000
FXUS61 KBTV 060026
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
826 PM EDT SUN SEP 5 2010

.SYNOPSIS...
A COLD UPPER LEVEL TROUGH ACROSS SOUTHEASTERN CANADA THIS
AFTERNOON IS RESULTING IN RELATIVELY COOL TEMPERATURES AND
SCATTERED LIGHT RAIN SHOWERS ACROSS THE NORTH COUNTRY. THIS UPPER
SYSTEM LIFTS NORTHWARD AND WEAKENS TONIGHT AND MONDAY...ALLOWING
RAIN SHOWERS TO GRADUALLY BECOME MORE ISOLATED OVERNIGHT.
TEMPERATURES WILL TREND UPWARD MONDAY AND TUESDAY AS A WARM FRONT
DEVELOPS AND LIFTS NORTHWARD INTO SOUTHERN QUEBEC. TEMPERATURES
WILL REACH THE LOW TO MID 80S TUESDAY...BEFORE A COLD FRONT
ARRIVES TUESDAY NIGHT ACCOMPANIED BY A PERIOD OF RAIN SHOWERS. THE
PASSAGE OF THE COLD FRONT WILL BE FOLLOWED BY A RETURN TO
SEASONABLY COOL CONDITIONS WEDNESDAY THROUGH FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AS OF 229 PM EDT SUNDAY...CYCLONIC LOW TO MID LEVEL FLOW FROM THE ERN
GREAT LAKES REGION PERSISTS THIS AFTN PROVIDING FOR LOW-LEVEL
MOISTURE ADVECTION AND FAVORABLE ENVIRONMENT FOR SHALLOW
INSTABILITY/UPSLOPE DRIVEN SHOWERS. EXPECT ISOLD/SCT -RW ACROSS
THE NRN ADIRONDACKS INTO THE CENTRAL/SRN CHAMPLAIN VALLEY AND
CENTRAL VT TO CONTINUE LATE THIS AFTN. ONE ADDITION SHEAR VORT
AXIS ACROSS SERN ONTARIO WILL BRING ANOTHER PERIOD OF SHOWERS
00-03Z. ADDITIONAL RAINFALL AMTS WILL GENERALLY BE SPOTTY AND LESS
THAN A TENTH OF AN INCH. THEREAFTER...700-500MB HGTS START TO
BUILD AND SHOWER ACTIVITY SHOULD WIND DOWN AS TEMPERATURES WARM
ALOFT. LAKE EFFECT RAIN BAND OFF LAKE ONTARIO MAY IMPACT SRN ST.
LAWRENCE COUNTY BEFORE DISSIPATING DURING THE PRE-DAWN HRS...AND
MAINTAINED 20-30 POPS 06-12Z FOR THIS POSSIBILITY. W-SW SFC WINDS
10-15KTS WITH GUSTS 20-24 KTS SHOULD SUBSIDE THIS EVENING AS PBL
STABILIZES...AND A FEW ADDITIONAL BREAKS AFTER MIDNIGHT MAY
CONTRIBUTE TO PATCHY FOG DEVELOPMENT AS SFC RIDGE TRIES TO BUILD
NWD ACROSS NY/NEW ENGLAND. WITH SOME CLOUDS/GRADIENT FLOW
REMAINING...ONLY HIGHLIGHTED FOG IN THE MORE FAVORABLE VALLEYS.
ALSO...WITH CLOUDS AND SOME W-SW WIND THE MOS LOW TEMPS ARE
PROBABLY BIASED A BIT LOW ONCE AGAIN /AS IS TYPICAL IN
SEPTEMBER/...SO WENT 1-2F ABOVE WARMER MET-MOS TEMPS OVERNIGHT.
THIS KEEPS LOWS IN THE LOW 50S ACROSS THE CHAMPLAIN AND ST.
LAWRENCE VALLEYS...AND IN THE MID-UPR 40S ACROSS MUCH OF THE
REMAINDER OF THE FORECAST AREA.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 229 PM EDT SUNDAY...WARMING TREND BEGINS MONDAY AS 850MB TEMPS
CLIMB FROM +5C OR SO SUNDAY AFTN TO AROUND +10C BY 00Z TUESDAY.
MID-LEVEL HEIGHTS CONTINUE TO RISE AND FLOW BECOMES MORE
ZONAL...WITH SHEAR VORT AXIS MOVING ALONG/JUST NORTH OF THE INTL
