Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 031750
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
150 PM EDT SUN MAY 3 2015

.SYNOPSIS...
CONDITIONS GRADUALLY WARM INTO MONDAY...WITH A CHANCE FOR A FEW
SHOWERS THIS AFTERNOON. HIGH PRESSURE BUILDS OVER THE REGION
DURING EARLY NEXT WEEK. A COLD FRONT SWEEPS SOUTH ACROSS THE
REGION TUESDAY AND THEN STALLS SOUTH OF NEW ENGLAND MIDWEEK. HIGH
PRESSURE REBUILDS WITH DRY AND WARMING WEATHER THE REMAINDER OF
THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
145 PM UPDATE...
SCATTERED SHOWERS HAVE FORMED IN WESTERN MA AND NORTHERN CT.
OTHERS WERE MOVING SOUTH THROUGH SOUTHERN NH. INSTABILITY IS QUITE
MARGINAL. A FEW OF THE STRONGER SHOWERS COULD ATTAIN SOME
LIGHTNING LATER THIS AFTERNOON. BUT BY EVENING WITH SUNSET...THEY
SHOULD BE RAPIDLY DIMINISHING.

TEMPERATURES WERE ABOUT AS FORECAST WITH MID AND UPPER 70S IN
THE FAR INTERIOR AND MUCH COOLER 50S AND 60S ADJACENT TO BAYS AND
THE OCEAN. LOWERED TEMPERATURES IN BOSTON PROPER AS EASTERLY SEA
BREEZES HAVE RESTRICTED TEMPERATURES TO NEAR 60 THUS FAR.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
TONIGHT...
PRECIP WILL COME TO AN END FAIRLY RAPIDLY AS SUNSET APPROACHES.
THE LOSS OF HEATING WILL DIMINISH ANY REMNANT INSTABILITY.
HOWEVER...LEFTOVER HIGHER DWPTS AND CLOUDS WILL LEAD TO A WARMER
NIGHT THAN PREVIOUS NIGHTS...MINS MAINLY IN THE UPPER 40S AND 50S.

MON...
PROBABLY THE WARMEST DAY WAVE EXPERIENCED THUS FAR. H85 TEMPS MAY
EVEN EXCEED +10C...BUT ONCE AGAIN AFTERNOON MIXING SHOULD EXCEED
THIS LEVEL. SW RETURN FLOW EXPECTED...SO WITH ANOTHER DOWNSLOPE
COMPONENT...EXPECT MANY AREAS TO APPROACH OR EVEN EXCEED LOWER 80S
THIS TIME AROUND...EVEN NEAR THE E COAST AS THE W COMPONENT MAY BE
ENOUGH TO PROHIBIT SEA BREEZE DEVELOPMENT. HOWEVER THE S COMPONENT
WILL KEEP SOUTHERN COAST REGION COOLER EVEN AWAY FROM THE COAST.
GOOD MIXING SUGGESTS VERY DRY WEATHER AND A BUILDING PRES GRADIENT
SUPPORTS WIND GUSTS APPROACHING 20-25 MPH...SEE THE FIRE WEATHER
SECTION BELOW FOR CONCERNS.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
BIG PICTURE... UPPER RIDGE BUILDS OVER THE EASTERN USA DURING THE
WEEK WHILE A TROUGH DIGS OVER THE WESTERN USA.  ONE SHORTWAVE PASSES
NORTH OF NEW ENGLAND TUESDAY...A SECOND APPROACHES ACROSS CANADA AT
THE END OF THE WEEK.  MODEL MASS FIELDS ARE SIMILAR THROUGH MOST OF
THE FORECAST PERIOD. THE ECMWF IS A LITTLE FASTER THAN THE GFS WITH
THE END OF WEEK WEATHER SYSTEM. WE USED A BLEND OF MODEL DATA.

THE DAILIES...

MONDAY NIGHT-TUESDAY... UPPER SHORTWAVE PASSES NORTH OF NEW ENGLAND.
THIS WILL PUSH A COLD FRONT ACROSS SOUTHERN NEW ENGLAND DURING
TUESDAY. WHILE MUCH OF THE SUPPORTING UPPER JET IS WELL TO THE
NORTH...THERE IS ENOUGH LOW LEVEL CONVERGENCE ALONG THE COLD FRONT
TO SUPPORT SHOWERS. TOTALS IN THE UPPER 40S SUGGEST THE AIRMASS IS
MARGINALLY SUPPORTIVE FOR THUNDERSTORMS. WE WILL MENTION SHOWERS
WITH A SLIGHT CHANCE OF THUNDER.  THE FRONT MOVES SOUTH OF OUR AREA
TUESDAY NIGHT WITH DRYING OVERNIGHT.

