Area Forecast Discussion
Issued by NWS Boston, MA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KBOX 310627
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
227 AM EDT FRI OCT 31 2014

.SYNOPSIS...
HIGH PRESSURE WILL BRING DRY AND SEASONABLE CONDITIONS THROUGH
THE END OF THE WORK WEEK. A DEVELOPING COASTAL STORM WILL MOVE UP
THE COAST SATURDAY AND PASS OFFSHORE SATURDAY NIGHT AND EARLY
SUNDAY. HIGH PRESSURE BUILDS OVER THE EASTERN U.S. FOR EARLY NEXT
WEEK. ONE OR TWO COLD FRONTS MAY CROSS SOUTHERN NEW ENGLAND
WEDNESDAY AND THURSDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...

210 AM UPDATE...
BAND OF LOW TO MID LEVEL CLOUDS HAS DEVELOPED ACROSS S NH/E MA AS
OF 06Z BASED ON LATEST IR SATELLITE TRENDS. TEMPS HAVE TENDED TO
LEVEL OFF WHERE THE CLOUDS HAVE DEVELOPED...THOUGH KCEF DOWN TO 29
DEGS WHERE SKIES HAVE REMAINED CLEAR AND WINDS ARE CALM. CALM
WINDS INLAND BEGINNING TO SHIFT TO LIGHT N-NE...WITH A NE WIND
5-10 KT ON THE OUTER CAPE. NAM BUFKIT SHOWING 5-6KFT CLOUD DECK
WELL FROM KBOS-KBED-KCON.

NOTING SOME PATCHY FOG STARTING TO DEVELOP WHERE THERE IS LOW
DEWPT DEPRESSION...AND SHOULD SEE MORE PATCHES OF FOG DEVELOP IN
NORMALLY PRONE LOCATIONS THROUGH THE REMAINDER OF THE NIGHT. WIDE
RANGE OF TEMPS CONTINUE...FROM THE LOWER-MID 30S WELL INLAND TO
45-50 ACROSS THE OUTER CAPE WITH N-NE WINDS.

HAVE UPDATED FORECAST TO BRING CONDITIONS CURRENT THROUGH THE NEAR
TERM.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 AM SATURDAY/...
TODAY...ANOTHER QUIET DAY AS HIGH PRESSURE LIFTS TO THE NORTH.
WITH WINDS SHIFTING TO THE EAST AS LOW PRESSURE MOVES TOWARDS
SOUTHERN NEW ENGLAND FROM THE CAROLINA COAST...EXPECT IT TO FEEL A
BIT COOLER THAN TODAY. OTHERWISE...INCREASING CLOUDS FROM THE
APPROACHING COASTAL LOW.

TONIGHT...WHILE THERE IS SOME UNCERTAINTY IN THE MODEL SOLUTIONS
WITH THE UPCOMING STORM MOST OF THIS WILL AFFECT THE WEEKENDS
WEATHER SO WILL MOSTLY DISCUSS IT IN THE LONG TERM SECTION. SHOULD
MOSTLY SEE AN INCREASE IN CLOUDS OVERNIGHT. THIS WILL KEEP
TEMPERATURES A FEW DEGREES WARMER THAN TONIGHT. IN ADDITION...RAIN
AND/OR SHOWERS WILL LIKELY MOVE ONTO THE SOUTH COAST AND INTO
SOUTHEAST MASSACHUSETTS TOWARDS DAYBREAK SATURDAY MORNING.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...

BIG PICTURE...
DEEP AMPLITUDE TROUGHS ON BOTH COASTS SATURDAY WITH A RIDGE IN
BETWEEN. SHORTWAVE MOVING THROUGH THE EASTERN TROUGH GENERATES A
CUTOFF UPPER LOW WITH TWO JET STREAMS...A NORTHERN STREAM ALONG
THE CANADIAN BORDER AND A SOUTHERN STREAM MOVING WITH THE SHORT
WAVE. THE PATTERN SHIFTS EAST DURING THE WEEK WITH THE RIDGE
BUILDING OVER NEW ENGLAND. THE PATTERN THEN TRANSFORMS TO A MORE
ZONAL FLOW. REMAINS OF THE PACIFIC COAST TROUGH MOVE ACROSS NEW
ENGLAND MIDWEEK.

