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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 192328
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
728 PM EDT SUN MAY 19 2013

.SYNOPSIS...
CLOUDS AND ISOLATED...LIGHT RAIN SHOWERS WILL CONTINUE
OVERNIGHT...FOLLOWED BY AN INCREASED CHANCE OF RAIN SHOWERS
MONDAY AFTERNOON...WITH THE POTENTIAL FOR A COUPLE OF
THUNDERSTORMS AS AN A DISTURBANCE MOVES INTO THE REGION WITH AN
ASSOCIATED WEAK WARM FRONT. UPPER LEVEL RIDGING WILL LEAD TO A
DRY NIGHT MONDAY NIGHT BUT A GREATER THREAT OF SHOWERS ON TUESDAY
AS THE AFOREMENTIONED WARM FRONT LIFTS NORTHWARD ACROSS THE NORTH
COUNTRY. ABOVE NORMAL TEMPERATURES WILL CONTINUE INTO THE MIDDLE
OF THE WEEK.

&&

.NEAR TERM /UNTIL 8 AM MONDAY MORNING/...
-- Changed Discussion --
AS OF 728 PM EDT SUNDAY...WITH THIS UPDATE I MADE SOME RELATIVELY
MINOR ADJUSTMENTS TO TEMPERATURES AND PRECIPITATION PROBABILITIES
TO REFLECT CURRENT CONDITIONS AS WELL AS LOWERING WIND GUSTS.
RADAR ECHOES SHOWN ON COMPOSITE RADAR ARE SAMPLING JUST THE
OVERCAST SKIES WITH OCCASIONAL ISOLATED LIGHT SHOWERS. BASED ON
ASOS OBSERVATIONS THIS EVENING PRECIPITATION AMOUNTS HAVE ONLY
AMOUNTED TO A FEW HUNDRETHS...WHICH SPEAKS TO HOW LIGHT THE
PRECIPITATION REALLY IS. THE RADAR ECHOES ARE ON THE COOL SIDE OF
THE SFC-850 MB TEMPERATURE GRADIENT ASSOCIATED WITH A WARM FRONT
EXTENDING FROM NEAR OTTAWA SOUTHEASTWARD TO THE NYC METRO AREA.
THIS FRONT WILL SLOWLY LIFT EAST-NORTHEASTWARD THROUGH THE
OVERNIGHT WITH ANY LIGHT SHOWERS GRADUALLY WINDING DOWN FROM
SOUTHWEST TO NORTHEAST. ONE THING THESE SHOWERS HAVE DONE IS TO
STOP MIXING OF GUSTS ASSOCIATED WITH A 20-30KT LOW- LEVEL JET.
THEREFORE...WITH LOW- LEVEL LAPSE RATES BECOMING MORE ISOTHERMAL
WITH TIME HAVE OPTED TO LOWER WIND GUSTS. TEMPERATURES NOT LIKELY
TO FALL VERY MUCH UNDER OVERCAST SKIES WITH LOWS IN THE 50S.
-- End Changed Discussion --

&&

.SHORT TERM /8 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 433 PM EDT SUNDAY...SFC LOW BECOMES SLGTLY MORE PRONOUNCED
WITH THE ASSOCIATED FRONT SETTLING SOUTH OF THE REGION LATE
MONDAY...PRODUCING THREAT OF SHOWERS AND THUNDERSTORMS AS IT
HEADS SOUTH. LIFTED INDICES LESS THAN ZERO WILL ONLY REACH THE
SOUTHERN HALF OF THE CWA...WITH MINIMAL CAPE VALUES. HAVE
INCLUDED MENTION OF SLGT CHC OF TS IN THE AFTN FOR SOUTHERN
ZONES. UPPER LEVEL RIDGING WILL CONTINUE THROUGHOUT THE DAY WITH
NW FLOW CONTINUING ALOFT...WHICH WILL ALSO KEEP BETTER
INSTABILITY TO THE SOUTH. WITH MOSTLY CLOUDY SKIES...SOUTHERLY
FLOW AT THE SFC FOR AT LEAST THE MORNING...AND 925MB TEMPS
INCREASING TO THE MID TEENS...MAX TEMPS WILL BE IN THE L-U70S.

