-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 181034
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
634 AM EDT SAT MAY 18 2013

.SYNOPSIS...
A LARGE AREA OF HIGH PRESSURE WILL CONTINUE TO BUILD DOWN FROM
EASTERN CANADA AND PERSIST OVER NORTHERN NEW ENGLAND THROUGH MUCH OF
THE WEEKEND. LOOK FOR MORE DRY WEATHER WITH JUST A SLIGHT CHANCE OF
SHOWERS SUNDAY AFTERNOON. A GRADUAL WARMING TREND IS ALSO EXPECTED
FOR THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
AS OF 634 AM EDT SATURDAY...A PRETTY NICE DAY IS ON TAP FOR THE
NORTH COUNTRY AS SURFACE HIGH PRESSURE OVER SOUTHERN ONTARIO/QUEBEC
SLOWLY SLIDES SOUTHEASTWARD ACROSS NEW ENGLAND. MID/UPPER LEVEL
FLOW REMAINS OUT OF THE NORTHWEST THOUGH AS AN UPPER TROUGH IS PARKED
OVER THE GULF OF MAINE. THIS WILL RESULT IN A GENERAL INCREASE IN
CLOUD COVER THROUGH THE DAY...THOUGH ONLY AS FAIR WEATHER CUMULUS
AND MAINLY OVER THE HIGHER TERRAIN. IN ADDITION...COULD SEE AN
ISOLATED SHOWER OR SPRINKLE ACROSS FAR NORTHEAST VERMONT AS
SHORTWAVE ENERGY GRAZES THE CWA BUT AREAL COVERAGE WILL LIKELY BE
LIMITED. MEAN 925MB TEMPS RISE TO AROUND +10C BY THIS AFTERNOON...
SUPPORTING HIGHS IN THE UPPER 60S TO MID 70S ACROSS THE REGION.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
AS OF 351 AM EDT SATURDAY...A FAIRLY QUIET NIGHT IS EXPECTED AS
THE AFOREMENTIONED AREA OF HIGH PRESSURE CONTINUES TO SLOWLY SLIDE
SOUTHEASTWARD OFF THE NEW ENGLAND COAST. UPPER TROUGH OVER THE
GULF OF MAINE ALSO SHIFTS EASTWARD A BIT ALLOWING MID LEVEL
HEIGHTS TO SLOWLY RISE ACROSS THE BTV CWA...AND THUS EXPECTING A
GENERALLY CLEAR TO PARTLY CLOUDY NIGHT WITH LOWS RUNNING AT OR
SLIGHTLY ABOVE NORMAL IN THE 40S TO LOCALLY NEAR 50 IN THE
CHAMPLAIN VALLEY. SOUTHERLY RETURN FLOW INCREASES GOING INTO
SUNDAY ALONG WITH AN INCREASE IN LOW/MID LEVEL MOISTURE. MID LEVEL
HEIGHTS CONTINUE TO SLOWLY RISE BUT FLOW ALOFT REMAINS OUT OF THE
NORTHWEST. THIS COMBINED WITH SOME WEAK SURFACE INSTABILITY IN THE
AFTERNOON COULD SPARK A FEW ISOLATED SHOWERS...THOUGH MAINLY
ACROSS THE HIGHER TERRAIN AND PROBABLY NOT REALLY AMOUNTING TO
MUCH. HIGHS CONTINUE TO RUN ABOVE NORMAL AS 925MB TEMPS RISE INTO
THE LOWER TEENS SUPPORTING HIGHS SIMILAR TO SATURDAY...MAYBE A
DEGREE OR TWO WARMER. ANY ISOLATED SHOWERS DISSIPATE SUNDAY NIGHT
WITH THE LOSS OF DAYTIME HEATING...AND EXPECT A FAIRLY MILD NIGHT
WITH PARTLY TO MOSTLY CLOUDY SKIES AND MODEST SOUTHERLY FLOW
KEEPING TEMPS FROM FALLING OUT OF THE 50S FOR MOST LOCATIONS.
CHAMPLAIN VALLEY MIGHT NOT EVEN BREAK 60. FOR MONDAY...UPPER
TROUGH OFF THE GULF OF MAINE FINALLY SHIFTS FAR ENOUGH EAST TO
ALLOW UPPER RIDGING TO BUILD INTO PORTIONS OF THE NORTHEAST. SIMILAR
TO SUNDAY...FLOW ALOFT REMAINS OUT OF THE NORTHWEST THOUGH...AND
WITH INCREASING MOIST SOUTHERLY FLOW AT THE SURFACE WE COULD AGAIN
SEE SOME ISOLATED SHOWERS ACROSS THE AREA. WARMING TREND ALSO
CONTINUES FOR MONDAY WITH HIGHS GOING A FEW MORE DEGREES HIGHER
THAN THE PREVIOUS DAYS INTO THE MID TO UPPER 70S TO LOCALLY NEAR
80 IN THE ST. LAWRENCE VALLEY.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 322 AM EDT SATURDAY...OVERALL A MORE ACTIVE PATTERN
ANTICIPATED FOR DAYS 4 THROUGH 7. RELATIVELY GOOD CONSISTENCY
BETWEEN 00Z ECMWF AND 00Z GFS THROUGH THE PERIOD. THAT SAID...SYNOPTIC
PATTERN INVOLVES A SLOW SWD MOVING FRONTAL ZONE TUE-WED FOLLOWED
BY THE APPROACH OF A CLOSED UPR LOW THU-FRI THAT SUGGESTS TIMING
ERRORS ARE POSSIBLE IN EXPECTED WX CONDITIONS.

