Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 041947 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 347 PM EDT MON MAY 4 2015 .SYNOPSIS...
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MILD WEATHER PREVAILS THIS EVENING AND OVERNIGHT AHEAD OF AN APPROACHING COLD FRONT. THIS BOUNDARY MAY TRIGGER ISOLATED TO WIDELY SCATTERED SHOWERS TUESDAY ALONG WITH WARM TEMPERATURES CONTINUING. HIGH PRESSURE BUILDS IN BEHIND THE FRONT WED PROVIDING MILD TEMPERATURES BUT LOWER HUMIDITY THAN TUESDAY. WARMER WEATHER FOLLOWS THU AND FRI AS THE HIGH SLIPS SOUTH AND THEN EAST OF NEW ENGLAND. A COLD FRONT LATE THIS WEEKEND INTO EARLY NEXT WEEK MAY YIELD SCATTERED SHOWERS. OTHERWISE DRY...WARM AND MORE HUMID WEATHER PREVAILS THIS WEEKEND.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/... 120 PM UPDATE... TEMPERATURES HAVE WARMED INTO LOW TO MID 80S ACROSS MUCH OF SOUTHERN NEW ENGLAND EARLY THIS AFTERNOON...WHICH IS THE WARMEST IT HAS BEEN SINCE LAST OCTOBER. MUCH OF SOUTH COAST...CAPE COD AND ISLANDS HAVE BEEN HOLDING IN UPPER 50S AND LOWER 60S DUE TO INFLUENCE OF COLDER OCEAN. EXPECT TEMPERATURES TO RISE A FEW MORE DEGREES THROUGH LATE AFTERNOON. STARTING TO SEE SOME CLOUDS FORM NEAR HIGHER TERRAIN...BUT THESE CLOUDS WILL STILL ALLOW FOR PLENTY OF SUNSHINE THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... TONIGHT... HIGH PRES WILL GIVE WAY TO AN APPROACHING COLD FRONT FROM THE NW. THIS FRONT WILL BE SLOWING AS IT BEGINS TO PARALLEL STEERING FLOW ALOFT. THEREFORE...ASIDE FROM INCREASING HIGH-MID CLOUDS ACROSS THE REGION ESPECIALLY AFTER MIDNIGHT IT WILL LIKELY TAKE UNTIL 09Z OR LATER FOR ENOUGH MOISTURE FLUX AND LIFT ASSOCIATED WITH THE FRONT TO YIELD -SHRA ACTIVITY MAINLY ACROSS NW MA. THIS BAND WILL GRADUALLY SHIFT TO THE S THROUGH THE MORNING...SO A DAMP COMMUTE IS EXPECTED FOR SOME. LOOKING AT BUFKIT PROFILES...SOUNDINGS ARE RELATIVELY STABLE FOR THE OVERNIGHT AND MORNING TIMEFRAME SO WILL RUN WITH JUST SHOWERS RATHER THAN INCLUDING ANY TSRA. THE INCREASING CLOUDS AND LOW LVL MOISTURE SUPPORT EVEN MILDER MINS THAN SUN NIGHT...MAINLY IN THE 50S ACROSS THE BOARD. TUE... SLOWING AND GRADUALLY DISSIPATING COLD FRONT WILL BE MAKING IT/S WAY FROM N-S ACROSS THE REGION. IT/S TIMING IS SLOW ENOUGH THAT IT WILL LIKELY BE JUST BARELY AT THE N BORDER OF MA BY 12Z AND ONLY JUST OFF THE S COAST BY 00Z. THEREFORE...THERE WILL BE A FOCUS FOR LIFT IN THE VICINITY PRETTY MUCH ALL DAY AND PWATS WILL INCREASE TO AROUND 1.25 INCHES. THEREFORE...LIKELY SEE PLENTY OF -SHRA ACTIVITY ACROSS THE REGION...ALTHOUGH A SLOW IMPROVEMENT WILL BEGIN FROM N-S THROUGH THE AFTERNOON AS STRONG RIDGING MOVES IN BEHIND THE EXITING FRONT. THERE IS SOME QUESTION OF CONVECTIVE POTENTIAL. SOUNDINGS ARE CONDITIONALLY UNSTABLE IN A NARROW CORRIDOR MAINLY THROUGH CT/RI AND SE MA /IN ESSENCE WHERE BETTER EARLY MORNING HEATING IS EXPECTED/. THIS WILL LIKELY YIELD CAPE VALUES ON THE ORDER OF 300-500J/KG BY THE AFTERNOON WITH MID LVL LAPSE RATES AROUND 6.5C/KM. THEREFORE...STILL CAN/T RULE OUT SOME ISOLATED THUNDER MAINLY ACROSS THE S AND MAINLY DURING THE AFTERNOON HOURS. MAIN ISSUE WILL BE A BRIEF HEAVY DOWNPOUR THANKS TO THE HIGHER PWAT AIRMASS. && .