Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 301415
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1015 AM EDT THU APR 30 2015

.SYNOPSIS...

ALTHOUGH WEAK HIGH PRESSURE REMAINS IN CONTROL...A SERIES OF UPPER
LEVEL DISTURBANCES WILL KEEP SOME CLOUDS AS WELL A FEW SHOWERS
AROUND THROUGH THE END OF THE WEEK. COASTAL LOW PRESSURE WILL
PASS WELL SOUTH OF NEW ENGLAND FRIDAY AND SATURDAY...BRINGING COOL
TEMPERATURES ESPECIALLY ALONG THE COAST. HIGH PRESSURE BUILDS
OVER THE REGION DURING THE WEEKEND AND EARLY NEXT WEEK. A COLD
FRONT SWEEPS SOUTH ACROSS THE REGION LATE TUESDAY OR TUESDAY
NIGHT.

&&

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

10 AM UPDATE...

ISOLATED LIGHT SHOWERS / SPRINKLES WILL PERSIST ALONG AND AHEAD OF
MID-LEVEL ENERGY LOBING ACROSS S NEW ENGLAND ALONG THE W-PERIPHERY
OF THE STUBBORN LOW OFF THE SE-COAST OF CANADA. NONE OF THE NEAR-
TERM HIGH-RES FORECAST GUIDANCE IS HANDLING THIS WELL AS ACTIVITY
IS SO LIGHT. MAINTAINED A FOCUS ON WHERE FORECAST GUIDANCE WAS
EXACERBATING CLOUD COVER COINCIDENCE WITH THE ACCOMPANYING LIFT
PER MID-LEVEL ENERGY OF A FOCUSED LOW- TO MID-LEVEL MOIST PROFILE.
ITS NOT PERFECT...BUT IT WILL DO THE TRICK OF CONVEYING THAT WITH
CLOUD DECKS ACROSS THE REGION THERE IS THE ISOLATED POSSIBILITY OF
SOME WET WEATHER IN THE FORM OF SPRINKLES.

WILL SEE THE CLOUD BAND SLOWLY PUSH S AND W...BUT EXPECT CLOUDS
TO FILL BACK IN BEHIND AHEAD OF THE BACKDOOR COLD FRONT WHICH IS
SHOWING UP NICELY IN MAINE WITH LIGHT SCATTERED SHOWER ACTIVITY
ALONG AND AHEAD AND NOTABLE COLD CLOUD TOPS ON SATELLITE. GUSTY
WINDS ALSO APPARENT BEHIND THE COLD FRONT.

FEEL THE BETTER CHANCE OF WET WEATHER WILL FALL TOWARDS THE LATER-
HALF OF THE DAY INTO THE OVERNIGHT PERIOD AS A STRONGER MID-LEVEL
VORTICITY LOBE AND ACCOMPANYING SURFACE COLD FRONT DROP S ACROSS
THE REGION AHEAD OF WHICH THERE SHOULD BE ENOUGH LIFT THROUGH A
MID-LEVEL MOIST-ADIABATIC PROFILE TO WARRANT A MODERATE CHANCE OF
LIGHT SHOWERS. THE AFOREMENTIONED BACK DOOR COLD FRONT WILL PUSH
COOLER TEMPERATURES ACROSS THE REGION IN ITS WAKE.

NE-ONSHORE FLOW CONTINUING BENEATH THE THICK CLOUD DECKS OF WHICH
IT WILL LIKELY BE COOLER MORE SO THAN THOSE LOCATIONS SEEING MORE
SUNSHINE /I.E. CT-VALLEY/. HIGHS INTO THE LOW- TO MID-60S...COOLER
ALONG THE COAST WITH ONSHORE FLOW.

&&

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

TONIGHT...

