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Area Forecast Discussion
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000
FXUS61 KBTV 051114
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
714 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 /12Z WEDNESDAY THROUGH SUNDAY/...
THROUGH 12Z THURSDAY...VFR OUTSIDE OF DEVELOPING SCT
SHOWERS/STORMS WITH BRIEFLY REDUCED VISBILITIES AS LOW AS IFR.
POTENTIAL FOR IFR/LIFR FOG AT MPV AND SLK INTO THE OVERNIGHT.

INFRARED SATELLITE SHOWS SCT-BKN CLOUDS EXTENDING FROM NORTHEAST
CORNER OF VT BACK THROUGH THE ADIRONDACKS AHEAD OF SFC TROUGH OVER
SOUTHERN QUEBEC. THESE SHOULD THIN OUT INTO THE MORNING HOURS.
HOWEVER WITH A COLD POOL ALOFT ASSOCIATED WITH DEEP UPPER LOW,
SCT SHOWERS/STORMS WILL DEVELOP WITH DAYTIME HEATING. ANY STRONG
STORM THAT DEVELOPS WILL BE CAPABLE OF BRIEF IFR-VISIBILITY
DOWNPOURS, SMALL HAIL AND GUSTY OUTFLOW PRODUCING LOCALIZED
TURBULENCE. OVERALL COVERAGE OF STRONG STORMS WILL BE LIMITED.
BASED ON HRRR AND RECENT BTV WRF GUIDANCE, SHOWERS/STORMS MOST
FAVORED FOR ALL TERMINALS EXCEPT RUT AND STARTING AROUND 17Z WITH
6SM SHRA. DAYTIME WINDS WEST TO WEST/SOUTHWEST 6-10 KTS GUSTS
UNDER 20 KTS.

ANY SHOWERS/STORMS QUICKLY DISSIPATE NEAR/AFTER SUNSET. RISK OF
IFR/LIFR FOG AT SLK AND MPV IS CONDITIONAL ON CLEARING, WHICH
ISN'T CERTAIN. I'VE OPTED TO LEAVE OUT FOR NOW. WINDS SHOULD
BECOME LIGHT NORTHWEST (VARIABLE AT TIMES) THIS EVENING.

OUTLOOK 12Z THURSDAY THROUGH SUNDAY... 

12Z THURSDAY - 00Z FRIDAY...MAINLY VFR WITH SPOTTY DIURNALLY-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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