Area Forecast Discussion
Issued by NWS Burlington, VT

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000
FXUS61 KBTV 050821
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
421 AM EDT WED AUG 5 2015

.SYNOPSIS...
SHOWERS WITH EMBEDDED THUNDERSTORMS WILL BE POSSIBLE
AGAIN TODAY WITH TEMPERATURES MAINLY IN THE 70S. A SLOW DRYING TREND
WILL OCCUR ON THURSDAY AND CONTINUE INTO THE WEEKEND AS SURFACE HIGH
PRESSURE BUILDS INTO THE NORTH COUNTRY. TEMPERATURES WILL FEATURE
COOL NIGHTS AND MILD DAYS WITH VALUES VERY CLOSE TO NORMAL FOR THIS
TIME OF YEAR.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 345 AM EDT WEDNESDAY...LARGE SCALE SHOWS DEEP MID/UPPER LEVEL
TROF ACROSS THE NE CONUS WITH NUMEROUS EMBEDDED 5H VORTS. WATER
VAPOR SHOWS BEST DEEP LAYER MOISTURE HAS SHIFTED INTO THE MID
ATLANTIC STATES WITH TROF AXIS DIRECTLY OVERHEAD. THIS WILL RESULT
IN COOL POOL ALOFT WITH 500 TEMPS NEAR -18C TODAY...WHICH WILL HELP
TO STEEPEN LAPSE RATES AND CREATE SOME INSTABILITY.
HOWEVER...SOUNDINGS SHOW LESS INSTABILITY THAN YESTERDAY FROM COOLER
SFC TEMPS AND DRIER DWPTS...IN ADDITION PW VALUES ARE LESS TODAY.
THESE FACTORS ALL SUPPORT LESS AREAL COVERAGE OF CONVECTION TODAY
AND WEAKER UPDRAFTS WITH LESS ORGANIZATION. WE WILL MENTION CHC POPS
WITH GREATEST COVERAGE FROM THE NORTHERN DACKS INTO CENTRAL/NORTHERN
VT THIS AFTN...ALONG WITH ISOLATED THUNDER. GIVEN LOW WET BULB
FREEZING LEVELS BTWN 7000 AND 8000 FEET SOME PEA SIZE HAIL WILL BE
POSSIBLE IN THE STRONGEST CELLS...BUT NOT WIDESPREAD IN COVERAGE.
QPF VALUES WILL GENERAL BE LESS 0.10" BUT LOCALIZED HIGHER IN THE
STRONGEST STORMS. PROGGED 85H TEMPS BTWN 8-10C SUPPORT HIGHS MAINLY
IN THE U60S TO LOWER 70S MTN TOWNS TO M/U 70S WARMER VALLEY
LOCATIONS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
AS OF 345 AM EDT WEDNESDAY...LITTLE OVERALL CHANGE TO LARGE
SCALE SYNOPTIC PATTERN IS EXPECTED THROUGH FRIDAY WITH GENERAL
MID/UPPER LVL TROF ACROSS THE NE CONUS. HOWEVER...BEST DEEP LAYER
MOISTURE WILL BE SUPPRESSED TO OUR SOUTH DURING THE PERIOD WITH MUCH
LESS AREAL COVERAGE OF SHOWER ACTIVITY EXPECT ON THURS. SFC HIGH
PRES LOCATED OVER HUDSON BAY IS PROGGED TO NOSE INTO NORTHERN NY
DURING THIS PERIOD...RESULTING IN DRIER WX WITH LARGE DAILY SWINGS
IN TEMPS. LATEST TRENDS IN GUIDANCE HAS BEEN FOR COASTAL SYSTEM TO
PASS WELL SOUTH OF OUR CWA WITH GREATEST IMPACTS ACROSS THE SE CONUS
INTO THE MID ATLANTIC STATES. NW FLOW ALOFT COMBINED WITH WEAK 5H
VORT AND COOL POOL ALOFT WILL PRODUCE SPOTTY MAINLY DAYTIME HEAT
DRIVEN SHOWERS ACROSS THE DACKS INTO THE MTNS OF CENTRAL AND
NORTHERN VT ON THURS. WL MENTION SCHC IN THE CPV AND CHC POPS IN THE
MTNS WITH QPF VALUES GENERALLY < 0.10.

PROGGED 85H TEMPS COOL ANOTHER DEGREE OR TWO AND SUPPORT
MID/UPPER 60S MTNS TO NEK AND MID 70S WARMER VALLEYS...SEVERAL
DEGREES BELOW NORMAL FOR EARLY AUGUST. LITTLE CHANGE ANTICIPATED
ON FRIDAY WITH GENERAL NW FLOW ALOFT AND BUILDING SFC HIGH PRES.
WILL MENTION SCHC POPS IN THE MTNS AND KEEP REST OF FCST DRY ATTM.
PROGGED 85H TEMPS BTWN 8-10C SUPPORT HIGHS MAINLY IN THE 60S MTNS
TO 70S VALLEYS. LOWS WILL GENERALLY BE IN THE 40S COLDER MTN
VALLEYS TO 50S IN THE WIDER CHAMPLAIN AND SAINT LAWRENCE VALLEYS
THRU THE PERIOD.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 331 AM EDT WEDNESDAY...MID-LEVEL CYCLONIC FLOW/LONGWAVE
TROUGHING PREVAILS IN THE MEAN ACROSS THE NORTH COUNTRY DURING THE
EXTENDED. ALL-IN-ALL, A GENERALLY UNEVENTFUL PERIOD OF WEATHER
INTO THE EARLY PART OF THE WEEKEND, WITH BETTER CHANCES FOR
PRECIPITATION HOLDING OFF UNTIL SUNDAY AND EARLY NEXT WEEK.
FORECAST FOLLOWS BLENDED GUIDANCE UNLESS NOTED OTHERWISE.