FRONTAL BOUNDARY SAGGING SWD FROM SERN ONTARIO/SRN QUEBEC IN
CONFLUENT ZONAL FLOW REGIME ALOFT HAS THE POTENTIAL TO BRING AN
UNSETTLED PERIOD OF WEATHER WITH ABUNDANT SHOWERS AND POSSIBLE TSTMS
TUESDAY INTO TUESDAY NIGHT. SOME QUESTION AS TO HOW FAR SOUTH THE
FRONTAL ZONE SAGS ON WEDNESDAY; WITH BUILDING HEIGHTS ALOFT IT IS
POSSIBLE THAT WEDNESDAY COULD BE DRIER (ESPECIALLY ACROSS THE NRN
HALF OF THE CWA)...BUT GFS/ECMWF HAVE FRONTAL PLACEMENT AND TEMPORAL
DIFFERENCES THAT ARE DIFFICULT TO RECONCILE AT THIS POINT. HAVE
CONTINUED CHANCE POPS FOR SHOWERS BUT LEFT MENTION OF TSTMS OUT OF
THE FCST FOR WEDNESDAY WITH LESS MOIST CONDITIONS NORTH OF THE
FRONT. UPSTREAM CLOSED UPR LOW/VORT MAX EVENTUALLY SHIFTS EWD FROM
THE GREAT LAKES WITH ESTABLISHMENT OF MOIST SWLY FLOW IN ADVANCE OF
THIS FEATURE BRINGING POTENTIAL INSTABILITY AND ADDITIONAL CHANCES
FOR SHOWERS AND TSTMS FOR THURSDAY AFTN. CHANCES FOR SHOWERS
CONTINUE THURSDAY NIGHT INTO FRIDAY GIVEN ANTICIPATED SLOW-MOVING
NATURE OF UPR LOW. TEMPERATURES THROUGH THE PERIOD ARE GENERALLY
EXPECTED SEVERAL DEGREES ABOVE NORMAL...WITH ABUNDANT CLOUDS KEEPING
OVERNIGHT LOWS ON THE MILD SIDE. GENERALLY LOOKING AT HIGHS IN THE
LOW TO MID 70S AND LOWS IN THE 50S...POSSIBLY LOW 60S IN THE
CHAMPLAIN VALLEY ON MONDAY NIGHT.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
THROUGH 12Z SUNDAY...SURFACE HIGH PRESSURE IN CONTROL ACROSS THE
NORTH COUNTRY WILL BRING JUST SCATTERED MID-LEVEL CLOUDS TO THE
REGION TODAY AND TONIGHT. OTHER THAN A CHANCE OF BRIEF RADIATIONAL
FOG AT KSLK FROM 07-11Z THIS MORNING...VFR CONDITIONS ARE EXPECTED
WITH GENERALLY LIGHT WIND CONDITIONS CONTROLLED BY LOCAL TOPOGRAPHIC
EFFECTS.

OUTLOOK 12Z SUNDAY THROUGH WEDNESDAY...HIGH PRESSURE SLIDES EWD INTO THE
GULF OF MAINE ON SUNDAY WITH SOUTH WINDS 10-15 KTS DEVELOPING AT THE
TAF SITES. THERE IS A SLIGHT CHANCE OF RAIN SHOWERS...MAINLY ACROSS
THE HIGHER ELEVATIONS WITH BEST CHANCE OF BRIEF MVFR CONDITIONS AT
SLK/MPV. OTHERWISE...SHOULD BE GENERALLY VFR SUNDAY INTO SUNDAY
NIGHT. A FRONTAL BOUNDARY SAGGING SWD FROM ONTARIO/QUEBEC EVENTUALLY
BRINGS THE THREAT FOR SHOWERS AND POSSIBLE TSTMS. SOME TIMING
UNCERTAINTIES AT THIS POINT...BUT BEST CHANCES FOR RAINFALL APPEAR
TO BE TUESDAY/WEDNESDAY. ANTICIPATE PERIODS OF MVFR AND PERHAPS
BRIEF IFR CONDITIONS.

&&

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

&&

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