Area Forecast Discussion
Issued by NWS Burlington, VT

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000
FXUS61 KBTV 260836
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
436 AM EDT SAT JUL 26 2014

.SYNOPSIS...
THOUGH TODAY WILL START OFF DRY...INCREASING CLOUDS ARE EXPECTED
LATE IN THE DAY. SHOWERS AND THUNDERSTORMS ARE EXPECTED TONIGHT
INTO PARTS OF SUNDAY AS A WARM FRONT INTERACTS WITH A WEAK UPPER-
LEVEL DISTURBANCE. A STRONGER STORM SYSTEM WILL BRING WITH IT A
RENEWED THREAT OF RAIN AND THUNDERSTORMS FOR MONDAY INTO TUESDAY.
SLIGHTLY BELOW NORMAL TEMPS EXPECTED FOR EARLY NEXT
WEEK...TRENDING BACK TOWARD SEASONAL NORMALS BY MIDWEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 435 AM EDT SATURDAY...WEST TO WEST-NORTHWEST FLOW PREVAILS AT
MID TO UPPER LEVELS ACROSS THE NORTH COUNTRY...BETWEEN NEARLY
STATIONARY CYCLONIC GYRE OVER NORTHERN QUEBEC AND LARGE HEAT RIDGE
CENTERED OVER THE SOUTHERN PLAINS STATES. HIGH CLOUDS THIS MORNING
PRECEDE A WEAK WARM FRONT ROUGHLY LOCATED EARLY THIS MORNING
ACROSS SOUTHERN NEW YORK AND INTO THE GREAT LAKES. THAT FRONTAL
ZONE WILL SLOWLY CREEP ITS WAY NORTHEASTWARD TOWARDS THE NORTH
COUNTRY LATER TODAY INTO TONIGHT. THOUGH THE MORNING HOURS WILL
START OFF WITH AT LEAST FILTERED SUN THROUGH THE HIGH
CLOUDS...ANTICIPATE CLOUDS TO INCREASE FURTHER FROM WEST TO EAST
BY LATE AFTERNOON/EARLY EVENING. 850 TEMPS OF +12C TODAY COMBINED
WITH PARTIAL SUNSHINE SHOULD ALLOW HIGHS TO TOP OUT IN THE 70S
WITH LOWER 80S IN THE CHAMPLAIN VALLEY AND SOUTHERN VERMONT.
SOUTHWEST WINDS AROUD 10 MPH TODAY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
AS OF 435 AM EDT SATURDAY...THE PATTERN THEN TURNS MORE ACTIVE
LATER TONIGHT/MOST OF SUNDAY AND ESPECIALLY GOING INTO MONDAY.

FOR TONIGHT: A WEAK VORTICITY MAX EMBEDDED IN WEST FLOW ALOFT
INTERACTS WITH APPROACHING WARM FRONT...SPAWNING AREAS OF SHOWERS.
MID-LEVEL LAPSE RATES DO STEEPEN SOME LATE TO AROUND 6C/KM TOWARD
MORNING...AND SLIGHTLY NEGATIVE SHOWALTER INDICES OF -1 TO -2 PER
00Z NAM/WRF AND GFS LEAVES OPEN THE POSSIBILITY OF THUNDER THOUGH
NOT EXPECTING ANYTHING SIGNIFICANT. I USED NAM/SREF 3-HRLY POP AND
ADJUSTED BASED ON HI-RES GUIDANCE...WITH LIKELY POPS (CHANCE
THUNDER) ANTICIPATED AROUND AND AFTER MIDNIGHT. OVERCAST SKIES
SHOULD KEEP LOWS IN THE 60S (COOLER MID-UPPER 50S IN THE TYPICALLY
COOLER NORTHEAST KINGDOM AND ADIRONDACKS).

