Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 290147 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 947 PM EDT THU AUG 28 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD IN WITH DRIER WEATHER AND LESS HUMIDITY FOR TONIGHT AND TOMORROW. HURRICANE CRISTOBAL WILL CONTINUE TO BRING DANGEROUS SURF AND RIP CURRENTS TO THE CAPE AND NANTUCKET TOMORROW. PLEASANT LATE SUMMER WEATHER WILL CONTINUE ON SATURDAY. A FRONT WILL SLOWLY MOVE ACROSS NEW ENGLAND LATE SUNDAY AND MONDAY BRINGING SCATTERED SHOWERS AND THUNDERSTORMS. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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A FEW CLOUD PATCHES OVER THE ISLANDS/GREATER HARTFORD- SPRINGFIELD/NORTHERN VT-NH ALL DRIFTING SOUTH-SOUTHEAST. EXPECT THESE CLOUDS TO BREAK UP OVERNIGHT AND SKIES TO BECOME MOSTLY CLEAR ALL AREAS. NORTHWEST WINDS AROUND 5 KNOTS WEST AND 10G15 KNOTS EAST...ALSO TRENDING LIGHTER. WITH DEW POINTS 45-50F THERE IS ROOM FOR MIN TEMPS IN THE M-U40S IN THE COLDER SPOTS. TEMPS AND DEWPOINTS HAVE BEEN ABOUT 2F LOWER THAN HOURLY FORECASTS...SO WE BUMPED THESE VALUES AND THE MIN TEMPS DOWN 2F. SEAS WILL TREND LIGHTER OVERNIGHT...BUT STILL HIGH ENOUGH TO GENERAL ROUGH SURF ALONG THE SOUTH COAST. THE HIGH SURF ADVISORY CONTINUES UNTIL MORNING.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... FRIDAY AND FRIDAY NIGHT... UPPER LEVEL RIDGE WILL BUILD OVER SOUTHERN NEW ENGLAND TOMORROW AND TOMORROW NIGHT. THIS WILL PUSH A SURFACE HIGH PRESSURE OVER THE REGION. EXPECT LIGHT WINDS AND MOSTLY SUNNY SKIES. COULD BE A FEW CU DEVELOPING AS THERE IS SOME LINGERING MOISTURE IN THE MID-LEVELS. OTHERWISE TEMPS WILL WARM INTO THE MID TO UPPER 70S WITH COOLER CONDITIONS ALONG THE COASTLINE THANKS TO SEABREEZE DEVELOPMENT. HAVE EXTENDED THE SURF ADV FOR THE CAPE AND NANTUCKET FOR TOMORROW AS SWELL WILL STILL BE ABOUT 4 TO 5 FEET WITH A PERIOD OF AROUND 11 SEC. ALTHOUGH THE SURF WILL NOT BE AS HIGH AS IT IS TODAY...THERE IS STILL THE DANGER OF A ROUGH WAVE AS WELL AS A HIGH RIP CURRENT RISK. BEACHGOERS SHOULD USE CAUTION WHEN VENTURING INTO THE WATERS TOMORROW AND SWIM AT LIFE GUARDED BEACHES. HIGH PRESSURE WILL BEGIN TO MOVE OFFSHORE LATE TOMORROW NIGHT. THIS WILL ALLOW FOR RETURN FLOW ACROSS THE REGION AND BEING TO SLOWLY INCREASE THE MOISTURE. SOME PATCHY FOG OVERNIGHT IS POSSIBLE...BUT HAVE A LOWER CONFIDENCE. && .LONG TERM /SATURDAY THROUGH THURSDAY/... */ HIGHLIGHTS... - HOT AND HUMID WEEKEND - BEST CHANCE OF WET-WEATHER LATE SUNDAY INTO MONDAY - COLD FRONT ACROSS THE REGION TUESDAY - DRY AND SEASONABLE FORECAST FOR THE REST OF THE WEEK */ OVERVIEW AND MODEL PREFERENCE... NOTING ENSEMBLE SIGNALS OF A NEGATIVE TO NEAR-NEUTRAL NAO AND PNA PATTERN...PREFER A ZONAL FLOW WITH HIGHER HEIGHTS AND WEAK RIDGING ACROSS THE NE-CONUS INTO EARLY SEPTEMBER. BROADLY SPEAKING OVER THE LONG-TERM