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000
FXUS61 KBTV 220157
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
857 PM EST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE ACROSS THE GREAT LAKES AND OHIO VALLEY STATES WILL
BUILD SLOWLY EAST TONIGHT AND SETTLE ACROSS THE NORTHEAST ON SUNDAY
INTO MONDAY. THEREFORE...OUTSIDE ANY LINGERING CLOUDS ACROSS THE
AREA THIS EVENING...EXPECT GENERALLY FAIR AND DRY WEATHER DURING
THE PERIOD AS TEMPERATURES REMAIN ON THE MILD SIDE. THE NEXT CHANCE
OF SIGNIFICANT PRECIPITATION WILL OCCUR BY THE MIDDLE TO LATER
PORTIONS OF NEXT WEEK AS LOW PRESSURE TRACKS EAST FROM THE CENTRAL
PLAINS.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 850 PM EST SATURDAY...HAVE MADE MINOR ADJUSTMENTS TO SKY AND
TEMPERATURE FORECAST TO ACCOUNT FOR PERSISTENT LAYER OF
STRATOCUMULUS CLOUDS BETWEEN 1500 AND 2500 FT AGL. WHILE
SIGNIFICANT CLEARING HAS OCCURRED THIS EVENING ACROSS THE CHAMPLAIN
VALLEY AND MUCH OF ERN/SERN VT...OVERCAST CONDITIONS PREVAIL
ACROSS ALL OF THE NRN ADIRONDACKS...THE ST. LAWRENCE VALLEY...AND
PORTIONS OF N-CENTRAL AND NERN VT. WITH WEAK WINDS OVERNIGHT AND
SUBSIDENCE ALOFT...IT WILL BE DIFFICULT TO ELIMINATE EXISTING
CLOUDS TRAPPED BELOW SUBSIDENCE INVERSION. AS SUCH...HAVE
INCREASED CLOUDS FOR SEVERAL ADDITIONAL HRS...WITH A SLOW
DECREASING TREND TOWARD DAYBREAK. FOG MAY BE LIMITED ACROSS NRN NY
OWING TO OVC SKIES...BUT ELSEWHERE DEWPOINT DEPRESSIONS ARE SMALL
/WITH DEWPOINTS GENERALLY IN THE 30S/ AND SOME RADIATIONAL COOLING
WILL BE FAVORED...ESPECIALLY WITH LONG MID-NOVEMEBER NIGHT. PATCHY FOG
REMAINS POSSIBLE...ESPECIALLY IN AREAS WITH MOSTLY CLEAR SKIES.
MINIMUM TEMPERATURES WILL BE FAIRLY MILD BY LATE NOVEMBER
STANDARDS...WITH READINGS MAINLY IN THE UPPER 20S TO LOWER 30S
ACROSS MOST PORTIONS OF THE NORTH COUNTRY.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
AS OF 217 PM EST SATURDAY...TRANQUIL AND MILD LATE FALL WEATHER THEN
CONTINUES THROUGH THE REMAINDER OF THE SHORT TERM AS AFOREMENTIONED
HIGH PRESSURE BUILDS ATOP THE NORTHEAST DURING SUNDAY/MONDAY TIME
FRAME. THEREFORE EXPECT FAIR AND DRY CONDS THROUGH THE PERIOD ALONG
WITH A FAIRLY WIDE DIURNAL RANGE IN TEMPS. WITH SHALLOW NATURE OF
PBL THIS TIME OF YEAR DAYTIME TEMPS WILL BE RATHER UNIFORM...
SLIGHTLY MILDER PERHAPS AT THE HIGHER ELEVATIONS WHERE SHALLOW PBL
MIXING MAY BE ABLE TO TAP INTO WARMER 925 MB TEMPS ALOFT. NIGHTTIME
LOWS WILL BE NEAR SEASONAL NORMS...THOUGH WITH AT LEAST SOME
RADIATIVE EFFECTS EXPECTED...HAVE UNDERCUT MOS MINS TEMPS SLIGHTLY
DURING OVERNIGHT PERIODS.
BY MONDAY NIGHT...SOME DISAGREEMENT BEGINS TO CREEP INTO THE MODELS
AS DEEPER MOISTURE ACROSS THE SOUTHEAST/WRN ATLANTIC ATTEMPTS TO
CREEP NORTHWARD BENEATH WESTERN EXTENSION OF DEPARTING RIDGE AXIS.
AT THIS TIME BELIEVE ANY DEEPER MOISTURE WILL HAVE A TOUGH TIME
REACHING THIS FAR NORTH GIVEN PLACEMENT OF LL RIDGE AXIS...AND WITH
BROAD SUPPORT FROM THIS MORNINGS OP ECMWF RUN AND GFS MEAN
ENSEMBLES HAVE KEPT SENSIBLE CONDS ESSENTIALLY DRY THROUGH 12Z
TUESDAY. MID TO UPPER LVL CLOUDS WILL LIKELY BE ON THE INCREASE
HOWEVER IN UPPER ANTICYCLONIC FLOW...THUS HAVE KEPT OVERNIGHT MIN
TEMPS SLIGHTLY MILDER THAN PRIOR COUNTERPARTS.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 345 PM EST SATURDAY...THE FORECAST AREA WILL BE BETWEEN TWO
LOW PRESSURE SYSTEMS ON TUESDAY...WITH ONE SYSTEM SOUTHEAST OF
CAPE COD AND ANOTHER SYSTEM APPROACHING THE WESTERN GREAT LAKES.
