Area Forecast Discussion
Issued by NWS Burlington, VT

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000
FXUS61 KBTV 301950
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
350 PM EDT SAT MAY 30 2015

.SYNOPSIS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR THROUGH THIS
EVENING AHEAD OF A COLD FRONT SAGGING SOUTH FROM ONTARIO AND
QUEBEC. DOWNPOURS AND GUSTY WINDS CAN BE EXPECTED WITH ANY
THUNDERSTORMS THROUGH THE EVENING HOURS. COLD FRONT BRINGS MUCH
COOLER AND CLOUDY CONDITIONS FOR SUNDAY AND MONDAY. SEVERAL UPPER
LEVEL DISTURBANCES WILL BRING PERIODS OF RAIN ACROSS OUR REGION
RESULTING IN A VERY UNSETTLED PERIOD OF WEATHER SUNDAY NIGHT
THROUGH EARLY TUESDAY. RAINFALL AMOUNTS OF 2 TO 3 INCHES ARE
GENERALLY EXPECTED ACROSS THE NORTH COUNTRY. HIGH TEMPERATURES
SUNDAY AND MONDAY ARE ONLY EXPECTED IN THE 50S.

&&

.NEAR TERM /UNTIL 7 AM SUNDAY MORNING/...
AS OF 315 PM EDT SATURDAY...VERY WARM PBL - WITH TEMPS IN THE MID
80S AND DEWPOINTS IN THE LOW TO MID 60S - CONTRIBUTING TO SBCAPE
VALUES OF 1000-2000 J/KG LATE THIS AFTERNOON. ISSUE WITH
CONVECTIVE COVERAGE MAINLY ASSOCIATED WITH LACK OF SIGNIFICANT
FORCING/CONVERGENCE AND SLIGHTLY ANTICYCLONIC 500MB FLOW REGIME.
BEST CONVECTIVE ORGANIZATION AT 1915Z IS ALONG THE COLD FRONT
NORTH AND WEST OF MONTREAL QUEBEC. MEANWHILE...WILL BE MONITORING
MULTICELLULAR CLUSTERS ACROSS W-CENTRAL NY AND THE UPPER HUDSON
VALLEY OVER THE NEXT SEVERAL HRS. IT APPEARS THE CLUSTER IN THE
UPR HUDSON VALLEY HAS A LARGE ENOUGH COLD POOL THAT CONTINUED CELL
REGENERATION IS LIKELY...AND WILL CARRY THIS ACTIVITY ACROSS
S-CENTRAL VT WHERE CINH IS NEAR ZERO. MEANWHILE...STORMS IN BEST
INSTABILITY AXIS ACROSS CENTRAL NY SHOULD CONTINUE TO INCREASE IN
COVERAGE AND EXPAND NORTHEASTWARD INTO THE ADIRONDACKS...AND
EVENTUALLY INTO THE CHAMPLAIN VALLEY THIS EVENING. WHILE SOME
STRONG STORMS ARE EXPECTED...WITH HEAVY DOWNPOURS (PWATS
1.75-1.9") AND GUSTY WINDS...ANY DAMAGING WIND THREAT WILL BE
LIMITED BY MARGINAL SFC- 6KM SHEAR (AROUND 20 KTS) AND WEAK MID-
LEVEL LAPSE RATES. MAY SEE SOME BACKBUILDING CELLS THIS EVENING AS
WELL AS CORFIDI VECTORS WEAKEN TO LESS THAN 5 KTS. LOCALIZED
RAINFALL TO 1"+ POSSIBLE WITH STRONGER AND MORE PERSISTENT
MULTICELLULAR BANDS THIS EVENING...ESPECIALLY GIVEN HIGH
PRECIPITABLE WATER VALUES AND FREEZING LEVELS 10-11 KFT. MAY SEE
STORMS BRIEFLY PULSE AT TIMES...BUT LONGEVITY OF STRONGER
UPDRAFT/DOWNDRAFT STRUCTURES WILL LIKELY BE SHORT. WILL CONTINUE
TO MONITOR SHORT-TERM CONVECTIVE TRENDS THIS EVENING.

