Area Forecast Discussion
Issued by NWS Burlington, VT

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000
FXUS61 KBTV 221122
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
722 AM EDT TUE JUL 22 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ATOP THE REGION TODAY INTO TONIGHT WITH
WARM AND DRY WEATHER CONTINUING. A COLD FRONT WILL APPROACH AND
CROSS THE AREA WEDNESDAY INTO WEDNESDAY EVENING WITH SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS...A FEW OF WHICH MAY BE STRONG TO
LOCALLY SEVERE. BEHIND THE FRONT...A RETURN TO MAINLY DRY AND
SEASONAL WEATHER IS EXPECTED BY THURSDAY INTO THE FIRST HALF OF THE
UPCOMING WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 718 AM EDT TUESDAY...NOISE LEVEL TWEAKS TO SKY COVER AND
HOURLY T/TDS TO MATCH CURRENT OBSERVATIONAL TRENDS AND TO BLEND
INTO EXISTENT DATA AT THE 9/10 AM HOUR. NO APPRECIABLE CHANGES TO
GOING FORECAST. PRIOR DISCUSSION FOLLOWS...

PRIOR DISCUSSION FROM 330 AM EDT TUESDAY...ANOTHER MAINLY SUNNY
AND WARM DAY ON TAP FOR THE REGION AS DEEP LAYER HIGH PRESSURE
REMAINS ACROSS THE REGION. BUILDING HEIGHTS AND MID/UPPER LEVEL
ANTICYCLONIC FLOW SHOULD FOSTER BROAD SCALE SUBSIDENCE...SO
LOOKING AT ONLY A FEW FAIR WX SHALLOW CUMULUS CLOUDS...MAINLY
ACROSS THE HIGHER TERRAIN WITH NIL POPS. MODEL AVERAGED 18-00Z 925
MB TEMPS SUPPORT HIGHS WELL INTO THE 80S WITH A FEW SPOT L90S IN
THE BROADER VALLEYS. WINDS LIGHT.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
AS OF 330 AM EDT TUESDAY...QUIET WX CONTINUES TONIGHT AS HIGH
PRESSURE SLIDES SLOWLY EAST AND OFFSHORE...MAINTAINING A LIGHT
SOUTHERLY FLOW ACROSS THE REGION. AN APPROACHING COLD FRONT TO OUR
WEST MAY TEND TO SPREAD SCT MID TO HIGH LEVEL CLOUD COVER INTO OUR
WESTERN COUNTIES LATER AT NIGHT...BUT OUTSIDE A STRAY SLV SHOWER
TOWARD SUNRISE WE`LL REMAIN DRY OVERNIGHT. LOWS CONTINUE MILD
GENERALLY IN THE 60S TO LOCALLY NEAR 70F IN THE CHAMPLAIN VALLEY.

BRIEF...THOUGH ACTIVE PERIOD OF WEATHER THEN DEVELOPS DURING
WEDNESDAY INTO EARLY WEDNESDAY EVENING AS AFOREMENTIONED COLD FRONT
MAKES STEADY PROGRESS THROUGH THE AREA. DECENT 0-6KM SHEAR PROFILES
AND AMPLE PBL INSTABILITY IN EXCESS OF 1000 J/KG SHOULD BE MORE THAN
ENOUGH TO SUPPORT SCT/NUMEROUS SHOWERS AND STORMS ACROSS THE
AREA...A FEW OF WHICH MAY BECOME STRONG TO LOCALLY SEVERE.
PRE-FRONTAL CLOUDS AND MORNING SHOWERS MAY LIMIT THREAT ACROSS THE
SLV AND TO SOME EXTENT THE ADIRONDACKS...BUT SUCH SUBTLE TIMING
DIFFERENCES WILL BE ALLOWED TO PLAY OUT AND HAVE MENTIONED THIS
THREAT IN ALL AREAS FOR NOW...IN CLOSE AGREEMENT TO SPC SWODY2.
GUSTY/STRONG WINDS AND HEAVY DOWNPOURS (PWATS TO NEAR 2") APPEAR TO
BE THE MAIN THREAT WITH LARGE HAIL A LESSER CONCERN GIVEN DEEPER WCD
VALUES AND WBZ HEIGHTS ABOVE 11 KFT. CONVECTIVE MODE WOULD BE LINEAR
WITH POSSBL QLCS DEVELOPMENT ACROSS OUR EASTERN COUNTIES WITH
RELATIVELY UNIDIRECTIONAL WIND PROFILES THROUGH THE PBL. ALSO CAN`T
RULE OUT LOCALIZED HYDRO CONCERNS GIVEN THE WCD DEPTHS AND HIGH PWAT
VALUES...BUT WIND FIELDS APPEAR STRONG ENOUGH TO KEEP MOST OF THE
ACTIVITY MOVING ALONG AND GIVEN THE RELATIVELY DRY ANTECEDENT
CONDS MOST WATERSHEDS SHOULD BE ABLE TO HANDLE THINGS OK.

