Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 181105 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 705 AM EDT FRI APR 18 2014 .SYNOPSIS... EAST TO NORTHEAST FLOW WILL KEEP TEMPERATURES COOL ALONG COASTAL AREAS...ALONG WITH THE POSSIBILITY OF GRAY SKIES THROUGH THE AFTERNOON. A WEAKENING FRONT WILL PUSH ACROSS THE REGION ON SATURDAY. HIGH PRESSURE WILL RESULT IN DRY AND PLEASANT WEATHER SUNDAY AND MONDAY. LOW PRESSURE WILL LIKELY BRING A PERIOD OF WET WEATHER TO THE REGION SOMETIME LATE TUESDAY INTO WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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705 AM UPDATE... A SCATTERED TO BROKEN DECK OF LOW CLOUDS HAVE MOVED INTO EASTERN NEW ENGLAND EARLY THIS MORNING. THE MAIN UNCERTAINTY TODAY WILL BE THE EXTENT OF LOW CLOUDS AND HOW FAR WEST THEY PROGRESS. FORECAST CONFIDENCE IS BELOW NORMAL IN CLOUD COVER TODAY. WE DO THINK THERE WILL BE A FAIR AMOUNT OF CLOUDS ALONG THE COAST WITH MORE IN THE WAY OF SUNSHINE ACROSS THE CT RIVER VALLEY. THIS IS SUPPORTED BY LATEST MODEL CROSS SECTIONS...BUT LOW CLOUDS CAN OFTEN BE A CHALLENGE FOR THE MODELS SO LATER SHIFTS WILL HAVE TO MONITOR CLOSELY. INVERTED RIDGING FROM HIGH PRES CENTER IN THE CANADIAN MARITIMES CONTINUES TO YIELD A DEEP DRY LAYER ABOVE SOME TRAPPED MOISTURE FROM THE DELMARVA TO NEW ENGLAND. THIS IS COMBINING WITH E TO NE FLOW...DRAWING AIR ACROSS THE WATERS WHERE SSTS ARE ONLY IN THE LOW 40S. WITH THIS FLOW EXPECTED TO CONTINUE UNTIL THE RIDGE SHIFTS E LATE TODAY...THE TRAJECTORY IS EXPECTED TO KEEP AREAS WITHIN BOTH THE I-495 AND I-95 CORRIDORS MUCH COLDER THAN AREAS FURTHER W. THEREFORE...EXPECT HIGHS ONLY IN THE LOW-MID 40S MAINLY E OF THESE HIGHWAYS WHILE HIGHS FURTHER W WILL BREAK INTO THE LOW- MID 50S IN THE LOWER CT RIVER VALLEY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... TONIGHT... SFC COLD FRONT WILL BE RAPIDLY SLIDING ACROSS THE AREA DURING THE OVERNIGHT HOURS. HOWEVER...SOUNDINGS SHOW MOISTURE LAYER REMAINS MAINLY ABOVE H6...WITH DWPT DEPRESSIONS EXCEEDING 10C FROM THE SFC TO H6. LOW-MID LVL F-GEN IS ALSO VERY WEAK AS IT ARRIVES GIVEN IT IS TRYING TO PUSH THROUGH RIDGING. THEREFORE...EXPECT LITTLE FANFARE WITH THIS FRONTAL PASSAGE EXCEPT MID-HIGH CLOUDINESS AND W WINDS INCREASING THROUGH SUNRISE. CONTINUE TO SUGGEST NIL POPS. BKN-OVC CLOUDS WILL KEEP MINS WARMER THAN PREVIOUS NIGHTS...BUT ANOMALOUSLY COOL AIRMASS SUGGESTS TEMPS STILL DROP TO THE LOW-MID 30S. SAT... HIGH PRES REGAINS CONTROL WITH COLD ADVECTION TO START THE DAY. THIS COLD ADVECTION WILL ALLOW MIXING UNDER ONLY PARTLY CLOUDY SKIES TO REACH HIGHER THAN H8...WHERE TEMPS ONLY DIP TO AROUND -1C. COMBINE THIS WITH W DOWNSLOPE FLOW...AND TEMPS SHOULD BE ABLE TO REBOUND INTO THE LOW 60S. LOW CHANCE OF A SEA BREEZE GIVEN H92 WINDS REACH AROUND 20-25 KT. THEREFORE...ALSO EXPECT WINDS AROUND 20 MPH THROUGH THE DAY. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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HIGHLIGHTS... * DRY SUNDAY AND MONDAY WITH CHILLY NIGHTS/MILD DAYS * WET WEATHER LIKELY SOMETIME LATE TUESDAY INTO WEDNESDAY DETAILS... SATURDAY NIGHT AND SUNDAY... HIGH PRESSURE OVERHEAD WILL RESULT IN DRY WEATHER WITH A CHILLY SATURDAY NIGHT BEING REPLACED BY A MILD SUNDAY AFTERNOON. LIGHT WINDS/MAINLY CLEAR SKIES WILL ALLOW FOR EXCELLENT RADIATIONAL COOLING CONDITIONS SAT NIGHT. LOW TEMPS SHOULD BOTTOM OUT IN THE MID TO UPPER 20S ACROSS THE NORMALLY COLDER OUTLYING LOCATIONS OF SOUTHWEST NH/NORTHWEST MA...TO MAINLY THE 30S ELSEWHERE. ON SUNDAY...PLENTY OF SUNSHINE WILL ALLOW FOR HIGHS TO REACH INTO THE UPPER 50S AND LOWER 60S JUST INLAND FROM THE COAST. HOWEVER...WEAK PRESSURE GRADIENT WILL ALLOW FOR SEA BREEZES ON THE IMMEDIATE COAST PROBABLY HOLDING HIGHS IN THE UPPER 40S TO LOWER 50S. SUNDAY NIGHT... HIGH PRESSURE WILL REMAIN ANCHORED OVER THE REGION ALLOWING FOR ANOTHER GOOD NIGHT OF RADIATIONAL COOLING. LOW TEMPS WILL BE MAINLY IN THE 30S. MONDAY... HIGH PRESSURE WILL STILL BE IN CONTROL OF OUR WEATHER WITH A MIXTURE OF SUN AND CLOUDS. 850 MB TEMPS MODERATE CONSIDERABLY FROM SUNDAY/S VALUES REACHING BETWEEN +6C TO +8C. THIS SHOULD ALLOW HIGH TEMPS TO REACH WELL INTO THE 60S ACROSS MUCH OF THE REGION...TO PERHAPS EVEN NEAR 70 IN A FEW LOCALES. ALONG THE IMMEDIATE COAST INCLUDING BOSTON...ITS UNCERTAIN IF SEA BREEZES WILL DEVELOP IN THIS TIME RANGE. IF SEA BREEZES ARE ABLE TO DEVELOP...IT WOULD PROBABLY KEEP HIGH TEMPS IN THE 50S...BUT THEY MAY END UP VERY LOCALIZED JUST AFFECTING AREAS WITHIN A FEW MILES OF THE COAST. TUESDAY AND WEDNESDAY... A POTENTIALLY STRONG UPPER LEVEL SHORTWAVE WILL DIVE SOUTHEASTWARD FROM CANADA. THIS WILL SPAWN A SURFACE LOW PRESSURE SYSTEM APPROACHING OUR REGION FROM THE WEST. AT THIS TIME RANGE...THERE IS LOW CONFIDENCE ON STRENGTH/TIMING OF SHORTWAVE AND TRACK/INTENSITY OF SURFACE LOW PRESSURE. IT DOES LOOK LIKE A DECENT SHOT FOR AT LEAST PERIOD OF WET WEATHER SOMETIME LATE TUESDAY INTO WEDNESDAY. THURSDAY... DRY WEATHER SHOULD FOLLOW BEHIND THE DEPARTING LOW PRESSURE SYSTEM. SOME INDICATIONS ARE THAT IT MAY BE WINDY BEHIND THE SYSTEM WITH NEAR OR BELOW NORMAL TEMPERATURES.
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&& .AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. MODERATE CONFIDENCE THROUGH EARLY EVENING...HIGHER CONFIDENCE INTO SAT... SCT TO BKN MVFR CIGS HAVE OVERSPREAD EASTERN SECTIONS OF NEW ENGLAND EARLY THIS MORNING. THERE IS A BIT OF UNCERTAINTY IN EXTENT OF LOW CLOUDS AND HOW FAR WEST THEY WILL VENTURE. FOR NOW WE MAY SEE THEM ADVANCE WEST OF A WORCESTER TO PROVIDENCE LINE FOR A TIME...BUT PROBABLY STAY EAST OF THE CT RIVER VALLEY. AGAIN...CONFIDENCE IS BELOW NORMAL AND LATER SHIFTS WILL HAVE TO MONITOR CLOSELY. BY EARLY EVENING...WINDS W OF THE LINE SHIFT FROM THE S TO W AND WINDS E OF THE LINE BEGIN TO SHIFT TO THE S...SO ANY LINGERING MVFR CIGS SHOULD BEGIN TO SCT OUT. AFTER THAT MAINLY VFR IS EXPECTED OVERNIGHT INTO SAT ALTHOUGH WITH INCREASING HIGH AND MID CLOUDS DURING THE OVERNIGHT AND EARLY MORNING HOURS. ALTHOUGH THERE IS THE LOW PROBABILITY OF SOME MVFR/IFR FOG BEFORE WINDS SHIFT TO THE W AT COASTAL TERMINALS EARLY SAT MORNING. WINDS THEN SHIFT TO THE W SAT MORNING WITH WNW WIND GUSTS AROUND 20 KT BY MID DAY SAT. KBOS TERMINAL...MODERATE CONFIDENCE. MAIN ISSUE IS EXTENT AND DURATION OF MVFR CIGS THROUGH THE AFTERNOON. KBDL TERMINAL...HIGH CONFIDENCE. SATURDAY NIGHT THROUGH MONDAY...HIGH CONFIDENCE IN VFR CONDITIONS. TUESDAY...LOW TO MODERATE CONFIDENCE. VFR CONDITIONS MAY DETERIORATE TO MVFR-IFR THRESHOLDS LATE TUE OR TUE NIGHT IN RAIN SHOWERS.