COLDER THAN NORMAL HEIGHTS WITH THE WEEKEND TROUGH. THESE BUILD TO
NORMAL OR A LITTLE MILDER THAN NORMAL BY MIDWEEK. THIS POINTS TO A
COLDER THAN NORMAL WEEKEND TRENDING TO NORMAL TEMPS BY MIDWEEK.

THE GFS...WHILE SERVICEABLE...IS A BIT OF AN OUTLIER. FOR THE GRIDS
WE WILL USE A BLEND OF MODEL DATA INCLUDING HPC AND /WHERE POSSIBLE/
THE 12Z ECMWF.

THE DAILIES...

SATURDAY-SUNDAY...

COASTAL STORM CONTINUES TO BE INDICATED FOR SATURDAY AND EARLY
SUNDAY. SUPPORT COMES FROM TWO SETS OF FORCING
MECHANISMS...SUGGESTING A TWO-PART EVENT. BUT FINE-TUNING THE TIMING
OF THESE PARTS IS DIFFICULT THIS FAR OUT. INITIAL FORCING COMES FROM
RIGHT ENTRANCE REGION OF NORTHERN STREAM JET SATURDAY MORNING.
SECOND FORCING COMES FROM LEFT EXIT REGION OF JET SUPPORTING
SHORTWAVE ROUNDING THE BASE OF THE EASTERN TROUGH LATE
SATURDAY/SATURDAY NIGHT. EVEN SO...MOST OF THE FRONTOGENETIC FORCING
WITH EACH SEGMENT IS FOCUSED ON THE MARITIMES AND MAINE. THE
WESTERN EDGE OF THIS FORCING SHOULD EXTEND INTO SOUTHERN NEW
ENGLAND WITH THE FIRST AND POSSIBLY THE SECOND OF THE SEGMENTS. WE
EXPECT RAIN SATURDAY AND SATURDAY NIGHT WITH HIGHEST POPS OVER
CAPE COD AND THE ISLANDS...LESSER VALUES NORTH AND WEST.

STRONG PRESSURE GRADIENT AT THE SURFACE AND A 50 KNOT LOW LEVEL JET
WILL CONTRIBUTE TO WINDY CONDITIONS. THE STRONGEST WINDS WILL BE
OVER THE EASTERN/SOUTHEAST WATERS. STRONGEST LAND WINDS WILL BE OVER
THE OUTER CAPE AND ISLANDS...DIMINISHING FARTHER WEST. HAVE FEATURED
45 KNOTS FOR THE STRONGEST WINDS AND 20-25 KNOTS IN THE INTERIOR.

THE COASTAL STORM WILL PASS US IN PIECES SATURDAY AND LATER SATURDAY
NIGHT...AS NOTED ABOVE. EXPECT PRECIPITATION TO DIMINISH WEST TO
EAST AFTER MIDNIGHT AND END ON THE MASS EAST COAST AROUND OR SHORTLY
AFTER SUNRISE SUNDAY.

TEMPERATURES THROUGH MOST OF THE STORM SHOULD REMAIN FAVORABLE FOR
RAIN.  AS THE WINDS SHIFT FROM NORTHEAST TO NORTHWEST SATURDAY
NIGHT...COLDER AIR WILL BE DRAWN IN WHICH COULD CHANGE THE LAST
SHOWERS OVER TO SNOW. ANY ACCUMULATIONS SHOULD BE NO MORE THAN A
TRACE. SOME HIGHLANDS SUCH AS IN THE MONADNOCK COULD PICK UP A LIGHT
ACCUMULATION AT STORM/S END.

DRIER AIR SUNDAY WILL BRING CLEARING SKIES. COLD ADVECTION WILL
PROMOTE MIXING THROUGH AT LEAST 850 MB. WINDS IN THIS LAYER WILL BE
35 TO 40 KNOTS...SO EXPECT NORTHWEST GUSTS TO AT LEAST THE LOWER END
OF THIS RANGE. WINDS DIMINISH SUNDAY NIGHT AS THE STORM MOVES
FARTHER AWAY.