FORECAST PERIOD...AM EXPECTING SEASONABLE TO ABOVE-AVERAGE TEMPERATURES AND MUGGIER CONDITIONS. LIKELY THERE WILL BE PERIODS IN WHERE MORE REFRESHING AIR WILL DIVE S OUT OF CANADA...YET AVERAGING OVER THE FORECAST PERIOD WILL LIKELY YIELD ANOMALOUSLY HIGHER VALUES OF TEMPERATURE AND MOISTURE AS HINTED BY ENSEMBLE MEMBERS. BUT ALSO ANTICIPATE A SUBDUED WEATHER PATTERN. ANY PACIFIC ENERGY TROUGHING ACROSS W N-AMERICA SHOULD BE KEPT WELL N OF THE REGION IF NOT STRETCHED THROUGH THE CONFLUENT ZONAL-FLOW PATTERN...AGAIN N OF THE REGION. WHILE CONVECTIVE PERIODS ARE EXPECTED...STRETCHED MID- LEVEL IMPULSES AND LESS AMPLIFIED PATTERN SHOULD YIELD LIMITATIONS IN CONVECTIVE SEVERITY...AS WELL AS KEEP CONVECTIVE EPISODES MAINLY CONFINED DURING THE DAYTIME PERIODS...DIFFUSING OVERNIGHT...HEAT AND MOISTURE BEING THE MAIN FUEL TO THE FIRE. HAVE HIGH PRAISE FOR THE ECMWF / ECENS WHICH HAS REMAINED FAIRLY CONSISTENT RUN-TO-RUN OVER THE PAST THREE DAYS. THOUGH NOT IGNORING OUTCOMES FROM OTHER MODEL SOLUTIONS...WILL PLACE GREATER WEIGHT ON THE ECMWF / ECENS TOWARDS THE FORECAST. HIGHLIGHTS/CONFIDENCE ARE BROKEN DOWN IN THE DAILY DISCUSSION BELOW. */ DAY-TO-DAY DETAILS... SATURDAY INTO SATURDAY NIGHT... WILL CONTINUE WITH A DRY FORECAST. RIDGE OF HIGH PRESSURE. DRY- SUBSIDENCE INVERSION IN PLACE. A WELL-MIXED BOUNDARY-LAYER WILL ALLOW FOR BREEZY S-WINDS...SCATTERED CUMULUS...AND LOW-80S HIGHS. OVERNIGHT...QUIET UNDER LIGHT S-FLOW. INCREASING SURFACE MOISTURE. SOME QUESTION AS TO WHETHER LOW CLOUDS SEEP IN FROM THE S OR RATHER MORE CLEAR CONDITIONS ALLOW FOR THE DEVELOPMENT OF PATCHY FOG...OR A COMBINATION OF BOTH. DRIZZLE POSSIBLE WITH INCREASING MOISTURE CONTENT UNDERGOING WEAK UPSLOPE? COULD NOT RULE IT OUT ALONG THE S- SHORE. MILD NIGHT WITH LOWS AROUND THE MID-60S. SUNDAY... A BUILDING CONVECTIVE ENVIRONMENT. FALLING HEIGHTS IN A REGION OF MID-LEVEL ASCENT PER DIFFERENTIAL VORTICITY ADVECTION WITHIN DECENT H85-7 LAPSE RATES...ABOVE COLLOCATED LOW-LEVEL MOIST-INSTABILITY AXES INTO THE LOWER HUDSON VALLEY / SW NEW ENGLAND. WHILE BETTER LOW- LEVEL WIND PROFILES / FRONTOGENESIS / H3 JET DYNAMICS RESIDES N AND W...SIGNALS OF MID-LEVEL MOIST-CONVERGENCE IN AN AREA OF FAVORABLE ASCENT SHOULD YIELD SOME ACTIVITY. MODEST INSTABILITY AND 0-6 KM BULK SHEAR. ALSO WOULD EXPECT OROGRAPHIC LIFT ALONG S/W-SLOPES OF HIGH TERRAIN AIDING WITH ASCENT. EXPECT CONVECTION TO DEVELOP N/W SLIDING SE WITH TIME. NO CONFIDENCE AS TO SPECIFICS NOR STORM SEVERITY...BUT DO EXPECT THE BRUNT OF IT TO REMAIN N/W OF THE FORECAST REGION PARENT WITH BETTER DYNAMICS. WHILE A WARM-SECTOR IS EXPECT THROUGH THE INTERIOR WITH HIGHS INTO THE UPPER-80S...CLOUDS MAY BE A HINDERANCE ALONG THE S/SE COASTLINE ESPECIALLY DURING THE MORNING PERIOD...HOPEFULLY ERODING WITH AN INCREASE IN SW-WINDS...BLUSTERY AT TIMES. SUNDAY NIGHT... WITH DAYTIME HEATING