Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 101923
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
323 PM EDT THU JUL 10 2014

.SYNOPSIS...
A STALLED COLD FRONT JUST OFFSHORE WILL FINALLY MOVE SOUTH OF THE
REGION EARLY FRIDAY. DRIER AND MORE SEASONABLE WEATHER WILL THEN
CONTINUE INTO SATURDAY. UNSETTLED WEATHER RETURNS LATE SUNDAY
INTO EARLY NEXT WEEK WITH THE RISK OF SHOWERS AND THUNDERSTORMS
ALONG WITH INCREASING HUMIDITY.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
CURRENTLY...MASS FIELDS AND AVAILABLE OBS SUGGEST COLD FRONTAL
BOUNDARY IS STALLED JUST OFF OF MAINLAND SRN NEW ENGLAND...FROM
ACK SOUND SW TO LONG ISLAND. CONVECTION NEAR SRN NJ AND THE
DELMARVA HAS BEGUN TO PUSH E...AND THE NRN EXTENT LOOKS TO CLIP
ESPECIALLY ACK BY LATE THIS AFTERNOON AND EVENING. CONVECTIVE
THREAT IS LIKELY TO STAY JUST TO THE S HOWEVER...SINCE INSTABILITY
IS INCREASES AND BEST THETA-E RIDGE EXTENDS S OF THE CURRENT
FRONTAL POSITION. WILL MAINTAIN ISO TS IN THE WX FOR THE TIME
BEING...BUT FEEL THAT ANYTHING THAT EFFECTS SRN NEW ENGLAND WILL
BE JUST A RAIN SHIELD BY THE TIME IT ARRIVES.

WILL NEED TO WATCH THE DEVELOPMENT OF A WEAK FRONTAL WAVE OFF THE
DELMARVA LIKELY TRIGGERED BY SCT CONVECTION CURRENTLY IN MARYLAND
AND DELAWARE...THIS MAY BE THE LAST THREAT FOR RAIN ACROSS
ACK/MVY OR EXTREME SRN CAPE COD DURING THE OVERNIGHT HOURS...WILL
CONTINUE A BAND OF CHANCE...TAPERING TO SLIGHT CHANCE POPS THROUGH
ABOUT 06 FOR THIS THREAT. AFTER THE FRONTAL WAVE...THE COLD FRONT
ITSELF SHOULD BEGIN A LOW MIGRATION FURTHER S.

ASIDE FROM THIS RAIN THREAT...DRYING DWPTS WILL CONTINUE INTO
TONIGHT AS HIGH PRES SLOWLY NOSES IN FROM THE W. THE COMBINATION
OF A REMNANT CI SHIELD FROM CONVECTION TO THE S IS LIKELY TO
MITIGATE RADIATIONAL COOLING SOMEWHAT...SO EXPECT OVERNIGHT LOWS
TO BE A BIT WARMER THAN THEY OTHERWISE COULD BE. EXPECT LOWS
MAINLY IN THE UPPER 50S TO MID 60S. A FEW NW VALLEYS...AWAY FROM
THE CI SHIELD MAY DROP INTO THE LOW 50S THANKS TO A BETTER SHOT
FOR RADIATIONAL COOLING.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM FRIDAY/...
TOMORROW...
WITH WEAK FRONTAL WAVE SHIFTING WELL TO THE SE OF NEW ENGLAND
EARLY IN THE MORNING...EXPECT THAT COLD FRONT WILL FINALLY BEGIN A
FURTHER MIGRATION TO THE S...ALLOWING HIGH PRES TO BEGIN TO CREST
ACROSS THE REGION DURING THE DAY. ASIDE FROM SOME EARLY CI FROM
THE WAVE...CLOUDS WILL COME IN THE FORM OF DIURNAL CU AS MODELS
SHOW A MODEST MOISTURE LAYER JUST ABOVE THE BL. MODELS ARE STILL
TRYING TO INDICATE A POCKET OR TWO OF VERY LIGHT QPF THANKS TO
RAZOR THIN CAPE PROFILE ABOVE THE MIXED LAYER PER LATEST
SOUNDINGS. HOWEVER...AGREE WITH PREVIOUS FORECAST SHIFT THAT THE
OVERALL COLUMN LOOKS MUCH TOO DRY AT THIS TIME. THEREFORE...WILL
CONTINUE WITH NIL POPS. TYPICAL MID SUMMER MIXING PROFILES AND H85
TEMPS NEAR +13C SUPPORT HIGHS MAINLY LOW-MID 80S /NEAR TYPICAL FOR
THIS TIME OF YEAR/ EXCEPT NEAR SHORELINES WHERE WEAK PRES GRADIENT
WILL SUPPORT SEA BREEZE DEVELOPMENT.