AS THE EVENING PROGESSES...SHOULD SEE STRONG SURFACE COLD FRONT
REACH THE ST. LAWRENCE VALLEY BY 02-03Z...AND THE CHAMPLAIN VALLEY
AROUND 06Z. STRONG N-NW WIND SHIFT EXPECTED WITH FROPA. ANAFRONTAL
STRUCTURE WILL BRING ADDITIONAL PERIODS OF LIGHT TO MODERATE RAINFALL
OVERNIGHT...WITH DIMINISHING THREAT OF T-STORMS AS ELEVATED
INSTABILITY WANES FROM NORTH TO SOUTH. WILL ALSO SEE TEMPERATURES
CRASH INTO THE UPPER 40S BY DAYBREAK IN THE ST. LAWRENCE
VALLEY...AND GENERALLY DOWN INTO THE 50S TOWARD DAYBREAK ACROSS
CENTRAL AND NRN VT. IT WILL BE QUITE A CHANGE IN LOW-LEVEL AIR
MASS OVERNIGHT.

&&

.SHORT TERM /7 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
AS OF 315 PM EDT SATURDAY...SIGNIFICANT RAINFALL EXPECTED THROUGH
THE PERIOD (2 TO 3 INCHES FORECAST) WITH MINOR POOR DRAINAGE TYPE
FLOODING POSSIBLE...ESPECIALLY ACROSS CENTRAL/S-CENTRAL VT.

SFC FRONTAL BNDRY STALLS SOUTH OF LONG ISLAND WITH WSW-ENE
ORIENTED 925-700MB FRONTAL ZONE REMAINING ACROSS SRN HALF OF OUR
FORECAST AREA. IT APPEARS SHOWERS WILL GRADUALLY PUSH SWD DURING
SUNDAY MORNING...BUT THEN GRADUALLY REDEVELOP NORTHWARD DURING
SUNDAY EVENING/NIGHT AS A SERIES OF SHORTWAVE TROUGHS MOVES THRU
THE FRONTAL ZONE IN SWLY FLOW ALOFT. THIS WILL MAINTAIN PERIODS OF
LIGHT TO MODERATE RAINFALL SUNDAY NIGHT AND MONDAY...WITH CLOSED
UPPER LOW FROM THE GREAT LAKES BRINGING ADDITIONAL RAINFALL MONDAY
NIGHT (AND INTO TUESDAY). MODELS ARE RELATIVELY CONSISTENT WITH
PLACEMENT AND AMTS OF QPF...AND GENERALLY LOOKING AT 2.5 TO 3"
FROM THE CHAMPLAIN VALLEY SWD ACROSS CENTRAL/S-CENTRAL VT AND THE
NRN ADIRONDACKS. SLIGHTLY LESS FREQUENT RAIN ACROSS THE ST.
LAWRENCE VALLEY...WITH AMTS 1.5-2" FORECAST THERE THRU THE PERIOD.
OVERALL HYDRO THREAT IS LOW GIVEN DRY ANTECEDENT CONDITIONS...BUT
POOR DRAINAGE FLOODING AND SHARP RISES ON SMALLER STREAMS/CREEKS
CAN BE EXPECTED - ESPECIALLY IN TERRAIN - AS WE HEAD THROUGH
MONDAY AND MONDAY NIGHT. A FEW RIVERS - AUSABLE FORKS AND CENTER
RUTLAND - MAY NEAR BANKFUL BY MONDAY NIGHT AS WELL (THOUGH
FLOODING IS NOT FORECAST).

WITH THE ENTIRE NORTH COUNTRY ON THE COOL SIDE OF THE FRONTAL
BNDRY AND OVERCAST SKIES...TEMPERATURES WILL BE WELL BELOW
NORMAL WITH SMALL DIURNAL RANGES...WITH HIGHS ONLY IN THE 50S
SUNDAY AND MONDAY...AND LOWS MAINLY IN THE 40S.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 256 PM EDT SATURDAY...WET AND COOL CONDITIONS CONTINUE TO
BEGIN THE EXTENDED PERIOD BUT WE TREND DRIER AND BACK TOWARDS
SUMMER-LIKE TEMPERATURES FOR MID-WEEK AND INTO NEXT WEEKEND.

POTENT UPPER LOW TRACKING EASTWARD FROM GREAT LAKES MONDAY NIGHT
INTO THE FORECAST AREA TUESDAY WILL CONTINUE CHANCES FOR RAINFALL
ACROSS THE NORTH COUNTRY. ADDITIONAL AMOUNTS OF 0.25-0.5" IS
POSSIBLE WITH TEMPERATURE REMAINING COOL WITH HIGHS GENERALLY IN THE
MID 50S TO LOW 60S. BY TUESDAY NIGHT THE UPPER LOW SHIFTS EAST OF
THE AREA INTO EASTERN CANADA WITH MID-LEVEL HEIGHTS ON THE RISE AS
AN UPPER RIDGE BUILDS INTO THE GREAT LAKES. MEANWHILE AT THE
SURFACE, HIGH PRESSURE BUILDS SOUTH FROM ONTARIO/QUEBEC AND WILL
TAKE RESIDENCE OVER THE NORTHEAST THROUGH THE END OF THE WORK WEEK.
THE RESULTING WEATHER WILL FEATURE DRY CONDITIONS, AND A RETURN TO
MORE SUMMER-LIKE TEMPERATURES WITH HIGHS THROUGH THE PERIOD STARTING
THE UPPER 60S TO LOW 70S FOR WEDNESDAY, WARMING INTO THE UPPER 70S
TO LOWER 80S BY FRIDAY. LOWS WILL BE COMFORTABLE AND RIGHT AROUND
SEASONAL NORMALS IN THE 40S AND 50S.

