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 300158
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
958 PM EDT FRI MAY 29 2015

.SYNOPSIS...
DRY WEATHER TONIGHT AND SATURDAY THANKS TO AN AREA OF HIGH
PRESSURE. A COLD FRONT WILL SLOWLY MOVE ACROSS THE REGION
SUNDAY...THEN STALL SOUTH OF NEW ENGLAND EARLY NEXT WEEK. THIS
WILL BRING A CHANCE OF SHOWERS AND A FEW THUNDERSTORMS
SUNDAY...AND A PERIOD OF RAIN EARLY NEXT WEEK. HIGH PRESSURE
BRINGS DRY WEATHER FOR THE LATTER PART OF THE WEEK.

&&

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

1000 PM UPDATE...

OVERALL TREND IN THE FORECAST IS ON TRACK FOR THIS EVENING. HIGH
LEVEL CLOUDS CONTINUE TO MOVE OVERHEAD WITHIN WAA PATTERN.
NOTICES STRATUS AND FOG BEGINNING TO PUSH OVER ACK OVER THE PAST
HOURS. ALSO A SITE OR TWO ALONG LONG ISLAND IS SEEING THE
STRATUS/FOG AS WELL.

STILL A LOT OF UNCERTAINTY ON THE POTENTIAL FOR DENSE FOG ALONG
THE COAST LINES OVERNIGHT INTO TOMORROW MORNING. HRRR SEEMS TO BE
TO BULLISH ON THE TIMING AND HOW FAR NORTH THE FOG WILL SPREAD.
UNLIKE THE PAST FEW NIGHTS...BUFKIT SOUNDINGS DO SHOW THE
POTENTIAL FOR FOG ALONG THE SOUTH COAST. WILL CONTINUE TO MONITOR
OVER THE NEXT FEW HOURS ON THE FOG POTENTIAL.

PREVIOUS DISCUSSION...

THE FOG SHOULD LINGER LONGEST ALONG THE NORTH SHORE AND MAY
TAKE AN EXTRA COUPLE OF HOURS TO LEAVE THERE.

SATELLITE IMAGERY ALSO SHOWS A FOG BANK SOUTH OF NANTUCKET. AS
WINDS TURN OUT OF THE SOUTH THEY SHOULD ADVECT THE FOG NORTH
TOWARD NEW ENGLAND. LOW CONFIDENCE ON HOW FAR NORTH THESE LOW
CLOUDS ADVECT...BUT PROBABLY AFFECT THE SOUTH COAST AND PERHAPS AS
FAR NORTH AS THE MA PIKE. SOME FOG IS ALSO EXPECTED AND CAN/T RULE
OUT A PERIOD OF DENSE FOG ACROSS SOUTHEAST NEW ENGLAND...BUT
CONFIDENCE ON THAT IS LOW.

OTHERWISE...A DRY NIGHT OTHER THAN PERHAPS A BIT OF MIST TOWARD
DAYBREAK ALONG WITH THE FOG ACROSS THE SOUTHEAST NEW ENGLAND COAST.
LOW TEMPS MAINLY IN THE UPPER 50S TO THE LOWER 60S.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
***A WARM AND SOMEWHAT HUMID SATURDAY AFTERNOON IS ON TAP INLAND
  FROM THE SOUTH COAST***

HIGH PRESSURE MOVING OFF THE COAST WILL ALLOW A WARMER AND MORE
HUMID AIRMASS TO OVERSPREAD SOUTHERN NEW ENGLAND ON SATURDAY.  LOW
CLOUDS THAT FORM SOUTH OF MA PIKE SHOULD SCOUR OUT BY SATURDAY
AFTERNOON IF NOT EARLIER FOR MOST OF THE REGION.  HOWEVER...LOW
CLOUDS AND FOG PATCHES MAY LINGER ACROSS THE IMMEDIATE SOUTH
COAST/CAPE/ISLANDS.

OTHERWISE...HIGH TEMPS SHOULD REACH INTO THE MIDDLE TO UPPER 80S TO
THE NORTHWEST OF A BOSTON TO PROVIDENCE LINE.  THE WARMEST OF THOSE
READINGS SHOULD BE FOUND IN THE MERRIMACK VALLEY.  TO THE SOUTHEAST
OF A BOSTON TO PROVIDENCE LINE...GUSTY SOUTHWEST WINDS WILL HOLD
HIGH TEMPS IN THE 70S TO NEAR 80.  IN FACT...SOUTHWEST WIND GUSTS OF
20 TO 30 MPH ARE EXPECTED FOR MOST OF THE REGION SATURDAY AFTERNOON
WITH GOOD MIXING.

