Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBOX 301807 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 207 PM 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/... 2 PM UPDATE... EROSION OF THE LOW- TO MID-LEVEL DECK LIKELY SUBSEQUENT OF MIXING WITHIN THE BOUNDARY-LAYER OF DRIER AIR AS THE BAND ENCROACHES TO THE W INTO REGIONS WHICH SAW ABUNDANT SUNSHINE IN THE MORNING. WILL STILL CONTINUE WITH SLIGHT CHANCE / ISOLATED WORDING OF SPRINKLES. MUCH OF THIS DERIVED FROM A CONSENSUS OF FORECAST SKY COVER. OTHERWISE EVALUATING UPSTREAM. STOUT ENERGY ROTATING ROUND THE LOW OFF THE SE-CANADIAN MARITIMES LOBING INTO NEW ENGLAND LENDING TO ANOTHER WAVE AND ATTENDANT BACKDOOR COLD FRONT ACROSS MAINE. THIS IS GOING TO BE OUR WEATHER FOCUS INTO THE OVERNIGHT PERIOD ON INTO FRIDAY. TEMPS QUITE CHILLY BEHIND THE FRONT ALONG WITH BREEZY NE- WINDS. CLOUDS SHOULD FILL BACK IN FROM THE NE AS WE GO LATER INTO THE DAY. FORECAST HIGHS REMAIN AROUND THE LOW- TO MID-60S. COOLER FOR THOSE LOCATIONS ALONG THE SHORE WITH THE ONSHORE FLOW...AND AREAS WHICH REMAINED BENEATH THE CLOUD DECK FOR A LONGER PERIOD OF TIME. && .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 /18Z THURSDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. .SHORT-TERM /THROUGH FRIDAY NIGHT/... REST OF TODAY...HIGH CONFIDENCE. BKN LOW-END VFR CIGS BENEATH WHICH A SPRINKLE IS POSSIBLE. E-WINDS THOUGH CONTOURED TO THE COASTLINE WITH SEA-BREEZE SUPPORT /I.E. A MORE SE-WIND FOR THE BOSTON TERMINAL/. TONIGHT...HIGH CONFIDENCE. COLD FRONT DROPS S. E-WINDS BACKING NE. GUSTS UP TO 25 KTS BEHIND THE FRONT POSSIBLE. CHANCE OF -SHRA WITH WIND SHIFT. LOW- END VFR DROPPING TO MVFR CIGS BEHIND THE FRONT. FRIDAY...HIGH 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. FRIDAY NIGHT...MODERATE CONFIDENCE. LOW-END VFR CIGS POSSIBLE ALONG WITH ANOTHER SHOT OF -SHRA. WINDS TURNING N. MAY SEE IFR CIGS AND DRIZZLE ACROSS E/SE-COASTAL TERMINALS WITH THE ONSHORE FLOW. KBOS TAF...HIGH CONFIDENCE IN TAF. WILL HOLD THE WIND DIRECTION PRESENTLY AT ESE. COLD FRONT SWEEPING DURING THE EVENING HRS DURING WHICH TIME THERE IS A BETTER CHANCE FOR MVFR CIGS. WINDS SHIFT NE...BREEZY. 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. 2 PM UPDATE...NO MAJOR CHANGES AT THIS TIME. 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

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