MONDAY-TUESDAY... HIGH PRESSURE BUILDS OVER THE REGION. MONDAY
SHOULD BE SUNNY AS THE HIGH MOVES OVERHEAD. MIXING WILL AGAIN
BRING INCREASED WIND GUSTS DURING THE AFTERNOON. WINDS IN THE
MIXED LAYER ARE EXPECTED AROUND 30 KNOTS WITH POTENTIAL FOR A
LITTLE STRONGER SPEEDS. WINDS WILL DIMINISH WITH SUNSET.

THE HIGH MOVES OFFSHORE TUESDAY. THIS WILL MAKE ROOM FOR A WARM
FRONT TO SWING PAST. SUFFICIENT LIFT AND MOISTURE TO SUPPORT MID AND
HIGH CLOUDS...BUT THE BEST WARM FRONTAL LIFT WILL REMAIN TO OUR
NORTH AND WEST SO EXPECT AT LEAST SOME SUN THROUGH THE DAY.

WEDNESDAY-THURSDAY... LOW CONFIDENCE ON MIDWEEK WEATHER.  AT LEAST
ONE TROUGH IN THE ZONAL FLOW WILL SWING ACROSS THE REGION DURING
THIS TIME. GFS AND ECMWF ARE HINTING AT ONE ON WEDNESDAY...BUT
SHOWING A MORE SUBSTANTIAL TROUGH PASSING ON THURSDAY.  THE FORECAST
WILL HAVE CLOUDS AND LOW-END CHANCE OR SLIGHT CHANCE POPS.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH TONIGHT/...

THROUGH 12Z...MAINLY VFR. LOCAL MVFR-IFR VSBYS IN PATCHY FOG IN
NORMALLY PRONE AREAS.

TODAY...HIGH CONFIDENCE. VFR. ANY LEFTOVER MVFR VSBYS IN PATCHY
FOG WILL IMPROVE BY 14Z.

TONIGHT...MODERATE CONFIDENCE. CONDITIONS DETERIORATE THROUGH THE
NIGHT TO MVFR/IFR FROM SOUTH TO NORTH. RAIN/SHOWERS EXPECTED ALONG
THE SOUTH COAST AND INTO SOUTHEASTERN MASSACHUSETTS AS WE NEAR
DAYBREAK SATURDAY.

KBOS...HIGH CONFIDENCE IN TAF.

KBDL...HIGH CONFIDENCE IN TAF.

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

SATURDAY-SUNDAY...IFR CIGS AND MVFR OR IFR VSBYS IN PERIODS OF RAIN
SATURDAY AND SATURDAY NIGHT. VFR AND DRIER WEATHER MOVE IN FROM WEST
TO EAST EARLY SUNDAY. NORTHEAST WINDS SATURDAY GUSTING 30-40 KNOTS
ON THE CAPE AND ISLANDS AND 25-30 KNOTS IN THE COASTAL PLAIN. WINDS
SHIFT TO NORTH SATURDAY NIGHT AND NORTHWEST ON SUNDAY WITH GUSTS 40-
45 KNOTS CAPE AND ISLANDS AND 30-35 KNOTS ACROSS SOUTHERN NEW
ENGLAND.

MONDAY...VFR. DAYTIME WIND GUSTS WILL INCREASE TO NEAR 30 KNOTS
INLAND AND 35 KNOTS CAPE AND ISLANDS...DIMINISHING TOWARD EVENING.

TUESDAY...VFR WITH INCREASING HIGH CLOUDS.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH TONIGHT/...HIGH CONFIDENCE.

HIGH PRESSURE DOMINATES TODAY WITH WINDS AND SEAS REMAINING BELOW
SMALL CRAFT CRITERIA. WINDS SHIFT FROM THE NORTHWEST TO THE
NORTHEAST THEN EAST DURING THE DAY. THESE EASTERLY WINDS AND SEAS
INCREASE TONIGHT AS LOW PRESSURE APPROACHES THE WATERS FROM THE
CAROLINAS. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED FOR ALL OF THE
WATERS FOR AT LEAST A PORTION OF TONIGHT.

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

SATURDAY...STRONG POTENTIAL FOR HIGH END GALES ON THE OUTER
WATERS WITH GUSTS TO 45 KNOTS. LOW POTENTIAL OF STORM FORCE WINDS
ON THE OUTER WATERS. RAIN WITH INCREASING NORTHEAST WINDS. GALE
FORCE GUSTS EXPECTED ON MOST WATERS.WAVEWATCH MODEL FORECASTS OF
SEA HEIGHTS ARE LOWER THAN OUR PREVIOUS FORECAST. WE HAVE BUMPED
SEAS UP 2-3 FEET WITH 15 FOOT SEAS DEVELOPING EAST OF
MASSACHUSETTS. A MARINE WEATHER STATEMENT CONTINUES TO ADDRESS
THIS CONCERN.

