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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 190808
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
408 AM EDT SUN MAY 19 2013

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN IN CONTROL ACROSS THE NORTH COUNTRY
TODAY INTO SUNDAY. TEMPERATURES AND MOISTURE WILL BEGIN TO
INCREASE BEGINNING ON SUNDAY. A FRONTAL BOUNDARY DROPPING
SOUTHWARD FROM CANADA WILL SERVE AS A FOCUS FOR SHOWERS AND
POSSIBLE THUNDERSTORMS ON MONDAY INTO MONDAY NIGHT. THE FRONTAL
BOUNDARY WILL LINGER AROUND THE NORTH COUNTRY LEADING TO A
CONTINUED UNSETTLED WEATHER PATTERN THROUGH THE REST OF THE WEEK.

&&

.NEAR TERM /UNTIL 7 AM THIS MORNING/...
AS OF 1228 AM EDT SUNDAY...MINOR UPDATE TO INHERITED FORECAST TO
INCREASE SKY COVER BASED ON LATEST SATELLITE IMAGERY. MID/HIGH
CLOUDS ON THE LEADING EDGE OF BUILDING UPPER RIDGE CONTINUE TO
SHIFT EASTWARD INTO THE BTV CWA OVERNIGHT...WITH GENERALLY PARTLY
TOM MOSTLY CLOUDY SKIES EXPECTED. TEMPS WILL LIKELY STABILIZE
ACROSS NORTHERN NEW YORK...AND MAYBE FALL A DEGREE OR TWO MORE
ACROSS VERMONT BEFORE STABILIZING AS CLOUD COVER INCREASES. SHOULD
END UP WITH OVERNIGHT LOWS MAINLY IN THE 40S.

&&

.SHORT TERM /7 AM THIS MORNING THROUGH TUESDAY/...
AS OF 334 PM EDT SATURDAY...WE START TO GET INTO MORE OF A
SOUTHERLY RETURN OF LOW-LEVEL MOISTURE ON SUNDAY WITH 500 MB
HEIGHTS CONTINUING TO BUILD. 850 MB TEMPERATURES WILL ALSO BEGIN
TO WARM TO AROUND +7C. GUIDANCE WANTS TO BRING IN PRECIPITATION
FROM TWO MAIN SOURCES ON SUNDAY: (1) INSTABILITY-DRIVEN SHOWERS
AND (2) CONVECTIVE DEBRIS FROM ONGOING CONVECTION OVER THE GREAT
LAKES ACROSS THE NORTHEAST KINGDOM AND ADJACENT TO THE CANADIAN
BORDER. THINK BOTH SOLUTIONS ARE OVERDONE THROUGH SUNDAY AS
CONVECTIVE DEPTH IS CAPPED AND WEST FLOW ALOFT ATOP THE CRESTING
RIDGE SHOULD KEEP ANY DEBRIS SHOWERS NORTH OF THE BORDER. THINK
ALL THIS SHOULD RESULT IN PARTLY TO MOSTLY CLOUDY SKIES WITH
INCREASING CUMULUS DEVELOPMENT. HIGHS ON SUNDAY SHOULD BE CLOSE TO
TODAY...THOUGH A DEGREE OR TWO COOLER GIVEN MORE CLOUDS. BROUGHT
IN A SLIGHT CHANCE OF SHOWERS FOR THE NORTHEAST KINGDOM ON SUNDAY
NIGHT BUT WITH THE REST OF THE NORTH COUNTRY STAYING CLOUDY BUT
DRY. LOW-LEVEL WARM ADVECTION CONTINUES SUNDAY NIGHT WITH
PROJECTED 850 MB TEMPERATURES AROUND +9 TO +10C BY 12Z MONDAY WITH
LOWS GENERALLY IN THE 50S.