THE BUILDING RIDGE WILL RESULT IN DRYING OF THE COLUMN FROM THE
TOP DOWN WHILE YET ANOTHER WEAK SHORTWAVE ENHANCES LIFT IN THE
LOW-MID LVLS. THEREFORE...SUSPECT WITH ONSHORE FLOW AND AND DRYING
ALOFT...THE DEVELOPMENT OF SOME LOW CLOUDS AND POSSIBLY EVEN SOME
DRIZZLE ACROSS E MA/RI LATE OVERNIGHT. THE QUESTION ON THE DRIZZLE
POTENTIAL IS IN REGARD TO A DRY LAYER NEAR THE FUTURE WHICH MAY
LEAD TO EVAPORATION...BUFKIT PROFILES SHOW THIS. CLOUD COVER KEEPS
MINS MAINLY IN THE 40S YET AGAIN.

FRIDAY...

THE DRIER AIR INTRUSION ALOFT WILL GRADUALLY ERODE THE CLOUD COVER
THROUGH THE MORNING. HOWEVER...THE DAMAGE WILL BE DONE. THE CLOUDY
START COMBINED WITH CONTINUED ONSHORE FLOW OFF THE COLD GULF OF
MAINE WATERS IS LIKELY TO LEAD TO ONE OF THE COOLEST DAYS
RECENTLY. SUSPECT MAINLY 40S NEAR SHORE WITH ONLY MID 50S IN THE
WARMER CT VALLEY OF MA/CT. LESS OF A CHANCE FOR PRECIP GIVEN THE
DRIER AIR THROUGH THE COLUMN...BUT IN ANY CASE...ESPECIALLY WHERE
MODEST INSTABILITY IS AT HAND...CAN/T RULE IT OUT FOR SURE.

&&

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

BIG PICTURE...

UPPER TROUGH MOVES EAST SATURDAY. UPPER RIDGE BUILDS OVER NEW
ENGLAND SUNDAY AND MONDAY. SHORTWAVE AND SUPPORTING UPPER JET MOVE
ACROSS CANADA AND PASS NORTH OF NEW ENGLAND TUESDAY. RIDGE THEN
REBUILDS ON WEDNESDAY. GENERAL AGREEMENT AMONG THE LONG RANGE
MODELS...SO WE USED A BLEND OF THE DATA.

THE DAILIES...

FRIDAY NIGHT...

LINGERING MOISTURE BELOW 700 MB. LIGHT NORTHEAST WIND OVER MOST
OF THE AREA BUT A 15 KNOT WIND AT NANTUCKET. THIS SUGGESTS AT
LEAST PARTLY CLOUDY SKIES THROUGH THE NIGHT.

SATURDAY-SUNDAY...

AIRMASS DRIES OUT WHICH SHOULD ALLOW FOR MORE SUNSHINE. ON
SATURDAY THE SURFACE PATTERN SHOWS A TROUGH OVER EASTERN PA WITH
TOTALS IN THE LOW 50S AND MODEL LI VALUES NEAR +2. WIND FIELDS
ALOFT SHOW NO JETS OR SHORTWAVES. BY SUNDAY THE SURFACE TROUGH
MIGRATES NORTHEAST INTO SOUTHERN NEW ENGLAND WHILE A SHORTWAVE
PASSES OVERHEAD. CONVECTIVE INDICES OVER SOUTHERN NEW ENGLAND SHOW
TOTALS IN THE LOW 50S AND MODEL CAPE 1000-1500 J/KG. THERE ARE
DIFFERENCES IN GEOGRAPHY WITH THE GFS FAVORING WESTERN SECTIONS
WHILE THE ECMWF FAVORS THE MERRIMACK VALLEY AND CENTRAL HILLS.
WILL KEEP POPS BELOW 15 PCT ON SATURDAY BUT FAVOR CHANCE POPS IN
WESTERN OR CENTRAL PARTS OF OUR AREA ON SUNDAY. TEMPS ALOFT 4-6C
ON SATURDAY FAVORING 60S INLAND AND 50S ALONG THE EAST COAST.
TEMPS ALOFT ON SUNDAY 7-8C WHICH FAVORS LOWER 70S INLAND AND 60S
ALONG THE COAST.

MONDAY-TUESDAY...

