Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBOX 090611 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 110 AM EST TUE FEB 9 2016 .SYNOPSIS... A BROAD AREA OF LOW PRESSURE WILL SETUP OVER SOUTHERN NEW ENGLAND TODAY AND WED MAINTAINING CLOUDS WITH SCATTERED SNOW SHOWERS EXPECTED ON WEDNESDAY. AN ARCTIC COLD FRONT WILL CROSS THE REGION THURSDAY...FOLLOWED BY BITTERLY COLD AIR INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 110 AM UPDATE... WE ALLOWED THE WINTER WEATHER ADVISORIES TO EXPIRE AT MIDNIGHT. STILL SOME LIGHT SNOW MAINLY ACROSS CENTRAL AND EASTERN MA. BULK OF THIS SHOULD COME TO AN END OVER THE NEXT HOUR OR SO. THE EXCEPTION WILL BE ACROSS PORTIONS OF THE IMMEDIATE EASTERN MA COAST...MAINLY FROM CAPE ANN AND ONTO COASTAL PLYMOUTH COUNTY. COLD LOW LEVEL NORTH TO NORTHEAST FLOW WILL RESULT IN SOME LAND/SEA INTERFACE AND SCATTERED OCEAN EFFECT SNOW SHOWERS. WE DID ISSUE A SPECIAL WEATHER STATEMENT AS UNTREATED ROADS WILL BE SNOW COVERED AND SLIPPERY WITH TEMPS WELL BELOW FREEZING. TEMPS WILL HOLD IN THE UPPER TEENS TO LOWER 20S THROUGH DAYBREAK ACROSS MUCH OF THE REGION. IT WILL BE A FEW DEGREES MILDER ACROSS THE CAPE/ISLANDS...BUT NORTHEAST WINDS WILL BE GUSTING TO BETWEEN 20 AND 25 MPH. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... BUNDLE OF JET ENERGY OVER THE OH VLY THIS AFTERNOON MOVES EAST TOMORROW AND SPAWNS SOUTH OF NEW ENGLAND IN THE MORNING WITH SURFACE LOW TRACKING AGAIN SE OF THE BENCHMARK. HOWEVER THIS SYSTEM IS MUCH WEAKER THAN TODAY/S SYSTEM. SO MUCH OF ITS AFFECTS WILL REMAIN OUT OVER THE OCEAN. HOWEVER THERE IS ENOUGH MOIST CYCLONIC FLOW ALOFT TO YIELD SCATTERED SNOW SHOWERS WITH ACTIVITY MOST NUMEROUS ACROSS CT/RI AND SOUTHEAST MA. COULD BE SOME OES ENHANCEMENT OVER PLYMOUTH COUNTY AND CAPE COD GIVEN MOIST NE FLOW BUT LAPSE RATES ARE MORE MARGINAL TOMORROW. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... HIGHLIGHTS... * SHORTWAVES BRING SNOW SHOWERS AND CLOUDS TUE NIGHT THRU THU * COLD FRONT THU * SNOW SHOWERS CONTINUE FRI AND SAT * MUCH COLDER AIR MOVES INTO SOUTHERN NEW ENGLAND FOR THE WEEKEND A COMPLEX FORECAST FOR THE LONG TERM. THE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE SYNOPTIC SCALE PATTERN WITH CONTINUED TROUGHING OVER THE EAST COAST AND RIDGING OVER THE WESTERN CONUS. DIFFERENCES AND CHALLENGES COME IN THE EXACT PATH OF THE SYNOPTIC FEATURES... INCLUDING SHORTWAVES...AS WELL AS THE MORE MESOSCALE FEATURES. TUESDAY NIGHT AND WEDNESDAY...HIGH CONFIDENCE. MULTIPLE SHORTWAVES WILL MOVE THROUGH OR NEAR SOUTHERN NEW ENGLAND AS THEY ROTATE AROUND AN UPPER LEVEL LOW IN QUEBEC. THIS WILL KEEP OVERCAST SKIES IN PLACE WITH OCCASIONAL SNOW SHOWERS EXPECTED THROUGHOUT SOUTHERN