MODELS SHOW AREA WILL HAVE A WEAK RIDGE OF HIGH PRESSURE OVER THE
REGION TUESDAY AND TUESDAY NIGHT...EXTENDING INTO MIDDAY ON
WEDNESDAY. WILL GO WITH A MAINLY DRY FORECAST TUESDAY THROUGH
MIDDAY ON WEDNESDAY. HOWEVER...WILL HAVE SLIGHT CHANCE POPS FOR
TUESDAY FOR RAIN SHOWERS ACROSS SOUTH CENTRAL VERMONT. HAVE GONE
BELOW GMOS POP GUIDANCE FOR TUESDAY AND TUESDAY NIGHT...AS WELL AS
FOR WEDNESDAY. AN UPPER LOW OVER THE GREAT LAKES WILL MOVE ACROSS
THE AREA LATE WEDNESDAY AND WEDNESDAY NIGHT...BRINGING A CHANCE
FOR SOME RAIN SHOWERS.
THANKSGIVING DAY...MODELS SHOW A DIGGING UPPER TROUGH AND CLOSED
UPPER LOW OVER THE WESTERN GREAT LAKES ON THURSDAY. LOOKS LIKE THE
FORECAST AREA WILL REMAIN DRY...BUT WITH MOSTLY CLOUDY SKIES EXPECTED.
HAVE PUT IN SLIGHT CHANCE POPS FOR RAIN SHOWERS ON THANKSGIVING DAY...
BUT GENERALLY FEEL THE DAYTIME WILL BE MAINLY DRY. HAVE GONE BELOW
GMOS POPS FOR THANKSGIVING DAY. GFS MODEL IS FASTER THAN THE ECMWF
MODEL IN BRINGING THE DIGGING UPPER TROUGH AND CLOSED UPPER LOW EASTWARD.
GIVEN THE FACT THAT THE UPPER TROUGH IS DIGGING SOUTHWARD AND
BUILDING THE UPPER RIDGE EAST OF IT...WOULD TEND TO FAVOR THE
SLOWER ECMWF...AS FEEL THE GFS LOOKE A TAD TOO FAST. WILL MENTION
A CHANCE OF SHOWERS THURSDAY NIGHT. WILL MENTION RAIN OR SNOW ON FRIDAY...
AS BOTH THE GFS AND ECMWF SUGGEST IT WILL BE WARM ENOUGH ALOFT FOR
SOME RAIN ON FRIDAY...BUT CHANGING TO SNOW LATER IN THE DAY ON FRIDAY.
THE ECMWF SHOWS A CLOSED 500 MB LOW WILL MOVE ACROSS THE REGION
FRIDAY NIGHT WHICH WILL RESULT IN DYNAMIC COOLING ALOFT. ECMWF SUGGESTS
SOME SIGNIFICANT WRAP AROUND PRECIPITATION IS POSSIBLE FRIDAY
NIGHT. THIS WILL HAVE TO BE WATCHED CLOSELY. HOWEVER...GIVEN MODEL
DIFFERENCES IN TIMING...CONFIDENCE LEVEL IS FAIR AT THIS TIME.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
THROUGH 00Z MONDAY...VFR/MVFR WITH FAIRLY TRANQUIL WEATHER EXPECTED
FOR THE FIRST 24 HOURS. HIGH PRESSURE SETTLING OVER THE REGION HAS
ALLOWED SKIES TO BECOME CLEAR IN SOME AREAS THIS EVENING.
HOWEVER...A STRONG SUBSIDENCE INVERSION HAS TRAPPED A SHALLOW LAYER
OF MOISTURE AT LOW LEVELS WHICH HAS KEPT LOW CLOUDS ACROSS MUCH OF
NORTHERN NEW YORK AND THE WESTERN SLOPES OF THE GREEN MOUNTAINS. AS
TEMPERATURES COOL AND APPROACH THE DEWPOINT OVERNIGHT...LOW CLOUDS
WILL FILL IN AT MOST SITES ALONG WITH PATCHY FOG. CEILINGS WILL
GENERALLY BE 1500-2500 FT AFTER MIDNIGHT ALTHOUGH KSLK WILL DROP
BELOW 1000 FT LATE TONIGHT. VISIBILITIES WILL RANGE FROM 3 TO 5 SM
WITH 2 SM AT KMPV. THE LOWEST CONDITIONS WILL OCCUR 08Z-12Z.
THEREAFTER EXPECT FOG AND CEILINGS TO SLOWLY THIN AND LIFT AND ALL
SITES WILL RETURN TO VFR BY 15Z. WINDS WILL BE LIGHT AND VARIABLE
THROUGH THE PERIOD.
OUTLOOK 00Z MONDAY THROUGH THURSDAY...
SUNDAY NIGHT THROUGH TUESDAY NIGHT...VFR UNDER HIGH PRESSURE.
INCREASING CLOUDS MONDAY AND TUESDAY.
WEDNESDAY THROUGH THURSDAY...VFR DIMINISHING TO MVFR IN RAIN AND
MOUNTAIN SNOW SHOWERS AS LOW PRESSURE SWINGS THROUGH THE GREAT
LAKES. OCCASIONAL IFR POSSIBLE IN ANY SNOW.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...JMG
NEAR TERM...BANACOS
SHORT TERM...JMG
LONG TERM...WGH
AVIATION...MB