UPPER LEVEL RIDGING SHOULD RESULT IN MAINLY A DRY DAY ACROSS THE
REGION.  BEST FORCING/INSTABILITY AND DYNAMICS WILL BE WELL TO OUR
NORTHWEST WITH AN APPROACHING COLD FRONT.  JUST A LOW RISK OF A SPOT
SHOWER/THUNDERSTORM LATE SATURDAY AFTERNOON/EARLY EVENING ACROSS
NORTHWEST MA.

SATURDAY NIGHT...

A COLD FRONT WILL BE SLOWLY APPROACHING OUR REGION FROM THE WEST.  A
SOUTHWEST LOW LEVEL JET WILL RESULT IN A MILD NIGHT...WITH LOW TEMPS
ONLY DROPPING TO BETWEEN 60 AND 65.  DRY WEATHER SHOULD DOMINATE THE
FIRST PART OF THE NIGHT...BUT WE MAY SEE SOME SCATTERED SHOWERS AND
PERHAPS AN EMBEDDED THUNDERSTORM OR TWO DEVELOP OVERNIGHT.  THIS IS
RESPONSE TO LOW LEVEL JET AND A BURST OF INSTABILITY.  ACTIVITY WILL
PROBABLY BE HIT AND MISS THROUGH DAYBREAK SUNDAY...WITH THE BULK OF
IT TO THE NORTHWEST OF I-95.  BULK OF LOW CLOUDS SHOULD BE CONFINED
TO THE SOUTHEAST NEW ENGLAND COAST.  ENOUGH WIND IN THE BOUNDARY
LAYER MAY PREVENT A LOT OF FOG FROM DEVELOPING...BUT STILL CAN NOT
RULE OUT SOME DEVELOPING.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
BIG PICTURE...

CHANGEABLE PATTERN THROUGH THE WEEK. UPPER RIDGE MOVES OFFSHORE
SUNDAY. UPPER TROUGH SLOWLY CROSSES THE NORTHEAST USA EARLY WEEK.
UPPER RIDGE FROM THE WESTERN USA THEN SHIFTS EAST OVER THE EASTERN
USA LATE WEEK.

DIFFERENCES AMONG THE MODELS REGARDING TIMING WITH THE UPPER TROUGH
EARLY WEEK WITH THE GGEM THE FASTEST AND ECMWF SLOWEST. WE USED A
MODEL CONSENSUS IN TIMING.

THE DAILIES...

SUNDAY THROUGH TUESDAY... COLD FRONT EITHER OVER OR JUST NORTH OF
NORTHERN MASS SUNDAY MORNING WILL MOVE SOUTH ACROSS THE REGION
DURING THE DAY. PRECIPITABLE WATER VALUES ALONG AND AHEAD OF THE
FRONT WILL BE 1.50 TO 1.75 INCHES WHICH IS AROUND 2 STD DEV ABOVE
NORMAL. TOTALS OF 47-49 AND SHOWALTERS OF 0 TO -2. ALL OF THIS
SUGGESTS SUFFICIENT MOISTURE FOR SHOWERS AND ENOUGH INSTABILITY OVER
THE LOW LEVEL CONVERGENCE TO SUPPORT A FEW THUNDERSTORMS.

DIFFERENCES AMONG THE MODELS ON TIMING THE FROPA BUT ALL MOVE IT
SOUTH OF THE COAST BY SUNDAY EVENING. THE FRONT IS THEN ALIGNED WITH
THE UPPER FLOW AND STALLS. SHORTWAVE MOVING THROUGH THE GREAT LAKES
IS FORECAST TO GENERATE A WAVE ALONG THE FRONT WHICH CROSSES THE
APPALACHIANS MONDAY AND PASSES SOUTH OF NEW ENGLAND TUESDAY. THIS
ALONG WITH HIGH PRESSURE IN EASTERN CANADA SHOULD BRING A COOL
NORTHEAST FLOW TO THE REGION MONDAY AND TUESDAY. MEANWHILE A
SOUTHWEST FLOW CONTINUES ABOVE 5OOO FEET AGL AND SUPPIES LIFT AND
MOISTURE OVER THE TOP. WE WILL MAINTAIN LIKELY POPS MONDAY
DIMINISHING TO CHANCE POPS DURING THE DAY TUESDAY AS THE LOW MOVES
EAST.

