000
FXUS61 KBTV 172335
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
735 PM EDT SAT MAY 17 2008
.SYNOPSIS...
A COLD FRONT MOVING FROM WEST TO EAST ACROSS THE NORTH COUNTRY
LATE THIS AFTERNOON AND THIS EVENING WILL BRING SCATTERED RAIN
SHOWERS FOR SEVERAL HOURS...AND A CHANCE OF A FEW RUMBLES OF
THUNDER...MAINLY FROM THE CHAMPLAIN VALLEY WESTWARD. AFTER BRIEF
CLEARING LATE TONIGHT AND SUNDAY MORNING...YET ANOTHER LOW
PRESSURE AREA IS EXPECTED TO FORM ACROSS PENNSYLVANIA EARLY
SUNDAY...AND THEN TRACK NORTHEASTWARD INTO WESTERN NEW ENGLAND BY
SUNDAY EVENING. THIS SYSTEM WILL BRING RAIN...REDEVELOPING ACROSS
THE NORTH COUNTRY FROM SOUTHWEST TO NORTHEAST SUNDAY AFTERNOON
WITH PERIODS OF RAIN AND PATCHY FOG CONTINUING INTO SUNDAY NIGHT.
ON MONDAY...AN UPPER LOW PRESSURE AREA LINGERS ACROSS NORTHERN NEW
ENGLAND BRINGING COOL TEMPERATURES AND MAINLY OVERCAST
CONDITIONS...WITH PERIODS OF LIGHT RAIN SHOWERS EXPECTED.
&&
.NEAR TERM /THROUGH SUNDAY/...
AS OF 220 PM SATURDAY...ORGANIZED PRE-FRONTAL RAINBAND EXTENDED
FROM THE FAR WRN PORTION OF ST. LAWRENCE COUNTY NY SWD TO 20E KSYR
AT 18Z. THIS BAND OF SHOWERS WILL CONTINUE STEADILY EASTWARD
ACROSS THE NORTH COUNTRY BRINGING A PERIOD OF SHOWERS TO MOST
SECTIONS OF THE CWA. CAPE IS LIMITED BY LOW SFC DEWPOINTS...AND
ANY POSSIBILITY OF TSTMS IS EXPECTED TO BE LIMITED TO AREAS FROM
THE CHAMPLAIN VLY WWD. THE FRONTAL RAINBAND SHOULD CLEAR ERN VT BY
05Z...AND SOME PARTIAL CLEARING IS EXPECTED LATE TONIGHT. THE
STRONG...QUASI-STATIONARY LOW PRESSURE SYSTEM SOUTH OF HALIFAX
NOVA SCOTIA MAY SLOW DOWN THE FRONT AND KEEP SOME LINGERING CLOUDS
4-5 KFT AGL DURING THE 06-12Z PERIOD TONIGHT. WLY GRADIENT FLOW
BEHIND THE FRONT SHOULD PRECLUDE ANY FOG FORMATION. MINIMUM
TEMPERATURES WILL SETTLE BACK INTO THE MID/UPR 40S IN THE VALLEYS
TONIGHT...WITH LOWER 40S EXPECTED IN THE NE KINGDOM OF VT. A FEW
READINGS IN THE MID 30S ARE ANTICIPATED IN THE NRN ADIRONDACKS AS
POTENTIAL FOR CLEARING SKIES LATE TONIGHT IS GREATER ACROSS NRN
NY.
RELATIVELY FAST FORWARD MOTION /30-35KT/ OF FRONTAL RAINBAND WILL
LIMIT OVERALL QPF THIS AFTERNOON AND TONIGHT. GENERALLY LOOKING AT
BASIN AVG RAINFALL OF ONE TO TWO TENTHS OF AN INCH...WITH ISOLATED
AMTS UP TO 0.25" POSSIBLE. A FEW CONVECTIVE GUSTS TO 40 MPH ARE
POSSIBLE WITH THIS LINE IN NRN NY DURING THE NEXT SEVERAL HRS...BUT
WE DON/T ANTICIPATE ANY SVR WX THREAT.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/...
