Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 180750
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
350 AM EDT MON AUG 18 2014

.SYNOPSIS...
DRY AND SEASONABLY WARM WEATHER WILL PERSIST INTO WEDNESDAY...THEN A
COOLING TREND IS EXPECTED THU AND FRI AS CLOUDS INCREASE ALONG WITH
ONSHORE WINDS AND THE RISK OF A FEW SHOWERS.  DRY WEATHER LIKELY
RETURNS FOR THE WEEKEND BUT WITH COOLER THAN NORMAL TEMPERATURES AS
HIGH PRESSURE BUILDS SOUTHWARD FROM THE CANADIAN MARITIMES.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

4 AM UPDATE...

FORECAST REMAINS ON TRACK FOR THE EARLY MORNING HOURS. UPPER LEVEL
SHORTWAVE HAS SPARKED SOME SHOWERS ACROSS UPSTATE NY AS WELL AS IN
NORTHERN NEW ENGLAND. THESE SHOWERS WILL STRUGGLE TO REACH SOUTHERN
NEW ENGLAND AS THERE IS A GOOD AMOUNT OF DRY AIR ALLOWING FOR THE
SHOWERS TO FIZZLE OUT AS THEY APPROACH. AT THE SURFACE...DRY AIR HAS
FILTERED INTO THE REGION WITH SITES DROPPING INTO THE LOW 50F FOR
DEWPOINTS. WINDS ARE FAIRLY LIGHT AND WITH CLEAR SKIES...ANTICIPATE
RADIATIONAL COOLING. IN FACT MVY HAS DROPPED DOWN TO 51F WHICH IS
ONE OF THE COOLEST TEMP ACROSS SOUTHERN NEW ENGLAND.

TODAY...

ALTHOUGH UPPER LEVEL TROUGH IS OVER THE REGION ANTICIPATE A DRY
WEATHER DAY THANKS TO HIGH PRESSURE BUILDING INTO THE REGION. EXPECT
MOSTLY CLEAR SKIES...WITH SOME DIURNAL CLOUDS DEVELOPING IN THE
AFTERNOON. BUFKIT SOUNDINGS SHOW THE BOUNDARY LAYER MIXING THIS
AFTERNOON SO GUSTS UP TO 15 MPH ARE POSSIBLE. OTHERWISE TEMPERATURES
WILL BE NEAR AVERAGE WITH HIGHS IN THE MID 70S TO PERHAPS 80F AS
850 MB WILL ONLY BE 8C. MAY NEED TO WATCH FOR THE POTENTIAL FOR
SEA BREEZES ALONG THE COASTLINE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...

TONIGHT AND TOMORROW...

UPPER LEVEL FLOW BECOMES MORE ZONAL DURING THIS TIME FRAME. UPPER
LEVEL SYSTEM MOVING ACROSS THE OHIO VALLEY TODAY WILL STAY SOUTH OF
THE REGION AND MOVE ACROSS THE MID-ATLANTIC TOMORROW THANKS TO A
STRONG GREENLAND BLOCK. AT THE SURFACE...HIGH PRESSURE WILL REMAIN
OVERHEAD. ANTICIPATE LIGHT WINDS AND MOSTLY CLEAR SKIES ASIDE FROM
SOME DIURNAL CU. PATCHY GROUND FOG MAY DEVELOP IN THE TYPICAL PRONE
REGIONS OVERNIGHT. TEMPERATURES TONIGHT WILL DROP INTO THE 50S TO
LOW 60S AND WILL WARM INTO THE UPPER 70S TO LOW 80S TOMORROW.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...

HIGHLIGHTS...

* DRY AND SEASONABLY WARM WEDNESDAY
* COOLER THU AND FRI WITH A RISK OF A FEW SHOWERS
* DRYING TREND NEXT WEEKEND BUT COOLER THAN NORMAL

SYNOPTIC OVERVIEW AND MODEL EVALUATION...

MAIN WEATHER FEATURE THIS PERIOD WILL BE A HIGH AMPLITUDE RIDGE OF
+2 TO +3 STANDARD DEVIATIONS ABOVE CLIMO OVER GREENLAND AND THE
DAVIS STRAIT. THIS RESULTS IN A REX TYPE BLOCK PATTERN TO DEVELOP
OVER THE NORTHEAST STATES INTO SOUTHEAST CANADA. THIS SHIFTS THE JET
STREAM/STORM TRACK/FRONTAL BOUNDARY SOUTH OF NEW ENGLAND...ALLOWING
MAINLY DRY WEATHER AS COOL MARITIME HIGH PRESSURE BUILDS SOUTHWARD
INTO NEW ENGLAND. REGARDING MODEL GUIDANCE...GEFS AND ECENS
ENSEMBLES IN GOOD AGREEMENT ON THE LARGE SCALE FLOW THIS PERIOD. AS
FOR THE DETERMINISTIC RUNS OF THE GFS AND ECMWF...TYPICAL TIMING AND
AMPLITUDE DIFFERENCES AT THIS TIME RANGE...BUT OVERALL IN GOOD
AGREEMENT ON THE OVERALL PATTERN AND THEME. THUS ABOVE AVERAGE
FORECAST CONFIDENCE THIS PERIOD.

SENSIBLE WEATHER DETAILS...

WED...

