Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 260654 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 254 AM EDT SUN APR 26 2015 .SYNOPSIS... UNSETTLED WEATHER EXPECTED BOTH EARLY AND LATE THIS WEEK...WITH A BRIEF RESPITE MID WEEK. BELOW NORMAL TEMPERATURES WILL CONTINUE THROUGH MOST OF THIS WEEK AS WELL. && .NEAR TERM /THROUGH TODAY/... 254 AM UPDATE... AS HAS BEEN THE CASE THE PAST FEW NIGHTS...CLOUDS WERE PLAYING A SIGNIFICANT ROLE IN THE FORECAST FOR THIS TIME OF NIGHT. LATEST SATELLITE IMAGERY CONTINUES TO SHOW ABUNDANT MID LEVEL CLOUDS ALONG AND NORTH OF I-90. THIS HAS KEPT TEMPERATURES FROM DROPPING OF AS MUCH AS THEY MIGHT HAVE WITH THE LIGHT WINDS AND LOW LEVEL DRY AIR IN PLACE. FARTHER SOUTH...A FROST ADVISORY CONTINUES ACROSS NORTHERN CT...AND PORTIONS OF RI AND SOUTHEAST MA. THESE AREAS RECENTLY CLEARED...BUT IT IS ONLY A MATTER OF TIME BEFORE MORE CLOUDS ARRIVE FROM THE NORTH AND EAST. 06Z MESONET TEMPERATURES SHOWED MANY AREAS WITHIN THE FROST ADVISORY AREA JUST A LITTLE HIGHER THAN THE NORMAL RANGE WHERE FROST WOULD DEVELOP. THE EXPECTATION IS WITH A BRIEF PERIOD OF CLEARING...TEMPERATURES WILL FALL QUICKLY AND FROST WILL REMAIN A POSSIBILITY. THE UPPER LOW WHICH HAS BEEN OVER THE MARITIMES THE PAST DAY OR SO IS EXPECTED TO MOVE SLIGHTLY CLOSER TO OUR REGION TODAY. THUS WE WILL BE IN A MORE FAVORABLE POSITION FOR DIURNAL CLOUDS AND SHOWERS. SKIES SHOULD START OFF PARTLY TO MOSTLY SUNNY THEN CLOUDS DEVELOP ALONG WITH A FEW SPOTTY SHOWERS. THESE SHOWERS ARE MORE LIKELY TO OCCUR NORTH OF THE MASS PIKE. HIGH TEMPERATURES SHOULD BE IN THE 50S ONCE AGAIN...THOUGH IF ENOUGH SUNSHINE PEEKS THROUGH THE CLOUDS...COULD SEE TEMPS NEAR 60 THROUGH THE CONNECTICUT VALLEY AND IN PARTS OF RI AND SOUTHEASTERN MA. && .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/... TONIGHT...ISOLATED TO SCATTERED SHOWERS WILL CONTINUE TO AFFECT SOUTHERN NEW ENGLAND WITH THE UPPER LOW JUST EAST OF THE AREA. WITH CLOUDY SKIES AND RAIN SHOWERS...EXPECTING TEMPERATURES TO BE A BIT WARMER THAN EITHER OF THE PREVIOUS TWO NIGHTS WITH LOWS IN THE UPPER 30S TO THE LOWER 40S. MONDAY...UPPER LOW RETROGRADES EVEN FURTHER WEST...AND INDUCES SOME LOW LEVEL MOISTURE CONVERGENCE...BESIDES THE COLD POOL ALOFT...TO SUPPORT SHOWERS. INCREASED POPS TO LIKELY ACROSS PORTIONS OF EASTERN MA...ESPECIALLY NORTHEAST MA...WHICH WILL BE CLOSER TO THE BETTER DYNAMICS. THAT SAID...STILL NOT EXPECTING A WASHOUT MONDAY WITH THE GREATEST RISK FOR SHOWERS IN THE AFTERNOON. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... HIGHLIGHTS... * RISK FOR SHOWERS AT TIMES BUT DRY MOST OF PERIOD * LOW CONFIDENCE AFTER WEDNESDAY OVERVIEW...PERSISTENT UPPER TROF OVER MARITIMES RETROGRADES EARLY IN THE WEEK BEFORE MOVING BACK OFFSHORE. SOUTHERN STREAM ENERGY WHICH CAME ASHORE LAST NIGHT IN CA MAY PHASE WITH NORTHERN STREAM ENERGY LATE IN THE WEEK. OPERATIONAL GFS DOES NOT SHOW PHASING. THE 12Z ECMWF DOES SHOW PHASING LIKE ITS PREDECESSOR...BUT ALSO LIKE ITS PRIOR RUN...STILL TAKES THE SURFACE LOW WELL SOUTH OF NEW ENGLAND. THE ECMWF HAS SHOWN BETTER RUN TO RUN CONTINUITY AND ITS 12Z OPERATIONAL RUN SEEMS FAIRLY CONSISTENT WITH ITS 00Z ENSEMBLE MEAN. THE OPERATIONAL GFS RUNS SHOW LITTLE RUN TO RUN CONTINUITY...AND ITS ENSEMBLES ARE WIDELY DISPERSED WITH MANY MEMBERS SHOWING NO SURFACE LOW OFF THE MID ATLC COAST AND A FEW OTHERS DEPICTING AN INTENSE COASTAL