SUNDAY: STILL EXPECT THERE TO BE SHOWERS/THUNDER ONGOING PRIMARILY
ACROSS THE EASTERN HALF OF THE CWA. A GENERAL DECREASE IN POPS IS
FORECAST AS WEAK 500-MB SHORTWAVE EXITS INTO EASTERN QUEBEC...BUT
STILL HAVE CARRIED AT LEAST CHANCE POPS INTO SUNDAY EVENING. SPC`S
DAY2 OUTLOOK PARTS OF RUTLAND AND WINDSOR COUNTIES IN A SLIGHT RISK
AREA. THERE`S LARGE VARIATION IN FORECAST CAPE VALUES BETWEEN
NAM/WRF AND GFS ACROSS CENTRAL AND SOUTHERN VERMONT (AS HIGH AS 1500
J/KG AT VSF PER THE GFS). THOUGH I`VE INCLUDED CHANCE THUNDER
SUNDAY...I DON`T THINK ACTUAL CAPE VALUES WILL GET THAT HIGH AS
THERE SHOULD BE PLENTY OF CLOUDS AROUND TO LIMIT BETTER SFC HEATING.
WIND FIELDS INCREASE SOME. UNDER PARTLY TO MOSTLY CLOUDY SKIES
LOOKING AT HIGHS ONLY IN THE 70S.

SUNDAY NIGHT: IF THERE`S A BREAK IN THE UNSETTLED WEATHER (ALBEIT
BRIEF) IT WILL BE ON SUNDAY NIGHT. THE NORTH COUNTRY WILL BE UNDER
WEAK 500 MB HEIGHT RISES EARLY SUNDAY NIGHT AHEAD OF A RATHER STRONG
SHORTWAVE TROUGH EXPECTED TO BE NEAR THE SOUTHERN GREAT LAKES.
STARTED TO INCREASE POPS AFTER MIDNIGHT TO HIGH CHANCE/LIKELY AHEAD
OF MORE SIGNIFICANT SYSTEM. LOWS GENERALLY MID 50S TO LOW 60S.

MONDAY: A POTENT SHORTWAVE TROUGH (NOW ACROSS THE CANADIAN
PRAIRIES) WILL BECOME NEGATIVELY TILTED DURING THIS PERIOD -
INDUCING A SFC LOW TO DEVELOP EARLY MONDAY OVER INTERIOR
CENTRAL/SOUTHERN NEW ENGLAND. NEARLY ALL GUIDANCE SHOW A GOOD AMOUNT
OF PRECIPITATION ESPECIALLY FOR EASTERN VERMONT MONDAY...FOCUSED
SOMEWHAT ON A MID-LEVEL DEFORMATION ZONE. A BIGGER QUESTION IS THE
TRACK OF THE SFC LOW AND WHERE/IF THE WARM SECTOR CAN GET
ESTABLISHED SOMEWHERE ACROSS THE NORTH COUNTRY. THE NAM IS FURTHEST
EAST WITH PROGGED LOW TRACK...WHILE THE GFS TAKES A MORE INLAND
TRACK INTO CENTRAL NEW ENGLAND. IF THE GFS WERE CORRECT...COULD SEE
POTENTIAL FOR STRONG THUNDERSTORMS FOR EASTERN VERMONT GIVEN STRONG
SYNOPTIC FORCING...0-6KM SHEAR VALUES OF 35-45 KTS AND CAPES OF
1000-1500 J/KG. IT`S SOMETHING THAT WILL BEAR CLOSE WATCH. HIGH
LIKELY POPS ACROSS EASTERN VT TAPER TO CHANCE ACROSS THE ST.
LAWRENCE VALLEY FOR RAIN/CHANCE THUNDER. QPF FROM 06Z - 18Z MONDAY
RUNS FROM .25" ST. LAWRENCE VALLEY TO .75"-1" FOR SOUTHERN AND
EASTERN VT.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 435 AM EDT SATURDAY...COOLER THAN NORMAL AND WET WEATHER IS
EXPECTED EARLY TUESDAY THEN IMPROVING THE REST OF THE WEEK. A SLOW
WARMING TREND TO NEAR NORMAL TEMPERATURES IS EXPECTED BY THE END
OF THE WEEK WITH ONLY SLIGHT CHANCES OF SHOWERS.