AS WE LOOK OUT FURTHER TOWARDS NEXT WEEKEND, CHANCE FOR SHOWERS
RETURN AS AN UPPER TROUGH OVER JAMES BAY LOOKS TO SLOWLY DRIFT
SOUTHWARD TOWARDS THE INTL BORDER ALLOWING A FAST ZONAL FLOW TO SET
UP ACROSS THE BTV CWA. NOT A WHOLE LOT OF CONFIDENCE TIMING
SHORTWAVE ENERGY PASSING THROUGH THE FLOW THIS FAR OUT, SO WILL LEAN
ON MODEL CONSENSUS LOW CHANCE POPS FOR NOW.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
THROUGH 12Z SUNDAY...GENERALLY VFR CONDITIONS ARE EXPECTED
THROUGH 00Z WITH SHOWER/THUNDERSTORM COVERAGE INCREASING AFTER 18Z
ACROSS NORTHERN NEW YORK AND AFTER 21Z ACROSS VERMONT. SOME STORMS
COULD TURN STRONG WITH GUSTY OUTFLOW WINDS...LIGHTNING AND REDUCED
VISIBILITY IN HEAVY DOWNPOURS. AFTER 00Z, THUNDERSTORMS ACTIVITY
DISSIPATES TO MORE STRATIFORM SHOWERS WITH FLIGHT CATEGORIES
TRENDING TO MVFR FOR THE OVERNIGHT HOURS WITH CIGS GENERALLY
020-030 AND VSBY 3-5SM. EARLY MORNING FROM ABOUT 08-10Z COLD FRONT
SHIFTS INTO THE REGION WITH WINDS TURNING FROM SOUTHWEST TO
NORTHWEST. WHILE I`VE INDICATED DRIER CONDITIONS IN THE TAFS,
CHANCES FOR RAIN CONTINUES AS THE FRONT STALLS OUT OVER THE
REGION.

OUTLOOK 18Z SUNDAY THROUGH THURSDAY...

18Z SUNDAY THROUGH 00Z WEDNESDAY...PERIODS OF RAIN WITH MVFR
CONDITIONS WITH STALLED FRONT OVER AND SOUTH OF THE AREA.

00Z WEDNESDAY THROUGH 00Z FRIDAY...TRENDING TO VFR UNDER BUILDING
HIGH PRESSURE.

&&

.MARINE...
AS OF 300 PM EDT SATURDAY...A LAKE THUNDERSTORM ADVISORY REMAINS
IN EFFECT THROUGH TONIGHT. SOUTH WINDS 20 TO 25 KNOTS MAY BRIEFLY
REACH 30 KNOTS ON THE BROAD LAKE DURING THE EVENING HOURS. A COLD
FRONT MOVING THROUGH FROM NW TO SE WILL SHIFT WINDS ABRUPTLY INTO
THE NORTH BETWEEN 1 AND 2 AM SUNDAY...WITH WINDS GENERALLY NORTH
TO NORTH- NORTHWEST AT 15-25 KNOTS THROUGH SUNDAY MORNING...DIMINISHING
TO 10 TO 15 KNOTS IN THE AFTERNOON. WAVES WILL GENERALLY BE IN
THE 2 TO 4 FOOT RANGE LATE THIS AFTERNOON AND EVENING...WITH
INCREASINGLY CHOPPY CONDITIONS DURING THE PRE-DAWN HOURS AS WINDS
SHIFT NEARLY 180 DEGREES. WAVES 2 TO 4 FEET WILL SUBSIDE TO 1 TO 3
FEET DURING THE AFTERNOON.

THE THREAT OF SHOWERS AND THUNDERSTORMS ALSO REMAINS THROUGH THIS
EVENING. ANY THUNDERSTORMS WILL BE CAPABLE OF PRODUCING HEAVY
DOWNPOURS AND DANGEROUS LIGHTNING.

&&

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

&&

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


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