SUNDAY...RAIN MOVES OFF TO THE EAST. WINDS SHIFT NORTHWEST WITH GALE
FORCE GUSTS 40-45 KNOTS. EXPECT THESE WINDS TO DIMINISH BELOW GALE
FORCE SUNDAY NIGHT. WITH THE WIND SHIFT...THE ROUGH SEAS WILL
MIGRATE FARTHER OFFSHORE WITH DIMINISHING SEAS CLOSER TO SHORE.
GALE WARNINGS WILL LIKELY LINGER INTO THE EVENING HOURS.

MONDAY... GUSTY NORTHWEST WINDS WITH SPEEDS APPROACHING GALE FORCE
AGAIN DURING THE DAY. WINDS DIMINISH TOWARD EVENING. SEAS WILL
LINGER AT 5-9 FEET ESPECIALLY ON THE OUTER WATERS.  SMALL CRAFT
ADVISORY IS LIKELY...LOW-END CHANCE THAT GALES MAY BE NEEDED ON SOME
OF THE WATERS.

TUESDAY...WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT LEVELS.

&&

.TIDES/COASTAL FLOODING...
ASTRONOMICAL HIGH TIDES ARE RATHER LOW SATURDAY EVENING AND AGAIN
EARLY SUNDAY MORNING.  HOWEVER...STRONG NORTHERLY WINDS AND HIGH
SEAS WILL HAVE THE POTENTIAL TO RESULT IN MINOR COASTAL FLOODING AND
BEACH EROSION ALONG THE EASTERN MA COAST...PARTICULARLY THE NORTH
SIDE OF CAPE COD AND NANTUCKET HARBOR DURING BOTH HIGH TIDE CYCLES.

THE MAIN UNCERTAINTY REVOLVES AROUND WHEN AND HOW STRONG THE
WINDS/SEAS WILL GET.  THE MODELS SEEM TO BE SHOWING TWO PULSES OF
WIND WITH TWO WAVES OF LOW PRESSURE.  THE FIRST ONE APPEARS TO BE
SATURDAY EVENING WITH THE SECOND ONE SUNDAY MORNING.  THE POTENTIAL
CONTINUES FOR WIND GUSTS UP TO 50 KNOTS AND SEAS BUILDING TO 20 FEET
ACROSS THE OPEN WATERS EAST OF MASSACHUSETTS.  THE TREND OF THE 12Z
GUIDANCE HAS BEEN TO SHOW THE STRONGEST WINDS/HIGHEST SEAS WITH THE
SATURDAY EVENING PULSE.  WILL HAVE TO WAIT AND SEE HOW THE MODELS
TREND...BUT STILL FEEL BOTH HIGH TIDE CYCLES ARE AT RISK WITH A 1 TO
2 FOOT STORM SURGE.

AREAS OF GREATEST CONCERN APPEAR TO BE THE NORTH SIDE OF CAPE
COD...SUCH AS SANDWICH...BARNSTABLE...DENNIS...BREWSTER AND POSSIBLY
EASTHAM. OTHER TYPICAL HOT SPOTS WILL BE SALISBURY AND PLUM
ISLAND...HULL...SCITUATE AND PERHAPS SANDWICH HARBOR AND NANTUCKET
HARBOR. AGAIN...THE MAIN CONCERNS WILL BE MINOR COASTAL FLOODING AS
WELL AS BEACH EROSION.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT
     SATURDAY FOR ANZ231>234-250.
     SMALL CRAFT ADVISORY FROM 5 AM TO 8 AM EDT SATURDAY FOR ANZ230-
     236-251.
     SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT
     SATURDAY FOR ANZ235-237-254>256.

&&

$$
SYNOPSIS...WTB/RLG
NEAR TERM...EVT
SHORT TERM...RLG
LONG TERM...WTB
AVIATION...WTB/RLG/EVT
MARINE...WTB/RLG/EVT
TIDES/COASTAL FLOODING...STAFF



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.