BY WEDNESDAY NIGHT SFC FRONT CLEARS EAST AND SOUTH WITH
SHOWERS/STORMS ENDING ACROSS OUR SOUTHERN VT COUNTIES BY MIDNIGHT OR
SO AND SKIES GRADUALLY TRENDING PC/CLR ACROSS THE NORTH OVERNIGHT.
LOWS A BLEND OF MODEL GUIDANCE...MAINLY 50S.

SFC HIGH PRESSURE THEN BUILDS EAST/SOUTH INTO THE FORECAST AREA BY
THURSDAY WITH CYCLONIC FLOW PERSISTING ALOFT UNDER BASE OF MEAN ERN
CANADA UPPER LONGWAVE TROUGH. UPWARD MOISTURE FLUXES FROM PRIOR
EVENING`S RAINFALL COMBINED WITH STRONG JULY SUN SHOULD LEAD TO
DECENT COVERAGE OF FAIR WX CUMULUS CLOUDS...ESP ACROSS THE HIGHER
TERRAIN. HOWEVER...ALL AND ALL A VERY NICE DAY IS EXPECTED WITH
LOWER HUMIDITY VALUES AND LIGHT NORTHERLY BREEZES AS HIGHS RANGE
THROUGH THE 70S.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 357 AM EDT TUESDAY...FAIRLY GOOD AGREEMENT AMONGST THE 00Z
GUIDANCE SUITE FOR THE LATTER PART OF THE WEEK INTO THE EARLY
WEEKEND. THEREAFTER DETAIL DIFFERENCES EMERGE BETWEEN 00Z
GFS...ITS ENSEMBLE MEAN AND 00Z ECMWF IN THE EVOLUTION AND
ULTIMATE RETROGRESSION OF A NORTHEASTERN NOAM MID-LEVEL TROUGH FOR
LATE WEEKEND/EARLY NEXT WEEK. THE SOURCE OF THOSE DIFFERENCES
STEMS FROM HOW QUICKLY TO PHASE A SHEARING-OUT SHORTWAVE ENTERING
THE CANADIAN PRAIRIES WITH THE EASTERN NOAM TROUGH. OVERALL
PATTERN FAVORS UNSETTLED CONDITIONS LATE WEEKEND INTO EARLY NEXT
WEEK WITH CLOUDY/OFF-AND-ON SHOWERS AND THUNDER - BUT NOTHING THAT
SEEMS TOO SIGNIFICANT. DESPITE PREVAILING CYCLONIC MID-LEVEL FLOW
THROUGH MUCH OF THE PERIOD...TEMPS WILL TEND TO RUN AROUND NORMAL.