AS OF 220 PM EDT SATURDAY...MODELS ARE IN FAIR AGREEMENT DURING THE
SHORT-TERM PERIOD WITH AMPLIFICATION OF BROAD MID-UPR
TROPOSPHERIC TROUGH - NOW OVER THE GREAT LAKES REGION - SEWD INTO
NEW ENGLAND BY 18Z MONDAY. A SHORTWAVE TROUGH ROTATING THRU THE
BASE OF THE TROUGH IS EXPECTED TO RESULT IN SFC CYCLOGENESIS OVER
PA DURING SUNDAY MORNING...WITH A DEEPENING LOW REACHING WRN NEW
ENGLAND BY 00Z MONDAY. OVERALL EVOLUTION OF QG FORCING AND SFC LOW
TRACK SUGGEST FAIR CONDITIONS SUNDAY MORNING OVER NRN NY AND
VT...BUT THEN A RAPID INCREASE IN CLOUDS AND RAIN DEVELOPING FROM
SW-NE ACROSS THE NORTH COUNTRY DURING SUNDAY AFTN. PERIODS OF RAIN
CONTINUE SUN NIGHT. LOOKING AT HIGH LOW-LEVEL RH AND PATCHY FOG
POTENTIAL...ESPECIALLY ACROSS VT SUNDAY NIGHT. FOG MAY BE LOCALLY
DENSE BUT WILL WORD AS PATCHY FOR NOW. GREATEST POPS/HIGHEST QPF
WILL GENERALLY BY ACROSS VT WHERE 0.5-0.75" PRECIP IS
POSSIBLE...WITH ISOLATED TOTALS UP TO ONE INCH BY 12Z MONDAY. MAIN
SYNOPTIC FORCING LIFTS NORTH OF THE AREA BY 12Z MONDAY.
HOWEVER...COLD MID-LVL TROUGH WILL TRANSLATE EWD ACROSS THE NORTH
COUNTRY DURING MONDAY BRINGING CONTINUED OVC AND WEAK ASCENT FOR
SCT -RW DURING MUCH OF THE DAY. HIGH TEMPS ON MONDAY ONLY EXPECTED
TO BE IN THE LOW TO MID 50S IN THE VLYS...AND MID 40S IN THE NRN
ADIRONDACKS AND OUTLYING AREAS OF NERN VT. NWLY GRADIENT FLOW MAY
FOCUS OROGRAPHIC PCPN ALONG THE WEST FACING SLOPES OF THE GREEN
MTNS AND NRN ADIRONDACKS DURING MONDAY. IN FACT...SOME OF THE NWP
GUIDANCE IS QUITE AGGRESSIVE WITH QPF FOR MONDAY WITH AMTS
0.25-0.5". FOR NOW...WITH RISING MID-LVL HEIGHTS...NOT OPTIMISTIC
ABOUT THAT MUCH RAIN WITH THE UPPER LOW AND HAVE UNDERCUT
QPF...CLOSER TO GFS BASED GRIDDED MOS VALUES.