WEDNESDAY THROUGH FRIDAY... HIGH PRESSURE BUILDS SURFACE AND ALOFT
BRINGING DRY WEATHER TO SOUTHERN NEW ENGLAND. WITH THE DEMISE OF THE
NORTHEAST MARINE FLOW...MIXING SHOULD RETURN WITH HEIGHTS REACHING
AT LEAST 875 MB WEDNESDAY AND AT LEAST 850 MB THURSDAY AND FRIDAY.
TEMPERATURES AT THE TOP OF THE MIXED LAYER EACH DAY SUGGEST MAX SFC
TEMPS IN THE MID 60S TO LOW 70S WEDNESDAY...70S TO NEAR 80
THURSDAY...AND 75-85 FRIDAY.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

TONIGHT...LOW TO MODERATE CONFIDENCE. SHIFTING WINDS SHOULD PUSH
THE FOG OFF TO THE NORTHEAST SITES TONIGHT. ADDITIONAL FOG SOUTH
OF NEW ENGLAND WILL MOVE UP TO THE SOUTH COAST AND MAY SPREAD
ACROSS CT- RI-SE MASS OVERNIGHT. THIS WILL MEAN IFR/LIFR
CIGS/VSBYS DEVELOPING ALONG THE SOUTH COAST OVERNIGHT AND POSSIBLY
SPREADING ACROSS CAPE COD AND ISLANDS...AND PVD AND BDL.

SATURDAY...MODERATE CONFIDENCE.  ANY LOW CLOUDS/FOG PATCHES SOUTH OF
PIKE PROBABLY SCOUR OUT BY LATE MORNING/EARLY AFTERNOON...EXCEPT
CAPE/ISLANDS WHERE THEY MAY LINGER INTO THE AFTERNOON.  DRY WEATHER
EXPECTED...ALTHOUGH THERE IS A LOW RISK OF A SPOT
SHOWER/THUNDERSTORM ACROSS NORTHWEST MA LATE IN THE AFTERNOON/EARLY
EVENING.

SATURDAY NIGHT...MODERATE CONFIDENCE.  MAINLY VFR TO MARGINAL MVFR
CIGS EXCEPT FAR SOUTHEAST NEW ENGLAND COAST WHERE IFR CIGS/VSBYS ARE
POSSIBLE.  SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM OR TWO WILL
BE POSSIBLE MAINLY ACROSS THE INTERIOR WITH THE HIGHER RISK DURING
THE OVERNIGHT HOURS.

KBOS TERMINAL...LOW CONFIDENCE IN TAF EARLY TONIGHT. LIFR CIGS AND
VSBYS WILL LINGER OVER OR NEAR THE AIRPORT FOR THE FIRST COUPLE OF
HOURS OF THE TAF. ONCE WINDS TURN SOUTH OR SOUTHWEST THAT SHOULD
MOVE THE FOG OFF TO THE NORTHEAST ACROSS CAPE ANN AND OFFSHORE.
LOW CONFIDENCE IN THIS TIMING.

KBDL TERMINAL...LOW TO MODERATE CONFIDENCE IN TAF.  MVFR TO IFR CIGS
MAY DEVELOP AFTER MIDNIGHT...THEN DISSIPATE AFTER SUNRISE.

OUTLOOK...SUNDAY THROUGH WEDNESDAY...MODERATE CONFIDENCE.

SUNDAY... COLD FRONT MOVES ACROSS SOUTHERN NEW ENGLAND FROM NORTH TO
SOUTH. VFR CIGS/VSBYS WITH AREAS OF MVFR IN SHOWERS/THUNDERSTORMS.
SOUTHWEST WINDS TO START...BECOMING NORTHEAST BY EVENING.  WINDS AT
2000-3000 FEET AGL START SOUTHWEST 25-35 KNOTS AND BECOME NORTHEAST
25 TO 30 KNOTS BY EVENING. SOUTHWEST WINDS LINGER THROUGH THE DAY AT
OR ABOVE 5000 FEET.  THIS MAY CREATE SOME LOW LEVEL WIND SHEAR AT
TIMES...DIRECTIONAL SHEAR IN THE VERTICAL IS LIKELY AND SPEED SHEAR
POSSIBLY.

