Area Forecast Discussion
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000
FXUS61 KBOX 281049
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
649 AM EDT TUE APR 28 2015

.SYNOPSIS...
THE COOL CONDITIONS TODAY GIVE WAY TO WARMER CONDITIONS BY
WEDNESDAY. AFTER THE RAIN ENDS THIS MORNING DRY WEATHER PREVAILS
THROUGH MID WEEK. COASTAL LOW PRESSURE WILL PASS SOUTH OF NEW
ENGLAND FRIDAY AND SATURDAY. THIS MAY COME CLOSE ENOUGH TO SPREAD
RAIN INTO THE COASTAL PLAIN. HIGH PRESSURE THEN BRINGS DRY WEATHER
TO THE REGION SUNDAY AND MONDAY.

&&

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

7 AM UPDATE...
TWO LINGERING SHOWER BANDS...OVER THE CENTRAL HILLS AND OVER
SOUTHEAST MASS. THESE SHOULD CONTINUE TO MOVE SOUTH AND EXIT THE
SOUTH COAST. CLOUDS LINGER EAST OF THE CT VALLEY AS WELL AS
UPSTREAM IN NORTHERN NEW ENGLAND. CLEAR TO PARTLY CLOUDY IN THE
WEST. WHILE THE CLEARING SHOULD REASSERT ITSELF IN THE WEST...IT
MAY TAKE UNTIL AFTERNOON IN RI AND EASTERN MASS.

NO SIGNIFICANT CHANGES TO THE FORECAST AT THIS TIME.

PREVIOUS DISCUSSION...CURRENT OBS SUGGEST THAT BACKDOOR COLD
FRONT IS DRAPED FROM NW MA THROUGH TO THE SE COASTLINE AND
CONTINUING TO SHIFT TO THE SSW THIS MORNING. THIS IS COMBINED WITH
KICKER UPPER LVL SHORTWAVE WHICH WILL FINALLY SHIFT THE CUTOFF
VORTEX WHICH HAS SO DEFINED OUR WEATHER LATELY TO THE E. LAST OF
THE REMNANT COLUMN MOISTURE IS CURRENTLY BEGIN SQUEEZED OUT WITH
THESE TWO MECHANISMS...CULMINATING IN AN AREA OF RAIN ACROSS E MA
AND RI. THESE TOO SHOULD GRADUALLY DIMINISH AND SHIFT TO THE S AS
THE FRONT MOVES AND THE UPPER LVL SHORTWAVE SHIFTS FURTHER
OFFSHORE.

THE NNE WINDS...WITH A BIT OF A DRAW OFF THE COOL WATERS OF THE
GULF OF MAINE...COMBINED WITH LEFTOVER CLOUDS WRAPPING AROUND THE
CUTOFF TO THE E WILL KEEP CONDITIONS GENERALLY NEAR OR SLIGHTLY
BELOW NORMAL TODAY. ALTHOUGH DO EXPECT TO SEE SOME CLEARING THIS
AFTERNOON THANKS TO SOME MODEST MESO-RIDGING BETWEEN A SECONDARY
CUTOFF DEVELOPING TO THE W. GIVEN THAT H85 VALUES RUN FAIRLY CLOSE
TO 0C...HIGHS IN THE UPPER 50S AND LOW 60S SOUND REASONABLE. THIS
SAME MIXING WILL ALLOW FOR SOME GUSTY WINDS AT TIMES. WITH GUSTS
MAINLY 20-25 MPH. THIS MAY LEAD TO MARGINAL FIRE WEATHER
CONCERNS...SEE BELOW FOR DETAILS ON THIS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
TONIGHT...
EXPECT SOME GRADUAL CLEARING ACROSS THE REGION AS A WEAK RIDGE OF
HIGH PRES GAINS CONTROL OF THE REGION. MASS FIELDS DO SHOW A
MODEST PRES GRADIENT REMAINS IN PLACE ACROSS THE REGION WHICH IS
LIKELY TO MITIGATE RADIATIONAL COOLING. DEWPOINTS TOO...ARE LIKELY
TO REBOUND BACK INTO THE UPPER 30S AND LOW 40S WITHOUT DIURNAL
MIXING SO WILL LIKELY SEE LOWS ONLY DROPPING INTO THE LOW-MID 40S.