TOMORROW NIGHT...
SIMILAR SETUP TO THU NIGHT AS DWPTS FALL INTO THE LOW 50S.
HOWEVER...DO EXPECT A BIT MORE CLEARING AND A GENERALLY WEAK PRES
GRADIENT. THEREFORE...MIGHT SEE A BIT MORE RADIATIONAL COOLING
ACROSS THE REGION. HAVE MINS A BIT COOLER...MAINLY IN THE LOW 50S
TO AROUND 60F. POSSIBLY A LITTLE WARMER IN THE URBAN SPOTS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
HIGHLIGHTS...

* PLEASANT/DRY WEATHER AND LESS HUMID FRI NIGHT/SAT
* BECOMING UNSETTLED LATE SUN INTO EARLY NEXT WEEK

SYNOPTIC SCALE FLOW AND MODEL PREFERENCES...

FLOW TEMPORARILY DEAMPLIFIES EARLY IN THE PERIOD TO PROVIDE DRIER AND
LESS HUMID MID SUMMER WEATHER ACROSS SOUTHERN NEW ENGLAND. BY LATER
SUNDAY/SUN NIGHT AND ESPECIALLY EARLY NEXT WEEK THE UPPER AIR
PATTERN UNDERGOES SIGNIFICANT AMPLIFICATION WITH A PIECE OF THE
POLAR VORTEX DIVING SOUTHWARD INTO THE GREAT LAKES. GEFS ANOMALIES
SUGGEST 500 MB HEIGHTS FALL TO ABOUT -3 SD BELOW OVER THIS REGION
EARLY NEXT WEEK.  THIS CLOSED LOW WILL THEN TRACK NORTHEAST INTO
SOUTHERN ONTARIO AND QUEBEC EARLY NEXT WEEK. HOWEVER THE LEADING EDGE
OF ITS FRONTAL ZONE WILL PROVIDE UNSETTLED WEATHER FOR SOUTHERN NEW
ENGLAND POSSIBLY AS EARLY AS LATER SUNDAY BUT MORE LIKELY MON AND
TUE OF NEXT WEEK. ALL OF THE MODEL GUIDANCE INCLUDING THE GEFS AND
ECENS IS IN VERY GOOD AGREEMENT ON THE EVOLUTION OF THIS HIGH
AMPLITUDE TROUGH ALONG WITH THE SYNOPTIC SCALE FLOW PATTERN ACROSS
NEW ENGLAND. THUS WILL FOLLOW A MODEL BLEND FOR THIS PORTION OF THE
FORECAST.

DAILY DETAILS...

FRI NIGHT AND SATURDAY...VERY PLEASANT DRY WEATHER WITH COMFORTABLE
HUMIDITY AND LIGHT WINDS AS HIGH PRES CREST OVER THE REGION. WEAK
PGRAD WILL SUPPORT AFTERNOON SEA BREEZES KEEPING THE COASTLINE
SLIGHTLY COOLER THAN THE INTERIOR. DEW PTS IN THE 50S WILL
SUPPORT LOWS IN THE U50S TO L60S AND HIGHS 80-85.

