE WED AFTERNOON AND
EVENING. GIVEN SUCH COLD MID LEVEL TEMPS…IT IS POSSIBLE THAT
SOME GRAUPEL/SMALL HAIL COULD OCCUR WITHIN ANY TALLER
SHOWERS…ALONG WITH PERHAPS A FEW RUMBLES OF THUNDER. THIS
POSSIBILITY LOOKS GREATEST ACROSS SOUTHERN AREAS…SUCH AS THE MID
HUDSON VALLEY…AND NW CT. ACROSS HIGHER ELEVATIONS…SCATTERED
COATINGS OF SNOW COULD OCCUR FROM THESE SHOWERS. AS THE MID LEVEL
TROUGH AXIS PASSES LATE WED NT…THE POTENTIAL FOR LAKE EFFECT
SNOWBANDS WILL INCREASE ACROSS PORTIONS OF THE WESTERN
ADIRONDACKS/MOHAWK VALLEY. FOR NOW…HAVE KEPT LIKELY POPS IN
THESE REGIONS…WITH A FEW INCHES OF SNOWFALL POSSIBLE WED NT. AS
FOR TEMPS…HAVE SIDED WITH THE SLIGHTLY WARMER MAV MOS FOR WED
MAXES GIVEN POTENTIAL FOR FAIRLY DEEP MIXING…WITH LOWER/MID 40S
IN MOST VALLEYS…AND 20S TO LOWER 30S ACROSS HIGHER ELEVATIONS.
SOME PORTIONS OF THE MID HUDSON VALLEY COULD STILL APPROACH 50
GIVEN A DOWNSLOPING W/NW WIND AND SOME BREAKS OF SUNSHINE. FOR WED
NT…MUCH COLDER AIR WILL FILTER INTO THE REGION…WITH MINS
FALLING INTO THE 20S IN VALLEYS…AND TEENS ACROSS HIGHER ELEVATIONS.

THU-THU NT…ALTHOUGH THE CORE OF THE MID LEVEL COLD POOL
PASSES…THE LOW LEVEL COLD POOL WILL STILL MOVE THROUGH. 850
TEMPS FALL INTO THE -13 TO -17 C RANGE…COLDEST ACROSS NORTHERN
AREAS. EXPECT MAX TEMPS TO RANGE FROM THE LOWER/MID 30S IN VALLEY
AREAS…WITH 20S ACROSS HIGHER ELEVATIONS. ISOLATED TO SCATTERED
SNOW SHOWERS AND FLURRIES WILL PERSIST THROUGH THURSDAY…ALONG
WITH PERHAPS SOME CELLULAR ELEMENTS OF LAKE EFFECT SNOW ACROSS
PORTIONS OF THE SCHOHARIE VALLEY/EASTERN CATSKILLS AND WESTERN
MOHAWK VALLEY. THE POTENTIAL FOR MORE ORGANIZED SNOWBANDS MAY ONCE
AGAIN INCREASE THU NT. EXPECT MIN TEMPS THU NT TO FALL INTO THE
TEENS TO LOWER 20S. IT WILL BE QUITE WINDY THU…WITH SOME GUSTS
POSSIBLY REACHING 40-45 MPH AT TIMES…ESP WITHIN THE MOHAWK RIVER
VALLEY/CAPITAL REGION AND BERKSHIRES. WINDS WILL GRADUALLY SUBSIDE
LATE THU NT.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/…
FRIDAY…THE NOSE OF A RIDGE OF HIGH PRESSURE WILL BE ACROSS THE FA
WITH PARTLY TO MOSTLY SUNNY SKIES AND SLIGHTLY BELOW NORMAL TEMPS
WITH HIGHS IN THE 30S TO LOWER 40S.

FRIDAY NIGHT AND SATURDAY…MODELS ARE IN FAIRLY GOOD AGREEMENT WITH
A CLIPPER TYPE SYSTEM EXPECTED TO RACE EASTWARD FROM THE CENTRAL
GREAT LAKES FRIDAY EVENING INTO THE EASTERN GREAT LAKES SATURDAY
MORNING AND OFF THE NEW ENGLAND COAST SATURDAY EVENING. SLIGHT
DIFFERENCE IN TRACK…TIMING AND STRENGTH OF SYSTEM WILL HAVE SOME
IMPACT ON LOCATION AND AMOUNT OF HEAVIEST PCPN. EXPECT PTYPE TO ALSO
BE AN ISSUE WITH MORE SNOW THAN RAIN IN THE MOUNTAINS AND ACROSS
NORTHERN AREAS AND MORE RAIN THAN SNOW ACROSS THE MID HUDSON VALLEY
EAST ACROSS SOUTHERN LITCHFIELD COUNTY. QPF AMOUNTS ARE GENERALLY
EXPECTED TO RANGE FROM TWO TENTHS TO A THIRD OF AN INCH THROUGH LATE
SATURDAY. EXPECT LOWS FRIDAY NIGHT IN THE MID TEENS TO UPPER 20S AND
HIGHS ON SATURDAY IN THE MID 30S TO MID 40S.

SATURDAY NIGHT THROUGH SUNDAY NIGHT…EXPECT MAINLY DRY CONDITIONS
AS A RIDGE OF HIGH PRESSURE BUILDS INTO THE FA FROM THE GREAT LAKES
AND CRESTS OVER OUR AREA LATE SUNDAY INTO SUNDAY EVENING BEFORE
SLIDING EAST OFF THE NEW ENGLAND COAST LATE SUNDAY NIGHT. LOWS
SATURDAY NIGHT AND SUNDAY NIGHT ARE EXPECTED TO BE IN THE MID TEENS
TO UPPER 20S WITH HIGHS ON SUNDAY IN THE UPPER 20S TO LOWER 40S.

