Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 231357 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 957 AM EDT THU OCT 23 2014 .SYNOPSIS... A POWERFUL EARLY SEASON COASTAL STORM WILL BRING STRONG WINDS AND PERIODS OF HEAVY RAIN IN SQUALLS AND ISOLATED THUNDERSTORMS THIS MORNING. RAIN WILL BECOME MORE SHOWERY THIS AFTERNOON ALONG WITH WINDS NOT QUITE AS STRONG. SHOWERS CONTINUE TO DIMINISH FRIDAY AS THE STORM SLOWLY PULLS AWAY FROM NEW ENGLAND. SHOWERS POSSIBLE AGAIN SATURDAY EVENING AND OVERNIGHT AS LOW PRES MOVES INTO SOUTHERN QUEBEC. DRY AND SEASONABLY COOL WEATHER RETURNS SUNDAY INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... *** A POWERFUL EARLY SEASON COASTAL STORM WILL CONTINUE TO BRING STRONG WINDS...HEAVY RAINFALL AND TIDAL FLOODING INTO THU MORNING *** 7 AM UPDATE... ONLY MINOR ADJUSTMENTS TO THE FORECAST THIS MORNING. UPDATED TEMPS/DWPTS TO BRING THEM UP TO CURRENT TRENDS BUT OTHER ISSUES REMAIN ON TRACK. WILL BE UPDATING FLOOD ADVISORY AND FLASH FLOOD WARNINGS. AS HEAVY RAIN BANDS CONTINUE TO PIVOT ACROSS THE N SHORE. ANOTHER CONCERN IS A BAND OF MODERATE TO HEAVY RAIN IN FRANKLIN COUNTY WHICH MAY YIELD SOME MINOR RIVER FLOODING. 1)HEAVY RAIN/FLOOD THREAT... DUAL POL HAS BEEN ESTIMATING HOURLY RAINFALL RATES OF ABOUT AN INCH OR SO IN THE RAIN BAND OVER MA MUCH OF THE NIGHT. RADAR MAY BE UNDER ESTIMATING GIVEN THE STRONG LOW LEVEL WINDS /PRECIP DRIFT/. AS THIS WARM CONVEYOR BELT SLOWLY LIFTS NORTHWARD THE HEAVY RAINFALL AND FLOOD THREAT WILL BE FOCUSED ACROSS NORTHERN MA INTO SOUTHERN NH THIS MORNING. THUS WORST CONDITIONS FOR THE MORNING COMMUTE WILL BE ACROSS THIS REGION. ELSEWHERE PRECIP WILL BE MORE SHOWERY AND NOT AS INTENSE. HOWEVER ANOTHER POTENT SHORT WAVE/PV ANOMALY WAS PIVOTING NORTHWARD AROUND THE MID LEVEL LOW AND THIS NEW WARM CONVEYOR BELT MAY CLIP SOUTHERN RI AND SOUTHEAST MA LATER TODAY WITH ADDITIONAL HEAVY RAINFALL. LAPSE RATES NOT AS IMPRESSIVE LATER TODAY AS THIS MORNING BUT CAN/T RULE OUT ISOLATED T-STORMS LATER THIS AFTERNOON AND EVENING ACROSS SOUTHERN RI INTO SOUTHEAST MA. GIVEN THE RISK OF ADDITIONAL FLOODING WILL LEAVE THE FLOOD WATCH AS IS WITH THE GREATEST RISK ACROSS NORTHEAST MA AND SOUTHEAST NH THIS MORNING. 2) STRONG WINDS: KBOX RADAR INDICATES LOW LEVEL JET HAS WEAKENED SOMEWHAT AND SHIFTED NORTHWARD. ELEVATED OBSERVING PLATFORMS SUCH AS ISLE OF SHOALS OFF THE NH COASTLINE CONFIRMS THIS WITH NE WINDS CONTINUING TO GUSTS OVER 50 KT! HOWEVER SURFACE WINDS HAVE SLACKENED A BIT OVER THE REGION AS WIND TRAJECTORY AS SHIFTED FROM NE TO N DURING THE PREDAWN HOURS. THIS IS A RESULT OF THE DEVELOPMENT OF A SUBTLE COASTAL FRONT. THIS MORE LAND TRAJECTORY IS A MORE STABLE THAN OVER THE RELATIVELY WARMER OCEAN ALONG WITH MORE FRICTION/DRAG. HENCE WIND SPEEDS HAVE LESSENED OVERNIGHT. HOWEVER GIVEN THE CORE OF THE LOW LEVEL JET WILL BE CLOSEST TO NORTHEAST MA ALONG WITH HEAVY RAIN/CONVECTION ENHANCING WIND THREAT FROM PRECIP DRAG WILL CONTINUE THE HIGH WIND WARNING FOR ESSEX COUNTY. ELSEWHERE LOW LEVEL JET WILL REMAIN STRONG ENOUGH TO SUPPORT WIND SPEEDS APPROACH ADVISORY CRITERIA. WHILE SPEEDS MAY FALL JUST SHY OF CRITERIA...FULLY TO PARTIAL LEAVED TREES WILL INCREASE THE RISK OF DOWN LIMBS AND BRANCHES. HENCE WILL CONTINUE THE WIND ADVISORY UNTIL 11 PM THIS EVENING WHEN THE LOW LEVEL JET IS EXPECTED TO WEAKEN. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... TONIGHT... OCCLUDED LOW SLOWLY MOVES SEAWARD. HOWEVER LIGHTER COMMA-HEAD RAINS WILL LIKELY IMPACT THE REGION MUCH OF THE NIGHT. HOWEVER THE FLOOD THREAT APPEARS TO DIMINISH. GUSTY NORTHEAST WINDS SHOULD BEGIN TO SLACKEN LATER IN THE EVENING AS THE LOW LEVEL JET WEAKENS. FRIDAY... FURTHER IMPROVEMENT ESPECIALLY DURING THE AFTERNOON FROM WEST TO EAST AS COMMA-HEAD EXITS AND MOVES OFFSHORE. RISK FOR SHOWERS WILL BE HIGHEST IN THE MORNING WITH BEST CHANCE OF DRYING AND LATE DAY SUNSHINE IS ACROSS THE CT RVR VLY. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... * SHOWERS POSSIBLE AGAIN SATURDAY AS LOW PRES MOVES INTO QUEBEC * MAINLY DRY AND SEASONABLE WEATHER EARLY NEXT WEEK OVERALL THE 12Z MODEL SUITE IS IN FAIRLY GOOD AGREEMENT THROUGH THE LONG TERM. THERE ARE SOME DISCREPANCIES IN THE MESOSCALE DETAILS BUT OTHERWISE THEY ARE IN GOOD AGREEMENT. AFTER THE COASTAL STORM CURRENTLY AFFECTING THE REGION MOVES AWAY FROM SOUTHERN NEW ENGLAND...THE WEATHER STARTS TO DRY OUT AND BECOME MORE SEASONABLE. THERE ARE A COUPLE OF COLD FRONTS EXPECTED TO MOVE THROUGH THE REGION AND EACH OF THESE MAY BRING SOME SHOWERS WITH THEM. SATURDAY...ANOTHER UPPER LEVEL TROUGH MOVES OVER THE NORTHEAST WITH LOW PRESSURE MOVING THROUGH SOUTHERN QUEBEC AND INTO THE MARITIMES. THE MODELS DON/T SHOW A WHOLE LOT OF MOISTURE OR A BIG WIND SHIFT WITH THIS FRONT BUT WE COULD SEE SOME SHOWERS. THE GFS HAS A STRONGER LOW LEVEL JET THAN THE ECMWF WHICH COULD ENHANCE THE AMOUNT OF RAINFALL BUT THERE IS STILL MUCH TO BE SEEN WITH THIS SYSTEM. SUNDAY THROUGH TUESDAY...HIGH PRESSURE STARTS TO BUILD INTO SOUTHERN NEW ENGLAND BRINGING DRY AND SEASONABLE WEATHER. TEMPERATURES BEGIN TO CLIMB AND MAY WARM TO WELL ABOVE NORMAL BY TUESDAY. WEDNESDAY...LOW PRESSURE MOVING THROUGH THE GREAT LAKES AND INTO QUEBEC MAY BRING A COLD FRONT THROUGH SOUTHERN NEW ENGLAND. ANOTHER CHANCE OF SOME SHOWERS POSSIBLE WITH THIS FRONT BUT PLENTY OF UNCERTAINTY. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THU/... TODAY... BAND OF HEAVY RAIN WITH EMBEDDED T-STORMS WILL SLOWLY LIFT NORTHWARD. MARGINAL IFR/MVFR CONDITIONS CONTINUE. GUSTY NE WINDS CONTINUE WITH STRONGEST WINDS FOCUSED ACROSS NORTHEAST MA. SOME VFR CAPE/ISLANDS GRADUALLY DIMINISH AGAIN LATER THIS MORNING. TONIGHT... IFR EASTERN MA WITH MVFR ELSEWHERE. SLOW IMPROVEMENT WITH SHOWERS BECOMING LESS NUMEROUS AND WINDS SLOWLY EASING. FRIDAY... MVFR BUT TRENDING TOWARD VFR LATE. SCATTERED SHOWERS BECOMING LESS NUMEROUS AS THE DAY PROGRESSES. NNW WINDS 10-20 KT. KBOS...HIGH CONFIDENCE IN TAF ON TRENDS BUT LOWER CONFIDENCE ON EXACT TIMING OF DETAILS. KBDL...HIGH CONFIDENCE IN TAF ON TRENDS BUT LOWER CONFIDENCE ON EXACT TIMING OF DETAILS. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... SATURDAY THROUGH MONDAY...MODERATE CONFIDENCE. VFR. LOW PROBABILITY OF SCATTERED SHOWERS SATURDAY. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH FRIDAY/... *** DANGEROUS COASTAL STORM IMPACTS THE NEW ENGLAND WATERS *** TODAY... COASTAL STORM SOUTH OF NEW ENGLAND WILL BRING NORTHEAST GALES AND DANGEROUS SEAS TO THE MASSACHUSETTS AND RHODE ISLAND WATERS. STRONGEST WINDS AND LARGEST SEAS WILL OCCUR OVER THE NORTHERN MA WATERS INTO NH COASTAL WATERS. WINDS AND SEAS NOT QUITE AS INTENSE THIS AFTERNOON BUT NEVERTHELESS DANGEROUS SEA CONDITIONS. HEAVY RAIN SQUALLS WITH EMBEDDED T-STORMS MAINLY CONFINED TO THE NORTHERN MA WATERS. TONIGHT... LOW SLOWLY WEAKENS AND MOVES SEAWARD WITH WINDS BECOMING SUBGALE AS THE NIGHT PROGRESSES. ALSO ANY LINGERING RAIN SQUALLS NOT AS INTENSE AS THIS MORNING. FRIDAY... SLOW IMPROVEMENT CONTINUES WITH WINDS BECOMING MORE NNW AND SHOWERS BECOMING LESS NUMEROUS LATE IN THE DAY AND AT NIGHT. OUTLOOK...SATURDAY THROUGH MONDAY... SATURDAY AND SUNDAY...MODERATE CONFIDENCE. AFTER A BRIEF LULL...SEAS AND WINDS WILL INCREASE AHEAD OF A COLD FRONT. SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED FOR AT LEAST A PORTION OF THE WATERS. MONDAY...MODERATE CONFIDENCE. WINDS AND SEAS DIMINISH AS HIGH PRESSURE BUILDS OVER THE WATERS. && .TIDES/COASTAL FLOODING...
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LAST NIGHT/S HIGH TIDE YIELDED A STORM SURGE OF 1.5 FT TO 2.0 FT. THIS COMBINED WITH LARGE WAVE ACTION RESULTED IN WIDESPREAD MINOR COASTAL FLOODING/INUNDATION FROM PLYMOUTH COUNTY NORTHWARD. BOTH ETSS AND ESTOFS ARE ABOUT 50% TOO LOW WITH THEIR SURGE VALUES WHEN COMPARED TO CURRENT OBSERVATIONS. THUS HAVE INCREASED GUID BY 50 PERCENT. WE ARE NOW RAMPING UP TO THE LATE MORNING/MIDDAY HIGH TIDE CYCLE. PRIOR STORM SURGE FORECAST LOOKS GOOD AND HAVE NOT CHANGED. AT 0945 EDT THE SURGE WAS RUNNING AT 2 FEET AT BOS...ABOUT TWICE AS HIGH AS THE GUIDANCE. WAVES JUST OFFSHORE RUNNING 16 TO 18 FEET. THE NNE GRADIENT APPEARS TO BE RETIGHTENING FOR A PERIOD AS ADVERTISED BY SHORT TERM MODELS AND THINK WAVES WILL HOLD AT THESE HEIGHTS OR POSSIBLY EVEN INCREASE ANOTHER FOOT OR TWO BEFORE SUBSIDING THIS EVENING. THE ASTRONOMICAL TIDE IS ABOUT A HALF FOOT HIGHER TODAY THAN LAST NIGHT AND WILL ALLOW WAVE ACTIVITY TO RUNUP SOMEWHAT FURTHER ALONG THE BEACH. HENCE...THE IMPACT COULD BE A LITTLE HIGHER THAN WHAT WAS EXPERIENCED LAST NIGHT. ALSO...WE HAVE THE ISSUE OF THIS BECOMING A FAIRLY LONG DURATION EVENT WITH CONTINUED EROSION OF THE DUNE SLOPES ALONG SANDY BEACH AREAS. WILL KEEP THE COASTAL FLOOD ADVISORY IN PLACE FOR SALISBURY TO CAPE ANN AND HULL TO PLYMOUTH. OUR GREATEST CONCERN CONTINUES TO BE BEACH EROSION IN THE SALISBURY AND PLUM ISLAND AREA. THERE MAY BE SOME SPLASHOVER AND MINOR BEACH EROSION FOR THE HIGH TIDE TONIGHT BUT DO NOT BELIEVE IT WILL REACH AN ADVISORY LEVEL.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...WIND ADVISORY UNTIL 11 PM EDT THIS EVENING FOR CTZ004. MA...WIND ADVISORY UNTIL 11 PM EDT THIS EVENING FOR MAZ005>007- 012>021. COASTAL FLOOD ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR MAZ007-019. NH...WIND ADVISORY UNTIL 11 PM EDT THIS EVENING FOR NHZ012. RI...WIND ADVISORY UNTIL 11 PM EDT THIS EVENING FOR RIZ001>007. MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ231>234-236-254-255. GALE WARNING UNTIL 11 PM EDT THIS EVENING FOR ANZ230-250-251- 256. GALE WARNING UNTIL 10 PM EDT THIS EVENING FOR ANZ235-237.
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&& $$ SYNOPSIS...NOCERA NEAR TERM...NOCERA/DOODY SHORT TERM...NOCERA LONG TERM...RLG AVIATION...NOCERA/DOODY/RLG MARINE...NOCERA/RLG TIDES/COASTAL FLOODING...THOMPSON/NOCERA

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