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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 SATURDAY/...HIGH CONFIDENCE. ALTHOUGH WINDS EACH DAY ARE EXPECTED TO REMAIN BELOW THE 25 KT THRESHOLD FOR SMALL CRAFT ADVISORY...A LINGERING SWELL WILL KEEP SEAS AT LEAST 5-7FT THROUGH THE DAY ON SAT ON THE OCEAN WATERS ESPECIALLY. THEREFORE WILL TRANSITION TO SMALL CRAFT FOR HAZ SEAS ACROSS THE WATERS INTO 12Z SAT AT LEAST...WITH NEAR SHORE WATERS DROPPING EARLIER. WINDS TODAY BEING OUT OF THE N-NE...SHIFTING TO THE SW TONIGHT THEN W DURING THE DAY ON SAT. OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY... SATURDAY NIGHT AND SUNDAY...MODERATE TO HIGH CONFIDENCE. HIGH PRESSURE OVER NORTHERN NEW ENGLAND AND LOW PRESSURE WELL TO THE SOUTH OF THE WATERS WILL RESULT IN NORTH TO NORTHEAST WINDS. WIND GUSTS OF 20 TO 25 KNOTS ALONG WITH 3 TO 5 FOOT SEAS ARE POSSIBLE ACROSS THE OUTER-WATERS. THIS MAY RESULT IN MARGINAL SCA CONDITIONS. MONDAY AND TUESDAY...MODERATE TO HIGH CONFIDENCE. WEAK PRESSURE GRADIENT SHOULD KEEP WINDS/SEAS GENERALLY BELOW SCA THRESHOLDS. WE MAY SEE MARGINAL SCA SEAS DEVELOP LATE TUE/TUE NIGHT AS A RESULT OF SOUTHEAST SWELL FROM LOW PRESSURE WELL EAST OF THE WATERS.
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&& .FIRE WEATHER... SATURDAY IS THE THREE DAY MARK SINCE LAST APPRECIABLE RAINFALL ACROSS SOUTHERN NEW ENGLAND. GIVEN THIS FACT...WITH TEMPERATURES RISING INTO THE LOW 60S AND LOW DWPTS IN THE 20S...MIN RH VALUES SHOULD DIP TO AROUND 30 PERCENT IN THE AFTERNOON. THIS WILL COMBINE WITH W WIND GUSTS OF 20 TO 25 MPH...WITH OCCASIONAL GUSTS TO 30 MPH. CONFIDENCE IS HIGH THAT THESE CONDITIONS WILL BE REALIZED. && .HYDROLOGY... MINOR FLOODING CONTINUES ALONG PORTIONS OF THE MAIN STEM CT RIVER. MOST POINTS HAVE REACHED CREST...BUT WILL TAKE MORE TIME TO DROP BELOW FLOOD STAGE. THE RIVER HAS DROPPED BELOW FLOOD STAGE AT MONTAGUE...AND IS NOT EXPECTED TO REACH MODERATE FLOOD ANY LONGER AT MIDDLE HADDAM. FLOOD WARNINGS REMAIN POSTED ALONG CT RIVER AT... NORTHAMPTON THOMPSONVILLE HARTFORD MIDDLE HADDAM && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 2 PM EDT THIS AFTERNOON FOR ANZ232. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 PM EDT THIS AFTERNOON FOR ANZ235-237. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT SATURDAY FOR ANZ250-251-254>256. && $$ SYNOPSIS...DOODY/FRANK NEAR TERM...FRANK/DOODY SHORT TERM...DOODY LONG TERM...FRANK AVIATION...FRANK/DOODY MARINE...DOODY/FRANK FIRE WEATHER...DOODY HYDROLOGY...DOODY

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