WED...
HIGH PRES REMAINS IN CONTROL. WINDS SHIFT MAINLY NW AS THE
RIDGELINE SHIFTS TO THE E. THE CAVEAT WILL BE NEAR SHORE LOCATIONS
WHICH ARE LIKELY TO EXPERIENCE SEA BREEZES THANKS TO A WEAK PRES
GRADIENT. H85 TEMPS ARE LIKELY TO REACH ABOUT +4C...BUT ITS
POSSIBLE THAT SOME AREAS MIX HIGHER. THEREFORE...WITH A W
COMPONENT...SOME HIGHS ON WED COULD REACH THE LOW 70S IN TYPICALLY
WARMER SPOTS /CT VALLEY/ TO THE MID AND UPPER 60S ELSEWHERE. THE
SEA BREEZES WILL KEEP COASTAL LOCATIONS COOLER THOUGH...MAINLY IN
THE 50S ALONG THE IMMEDIATE COASTLINE. YET ONE MORE SHORTWAVE
ASSOCIATED WITH THE CUTOFF TO THE E WILL BE ROTATING THROUGH
DURING THE AFTERNOON...BUT SUSPECT LITTLE FANFARE EXCEPT
INCREASING CLOUDS FROM THE N GIVEN THE DRIER AIR MOVING IN UNDER
THE W COMPONENT TO THE FLOW.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
BIG PICTURE... UPPER TROUGH REMAINS OVER THE EASTERN USA DURING THE
LATTER HALF OF THE WEEK.  UPPER RIDGE THEN BUILDS EAST AND BRINGS
DRIER MORE SEASONABLE WEATHER SUNDAY AND MONDAY.

LONG RANGE GUIDANCE IS SIMILAR IN GENERAL PATTERN BUT DIFFERS IN
DETAIL ON FRIDAY AND SATURDAY. THE 00Z GFS IS SLOWER/FARTHER WEST
WITH THE CLOSED UPPER LOW DRAWING A COASTAL SURFACE LOW UP THE
COAST.  THE 12Z ECMWF IS FASTER/FARTHER EAST BY ROUGHLY 9 HOURS.
THIS DIFFERENCE BRINGS TWO DIFFERENT PROJECTIONS FOR OUR AREA WITH
THE GFS SPREADING RAIN AND NORTHEAST WIND INTO RI AND EASTERN MASS
WHILE THE ECMWF KEEPS MOST EVERYTHING OFFSHORE. THE ECMWF SOLUTION
SHOWS A MAINLY FRIDAY STORM WHILE THE GFS SOLUTION SHOWS A FRIDAY
NIGHT/SATURDAY STORM.

THE GFS SEEMS AN OUTLIER COMPARED WITH THE ECMWF OP AND ECMWF/GFS
ENSEMBLES. RATHER THAN USE OUR USUAL BLEND...WE USED AN ADJUSTED
BLEND THAT LEANS TOWARD THE ECMWF.

THE DAILIES...

WEDNESDAY NIGHT-THURSDAY... WEAK CANADA HIGH PRESSURE OVER THE
REGION SHOULD KEEP THE WEATHER DRY.  DEWPOINTS WILL BE EITHER SIDE
OF 40 DEGREES. LIGHT EAST FLOW WILL KEEP DAYTIME TEMPS COOLEST ALONG
THE COAST WITH WARMER TEMPS INLAND. MIXING DEPTHS INLAND WILL REACH
850-900 MB. DEW POINTS AND PARTIAL SKY COVER SUGGEST MIN TEMPS IN
THE 40S. MIXING TEMPS SUGGEST MAX SFC TEMPS 50S COAST AND 60-65
INLAND.

FRIDAY-SATURDAY... SFC LOW PRESSURE MOVES OUT OF THE GULF OF MEXICO
WEDNESDAY AND UP THE CAROLINA COAST THURSDAY. THE FASTER ECMWF
SOLUTION KEEPS MOST PCPN OFFSHORE BUT GRAZES THE SOUTH COAST. PCPN
MOVES OFFSHORE FRIDAY NIGHT. WE SHOW SLIGHT CHANCE POPS FOR ALL OF
SOUTHERN NEW ENGLAND FRIDAY BUT LIMIT CHANCE VALUES TO RI AND
SOUTHEAST MASS. THE GFS PCPN FIELD IS SIMILAR BUT SLOWER AND EXTENDS
A LITTLE FARTHER NORTH.  WITH THE FASTER TIMING...EXPECT PARTIAL
CLEARING SATURDAY. MOISTURE PROFILES DO SHOW SOME LINGERING MOISTURE
AROUND 850 MB IS MORE SHALLOW THAN ON PREVIOUS DAYS...BUT ENOUGH TO
SUGGEST SOME SKY COVER. CLOUDS AND NORTHEAST FLOW SHOULD KEEP DAY
TEMPS IN THE 50S FRIDAY...BREAKS OF SUN AND DEEPER MIXING SHOULD
ALLOW SATURDAY TEMPS TO REACH 50S EAST AND 60-65 WEST.