BORDER MONDAY AFTN. GENERALLY EXPECT DRY CONDITIONS...BUT A SLIGHT
CHANCE OF A RAIN SHOWER EXISTS ACROSS NRN SECTIONS 18Z MON-00Z
TUE. HIGH TEMPS MONDAY SHOULD REACH THE MID 70S IN THE WARMER
VALLEYS AND LOW 70S ELSEWHERE. WARM FRONT SHARPENS TO OUR NORTH
MONDAY NIGHT AS SHORTWAVE RIDGE BEGINS TO BUILD IN FROM THE WEST.
A LIGHT SOUTH/SW FLOW REGIME IS ANTICIPATED MONDAY NIGHT AND
SHOULD KEEP LOWS MAINLY IN THE 50S. TUESDAY SHOULD BE MOSTLY SUNNY
WITH SHORTWAVE RIDGE CRESTING OVER THE NORTH COUNTRY AND 850MB
TEMPS WARMING FURTHER TO +16 TO +17C. LOOKS LIKE MID 80S FOR MOST
LOWER ELEVATIONS TUESDAY WITH SOUTH WINDS AROUND 10 MPH. COLD
FRONT SHIFTING EWD ACROSS SERN ONTARIO LATE IN THE AFTN WILL BRING
A SLIGHT CHANCE OF A SHOWER TO ST. LAWRENCE COUNTY BY 21-00Z...BUT
REMAINDER OF THE REGION SHOULD BE DRY. LARGE-SCALE FORCING AND
850MB TEMP GRADIENT RELATIVELY STRONG IN ASSOCIATION WITH A COLD
FRONT SWEEPING EWD TUESDAY NIGHT ACROSS THE NORTH COUNTRY. HAVE
INDICATED POPS AROUND 60 PERCENT FOR NRN NY 00-06Z...AND ACROSS VT
06-12Z...TRYING TO FOLLOWING 12Z GFS TIMING. ALSO NOTING MARGINAL
INSTABILITY ALONG/IN ADVANCE OF FRONTAL BNDRY. HAVE CARRIED A SLIGHT
CHANCE OF A THUNDERSTORM AT THIS POINT...GIVEN UNCERTAINTY IN
INSTABILITY AND UNFAVORABLE TIME OF DAY DURING TUESDAY NIGHT.
RAINFALL AMTS OF 0.2 TO 0.4 INCHES GENERALLY POSSIBLE WITH FRONTAL
RAIN SHOWERS. LOW TEMPERATURES TUESDAY NIGHT GENERALLY IN THE LOW
60S WITH FROPA NOT OCCURRING UNTIL NEAR SUNRISE ACROSS VT.
GENERALLY MID 50S FOR LOWS ACROSS NY WITH SOME POTENTIAL FOR GUSTY
WEST WINDS 15-25 MPH TOWARD 12Z WEDNESDAY WITH STEEP LAPSE RATES
BEHIND THE COLD FRONT.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 259 PM EDT SUNDAY...AT THE START OF THIS FORECAST PERIOD,
WE WILL BE DEALING WITH THE PASSAGE OF A COLD FRONT. TIMING THIS
FAR OUT IS PROBLEMATIC, BUT CURRENT GUESS IS THAT IT WILL BE EAST
OF HERE BY LATE MORNING. IT WON`T BE A `CLEAN` FRONTAL PASSAGE --
IN OTHER WORDS, IT WILL CONTINUE TO BE CLOUDY AND SHOWERY BEHIND
IT. IN FACT, THE PATTERN FOR WEDNESDAY LOOKS SIMILAR TO WHAT IT
HAS BEEN YESTERDAY AND TODAY. WESTERLY FLOW SHOULD BRING SOME
MOISTURE OFF THE LAKES, AND CYCLONIC FLOW ALOFT WITH MAIN TROF
AXIS STILL TO OUR WEST WILL MEAN SHOWERS WILL CONTINUE. KEPT IN
WITH MODEL GUIDANCE AND PAINTED IN ROUGHLY 50% POPS. ULTIMATELY,
TEMPERATURES MAY BE TRICKY TOO. WE MAY SEE EARLY HIGHS, WITH
STEADILY/SLOWLY FALLING IN THE AFTERNOON. AGAIN, THIS FAR OUT JUST
KEPT WITH GUIDANCE AS ANY TIMING DIFFERENCES IN FORECAST MODELS
WILL RESULT IN FAIRLY SIGNIFICANT CHANGES IN SOME OF THE SENSIBLE
WEATHER ELEMENTS WE FORECAST.