CONCLUDING AND THE BULK OF MID-LEVEL ENERGY STRETCHED / SHEARED TO THE N...EXPECT ACTIVITY TO WEAKEN SE WITH TIME. APPROACHING SURFACE FRONTAL BOUNDARY BECOMING DIFFUSE AGAINST THE DOMINANT W-ATLANTIC RIDGE. YET BETTER LOW-LEVEL MOISTURE ALONG WITH COLLOCATED MID-LEVEL LAPSE RATES AHEAD OF THE FRONT SHOULD YIELD SOME ASCENT TO ALLOW SCATTERED SHOWERY WEATHER TO CONTINUE. ABUNDANCE OF CLOUDS AND MOISTURE UNDER SW-FLOW...A VERY MILD NIGHT WITH LOWS DOWN TO AROUND THE UPPER-60S. MONDAY INTO MONDAY NIGHT... COOLER AIR DIGGING SE INTO THE NE-CONUS YIELDING CONDITIONALLY UNSTABLE MID-LEVEL PROFILES ABOVE A WELL-MIXED BOUNDARY LAYER... SHOULD SEE SUBSEQUENT DAYTIME LIFT OF AVAILABLE MOISTURE YIELDING SCATTERED SHOWERS MAYBE EVEN A THUNDERSTORM. MINOR INSTABILITY AND WEAK SHEAR...ANY STORMS WOULD APPEAR TO BE AIRMASS RELATED BENEATH THE WEAK COLD POOL. BEST ACTIVITY MAY OCCUR ACROSS HIGH TERRAIN WITH W-WINDS UNDERGOING OROGRAPHIC LIFT PROVIDING FAVORABLE ASCENT. OTHERWISE SCATTERED TO BROKEN CUMULUS. MILD DAY WITH HIGHS AROUND THE LOW-80S. TURNING QUIET AND COOLER OVERNIGHT AS HIGH PRESSURE IS ANTICIPATED TO SETTLE ACROSS THE REGION. LIGHT WINDS AND MOSTLY CLEAR CONDITIONS MAY ALLOW FOR EFFECTIVE RADIATIONAL COOLING. TUESDAY... EXPECTING A COLD FRONT TO PUSH INTO THE REGION AHEAD OF WHICH MODEST INSTABILITY / WEAK SHEAR COLLOCATED WITH A SW-PLUME OF HIGH MOISTURE RESIDES OVER S NEW ENGLAND. ONCE AGAIN...WITH BETTER DYNAMICS N/W OF THE REGION...ANTICIPATE TRAILING SCATTERED SHOWERS AND THUNDERSTORMS OVER THE FORECAST AREA. ZONAL-FLOW AND WEAK RIDGING SHOULD SUPPRESS ACTIVITY TO SOME DEGREE IN ADDITION TO THE LACKING DYNAMICS... POTENTIALLY DIFFUSE MORE SO SHOULD THE FRONT SWEEP THE REGION DURING THE EVENING PERIOD. HIGHS AGAIN AROUND THE LOW-80S WITH A MILD NIGHT WITH LOWS AROUND THE MID-60S. WEDNESDAY INTO FRIDAY... FAVOR THE ECMWF WITH THE ZONAL-FLOW PATTERN OF HIGHER HEIGHTS. SHALL PREVAIL WITH HIGH PRESSURE. EXPECTING CONDITIONS AROUND SEASONABLE LEVELS AND OVERNIGHT PERIODS WHICH MAY TURN COOL WITH EFFECTIVE RADIATIONAL COOLING AT TIMES UNDER LIGHT WINDS. WEAK IMPULSES THROUGH THE ZONAL FLOW WILL NEED TO BE MONITORED FOR THE POTENTIAL OF LIKELY CLOUDS AND POSSIBLE SHOWERS...BUT SO LATE IN THE FORECAST PERIOD...JUST TOO DIFFICULT TO SUGGEST OUTCOMES. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM /TODAY THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE. VFR. PATCHY MVFR-IFR FOG POSSIBLE ACROSS THE CT-RIVER VALLEY UNDER LESSENING N/NW FLOW. LIGHT WINDS FRIDAY WITH ACCOMPANYING SEA- BREEZES BY LATE MORNING...DIMINISHING DURING THE EVENING HOURS. COULD SEE PATCHY FOG / STRATUS DURING THE FRIDAY OVERNIGHT PERIOD. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. SEA-BREEZES TOWARDS NOON. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...SATURDAY THROUGH TUESDAY... SATURDAY INTO SUNDAY...MODERATE CONFIDENCE. VFR. BREEZY S/SW WINDS. SCT CIGS 4-6 KFT SATURDAY. MVFR-IFR CIGS / VSBYS POSSIBLE ALONG THE S-COAST SATURDAY NIGHT. SHRA/TSRA POSSIBLE FOR N/W NEW ENGLAND LATE SUNDAY. SUNDAY NIGHT INTO MONDAY...LOW CONFIDENCE. MIX OF LOW-END VFR TO MVFR. WIDESPREAD SHRA ACROSS THE TERMINALS. POSSIBLE TSRA ACROSS THE INTERIOR MONDAY. CONTINUED S/SW WINDS. TUESDAY...MODERATE CONFIDENCE. COLD FRONT SWEEPING ACROSS THE TERMINALS. LOW-END VFR. CHANCE OF SHRA/TSRA ACROSS THE INTERIOR. WINDS BACKING OUT OF W BEHIND THE FRONT. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM /TONIGHT THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE. TONIGHT... SOUTH TO SOUTHEAST SWELL FROM HURRICANE CRISTOBAL WILL SLOWLY SUBSIDE OVERNIGHT. HOWEVER THE COMBINATION OF THE LONG PERIOD AND DESCENT SWELL AND WAVES WILL CONTINUE TO CREATE A RISK FOR HIGH SURF. HAVE EXTENDED THE SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS AND INCREASED IT TO ANZ250 AS THE NORTHEAST TRAJECTORY COULD CREATE 5 FOOTERS. TOMORROW... HIGH PRESSURE BUILDS OVER NEW ENGLAND AND THE WATERS. THIS WILL MEAN LIGHT WIND...BECOMING ONSHORE NEAR THE COAST. SEAS WILL DIMINISH THROUGH THE DAY. HOWEVER ROUGH SEAS MAY LINGER ON THE WATERS SOUTH AND EAST OF CAPE COD AND NANTUCKET. HAVE CONTINUED THE SMALL CRAFT ADVISORY FOR THE OUTER WATERS THROUGH THE DAY. TOMORROW NIGHT...WAVES WILL BE BELOW 5FT AND WINDS BELOW 15 KTS AS HIGH PRESSURE SETS UP OVER THE WATERS. OUTLOOK...SATURDAY THROUGH TUESDAY... SATURDAY INTO SUNDAY...MODERATE CONFIDENCE. INCREASING S/SW-WINDS. PROLONGED FETCH LENDING TO WAVE HEIGHTS IN EXCESS OF 5-FEET ACROSS THE S/SE WATERS ON SUNDAY. FOG POSSIBLE DURING THE OVERNIGHT HOURS...ESPECIALLY ALONG THE S-COAST. SUNDAY NIGHT INTO MONDAY...MODERATE CONFIDENCE. BREEZY S/SW WINDS CONTINUING. SEAS OF 5-FEET ON THE S/SW WATERS. SHOWERS IMPACTING THE WATERS. PATCHY DENSE FOG POSSIBLE DURING THE OVERNIGHT PERIOD...BUT WITH BRISK WINDS...HAVE GREATER CONFIDENCE TOWARDS LOW CLOUDS. WET WEATHER CLEARING OUT LATE IN THE DAY ON MONDAY. TUESDAY...MODERATE CONFIDENCE. EXPECTING A PERIOD OF QUIET WEATHER OVER THE WATERS WITH BREEZY S- WINDS AHEAD OF A COLD FRONT EXPECTING TO SWEEP THE WATERS TOWARDS WEDNESDAY MORNING. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...HIGH SURF ADVISORY UNTIL 8 AM EDT FRIDAY FOR MAZ020-023. HIGH SURF ADVISORY UNTIL 9 PM EDT FRIDAY FOR MAZ022-024. NH...NONE. RI...HIGH SURF ADVISORY UNTIL 8 AM EDT FRIDAY FOR RIZ006>008. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT FRIDAY FOR ANZ235-237. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 9 PM EDT FRIDAY FOR ANZ250-254>256. && $$ SYNOPSIS...DUNTEN/SIPPRELL NEAR TERM...WTB/DUNTEN/SIPPRELL SHORT TERM...DUNTEN LONG TERM...SIPPRELL AVIATION...DUNTEN/SIPPRELL MARINE...SIPPRELL

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