MOSTLY CLEAR SKIES AND LIGHT SFC WINDS THURSDAY NIGHT SHOULD
PROMOTE STRONG RADIATIONAL COOLING. THURDSDAY NIGHT LOOKS TO BE THE
COOLEST NIGHT IN THE PERIOD (MID 40S TO VALLEY MID 50S). I DIDN`T
INTRODUCE INTO THE FORECAST YET BUT RIVER VALLEY FOG LOOKS TO BE A
GOOD POSSIBILITY THURS NIGHT AS WELL GIVEN WET SOIL CONDITIONS FROM
EXPECTED RAINFALL WEDNESDAY/WED NIGHT. CYCLONIC FLOW ALOFT COMBINED
WITH DAYTIME HEATING FRIDAY WILL LIKELY PRODUCE AT LEAST PARTLY
CLOUDY SKIES WITH SLIGHT CHANCE TO CHANCE POPS MORE FOCUSED TO THE
HIGHER TERRAIN. THERE ISN`T MUCH MOISTURE TO WORK WITH BUT COULDN`T
REALLY DISCOUNT SOME ISOLATED TO SCATTERED SHOWERS. OPTED FOR A DRY
FORECAST FOR THE FIRST HALF OF SATURDAY AS THE MID-LEVEL TROUGH AXIS
PIVOTS NORTHEAST WITH NEUTRAL TO SLIGHT HEIGHT RISES. THE REST OF
THE WEEKEND INTO EARLY NEXT WEEK HAS SLIGHT CHANCE/CHANCE POPS
GRADUALLY INCREASING TO HIGH-CHANCE TOWARD EARLY NEXT WEEK AS THE
LARGE-SCALE TROUGH RETROGRADES TOWARD THE GREAT LAKES...LEAVING THE
NORTH COUNTRY UNSETTLED IN SOUTHWEST FLOW ALOFT. TEMPS FOR SATURDAY
INTO TUESDAY PRETTY SIMILAR...HIGHS IN THE 70S TO LOW 80S AND LOWS
IN THE 50S TO LOW 60S.

&&

.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
THROUGH 12Z WEDNEDSAY...VLIFR FOG AT SLK BURNS OFF EARLY THIS
MORNING WITH VFR EXPECTED FOR ALL TAF SITES. A FEW-SCT CU POSSIBLE
AT MPV AND SLK NEAR TERRAIN BUT OTHERWISE UPPER-LEVEL RIDGING
LARGELY SUPPRESSES CU DEVELOPMENT TODAY. WILL SEE AN INCREASE IN
CIRRUS LATE IN THE DAY AND ESPECIALLY EVENING/OVERNIGHT WELL AHEAD
OF FRONTAL SYSTEM. ANY RAIN/T-STORMS LOOK TO HOLD OFF UNTIL AFTER
12Z WEDNESDAY HOWEVER. MIST/FOG UNLIKELY TONIGHT GIVEN INCREASING
CLOUDS AND PROGGED 10-15 KT BL WINDS. WINDS MOSTLY SOUTHERLY
UNDER 10 KTS (INITIALLY SE AT PBG THIS MORNING FROM LAKE BREEZE).

OUTLOOK 12Z WEDNESDAY THROUGH SATURDAY...

12Z WED - 06Z THU...VFR WITH BRIEF PERIOD MVFR/IFR IN HEAVY
SHOWERS/T-STORMS WITH FRONTAL PASSAGE. STORMS WEDNESDAY COULD BE
STRONG...CAPABLE OF TURBULENCE AND HEAVY DOWNPOURS WITH LIMITED
RISK OF SMALL HAIL.

06Z THU - 12Z THU...MOST TAFS VFR. HOWEVER...POSSIBLE IFR OR LOWER
VISIBILITY IN FOG/MIST AT SLK AND POSSIBLY MPV PENDING CLEARING.

12Z THU - 00Z FRI...VFR UNDER HIGH PRESSURE DURING THE DAY
THURSDAY.

00Z FRI - 12Z FRI...IFR OR LOWER VISIBILITY IN FOG/MIST MPV AND
SLK...OTHERWISE VFR.

12Z FRI - 00Z SUN...VFR UNDER SURFACE HIGH PRESSURE. AN ISOLATED
AFTERNOON SHOWER OVER THE HIGHER TERRAIN IS POSSIBLE FRIDAY.

&&

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

&&

$$
SYNOPSIS...JMG
NEAR TERM...JMG
SHORT TERM...JMG
LONG TERM...LOCONTO
AVIATION...LOCONTO











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