SHORT WAVE RIDGING PERSIST OVER NEW ENGLAND TO YIELD DRY WEATHER AND
SEASONABLY WARM TEMPS...U70S TO L80S. WEAK HIGH PRES OVER THE AREA
WILL SUPPORT LIGHT WINDS BUT ALSO AFTERNOON SEABREEZES KEEPING THE
COASTLINE SLIGHTLY COOLER.  FAIRLY COMFORTABLE WITH DEW PTS IN THE
U50S TO L60S. SHORT WAVE TROUGH AND DEEPER MOISTURE FROM THE GREAT
LAKES APPROACHES NEW ENGLAND LATE IN THE DAY AND ESPECIALLY WED
NIGHT. THUS A LOW RISK OF A FEW SHOWERS ACROSS WESTERN CT-MA-
SOUTHWEST NH. ELSEWHERE DRY WEATHER SHOULD PREVAIL. NOT EXPECTING
ANY THUNDER GIVEN THE LACK OF SFC BASED AND INSTABILITY ALOFT.

THU INTO FRI...

SHORT WAVE TROUGH TRACKS FROM THE GREAT LAKES TO SOUTHERN NEW
ENGLAND. THE BULK OF THE DEEP LAYER MOISTURE AND SURFACE LOW TRACK
WELL SOUTH OF NEW ENGLAND. HOWEVER THE ONSHORE FLOW AND ESPECIALLY
THE UPSLOPE COMPONENT ACROSS THE HIGHER TERRAIN OF WESTERN CT-MA
INTO SOUTHWEST NH ALONG WITH CYCLONIC FLOW ALOFT MAY YIELD PERIODIC
SHOWERS. GREATEST RISK WILL BE ACROSS THE INTERIOR. ELSEWHERE LOWER
RISK OF SHOWERS. OVERALL NOT A WASHOUT JUST A FEW SPOTTY SHOWERS...
PERHAPS MORE NUMEROUS OVER THE HIGHER TERRAIN. GIVEN THE COOL
ONSHORE WINDS...SB INSTABILITY IS NIL AND MID LEVEL LAPSE RATES ARE
LESS THAN 6C/KM. THUS NOT ANTICIPATING ANY THUNDER.

NEXT WEEKEND...

MEAN MID LEVEL TROUGH AXIS EXPECTED TO MOVE OFFSHORE AND ALLOWS 1024
MB MARITIME HIGH TO BUILD SOUTHWARD INTO NEW ENGLAND. THIS PROMOTES
A DRYING TREND BUT ALSO COOLER THAN NORMAL TEMPS WITH HIGHS MAINLY
IN THE LOW TO MID 70S.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

SHORT TERM...THROUGH TUESDAY...HIGH CONFIDENCE.

TODAY...VFR. W/NW WINDS WITH OCCASIONAL GUSTS UP TO 15-20 KTS.
LOW CONFIDENCE ON THE AFTERNOON SEA BREEZE POTENTIAL. IF IT DOES
DEVELOP...SHOULD BE AFTER 18Z TODAY.

TONIGHT...VFR. PATCHY GROUND FOG IS POSSIBLE IN TYPICALLY PRONE
SITE.

TUESDAY...VFR. SEA BREEZE DEVELOPMENT AFTER 14Z.

KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. NW FLOW...LOW
CONFIDENCE ON SEA BREEZE POTENTIAL TODAY. IT MAY STRUGGLE TO REACH
THE TERMINAL/OR PARK OVER THE RUNWAY.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF.

OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY...

TUE NIGHT/WED...HIGH CONFIDENCE FOR VFR/DRY WEATHER AND AFTERNOON
SEA BREEZES.

WED NIGHT/THU/FRI...MODERATE CONFIDENCE. MAINLY VFR WITH A LOW RISK
OF MVFR AT TIMES IN SCT SHOWERS...ESPECIALLY WESTERN NEW ENGLAND IN
HIGHER TERRAIN.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

TODAY THROUGH TUESDAY...HIGH CONFIDENCE. QUIET BOATING WEATHER IS
EXPECTED. NORTHWEST FLOW WITH OCCASIONAL GUSTS TO 20 KTS IN THE
AFTERNOON. SEA BREEZES POSSIBLE MON AFTERNOON AND TUESDAY
AFTERNOON.

OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY...MODERATE TO HIGH CONFIDENCE.

STORM TRACK REMAINS SOUTH OF NEW ENGLAND WITH A SERIES OF WEAK LOWS
EXITING THE MID ATLC COAST AND TRACKING SOUTH OF 40N LATITUDE.
HOWEVER HIGH PRES BUILDING SOUTH FROM QUEBEC COMBINED WITH THESE
SERIES OF WEAK LOWS SOUTH OF NEW ENGLAND MAY RESULT IN ENE WINDS UP
TO 20-25 KT ACROSS THE SOUTH COASTAL WATERS THU NIGHT INTO FRI. AS
FOR VSBY MAINLY GOOD BUT MAY LOWER IN PATCHY FOG AND ISOLATED SHOWER
WED NIGHT THRU FRI.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...NOCERA/DUNTEN
NEAR TERM...DUNTEN
SHORT TERM...DUNTEN
LONG TERM...NOCERA
AVIATION...NOCERA/DUNTEN
MARINE...NOCERA/DUNTEN


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