EARLIER CYCLES OF GLOBAL GUIDANCE SUITE HAD INDICATED A POTENTIAL
COASTAL LOW DEVELOPING OFF THE MID-ATLANTIC COAST LATER FRIDAY AND
ITS PRECIPITATION SHIELD EXPANDING INTO EASTERN SECTIONS OF
VERMONT ON SATURDAY. WHILE RECENT GUIDANCE STILL SHOWS THIS
SYSTEM, A NOTED TREND HAS BEEN TO A POSITION FURTHER OFF THE COAST
RESULTING IN A MORE OPTIMISTIC EARLY-WEEKEND FORECAST. SO THE
BIGGEST CHANGE TO THE INHERITED FORECAST WAS TO LOWER POPS FOR THE
SATURDAY/SATURDAY NIGHT PERIOD FOR VERMONT. I DIDN`T WANT TO
COMPLETELY GO DRY ON THE CHANCE THAT A WESTWARD RECURVE REVEALS
ITSELF IN SUBSEQUENT GUIDANCE RUNS, BUT I`VE LOWERED DOWN TO
SLIGHT CHANCE.

00Z GFS/EC SOLUTIONS START TO DIFFER AFTER SUNDAY ON SENSIBLE
WEATHER DETAILS. WHILE BOTH GLOBAL SOLUTIONS DEPICT A 1000-500 MB
THICKNESS GRADIENT/WARM FRONT ACROSS THE NORTH COUNTRY AND RATHER
WEAK LOBES OF VORT MAXIMA ACTING ON THE BOUNDARY, THE GFS SHOWS
HARDLY ANY PRECIPITATION AT ALL. THAT`S A STRANGE/UNREALISTIC
RESULT. I`VE THEREFORE HEDGED CLOSER TO THE WETTER ECMWF IN
KEEPING CHANCE POPS GOING SUNDAY. CHANCE POPS CONTINUE INTO EARLY
NEXT WEEK AS THE BAROCLINIC ZONE MAKES LITTLE EASTWARD OR
NORTHWARD INROADS AND MAY SERVE AS A CONDUIT FOR CONTINUED RAIN
CHANCES. THERE IS SOME LIMITED INSTABILITY (LIFTED INDICES OF -1
TO -2), SO OPTED FOR SHOWERS/THUNDERSTORMS EACH DAY.

TEMPS THROUGH THE PERIOD ARE CLOSE TO NEAR EARLY-/MID-AUGUST
NORMALS WITH HIGHS IN THE 70S AND LOWS IN THE 50S/NEAR 60.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
THROUGH 06Z THURSDAY...EXPECT GENERALLY VFR CONDITIONS EXCEPT FOR
POSSIBLE FOG/MIST WITH IFR OR LOWER VISIBILITY AT MPV, SLK AND
MSS THROUGH THE OVERNIGHT. POTENTIAL FOR SCT SHOWERS/STORMS
WEDNESDAY DURING THE DAYLIGHT HOURS.

INFRARED SATELLITE AND RADAR MOSAIC SHOWS BKN CLOUDINESS WITH
VERY LIGHT SHOWERS FROM CHAMPLAIN INTO ST. LAWRENCE VALLEYS.
SHOWERS SHOULD CONTINUE EAST IN SHORT ORDER, BUT THERE`S SOME
QUESTION ON IF MID-LEVEL CLOUD SHIELD CAN CLEAR OUT ENOUGH TO
PROMOTE MIST/FOG FORMATION. A POCKET OF CLEARING BACK INTO THE
OTTAWA VALLEY SHOULD HELP TO CLEAR OUT MSS AND PERHAPS SLK. THOUGH
ITS CURRENTLY CLEAR AT MPV NOW, IT`S LESS CERTAIN THAT CLEARING
COULD HAPPEN ONCE CLOUD DECK MOVES IN. IN EACH CASE, OPTED FOR
TEMPO IFR VISIBILITIES. WINDS GENERALLY LIGHT NORTH UNDER 5 KTS.

THREAT OF SHOWERS/STORMS DEVELOPS ONCE AGAIN, TIED PRIMARILY TO
THE DIURNAL HEATING PERIOD. HI-RES GUIDANCE POINTS SHOWS POTENTIAL
FOR ALL TAF SITES EXCEPT RUT. ROUGHLY FOLLOWED THIS BY INDICATING
6SM SHRA FOR THIS TAF FORECAST. STRONGER STORMS CAPABLE OF SMALL
HAIL AND GUSTY OUTFLOW CAPABLE OF TURBULENCE. WEST TO NORTHWEST
WINDS AROUND 10 KTS (GUSTS UNDER 20 KTS) BECOME LIGHT WEST BY
EVENING.

OUTLOOK 06Z THURSDAY THROUGH SUNDAY...

06Z THURSDAY - 12Z THURSDAY...VFR WITH PERIODS IFR/LIFR FOG AT MPV
AND SLK TERMINALS.

12Z THURSDAY - 00Z FRIDAY...MAINLY VFR WITH SPOTTY DIURNAL-DRIVEN
SHOWERS.

00Z FRIDAY ONWARD...DAYTIME VFR WITH EVENING IFR/LIFR FOG AT MPV
AND SLK TERMINALS.

&&

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

&&

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



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