A FEW SHOWERS MAY LINGER INTO MONDAY NIGHT...PERHAPS MIXING WITH
SNOW AT SUMMIT LEVEL BEFORE ENDING. LOWS MONDAY NIGHT WILL RANGE
FROM THE LOWER 40S IN THE CHAMPLAIN AND ST. LAWRENCE VLYS...AND IN
THE MID 30S IN THE NRN ADIRONDACKS AND ABOVE 1000 FT ACROSS
CENTRAL/ERN VT.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
AS OF 225 PM EDT SATURDAY...LARGE UPPER CLOSED LOW WILL REMAIN
ACROSS QUEBEC DURING THE EARLY TO MIDDLE PORTIONS OF NEXT
WEEK...GRADUALLY EASING INTO THE CANADIAN MARITIMES BY FRIDAY. THIS
IS SUPPORTED BY THIS MORNING/S ENSEMBLE MEAN SOLNS AND LAST NIGHT/S
EURO OPERATIONAL RUN. THUS WILL ADVERTISE A CONTINUATION OF PC/MC
CONDS ALONG WITH BELOW NORMAL TEMPERATURES AND DAILY CHCS OF
SHOWERS. AGREE W/PREVIOUS FCST THAT GFS POPS LIKELY SOMEWHAT
OVERDONE. HOWEVER...LINGERING COLD POOL ALOFT COMBINED WITH DIURNAL
BNDRY LYR HEATING SHOULD ALLOW FAIRLY STEEP LOW TO MID LVL LAPSE
RATES AND SCT -SHRAS TO DEVELOP EACH DAY IN THE TUESDAY THROUGH
THURSDAY TIME FRAME. HIGHEST THREAT FOR RAFL TO OCCUR DURING
THE AFTERNOON/EARLY EVENING HOURS DURING MAX INSOLATION
PERIOD...WITH PARTICULAR FOCUS ACROSS THE NORTH/NORTHERN MTNS IN
BROAD WNW OR NW FLOW. BY NEXT WEEKEND...CLOSED SYSTEM SHOULD PUSH
FAR ENOUGH EAST TO ALLOW A RETURN OF AMPLIFIED SHORTWAVE RIDGING
ACROSS THE AREA. BEST ESTIMATE WOULD BE FOR INCREASING AMTS OF SUN
ALONG WITH A MODERATION IN TEMPS TO NEAR SEASONAL NORMAL LEVELS AS
MID TO UPPER LVL HEIGHTS BUILD ACCORDINGLY.
&&
.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
THROUGH 00Z MONDAY...A SURACE COLD FRONT WILL MOVE THROUGH THE
AREA THIS EVENING...WITH CLEARING LATER TONIGHT BEFORE AN UPPER
LEVEL LOW MOVES INTO THE AREA TOMORROW AFTERNOON. CURRENT RADAR
SHOWS COLD FRONT MOVING THROUGH WESTERN NY...FRONT WILL CONTINUE
TO MOVE ACROSS THE AREA TONIGHT. EXPECT SCT -SHRA AND ISOLATED
THUNDERSTORMS DURING FROPA...BUT OVERALL CIGS/VIS SHOULD STAY VFR.
AFT 07Z THERE IS A SLIGHT CHANCE FOR SOME FOG DUE TO CLEARING
SKIES/HIGH DEWPOINTS...BUT STRONGER WNDS ABOVE THE SURFACE COULD
ALLOW ENOUGH MIXING IN THE PBL WHICH COULD MITIGATE DEVELOPMENT.
EXPECT VFR CONDITIONS UNTIL 20Z DURING THE DAY TOMORROW BEFORE
MORE RAIN MOVES INTO THE AREA. CONDITIONS WILL BECOME MVFR AT ALL
LOCALS BY THE END OF THIS PERIOD.
00Z MONDAY THROUGH THURSDAY...THIS PERIOD WILL BE DOMINATED BY
SHOWERS AS AN UPPER LEVEL TROUGH BECOMES ENTRENCHED OVER THE AREA.
EXPECTED VFR CONDITIONS WITH TEMPO MVFR DURING AFTERNOON RAIN
SHOWERS AS DAYTIME HEATING DESTABILIZES THE ATMOSPHERE. BEST CHANCE
FOR WIDESPREAD RAIN LOOKS LIKE MONDAY EVENING. CIGS WILL
GENERALLY BE 020-040AGL DURING THIS PERIOD.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...BANACOS
NEAR TERM...BANACOS
SHORT TERM...BANACOS
LONG TERM...JMG
AVIATION...JMG/DUMONT