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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348 PM UPDATE... HIGHLIGHTS... * SPRING TO SUMMER-LIKE TEMPS MUCH OF THE PERIOD * MAINLY DRY WEATHER WED THRU SAT WITH INCREASING RISK OF SHOWERS SUN/MON SYNOPTIC OVERVIEW AND MODEL/GUIDANCE EVALUATION... 00Z ECENS/EPS AND 12Z GEFS ENSEMBLES IN GOOD AGREEMENT ON THE LARGE SCALE FLOW THIS PERIOD WHICH FEATURES AN ANOMALOUS CLOSED LOW EVOLVING OVER THE NORTHWEST ATLANTIC OF ABOUT -3 STD DEVIATIONS FROM CLIMO...ALONG WITH A RIDGE CENTERED OVER THE GREAT LAKES AND OHIO VALLEY. THIS PLACES NEW ENGLAND IN A DRY NORTHWEST FLOW REGIME WED THRU FRI. BY THE WEEKEND THE UPPER AIR PATTERN BECOMES SOMEWHAT PROGRESSIVE WITH THE CLOSED LOW MOVING INTO THE CENTRAL ATLANTIC ALLOWING GREAT LAKES RIDGE/HEIGHT ANOMALY TO ADVECT EASTWARD INTO NEW ENGLAND...CONTINUING THE DRY WEATHER INTO AT LEAST THE FIRST HALF OF THE WEEKEND. THEN BY LATE IN THE WEEKEND AND ESPECIALLY EARLY NEXT WEEK THE QUESTION BECOMES HOW QUICKLY DOES THE RIDGE ERODE AS UPSTREAM TROUGH APPROACHES. IN ADDITION...RIDGE BECOMES SOMEWHAT OF A DIRTY RIDGE WITH MOISTURE FROM REMNANT CLOSED LOW OVER THE SOUTHEAST STATES ADVECTING NORTHWARD UP THE EASTERN SEABOARD. AS EXPECTED AT THIS TIME RANGE THE DETERMINISTIC RUNS OF THE 12Z ECMWF AND 12Z GFS HANDLE THIS DIFFERENTLY ALONG WITH ENSEMBLES. THUS FORECAST CONFIDENCE BECOMES LOW ON SHOWER POTENTIAL LATER THIS WEEKEND INTO EARLY NEXT WEEK. TEMPERATURES... BRIEF COOL DOWN OR BETTER LABELED AS NOT AS WARM WED /LOW TO MID 70S/ IN THE POST FRONTAL AIRMASS ALONG WITH LOWER DEW PTS /30S/. HOWEVER AS SURFACE HIGH SLIPS SOUTH OF NEW ENGLAND THU...SURFACE WINDS BECOME WSW AND THIS WILL SUPPORT TEMPS WARMING TO 75 TO 80 AND POTENTIALLY CLIMBING INTO U70S AND L80S BY FRI. WARM WEATHER CONTINUES SAT WITH HIGHS IN THE L80S AWAY FROM THE SOUTH COAST. IN ADDITION WITH SSW SURFACE WINDS DEW PTS WILL CLIMB INTO THE 50S. STILL COMFORTABLE BUT THIS WILL RESULT IN NIGHTLY TEMPS NOT AS COOL ALONG WITH PATCHY FOG. SUNDAY...TRICKY AS POTENTIAL BACKDOOR FRONT IMPACTS EASTERN MA AND POSSIBLY RI. NOT AS WARM EARLY NEXT WEEK GIVEN LIKELY CLOUD COVER...SOUTHERLY FLOW AND RISK OF SHOWERS. HOWEVER TEMPS WILL STILL AVERAGE WARMER THAN NORMAL. PRECIPITATION... AS MENTIONED ABOVE DRY PATTERN PREVAILS WED THRU FRI AND PROBABLY INTO SAT. RISK OF SHOWERS INCREASES SUNDAY AS UPSTREAM TROUGH APPROACHES ALONG WITH REMNANT MOISTURE OFFSHORE FROM CLOSED LOW OVER THE SOUTHEAST STATES LATER THIS WEEK. HOWEVER GREATEST RISK OF SHOWERS APPEARS TO BE EARLY NEXT WEEK AS UPSTREAM TROUGH GETS CLOSER TO THE REGION AND BEGINS TO INTERACT WITH DEEPER MOISTURE ALONG AND OFF THE EASTERN SEABOARD.