WEDNESDAY THROUGH FRIDAY...HIGH PRESSURE BUILDS OVER THE REGION.
TEMPS ALOFT SUPPORT MAX SFC TEMPS IN THE LOW TO MID 70S. BOTH THE
GFS AND ECMWF SHOW THE UPPER FLOW BECOMING NORTHWEST WEDNESDAY AND
THURSDAY. A SHORTWAVE MOVES THROUGH THIS FLOW AND COULD PUSH A
BACKDOOR COLD FRONT INTO EASTERN MASS. IF SO THEN THIS WOULD BRING
COOLER DAYTIME TEMPS IN THE EAST...PROBABLY 60S.

SATURDAY...NORTHERN STREAM WEATHER SYSTEM MOVES ACROSS CANADA LATE
WEEK. THIS DRIVES A SURFACE COLD FRONT TOWARD NEW ENGLAND LATER
FRIDAY AND SATURDAY. MOST OF THE SUPPORT WITH THIS SYSTEM IS TO OUR
NORTH...OUR NORTHERN AREAS WOULD HAVE THE BEST CHANCE OF ANY
SHOWERS.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...

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

THIS AFTERNOON...HIGH CONFIDENCE. VFR. SEA BREEZES AT BOTH COASTS
CONTINUE THIS AFTERNOON...OTHERWISE MAINLY LIGHT SOUTHERLY FLOW.
SCATTERED SHOWERS ESPECIALLY WESTERN AND CENTRAL PORTIONS OF THE
FORECAST AREA. AN ISOLATED CLAP OF THUNDER CANNOT BE RULED OUT.
BRIEF MVFR VSBY POSSIBLE IN ANY SHOWERS.

TONIGHT INTO MONDAY...HIGH CONFIDENCE. VFR. WINDS BECOME MORE SW
OVERNIGHT AND CONTINUE INTO MON...WHEN GUSTS AROUND 20 KT ARE
POSSIBLE AT TIMES.

KBOS TAF...HIGH CONFIDENCE IN TAF. LOW RISK OF A FEW AFTERNOON
SHOWERS 19Z-23Z. SEA BREEZE CONTINUES THROUGH THE AFTERNOON.

KBDL TAF...HIGH CONFIDENCE IN TAF.

OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...MODERATE TO HIGH
CONFIDENCE.

MAINLY VFR. A COLD FRONT MOVES THROUGH SOUTHERN NEW ENGLAND ON
TUESDAY AND MAY BRING SCATTERED SHOWERS...POSSIBLY A THUNDERSTORM.
CIGS/VSBYS COULD BRIEFLY LOWER TO MVFR IN ANY SHOWERS.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

.SHORT-TERM /THROUGH MONDAY/...

THROUGH TONIGHT...HIGH CONFIDENCE.
MAINLY QUIET BOATING WEATHER EXPECTED WITH HIGH PRES SLIDING E OF
THE WATERS. ONSHORE SEA BREEZES NEAR THE COAST THIS AFTERNOON
OTHERWISE WINDS GENERALLY TURN FROM S TO SW THIS AFTERNOON AND
OVERNIGHT.

MONDAY...MODERATE CONFIDENCE.
SW FLOW MAY APPROACH 25 KT NEAR THE SE COAST OF MA...BUT REMAIN 20
KT OR LESS ON THE OPEN OCEAN. THIS STEADY SW FLOW COULD ALSO ALLOW
A BUILDING SWELL IN THE GULF OF MAINE TO EXCEED 5 FT...WHICH COULD
IMPACT THE NE WATERS. NOT CONFIDENT ENOUGH ON THESE POTENTIAL
SMALL CRAFT CONDITIONS TO SUPPORT AN ADVISORY AT THIS TIME...BUT
IT MAY BE NEEDED.

OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...MODERATE TO HIGH
CONFIDENCE.

MONDAY NIGHT-TUESDAY...A COLD FRONT MOVES ACROSS THE WATERS WITH
SHOWERS. WINDS GUST TO 20-22 KNOTS IN ADVANCE OF THE FRONT...THEN
SHIFT NORTHWEST WITH THE FRONTAL PASSAGE. SEAS 5-6 FEET ON THE OUTER
WATERS. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR THE OUTER WATERS.

WEDNESDAY-THURSDAY...WINDS AND SEAS WILL BE BELOW SMALL CRAFT LEVELS.

&&

.FIRE WEATHER...
STILL WATCHING FIRE WEATHER CONDITIONS FOR MONDAY. MINIMUM
AFTERNOON RELATIVE HUMIDITY VALUES DROPPING TO 20-30 PERCENT WITH
AFTERNOON WIND GUSTS OF 20 TO PERHAPS 25 MPH.
THEREFORE...MARGINALLY CLOSE TO RED FLAG CONDITIONS ON MONDAY.

&&

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

&&

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


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