A WEAK BAROCLINIC ZONE BEGINS TO DRIFT SOUTHWARD OUT OF CANADA ON
MONDAY...STALLING LATE MONDAY NIGHT ACROSS INTERIOR NEW ENGLAND.
CONVECTIVE INDICES BECOME MORE FAVORABLE FOR THUNDERSTORMS ON
MONDAY AHEAD OF THE FRONTAL ZONE /LIFTED INDICES DROPPING TO AS LOW
AS -2/. HAVE PUT IN CHANCE SHOWERS/SLIGHT CHANCE THUNDER DURING THE
DAYTIME HOURS ON MONDAY MAINLY ACROSS CENTRAL AND SOUTHERN VERMONT
INTO ESSEX COUNTY NEW YORK. WHERE THAT BOUNDARY STALLS OUT WILL
DETERMINE THE NORTHWARD EXTENT OF PRECIPITATION MONDAY NIGHT. WITH
INDICATIONS THAT THE STALLING FRONTAL BOUNDARY WILL LIE ACROSS
CENTRAL NEW ENGLAND HAVE SHOWN TAPERED PRECIPITATION PROBABILITIES
FROM CHANCE TO HIGH CHANCE WITH HIGH CHANCE ACROSS CENTRAL AND
SOUTHERN VERMONT...THE SOUTHERN SAINT LAWRENCE VALLEY AND THE
NORTHERN ADIRONDACKS.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
-- Changed Discussion --
AS OF 407 AM EDT SUNDAY...RATHER UNSETTLED PERIOD ANTICIPATED AS
E-W ORIENTED FRONTAL ZONE WILL BE DRAPED ACROSS/NEAR THE NORTH
COUNTRY. BEGINNING TUESDAY NIGHT...BOTH THE 00Z ECMWF AND 00Z GFS
INDICATE SFC-850MB FRONTAL ZONE WILL BE LIFTING NEWD AS A WARM
FRONT ACROSS OUR REGION. ASSOCIATED ISENTROPIC ASCENT WILL BRING
INCREASING CLOUDS AND A CHANCE FOR RAIN SHOWERS...ESPECIALLY AFTER
MIDNIGHT. ASSOCIATED S-SW WINDS AND CLOUDS WILL ALSO KEEP LOW
TEMPERATURES ON THE MILD SIDE DURING TUESDAY NIGHT...WITH LOWS IN
THE MID 40S TO LOWER 50S (WARMEST CHAMPLAIN VALLEY). ON
WEDNESDAY...IT APPEARS THE NORTH COUNTRY WILL EMERGE INTO THE
CYCLONE WARM SECTOR WITH BROAD/LOW-AMPLITUDE RIDGE IN PLACE ALOFT.
AIR MASS HAS THE POTENTIAL TO BE QUITE MILD; 00Z ECMWF SHOWING
850MB TEMPS OF +14 TO +15C. QUESTION WILL BE AMT OF SUNSHINE IN
WARM SECTOR...WHICH IS A BIT DIFFICULT TO DETERMINE AT THIS POINT.
HAVE ADJUSTED ABOVE MEX-MOS GUIDANCE WITH HIGHS IN THE LOW-MID
70S...BUT THERE IS A CHANCE THAT TEMPS COULD BE CLOSER TO 80F FOR
AFTN HIGHS. AIR MASS MAY ALSO BECOME MARGINAL UNSTABLE...SO
INCLUDED A CHANCE FOR ISOLD/SCT TSTMS DURING THE AFTN/EVENING
HOURS WEDNESDAY. AT THIS POINT...ACTIVITY WILL LIKELY NOT BE WELL-
ORGANIZED...BUT LOCAL OROGRAPHIC EFFECTS AND INSTABILITY MAY BE
SUFFICIENT WITH DAYTIME HEATING TO GENERATE A FEW TSTMS. UPSTREAM
SHORTWAVE TROUGH ACROSS THE GREAT LAKES AMPLIFIES THURSDAY INTO
FRIDAY MORNING AND ASSOCIATED CYCLONIC FLOW AND PASSAGE OF A COLD
FRONT ACROSS THE NORTH COUNTRY WILL BRING ADDITIONAL CHANCES FOR
RAIN SHOWERS THURSDAY INTO FRIDAY (POPS 30-50 PERCENT). TIMING
UNCERTAINTIES REMAIN WITH REGARD TO THIS EVOLUTION...SO MOST
CONCENTRATED TIME FOR ASSOCIATED SHOWERS IS NOT KNOWN. SHOULD
TREND COOLER AND DRIER FOR FRIDAY AND INTO NEXT WEEKEND WITH HIGHS
IN THE MID-UPR 60S. LOWS WILL MAINLY BE IN THE 40S FRIDAY AND
SATURDAY NIGHT.
-- End Changed Discussion --

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
THROUGH 12Z MONDAY...MID-UPR CLOUDS WILL INCREASE TODAY WITH
CEILINGS GENERALLY AOB 10 KFT. HIGH PRESSURE DRIFTING EWD INTO THE
GULF OF MAINE WILL BRING OUR WINDS AROUND TO SOUTH...AND COULD SEE
SOME GUSTS 20-24 KTS AT BTV BETWEEN 14-23Z. BEFORE 14Z...WINDS
GENERALLY LIGHT AND VARIABLE. SOUTH TO SOUTHWEST WINDS AROUND 10
KTS CONTINUE TONIGHT AND PASSAGE OF A WEAK WARM FRONT MAY BRING
SOME MVFR CEILINGS AT KSLK DURING SUNDAY NIGHT.

OUTLOOK 12Z MONDAY THROUGH THURSDAY... A FRONTAL BOUNDARY SAGGING
SWD FROM ONTARIO/QUEBEC BRINGS THE THREAT FOR SHOWERS AND POSSIBLE
TSTMS FOR MUCH OF NEXT WEEK. THE FRONTAL BNDRY WILL BECOME QUASI-
STATIONARY VCNTY OF NRN NY AND NRN NEW ENGLAND THRU MUCH OF THE
PERIOD. TIMING UNCERTAINTIES CURRENTLY EXIST BUT ANTICIPATE
SEVERAL PERIODS OF MVFR AND PERHAPS BRIEF IFR CONDITIONS DURING
THIS TIME FRAME WITH SHOWERS AND POSSIBLE TSTMS...ESPECIALLY
TUESDAY AND THURSDAY.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.

&&

$$
SYNOPSIS...LOCONTO
NEAR TERM...LAHIFF
SHORT TERM...LOCONTO
LONG TERM...BANACOS
AVIATION...BANACOS