FAIRLY CONFIDENT THAT THE UPPER TROUGH WILL BE SLOW TO PUSH EAST
OF THE REGION. THUS THE WESTERLY FLOW SLOWLY TRANSITIONS TO A
NORTHWESTERLY UNSETTLED PATTERN FOR LATE WEDNESDAY NIGHT, THURSDAY
AND THURSDAY NIGHT. WITH SUCH A FLOW, THE OROGRAPHIC EFFECTS WILL
BE THE PRIMARY DRIVERS FOR THE PRECIPITATION. THUS BUMPED UP
THINGS A BIT MORE ALONG THE WESTERN SIDES OF THE `DACKS AND GREEN
MOUNTAINS.

TEMPERATURE GUIDANCE HAS BEEN FAIRLY CONSISTENT, AND WITH 850MB
TEMPERATURES PROGGED TO BE IN THE 4-6C RANGE ALONG WITH PLENTY OF
CLOUDS, TEMPERATURES WILL ONLY BE IN THE 60S, WITH 50S IN THE
HIGHER ELEVATIONS. MAY AGAIN BE FAIRLY BREEZY THURSDAY, WITH GUSTS
OVER 20 MPH AT TIMES.

IMPROVING WEATHER FOR FRIDAY AS THE TROUGH FINALLY MOVES FAR
ENOUGH EAST OF HERE AND RIDGING STARTS COMING IN. SHOULD BE A MOSTLY
SUNNY, DRY DAY. HOWEVER TEMPERATURES ALOFT WILL STILL BE FAIRLY
COOL, SO LOOKS TO BE ANOTHER DAY IN THE 60S. I GUESS SINCE FALL IS
AROUND THE CORNER, WE NEED TO BE EXPECTING THESE KINDS OF DAYS
MORE OFTEN.

CONFIDENCE DECREASES FOR THE WEEKEND. GFS PUSHES ANOTHER SYSTEM IN
FOR SATURDAY, HOWEVER THINK THAT MODEL IS A BIT FAST AS IT
RECENTLY HAS BEEN HAVING THAT TENDENCY, ESPECIALLY WITH THE RATHER
AMPLIFIED PATTERN WE`LL BE HAVING BY THE WEEKEND. THE ECMWF IS
MUCH SLOWER AND TAKEN AT FACE VALUE WOULD SUGGEST A DRY WEEKEND.

BEST COURSE OF ACTION AT THIS TIME IS TO TAKE A BLEND OF THE TWO.
THUS PAINTED IN LOW CHANCE OF SHOWERS LATER ON SATURDAY AND
CONTINUING INTO SUNDAY, WITH TEMPERATURES NEAR NORMAL. LATER
FORECASTS WILL BETTER FINE TUNE NEXT WEEKEND`S WEATHER.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
THROUGH 00Z TUESDAY...MAINLY VFR CONDS EXPECTED THRU THE PRD WITH
WIDESPREAD STRATO-CUMULUS CLOUDS. MOST SHOWERS IN THE REGION HAVE
DISSIPATED THIS EVENING AND THE GUSTY WINDS HAVE EASED LIGHT
EVERYWHERE BUT KMSS AND KSLK...WHICH WILL OVERNIGHT. THERE IS A
SLIGHT CHANCE OF VIS TO DROP TO MVFR IN SOME EARLY MORNING FOG AT
KSLK AND KMPV. THIS WOULD ONLY LAST A FEW HOURS, BETWEEN 08-12Z,
AND BE DEPENDENT ON WHETHER THE WINDS GO CALM AND THE CLOUDS
CLEAR OUT FOR LONG ENOUGH. AFTER 12Z SWLY WINDS WILL BEGIN TO
INCREASE AGAIN...WITH 15-20KT GUSTS BY AFTN. THE STRATO-CUMULUS
WILL LIKELY REDEVELOP WITH SOME LIGHT SCATTERED SHOWERS IN THE
AFTN AS WELL...BUT REMAINING VFR.

OUTLOOK 00Z TUESDAY THROUGH FRIDAY...A FEW LIGHT SHOWERS WILL
REMAIN POSSIBLE ACROSS THE NORTHERN TAF SITES ON TUESDAY...BUT
REMAINING VFR. A LOW PRESSURE SYSTEM WILL BRING PERIODS OF MVFR
CONDS IN SHOWERS 03-15Z WEDNESDAY. SOUTHERLY WINDS BECOME GUSTY
AT THIS TIME AND INTO THE AFTN AHEAD OF THE ASSOC COLD FRONT.
THUNDERSTORMS ARE POSSIBLE ALONG THIS BOUNDARY AND WINDS WILL
SHIFT WEST AND EASE BEHIND IT AFTER 18Z WED. AS THE LOW PRESSURE
SYSTEM REMAINS TO THE NORTH...KEEPING THE REGION UNDER
CAA...SCATTERED LIGHT RAIN IS EXPECTED CONTINUE INTO FRIDAY. THIS
WILL CAUSE THE MAINLY VFR CONDS TO OCCASIONALLY DROP TO
MVFR...SIMILAR TO THE CURRENT CONDITIONS.

&&

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

&&

$$
SYNOPSIS...BANACOS
NEAR TERM...BANACOS
SHORT TERM...BANACOS
LONG TERM...NASH
AVIATION...NH

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