MONDAY THROUGH TUESDAY... MVFR/IFR CIGS AND VSBYS WITH BEST CHANCE
OVER THE COASTAL PLAIN AND EASTERN SLOPES OF THE WORCESTER HILLS.
SHOWERS POSSIBLE THROUGH BOTH DAYS.

WEDNESDAY... VFR WITH A NORTH-NORTHWEST WIND.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...

TONIGHT...MODERATE TO HIGH CONFIDENCE.  WEAK PRESSURE GRADIENT WILL
KEEP WINDS/SEAS BELOW SMALL CRAFT ADVISORY THRESHOLDS.
HOWEVER...AREAS OF FOG MAY DEVELOP OVERNIGHT ACROSS OUR SOUTHERN
WATERS BUT ITS UNCERTAIN IF IT WILL BECOME DENSE.

SATURDAY...MODERATE TO HIGH CONFIDENCE.  EXCELLENT MIXING OVER THE
LAND WILL GENERATE NEAR SHORE SMALL CRAFT WIND GUSTS OF 25 TO 30
KNOTS SATURDAY AFTERNOON.  IN ADDITION...SOUTHEAST SWELL WILL
GENERATE 5 FOOT SEAS ACROSS THE OUTER-WATERS.  THEREFORE...SMALL
CRAFT HEADLINES POSTED FOR ALL WATERS.  AREAS OF FOG MAY BE LOCALLY
DENSE IN THE MORNING ALONG THE SOUTH COAST...SHOULD IMPROVE SOMEWHAT
BY AFTERNOON.

SATURDAY NIGHT...MODERATE TO HIGH CONFIDENCE.  NEAR SHORE SMALL
CRAFT WIND GUSTS SHOULD DIMINISH SATURDAY EVENING.  HOWEVER...5 FOOT
SWELL WILL CONTINUE ACROSS THE OUTER-WATERS.  SOME FOG POSSIBLE SAT
NIGHT...BUT PROBABLY NOT AS WIDESPREAD AS TONIGHT GIVEN SOME MORE
BOUNDARY LAYER WIND.

OUTLOOK...SUNDAY THROUGH WEDNESDAY...MODERATE CONFIDENCE.

SUNDAY...SMALL CRAFT ADVISORY MAY BE NEEDED ON SOME OF THE WATERS. A
COLD FRONT CROSSES THE EASTERN WATERS DURING THE DAY. THE FRONT
CROSSES THE SOUTHERN WATERS SUNDAY EVENING. SHOWERS AND POSSIBLE
THUNDERSTORMS ALONG AND AHEAD OF THE FRONT. EXPECTING SOUTHWEST
GUSTS TO 20 KNOTS AHEAD OF THE FRONT. WINDS THEN SHIFT TO NORTHEAST
AND EAST BEHIND THE FRONT WITH GUSTS TO 20 KNOTS FROM THAT
DIRECTION. SEAS LINGER AROUND 5 FEET ON THE OUTER WATERS.

MONDAY-TUESDAY...SMALL CRAFT ADVISORY MAY BE NEEDED ESPECIALLY ON
THE EASTERN WATERS. NORTHEAST WINDS GUSTING 20 TO 25 KNOTS EACH DAY.
SEAS 5 TO 8 FEET ON THE EASTERN MASS WATERS...AND 3 TO 5 FEET ON THE
SOUTHERN WATERS.

WEDNESDAY...A SMALL CRAFT ADVISORY MAY BE NEEDED...MAINLY ON THE
EASTERN WATERS. DIMINISHING NORTHEAST TO NORTH WINDS. SEAS OF 5 FEET
MAY LINGER ON THE EASTERN WATERS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TO 10 PM EDT SATURDAY FOR
     ANZ230>237-251.
     SMALL CRAFT ADVISORY FROM 2 PM SATURDAY TO 8 AM EDT SUNDAY FOR
     ANZ250-254>256.

&&

$$
SYNOPSIS...WTB/FRANK
NEAR TERM...FRANK/DUNTEN
SHORT TERM...FRANK
LONG TERM...WTB
AVIATION...WTB/FRANK
MARINE...WTB/FRANK


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