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&& .AVIATION /20Z MONDAY THROUGH SATURDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. HIGH CONFIDENCE THROUGH TUE NIGHT. SW WINDS MAY BRING SOME 20-25KT GUSTS THROUGH EARLY EVENING ACROSS INTERIOR...OTHERWISE VFR THROUGH TONIGHT. VFR CIGS TUE AS COLD FRONT DROPS THROUGH SOUTHERN NEW ENGLAND...WITH SCATTERED SHOWERS POSSIBLE. MAY SEE SOME MVFR CIGS NEAR S COAST TUE AFTERNOON. VFR TUE NIGHT. KBOS TAF...HIGH CONFIDENCE IN TAF. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...WEDNESDAY THROUGH SATURDAY... 348 PM UPDATE... HIGH CONFIDENCE FOR VFR AND DRY WEATHER. LOW RISK FOR PATCHY FOG EACH NIGHT BETWEEN MIDNIGHT AND SUNRISE WITH LOCAL IFR CIGS/VSBYS.
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&& .MARINE...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY/... THROUGH TODAY...HIGH CONFIDENCE. SW WINDS MAY GUST TO AROUND 20KT NEAR SHORE THIS AFTERNOON. TONIGHT INTO TOMORROW...MODERATE CONFIDENCE. THE SW FLOW WILL SLOWLY GIVE WAY TO W FLOW AS A COLD FRONT CROSS THE WATERS DURING THE TUE EVENING HOURS. WITH THE PERSISTENT SW FLOW TODAY...SOME SUGGESTION WIND DRIVEN SEAS COULD APPROACH 5 FT ON THE OCEAN WATERS...BUT DO NOT HAVE HIGH ENOUGH CONFIDENCE TO ISSUE A SMALL CRAFT ADVISORY AT THIS TIME. THIS WILL NEED TO BE MONITORED. CONDITIONS IMPROVE ON TUE IF THEY REACH CRITERIA AT ALL...BUT SOME SHOWERS AND POSSIBLY EVEN A THUNDERSHOWER OUTLOOK...WEDNESDAY THROUGH SATURDAY... 348 PM UPDATE... WEDNESDAY...HIGH PRES OVER THE WATERS WITH TRANQUIL/DRY WEATHER AND GOOD VSBY. HIGH FORECAST CONFIDENCE. THURSDAY...HIGH SLIPS SOUTH OF NEW ENGLAND WITH WINDS BECOMING SSW. TRANQUIL/DRY WEATHER WITH GOOD VSBY CONTINUES. FRIDAY...HIGH PRES MOVES EAST OF NEW ENGLAND. DRY/TRANQUIL WEATHER CONTINUES.
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&& .FIRE WEATHER...
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RED FLAG WARNING REMAINS POSTED PRIMARILY FOR THE TERRAIN INFLUENCE IN WESTERN MASSACHUSETTS. TEMPERATURES IN THE UPPER 70S AND LOW 80S WILL COMBINE WITH DEWPOINTS IN THE UPPER 30S AND LOW 40S TO YIELD MIN RH VALUES AROUND 20 PERCENT THIS AFTERNOON. SW WINDS 10 TO 15 MPH WILL OCCASIONALLY GUST TO 20-25 MPH THROUGH 7 PM. SCATTERED SHOWERS EXPECTED TUE BUT RAINFALL AMOUNTS SHOULD BE UNDER 0.25 INCH. LIGHT W/NW WINDS EXPECTED WITH MORE CLOUD COVER. 348 PM UPDATE... THURSDAY...LOW RISK OF ELEVATED FIRE WEATHER CONCERNS WITH MIN RH VALUES DIPPING TO 25 TO 30 PERCENT ALONG WITH WSW WIND GUSTS UP TO 20 MPH. SUSTAINED WINDS WILL BE LESS 10-15 MPH BUT AGAIN GUSTS UP TO 20 MPH AND PERHAPS 25 MPH ARE POSSIBLE. WHILE ISOLATED OR WIDELY SCATTERED SHOWERS ARE POSSIBLE TUE MOST OF THE REGION WILL BE DRY WITH ANY RAINFALL LIKELY LESS THAN 0.25 INCHES.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR MAZ002>004- 008>012-026. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...NOCERA NEAR TERM...BELK/DOODY/JWD SHORT TERM...DOODY LONG TERM...NOCERA AVIATION...NOCERA/DOODY/JWD MARINE...NOCERA/DOODY FIRE WEATHER...STAFF

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