MONDAY NIGHT WILL SEE A BREAK FROM PRECIP DAYTIME HEATING
ENDS...BUT CONTINUED CLOUD COVER WITH MIN TEMPS IN THE 50S.
TUESDAY MORNING WILL START MOSTLY DRY BUT SEE CHANCE POPS IN THE
AFTN AS THE FRONT BEGINS TO LIFT BACK NORTH AS A WARM FRONT. POPS
WILL CONTINUE TO INCREASE TO 40-50 PERCENT TUESDAY NIGHT AS THE
WARM FRONT MOVES ACROSS THE NORTH COUNTRY. MAX TEMPS IN THE M60S-
M70S WITH CONTINUED CLOUDS AND LGT FLOW. AND MIN TEMPS TUESDAY
NIGHT WILL GENERALLY BE IN THE 50S.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 433 PM EDT SUNDAY...TRANSITION FROM WEST TO NORTHWEST FLOW
ALOFT TO A MORE SOUTHWEST FLOW ALOFT WEDNESDAY THROUGH FRIDAY
WILL RESULT IN AN INCREASED THREAT FOR SHOWERS AND SOME
THUNDERSTORMS. GOING FORECAST ALREADY HAS THIS IDEA HANDLED WELL
AND DID NOT CHANGE FROM THIS THINKING. THE SOUTHWEST FLOW ALOFT
IS IN RESPONSE TO AN UPSTREAM UPPER TROUGH WHICH WILL NOT MOVE
INTO THE AREA UNTIL LATER FRIDAY. AS A RESULT...A WARMER AND MORE
MOIST AIR MASS WILL EXIST AHEAD OF A FRONTAL BOUNDARY. THE
RESULTING INSTABILITY WILL BE SUFFICIENT ENOUGH AND COMBINED WITH
THE LIFT ASSOCIATED WITH SURFACE FRONT/UPPER TROUGH...THE THREAT
FOR SHOWERS AND SOME THUNDERSTORMS WILL BE THE RULE. SHOULD SEE
HIGH CHANCE TO LOW LIKELY PRECIPITATION PROBABILITIES FOR
WEDNESDAY AND THURSDAY. UPPER TROUGH EXITS THE AREA ON
FRIDAY...SO JUST A CHANCE OF SHOWERS WILL EXIST. ONE NOTICEABLE
FEATURE ON THE BACKSIDE OF THE UPPER TROUGH WILL BE THE LOW LEVEL
COLD AIR ADVECTION AND WE SHOULD SEE SOME BELOW NORMAL
TEMPERATURES MOVING INTO THE AREA FOR THE WEEKEND. COULD SEE A
FEW INSTABILITY SHOWERS ON SATURDAY WITH DRIER WEATHER FOR
SUNDAY...THE DAY OF THE VERMONT CITY MARATHON. AT THIS
TIME...TEMPERATURES WILL BE A FEW DEGREES BELOW NORMAL FOR THE
RACE.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
THROUGH 00Z TUESDAY...HAVE TREATED CURRENT VERY LIGHT SHOWERS
WITH P6SM -SHRA AS OBSERVATIONS INDICATE THAT THE SHOWERS AREN`T
RESULTING IN ANY SIGNIFICANT REDUCTION IN VISIBILITY. LOOK FOR
THESE SHOWERS TO COME TO AN END FROM WEST TO EAST BY 03Z.
EXPECTING MAINLY BKN/OVC VFR CEILINGS FOR THE REST OF THE
EVENING...THOUGH HAVE TEMPO`D IN SOME MVFR CEILINGS 03-06Z AT RUT
AND MPV GIVEN LIGHT SOUTHEAST FLOW AND LOWER CEILINGS THAT ARE IN
PLACE ACROSS PARTS OF CENTRAL NEW HAMPSHIRE AND SOUTHERN VERMONT.
WINDS WILL BE MAINLY SOUTHERLY 5-10KTS THROUGH 12Z MONDAY.

A FRONTAL BOUNDARY WILL DROP SOUTHWARD OUT OF CANADA ON MONDAY
/BETWEEN 13-18Z/. GUIDANCE HAS TRENDED DRIER WITH THE FRONT...BUT
SOME LIMITED INSTABILITY AT RUT AND MPV MAY TRIGGER SOME ISO/SCT
SHOWERS AND PERHAPS SOME THUNDER. HAVE INDICATED VCSH FOR THIS
POTENTIAL FROM 15Z ONWARD. OTHERWISE EXPECT VFR CONDITIONS WITH
WINDS INITIALLY SOUTH AT 5-10KTS BECOMING NORTHWEST /WEST-
NORTHWEST AT SIMILAR SPEEDS UPON FRONTAL PASSAGE.

OUTLOOK 00Z TUESDAY 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.
-- End Changed Discussion --

&&

.MARINE...
A LAKE WIND ADVISORY HAS BEEN ISSUED FOR TONIGHT. A LOW LEVEL JET
WILL STRENGTHEN THIS EVENING AND AT THE SFC...SOUTHERLY WINDS
WILL CONTINUE TO CHANNEL UP THE CHAMPLAIN VALLEY...PRODUCING
WINDS OF 17-27 KTS THROUGH LATE TONIGHT/EARLY MONDAY MORNING.
WAVES OF 2 TO 4 FEET CAN BE EXPECTED WITH THESE WINDS.

&&

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

&&

$$
SYNOPSIS...LAHIFF/KGM
NEAR TERM...KGM/LOCONTO
SHORT TERM...KGM
LONG TERM...EVENSON
AVIATION...EVENSON/LOCONTO
MARINE...