SUNDAY-MONDAY... HIGH PRESSURE BUILDS OVER THE REGION AND SHOULD
TREND US TOWARD PARTIAL CLEARING. BUILDING HEIGHTS AND A
DEVELOPING SOUTHWEST FLOW LATE SUNDAY AND MONDAY WOULD BRING BACK
SEASONABLE OR SEASONABLY MILD TEMPS THESE TWO DAYS. MIXING BOTH
DAYS SHOULD REACH AT LEAST 900 MB...WHICH SUPPORT AT LEAST 65-70
SUNDAY AND 70S MONDAY.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...

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

TODAY...HIGH CONFIDENCE. LOW-END VFR CIGS WILL TREND TO CLEARING
OR PARTIAL CLEARING. WIND GUSTS DROP TO MAINLY 15-25 KT THROUGH
THE DAY.

TONIGHT AND WEDNESDAY...HIGH CONFIDENCE.
VFR. INCREASING MID-LOW VFR CLOUDS BUILD IN FROM THE N DURING THE
DAY. LOW CHANCE FOR A SPRINKLE.

KBOS TAF...HIGH CONFIDENCE IN TAF.

KBDL TAF...HIGH CONFIDENCE IN TAF.

.OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...MODERATE CONFIDENCE.

FRIDAY...LOW-MODERATE CONFIDENCE. VFR...EXCEPT AREAS OF MVFR IN
SHOWERS IN RI AND SOUTHEASTERN MASS. NORTHEAST WIND GUSTING 20-30
KNOTS CAPE COD AND ISLANDS...15-20 KNOTS BOSTON AND PROVIDENCE.

SATURDAY...VFR. MODERATE CONFIDENCE. NORTH-NORTHEAST WIND BELOW 20
KNOTS.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

.SHORT-TERM /THROUGH WEDNESDAY/...

TODAY AND TONIGHT...HIGH CONFIDENCE.
WILL EXPERIENCE NNE FLOW WITH GUSTS AROUND 25-30 KT AT TIMES
THROUGH THE MORNING...THEN DIMINISHING THIS AFTERNOON. A
DEVELOPING SWELL IN THE GULF OF MAINE WILL LEAD TO SEAS BUILDING
5-8 FT MAINLY ON THE E WATERS...WHICH WILL TAKE INTO THE OVERNIGHT
HOURS AND EARLY WED TO SUBSIDE. THEREFORE...WILL CONTINUE SMALL
CRAFT ADVISORIES...WITH THE EXPECTATION THAT THOSE ALONG THE S
COAST CAN BE DROPPED THIS AFTERNOON AS WINDS DIMINISH.

WED...HIGH CONFIDENCE.
MAINLY QUIET BOATING WEATHER EXPECTED.

.OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...

COASTAL LOW PRESSURE MOVING UP FROM THE GULF OF MEXICO PASSES SOUTH
OF THE WATERS FRIDAY. NORTHEAST WINDS ON THIS SIDE OF THE LOW WILL
BRING BUILDING SEAS FRIDAY AND SATURDAY. SEAS WILL BUILD TO AT LEAST
5 TO 10 FEET ON THE EXPOSED WATERS...POSSIBLY A LITTLE HIGHER EAST
AND SOUTHEAST OF CAPE COD. NORTHEAST WINDS 20-25 KNOTS FRIDAY AND
SATURDAY. UNCERTAINTY IN THE TRACK AND RESULTING EFFECTS SO
CONFIDENCE IS LOWER THAN MODERATE. A SMALL CRAFT ADVISORY MAY BE
NEEDED THOSE TWO DAYS.

&&

.FIRE WEATHER...
NNE SUSTAINED WINDS WILL BE MAINLY AROUND 15 MPH /EXCEPT STRONGER
ON THE ISLANDS/ WITH GUSTS UP AROUND 25 MPH. A FEW GUSTS TO 30 MPH
POSSIBLE. THIS WILL COMBINE WITH MIN RH VALUES IN THE AFTERNOON OF
30-40 PERCENT. HOWEVER...THE COMBINATION OF SOME LIGHT RAINFALL
THIS MORNING...MARGINAL RH VALUES AND RELATIVELY COOL TEMPERATURES
MITIGATE THE RISK SOMEWHAT. THEREFORE...MARGINAL FIRE WEATHER WILL
BE OBSERVED TODAY...BUT THERE ARE SOME LIMITING FACTORS...SO NO
HEADLINES WILL BE ISSUED.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR ANZ231-
     232.
     SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR ANZ230-
     233>235-237-256.
     SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR ANZ250-255.
     SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ251.
     SMALL CRAFT ADVISORY UNTIL 11 AM EDT WEDNESDAY FOR ANZ254.

&&

$$
SYNOPSIS...WTB/DOODY
NEAR TERM...WTB/DOODY
SHORT TERM...DOODY
LONG TERM...WTB
AVIATION...WTB/DOODY
MARINE...WTB/DOODY
FIRE WEATHER...


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