HIGH PRESSURE IN PLACE WHICH SHOULD BRING FAIR WEATHER MONDAY AND
THE FIRST PART OF TUESDAY. SHORTWAVE PASSING NORTH OF US TUESDAY
WILL PUSH A COLD FRONT ACROSS SOUTHERN NEW ENGLAND LATER TUESDAY
OR TUESDAY NIGHT. PRECIPITABLE WATER VALUES ARE FORECAST AROUND
1.4 INCHES WHICH IS NEAR 2 STD DEVIATIONS ABOVE NORMAL FOR MAY. WE
WILL MAINTAIN CHANCE POPS WITH THE COLD FROPA TUESDAY.

WEDNESDAY...
HIGH PRESSURE BUILDS IN WITH A RETURN TO DRIER WEATHER.

&&

.AVIATION /14Z 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/...

TODAY...HIGH CONFIDENCE.
LOW-END VFR CIGS. PATCHY MVFR MORE LIKELY ACROSS THE HIGH TERRAIN.
E-WINDS PERSIST WITH SPRINKLE ACTIVITY FOR THOSE TERMINALS BENEATH
A BKN-OVC CLOUD DECK.

TONIGHT...HIGH CONFIDENCE.
COLD FRONT DROPS S APPARENT IN MAINE PRESENTLY. E-WINDS BACKING NE.
GUSTS UP TO 25 KTS IMMEDIATE. CHANCE OF -SHRA WITH WIND SHIFT.
LOW-END TO MVFR CIGS...MIXED.

FRIDAY...MODERATE CONFIDENCE.
CONTINUED ONSHORE FLOW. WINDS RELAXING AS THEY TURN E. LOW-END
VFR / MVFR CIGS LIFTING DURING THE MID-MORNING TO MIDDAY HOURS.
-SHRA CHANCES DIMINISH.

KBOS TAF...HIGH CONFIDENCE IN TAF. COLD FRONT SWEEPING DURING THE
EVENING HRS DURING WHICH TIME THERE IS A BETTER CHANCE FOR MVFR
CIGS.

KBDL TAF...HIGH CONFIDENCE IN TAF.

.OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/...

VFR MOST OF THE PERIOD. LOCAL MVFR CIGS/VSBYS POSSIBLE SUNDAY IN
SCATTERED SHOWERS...MAINLY WORCESTER AND POINTS WEST. NORTHEAST
WINDS GUSTING TO 20 KNOTS ON NANTUCKET SATURDAY.

&&

.MARINE...

FORECASTER CONFIDENCE LEVELS...

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

.SHORT-TERM /THROUGH FRIDAY/...HIGH CONFIDENCE.

10 AM UPDATE...

E-FLOW PERSISTING OVER THE WATERS INTO TONIGHT WILL BACK NE AND
PERHAPS BECOME BLUSTERY UP AROUND 20 KTS DURING THE OVERNIGHT
HOURS AS A COLD FRONT /PRESENTLY DROPPING S ACROSS MAINE/ SWEEPS
S ACROSS THE WATERS ALONG WITH THE CHANCE OF SHOWERS. SEAS COULD
RISE EVER BRIEFLY TO 5-FEET ON THE OUTER WATERS...OTHERWISE
MAJORITY OF THE TIMEFRAME HAS SUB-SMALL-CRAFT-ADVISORY CRITERIA.

.OUTLOOK...FRIDAY THROUGH MONDAY...MODERATE TO HIGH CONFIDENCE.

LOW PRESSURE PASSING WELL SOUTHEAST OF NANTUCKET WILL BRING
NORTHEAST WINDS GUSTING TO 20 KNOTS EAST AND SOUTH OF NANTUCKET ON
SATURDAY. SEAS LESS THAN 5 FEET THROUGH THE PERIOD.  SMALL CRAFT
HEADLINES ARE NOT ANTICIPATED.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...

CT...NONE.
MA...NONE.
RI...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...WTB/DOODY
NEAR TERM...WTB/DOODY/SIPPRELL
SHORT TERM...DOODY
LONG TERM...WTB
AVIATION...WTB/DOODY/SIPPRELL
MARINE...WTB/DOODY/SIPPRELL



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