MODELS IN GOOD AGREEMENT THAT A DEEP LARGE SCALE TROUGH WILL
REMAIN OVER THE EASTERN US CENTERED NEAR 80 DEG W WITH A RIDGE OVER
THE INTERMOUNTAIN WEST THROUGHOUT THE PERIOD...THOUGH WEAKENING
WITH RISING HEIGHTS WED - FRI.

THE BEST CHANCE FOR SEEING WIDESPREAD RAIN WILL BE MONDAY NIGHT
INTO EARLY TUESDAY. RAIN WILL BE FORCED BY BLOCKED COOL MOIST NORTH
TO NORTHWEST CYCLONIC UPSLOPE FLOW RIGHT UNDER THE TROUGH ALOFT AND
BEHIND DEPARTING LOW PRESSURE IN EASTERN CANADA. GFS FROUDE NUMBERS
ARE VERY LOW (0.10) SUGGESTING THAT PRECIP MAY BE ENHANCED FROM
THE GREEN MOUNTAINS WESTWARD ALL THE WAY BTV IN THE CHAMPLAIN
VALLEY WITH GENERAL LIGHTER RAINS ELSEWHERE.

EXPECTING PRECIP CHANCES TO DROP OFF LATER TUESDAY AS THE LOW MOVES
AWAY.

THE UPPER TROUGH WEAKENS BUT REMAINS IN PLACE WEDNESDAY THROUGH
FRIDAY. WITH AFTERNOON INSTABILITY FROM RELATIVELY COOL TEMPERATURES
ALOFT...THERE ARE SLIGHT CHANCES FOR SHOWERS EACH DAY MAINLY DURING
THE AFTERNOON HOURS.

5 TO 10 DEGREE BELOW NORMAL MAX TEMPS ARE EXPECTED TUESDAY WITH
CLOUDS AND SHOWERS. HIGHS TEMPS WILL ONLY REACH THE UPPER 60S TO
LOWER 70S WITH 850 TEMPS ONLY AROUND +7C.

850 MB TEMPS WARM A COUPLE DEGREES EACH DAY SO THAT BY FRIDAY
SHOULD BE 12-13C. WITH PARTIAL SUN UNDER DIURNAL CUMULUS CLOUDS
EXPECT HIGHS ONLY IN THE 70S WED BUT MODERATING TO NEAR NORMAL -
UPPER 70S LOWER 80S - BY THURSDAY AND FRIDAY.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
THROUGH 06Z SUNDAY...MAINLY VFR EXPECTED UNDER WEST TO SOUTHWEST
SURFACE FLOW.

THE ONLY EXCEPTION WILL BE SOME LOCAL IFR/VLIFR IN FOG AND STRATUS
7-12Z AT KMPV/KSLK WHERE CROSSOVER TEMP HAS BEEN MET.

WINDS WILL GENERALLY BE LIGHT S-SW...THOUGH LOCALLY SW AROUND 10
KTS AT KMSS WITH SOMEWHAT STRONGER GRADIENT FLOW AND CHANNELING IN
THE ST. LAWRENCE RIVER VALLEY.

GENERALLY VFR AFTER 12Z SATURDAY. LOOKING AT SCT CUMULUS CLOUDS
AND SCT-BKN MID TO HIGH LEVEL CLOUDS. WINDS BECG SWLY AROUND 10
KTS AREAWIDE ON SATURDAY.

A WEAK FRONTAL SYSTEM WILL BRING INCREASING CLOUDS AND A THREAT OF
SHOWERS PERHAPS A THUNDERSTORM TOWARD 06Z SUN.

OUTLOOK 06Z SUNDAY THROUGH WEDNESDAY...

06Z SUN - 12Z MON...MOSTLY VFR. BRIEF PERIODS MVFR VISIBILITY IN
SCT SHOWERS/STORMS.

12Z MON - 00Z WED...PERIODS OF MVFR IN SHOWERS.

00Z WED ONWARD...TRENDING VFR. POSSIBLE IFR/LOWER VISIBILITY IN
OVERNIGHT FOG/MIST MPV AND SLK.

&&

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

&&

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









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