ON MONDAY…ANOTHER SYSTEM IS EXPECTED TO MOVE INTO THE CENTRAL
GREAT LAKES PUSHING A WARM FRONT IN OUR DIRECTION. EXPECT A CHANCE
OF PCPN ACROSS SRN AREAS MAINLY DURING THE AFTERNOON. HIGHS ON
MONDAY ARE EXPECTED TO BE IN THE MID 30S TO LOWER 40S.

OVERALL EXPECT TEMPS TO AVERAGE SLIGHTLY BELOW NORMAL WITH PCPN NEAR
NORMAL DURING THE LONG TERM PERIOD FRIDAY THROUGH MONDAY.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/…
CONDITIONS WILL DETERIORATE THIS MORNING AS CLOUDS CONTINUE TO
THICKEN AND LOWER. A WAVE OF LOW PRESSURE IS EXPECTED TO TRACK
NORTHWARD ALONG A STATIONARY FRONT WITH MVFR CONDITIONS GIVING WAY
TO IFR CONDITIONS MID TO LATE MORNING AS RAIN BECOMES STEADIER AND
HEAVIER. IFR CONDITIONS ARE EXPECTED TO REMAIN INTO THIS AFTERNOON
WITH THE HEAVIEST RAINFALL LASTING UNTIL MID AFTERNOON WHEN
THE SYSTEM`S COLD FRONT MOVES GRADUALLY ACROSS THE AREA.
THE FRONT WILL BE SLOW TO MOVE OFF TO OUR EAST SO RAIN WILL LINGER
THROUGH MUCH OF THE AFTERNOON WITH AN IMPROVEMENT TO MVFR EXPECTED
WITH ITS PASSAGE AND THEN EVENTUALLY VFR CONDITIONS LATE TONIGHT.

SOUTHERLY WINDS WILL CONTINUE THROUGH THIS AFTERNOON FINALLY
SHIFTING TO THE WEST WITH THE PASSAGE OF A COLD FRONT LATE IN THE
AFTERNOON.

A STRONG LOW LEVEL JET WILL ACCOMPANY THIS SYSTEM WHILE WINDS AT THE
SURFACE REMAIN LOWER. SO HAVE LOW LEVEL WIND SHEAR IN THE TAFS
STARTING CONTINUING THROUGH 18Z WITH SOUTHERLY WINDS OF AROUND 50
KNOTS AT 2 KFT. IN THE WAKE OF THE COLD FRONT WINDS WILL BE WEST TO
NORTHWEST AND GRADUALLY DIMINISH TO ARND 5 KTS LATE TONIGHT.

OUTLOOK…
WED…VFR. SLIGHT CHC -SHRA.
WED NIGHT…MAINLY VFR. CHC -SHRA/-SHSN IN THE EVENING THEN -SHSN.
THU…VFR. SLIGHT CHC -SHSN.
FRI…VFR. NO SIG WX.
SAT…VFR/MVFR. CHC -SHSN/-SHRA.

&&

.HYDROLOGY…
RAINFALL AMTS OF 0.75-1.5 INCHES ARE EXPECTED TODAY…WITH THE
GREATEST AMTS ACROSS WESTERN NEW ENGLAND…AND SOME PORTIONS OF
THE SOUTHERN ADIRONDACKS. IN ADDITION TO THIS RAINFALL…SNOWMELT
WILL OCCUR ACROSS HIGHER ELEVATIONS OF THE SOUTHERN
ADIRONDACKS/EASTERN CATSKILLS/TACONICS/SOUTHERN GREENS/BERKSHIRES
AND LITCHFIELD HILLS DUE TO PERSISTENT TEMPS REMAINING WELL ABOVE
FREEZING…AND STRONG WINDS. THIS ADDED SNOWMELT IS EXPECTED TO
CONTRIBUTE ANOTHER 1-3 INCHES OF WATER TO THE EXPECTED RAINFALL.
THIS COMBINATION OF RAINFALL AND SNOWMELT COULD PRODUCE FLOODING
OF SMALL STREAMS AND ALONG A FEW MAIN STEM RIVERS WITHIN THE WATCH
AREA LATER TODAY INTO TONIGHT. RUNOFF IS EXPECTED TO PERSIST THROUGH
LATE TONIGHT BEFORE TEMPS FALL BACK TO NEAR OR BELOW FREEZING.

SCATTERED…LIGHT SHOWERS OF RAIN AND SNOW WILL BE POSSIBLE
THROUGH FRIDAY…WITH LIGHT SNOW OR SNOW SHOWERS POSSIBLE LATE FRI
INTO SAT. THESE ADDITIONAL AMTS OF PRECIP ARE NOT EXPECTED TO
PRODUCE HYDRO ISSUES.

&&

.ALY WATCHES/WARNINGS/ADVISORIES…
CT…FLOOD WATCH THROUGH WEDNESDAY MORNING FOR CTZ001-013.
NY…FLOOD WATCH THROUGH WEDNESDAY MORNING FOR NYZ032-033-038>040-
042-043-047-048-051-054-058-061-063-066-082.
MA…FLOOD WATCH THROUGH WEDNESDAY MORNING FOR MAZ001-025.
VT…FLOOD WATCH THROUGH WEDNESDAY MORNING FOR VTZ013>015.

&&

$$
SYNOPSIS…KL
NEAR TERM…KL
SHORT TERM…KL
LONG TERM…11
AVIATION…11/IAA
HYDROLOGY…KL/11

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