LOW JUST SE OF NEW ENGLAND. ALTHOUGH OVERALL CONFIDENCE IS LOW AFTER WEDNESDAY...TEND TO HAVE A LITTLE MORE CONFIDENCE IN THE ECMWF SOLUTION AT THIS TIME GIVEN ITS BETTER INTERNAL CONSISTENCY. DETAILS... MONDAY NIGHT...MAY SEE SHOWERS LINGER INTO THE EVENING HOURS BEFORE GRADUALLY DISSIPATING AND UPPER TROF STARTS TO SHIFT SE IN ADDITION TO LOSS OF DAYTIME HEATING. TUESDAY...HAVE KEPT SLIGHT CHANCE OF SHOWERS FOR THE AFTERNOON IN THE EAST GIVEN SOME LINGERING MOISTURE...CYCLONIC FLOW AND PROXIMITY OF COLD POOL ALOFT. WEDNESDAY AND THURSDAY...WEDNESDAY IS LOOKING DRY FOR NOW. GFS BRINGS UPPER SHORT WAVE TOWARD NEW ENGLAND LATE IN DAY/EVENING BUT ECMWF HOLDS IT BACK. ENOUGH UNCERTAINTY THAT HAVE JUST LOW END SLIGHT CHANCE POPS FOR THURSDAY. THURSDAY NIGHT THROUGH SATURDAY...A LOT OF UNCERTAINTY FOR THIS PERIOD DEPENDENT UPON EVOLUTION OF PROBABLE LOW DEVELOPMENT OFF THE MID ATLC COAST. THE ECMWF SHOWS BEST CONSISTENCY RUN TO RUN AND WITH ITS ENSEMBLES SO LEANING IN THAT DIRECTION FOR THE MOMENT. THIS WOULD SUGGEST THE POTENTIAL OF A SIGNIFICANT SURFACE LOW FORMING NEAR THE MID ATLC COAST BUT PROBABLY REMAINING SE OF NEW ENGLAND. IT IS POSSIBLE THAT BY SATURDAY WILL SEE BUILDING HEIGHTS ALOFT AND INCREASING THICKNESSES AS A RIDGE AMPLIFIES OVER THE OH VALLEY AND ATTEMPTS TO BUILD TOWARD NEW ENGLAND. THIS MAY SIGNAL THE START OF A WARMER PERIOD FOR THE AREA. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TODAY...HIGH CONFIDENCE. VFR WITH LIGHT WINDS. SEA BREEZES EXPECTED...ESPECIALLY ALONG THE EAST COAST OF MA. POSSIBLE BRIEF MVFR IN SPOTTY SHOWERS. TONIGHT...HIGH CONFIDENCE. VFR WITH LIGHT WINDS. POSSIBLE BRIEF MVFR IN SPOTTY SHOWERS. MONDAY...VFR MOST OF THE TIME. AREAS OF MVFR CIGS/VSBYS IN SCATTERED SHOWERS...ESPECIALLY IN THE AFTERNOON. KBOS TAF...HIGH CONFIDENCE IN OVERALL TAF. SEA BREEZE EXPECTED... BUT ONSET TIMING MAY BE OFF BY AN HOUR OR SO. KBDL TAF...HIGH CONFIDENCE IN OVERALL TAF. OUTLOOK...MONDAY NIGHT THOUGH THURSDAY... MONDAY NIGHT...VFR MOST OF THE TIME BUT AREAS OF MVFR CIGS/VSBYS IN SCATTERED SHOWERS. TUESDAY THROUGH THURSDAY...VFR CONDITIONS APPEAR LIKELY AT THIS TIME. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. HIGH CONFIDENCE. RELATIVELY TRANQUIL WINDS AND SEAS EXPECTED THROUGH MONDAY. LIGHT AND VARIABLE WINDS BECOME MORE NORTHWEST TONIGHT...THEN MORE NORTHERLY MONDAY. OUTLOOK...MONDAY NIGHT THROUGH THURSDAY... MODERATE TO HIGH CONFIDENCE. ENOUGH NORTHERLY GRADIENT ANTICIPATED MON NIGHT INTO TUE MORNING THAT SMALL CRAFT ADVISORY CONDITIONS MIGHT BE MET...ESPECIALLY COASTAL WATERS TO THE EAST. MAY TAKE UNTIL TUE EVENING BEFORE SEAS SUBSIDE BACK BELOW 5 FEET. OFFSHORE LOW MAY BRING INCREASING WINDS AND SEAS...PERHAPS NEAR OR ABOVE SMALL CRAFT ADVISORY THRESHOLDS...TO THE OUTER SOUTH COASTAL WATERS LATE THU OR THU NIGHT...BUT CONFIDENCE IS LOW ON THE EVOLUTION OF THE WIND FIELD FOR THAT TIME FRAME GIVEN HIGHER THAN AVERAGE NUMERICAL WEATHER PREDICTION MODEL UNCERTAINTIES. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR CTZ002>004. MA...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MAZ017-018. RI...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR RIZ001-003. MARINE...NONE. && $$ SYNOPSIS...BELK/THOMPSON NEAR TERM...BELK/THOMPSON SHORT TERM...BELK LONG TERM...THOMPSON AVIATION...BELK/THOMPSON MARINE...BELK/THOMPSON

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