SUN/MON/TUE....WEATHER BECOMES UNSETTLED AS UPPER AIR PATTERN
AMPLIFIES SIGNIFICANTLY. THE GFS AND ITS ENSEMBLES ARE ON THE FAST
EDGE OF THE GUIDANCE WITH THE THREAT OF SHOWERS ARRIVING SUN.
REMAINDER OF THE GUID IS SLOWER KEEPING DRY WEATHER HERE UNTIL
NIGHTFALL/SUN EVENING. HIGHER RISK OF SHOWERS/T-STORMS COMES MON AND
TUE AS FULL LATITUDE TROUGH OVER THE GREAT LAKES ADVECTS NORTHEAST
INTO SOUTHERN ONTARIO AND QUEBEC. STRONG FRONTAL ZONE ASSOCIATED
WITH THIS SYSTEM WHICH WILL IMPACT THE REGION MON AND TUE WITH AN
INCREASED RISK OF SHOWERS/T-STORMS. TROUGH MAY HAVE ENOUGH
AMPLIFICATION TO BACK THE MID LEVEL FLOW FOR GOOD ATLC INFLOW
YIELDING HEAVY RAINFALL THREAT. ALSO TURNING WARMER AND MORE HUMID
THIS PERIOD AS WELL.

MIDDLE OF NEXT WEEK...ENSEMBLES SUGGEST MID/UPR LVL TROUGH SHOULD BE
MOVING OFFSHORE AROUND THE MIDDLE OF NEXT WEEK. THIS WOULD SUPPORT A
TREND TOWARD DRIER AND LESS HUMID WEATHER.

&&

.AVIATION /17Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE FOR MOST
EXCEPT ACK THIS EVENING.

THROUGH TONIGHT...
VFR FOR MOST. ONLY CAVEAT WILL BE ACK...WHERE ANOTHER ROUND OF
STRATUS AND LOW VSBYS ARE POSSIBLE IN FOG UNTIL LATE. ALSO...SOME
RAIN POSSIBLE LATE THIS AFTERNOON/EVENING FOR ACK.
OTHERWISE...LIGHT LATE DAY SEA BREEZES AT NEAR SHORE TERMINALS
WITH LIGHT W WINDS ELSEWHERE.

TOMORROW AND TOMORROW NIGHT...
VFR. SEA BREEZES ONCE AGAIN LIKELY AT NEAR SHORE TERMINALS. START
TIME IS LIKELY 15Z-17Z.

KBOS TAF...HIGH CONFIDENCE IN TAF. AFTERNOON SEA BREEZE MAY TAKE
UNTIL 18Z-20Z TO START THIS TODAY. SHOULD START 14-15Z TOMORROW.

KBDL TAF...HIGH CONFIDENCE IN TAF.

OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...MODERATE CONFIDENCE.

FRIDAY NIGHT AND SATURDAY...HIGH CONFIDENCE FOR VFR/DRY WEATHER AND
LIGHT WINDS.

SUNDAY-MONDAY...VFR TO START BUT LOWERING TO MVFR LATE SUN/SUN NIGHT
AND ESPECIALLY MON AS RISK OF SHOWERS/T-STORMS INCREASES. LOCALLY
HEAVY DOWNPOURS POSSIBLE IN ANY THUNDERSTORMS.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /TODAY THROUGH FRI NIGHT/...HIGH CONFIDENCE.

A COLD FRONT WILL SLOWLY MOVE S OF THE WATERS EARLY
TOMORROW...UNTIL THEN A FEW POCKETS OF SHOWERS...AND POSSIBLY EVEN
A RUMBLE OF THUNDER IS POSSIBLE MAINLY ON THE WATERS S OF BLOCK
ISLAND TO NANTUCKET THROUGH THE EARLY HALF OF THE OVERNIGHT. WINDS
AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS THROUGH
FRI NIGHT. OUTSIDE OF AN ISOLATED TS.

OUTLOOK...SATURDAY THROUGH TUESDAY...MODERATE CONFIDENCE.

FRIDAY NIGHT THROUGH SUNDAY...IDEAL BOATING WEATHER WITH GOOD
VSBY/DRY WEATHER AND LIGHT WINDS AS HIGH PRES CREST OVER THE WATERS.

SUNDAY NIGHT-MONDAY...HIGH PRES MOVES OFFSHORE WITH RISK OF
SHOWERS/T-STORMS INCREASING. SSW WINDS INCREASE AS WELL.

&&

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

&&

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


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