Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 050553 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 141 AM EDT TUE MAY 5 2015 .SYNOPSIS...
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A COLD FRONT WILL TRIGGER ISOLATED TO WIDELY SCATTERED SHOWERS TODAY...BUT THE VAST MAJORITY OF THE DAY WILL BE DRY AT A GIVEN LOCATION. HIGH PRESSURE BUILDS IN BEHIND THIS 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 SLIGHTLY MORE HUMID WEATHER PREVAILS THIS WEEKEND.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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150 AM UPDATE... MID/HIGH LEVEL CLOUDINESS CONTINUE WILL CONTINUE TO INCREASE FROM NORTHWEST TO SOUTHEAST OUT AHEAD OF A COLD FRONT EARLY THIS MORNING. MOISTURE IS QUITE LIMITED AHEAD OF THE FRONT...BUT WILL PROBABLY SEE A FEW SPOT SHOWERS DEVELOP TOWARD DAYBREAK BUT NOTHING WIDESPREAD. INCREASING CLOUD COVER AND LACK OF DECOUPLING SURFACE WINDS WILL RESULT IN UNSEASONABLY MILD CONDITIONS INTO THE EARLY MORNING HOURS. LOWS BY DAYBREAK SHOULD ONLY BOTTOM OUT IN THE UPPER 50S TO LOWER 60S...EXCEPT A FEW DEGREES COOLER ACROSS THE CAPE/ISLANDS WITH THE MARINE INFLUENCE ON SOUTHWEST WINDS.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... A WEAKENING COLD FRONT WILL PROVIDE A FOCUS FOR ISOLATED TO SCATTERED SHOWERS ACROSS SOUTHERN NEW ENGLAND. INSTABILITY IS NOT GREAT...BUT CANNOT COMPLETELY RULE OUT THE POSSIBILITY OF AN ISOLATED THUNDERSTORM OR TWO. THE MOST LIKELY SCENARIO IS FOR SCATTERED SHOWERS...ESPECIALLY DURING THE MORNING HOURS. THE FRONT CONTINUES TO WEAKEN DURING THE AFTERNOON...WITH WEAK RIDGING ARRIVING DURING TUESDAY EVENING AND OVERNIGHT. THIS SHOULD MEAN A SLOW DRYING TREND TUESDAY NIGHT. TEMPERATURES WILL STILL BE SLIGHTLY ABOVE NORMAL TUESDAY AND TUESDAY NIGHT. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... 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. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TODAY THROUGH WEDNESDAY/... TODAY...HIGH CONFIDENCE. LLWS AROUND 2 THOUSAND FEET OF 40 TO 50 KNOTS WILL WEAKEN AFTER 12Z. OTHERWISE...VFR CONDITIONS EXPECTED THE VAST MAJORITY OF THE DAY. VERY BRIEF LOCALIZED MVFR CONDITIONS ARE POSSIBLE IN A FEW BRIEF SHOWERS LATER THIS MORNING AND AFTERNOON. TONIGHT AND WEDNESDAY...HIGH CONFIDENCE. MAINLY VFR CONDITIONS. A BRIEF PERIOD OF SCATTERED SHOWERS MAY AFFECT NORTHERN CT AND POSSIBLY A PART OF RI/SOUTHEAST MA FOR A TIME WED AM. THIS MAY RESULT IN VERY BRIEF LOCALIZED MVFR CONDITIONS. KBOS TAF...HIGH CONFIDENCE IN TAF. SEA BREEZES EXPECTED TO DEVELOP THIS AFTERNOON AS A RESULT OF A WEAK PRESSURE GRADIENT. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY... 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... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY/... 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 CONCERN WIND-DRIVEN SEAS COULD APPROACH 5 FT ON THE OCEAN WATERS. IT IS MARGINAL...BUT DID HAVE ENOUGH CONFIDENCE TO ISSUE A SMALL CRAFT ADVISORY ACROSS THE OUTER COASTAL WATERS. THE MAIN RISK WILL BE ROUGH SEAS...BUT COULD SEE A FEW GUSTS TO 25 KT AS WELL AHEAD OF A COLD FRONT. CONDITIONS IMPROVE TUESDAY AFTERNOON. SOME SHOWERS...WITH POSSIBLY EVEN A THUNDERSHOWER. TUESDAY NIGHT...WINDS AND SEAS CONTINUE TO DIMINISH. 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. && .FIRE WEATHER...
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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...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EDT THIS MORNING FOR ANZ250. SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR ANZ254>256.
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&& $$ SYNOPSIS...NOCERA NEAR TERM...FRANK SHORT TERM...BELK LONG TERM...NOCERA AVIATION...FRANK/NOCERA MARINE...BELK/NOCERA FIRE WEATHER...STAFF

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