NEW ENGLAND. SEASONABLE TEMPERATURES EXPECTED. THURSDAY AND FRIDAY...MODERATE CONFIDENCE. AN UPPER LEVEL TROUGH MOVES THROUGH SOUTHERN NEW ENGLAND. COUPLED WITH THIS IS A LOW PRESSURE SYSTEM THAT WILL MOVE NORTH OF THE REGION...EXACT TRACK UNKNOWN AT THIS TIME... BRINGING AN ARCTIC FRONT THROUGH THE REGION. AGAIN...THIS WILL BRING A CHANCE OF SNOW SHOWERS AHEAD OF THE FRONT. JUST LIGHT AMOUNTS EXPECTED AT THIS TIME...A DUSTING TO MAYBE AN INCH OR TWO. THE BIG STORY WITH THIS FRONT WILL BE THE STRONG PUSH OF ARCTIC AIR MOVING INTO THE REGION. TEMPERATURES DURING THIS TIME WILL ALREADY BE 5 TO 10 DEGREES BELOW NORMAL FOR MID FEBRUARY AND THE COLDER AIR IS YET TO COME. THIS WEEKEND...MODERATE CONFIDENCE. NOT MUCH...IF ANY...PRECIPITATION EXPECTED. INSTEAD THE COLD WILL TAKE CENTER STAGE...ALONG WITH SOME BITTERLY COLD WIND CHILLS. ARCTIC AIR CONTINUES TO SEEP INTO SOUTHERN NEW ENGLAND WITH HIGHS EXPECTED TO BE 15-20 DEGREES BELOW NORMAL. WHILE THIS IS STILL NEARLY A WEEK OUT AND THERE IS SOME UNCERTAINTY TO BE HAD...08/12Z EPS PROBABILITIES HAVE AN OVER 80 PERCENT CHANCE OF LOW TEMPERATURES DROPPING BELOW ZERO AND OVER 50 PERCENT CHANCE OF LOW TEMPERATURES BELOW NEGATIVE 10 DEGREES! IN ADDITION...ON SATURDAY...STRONG LOW PRESSURE IN THE MARITIMES COUPLED WITH AN EQUALLY STRONG HIGH PRESSURE IN THE GREAT LAKES/OHIO VALLEY REGION WILL RESULT IN A TIGHT PRESSURE GRADIENT ACROSS SOUTHERN NEW ENGLAND. THIS WILL RESULT IN BREEZY CONDITIONS IF NOT DOWNRIGHT STRONG WINDS ACROSS THE AREA. BUT WITH TEMPERATURES AS COLD AS THEY ARE CURRENTLY FORECAST TO BE...EVEN JUST SLIGHTLY BREEZY CONDITIONS WILL RESULT IN VERY COLD WIND CHILLS. POSSIBLY EVEN INTO WIND CHILL ADVISORY CRITERIA AT POINTS DURING THE WEEKEND. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TODAY...MODERATE CONFIDENCE. LOW END VFR TO MAINLY MVFR CIGS WILL PERSIST TODAY UNDER A BROKEN TO OVERCAST DECK OF CLOUDS. BULK OF THE LIGHT SNOW WILL EXIT THE REGION BY 7 OR 8Z. OTHERWISE...MAINLY DRY WEATHER EXPECTED TODAY OTHER THAN PERHAPS AN SPOT FLURRY/SNOW SHOWER. THE EXCEPTION TO THIS MIGHT BE ALONG PORTIONS OF THE IMMEDIATE EASTERN MA COAST...ESPECIALLY FROM CAPE ANN AND INTO COASTAL PLYMOUTH COUNTY WHERE SCATTERED OCEAN EFFECT SNOW SHOWERS MAY PERSIST WELL INTO THE MORNING HOURS. TONIGHT AND WEDNESDAY...MODERATE CONFIDENCE. MAINLY LOW END VFR TO MVFR CIGS TONIGHT. SCATTERED SNOW SHOWERS WHICH MAY BE BRIEFLY HEAVY ARE EXPECTED TO WORK INTO THE REGION FROM SOUTHWEST TO NORTHEAST BETWEEN 6Z AND 12Z WEDNESDAY. SCATTERED SNOW SHOWERS WILL BE MOST PREVALENT IN THE MORNING ESPECIALLY SOUTH OF THE MA PIKE...BUT MAY LINGER INTO THE AFTERNOON. EXPECT MAINLY MVFR CONDITIONS ON WED....BUT BRIEF IFR TO EVEN LIFR CONDITIONS POSSIBLE IN LOCALLY BRIEF HEAVIER SNOW SHOWERS. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...MODERATE CONFIDENCE. THURSDAY THROUGH FRIDAY...MODERATE CONFIDENCE. MAINLY VFR CONDITIONS. ARCTIC FRONT MOVES THROUGH THE REGION WITH GUSTY NW WINDS. CHANCE OF -SHSN. EXPECTED ACCUMULATION LESS THAN ONE INCH. SATURDAY...MODERATE CONFIDENCE. MAINLY VFR CONDITIONS. GUSTY NW WINDS CONTINUE. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY/...HIGH CONFIDENCE. OVERNIGHT... HAVE CONVERTED ALL GALES TO SMALL CRAFT HEADLINES AS OCEAN STORM CONTINUES TO PULL EVEN FURTHER AWAY. NORTHERLY SCA WIND GUSTS WILL GRADUALLY DISSIPATE TOWARD DAYBREAK. SEAS WERE STILL BETWEEN 15 AND 20 FEET ACROSS OUR EASTERN OUTER-WATERS. THESE GRADUALLY SHOULD SUBSIDE...BUT LEFT OVER SWELL WILL MAKE THIS A SLOW PROCESS. TUESDAY... NE WINDS 15-20 KT AS WEAK LOW PRES TRACKS SOUTHEAST OF THE BENCHMARK. VSBY 1-3 MILES AT TIMES IN SNOW SHOWERS ACROSS SOUTHERN OCEAN WATERS AND EASTERN MA WATERS SOUTH OF BOSTON. OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...MODERATE CONFIDENCE. TUESDAY NIGHT THROUGH WEDNESDAY...HIGH CONFIDENCE. WINDS REMAIN MAINLY BELOW SMALL CRAFT CRITERIA. SEAS REMAIN ELEVATED AS SEVERAL WEAK LOW PRESSURE SYSTEMS MOVE THROUGH THE WATERS. EXPECT SMALL CRAFT ADVISORIES FOR SEAS TO BE NECESSARY FOR THIS PERIOD. THURSDAY THROUGH FRIDAY...MODERATE CONFIDENCE. NORTHWESTERLY WINDS AND SEAS INCREASE THURSDAY AS A STRONG ARCTIC FRONT APPROACHES AND THEN CROSSES THE WATERS. SEAS SUBSIDE FRIDAY AS HIGH PRESSURE BUILDS IN BEHIND THE FRONT. SMALL CRAFT ADVISORIES LIKELY. SATURDAY...MODERATE CONFIDENCE. NORTHWESTERLY WINDS CONTINUE BETWEEN LOW PRESSURE IN THE MARITIMES AND HIGH PRESSURE IN THE GREAT LAKES. SMALL CRAFT ADVISORIES LIKELY. && .TIDES/COASTAL FLOODING... ***MINOR COASTAL FLOODING LIKELY WITH POCKETS OF MODERATE COASTAL FLOODING POSSIBLE ALONG SOME EAST AND NORTH FACING SHORELINES SOUTH OF BOSTON TONIGHT*** 830 PM UPDATE... HAVE ADJUSTED WAVES AND SURGE TO FIT CURRENT TRENDS. SEAS ARE STILL RUNNING HIGH AND NOW WITH LONGER PERIODS OF 11 OR 12 SECONDS. AT 830 PM...SEAS WERE RUNNING 16 TO 18 FEET ACROSS MASS BAY AND 22 TO 25 FEET EAST OF CAPE COD AND EAST OF NANTUCKET. THE SURGE IS ALSO RUNNING ABOVE GUIDANCE AND OUR FORECAST...HAVING RISEN TO 3+ FEET AT NANTUCKET AND CHATHAM...AND STILL AROUND 2.4 FEET IN BOSTON. AFTER MAKING WAVE AND SURGE ADJUSTMENTS...IT NOW LOOKS LIKE MORE WIDESPREAD MINOR COASTAL FLOODING FOR THE HIGH TIDE NEAR MIDNIGHT WITH POCKETS OF MODERATE POSSIBLE...ESPECIALLY ON NANTUCKET. STILL EXPECT BOTH SEAS AND SURGE TO START TO SUBSIDE A LITTLE BY THE TIME OF THE HIGH TIDE AND SO HAVE OPTED TO KEEP THE HEADLINE AS AN ADVISORY VERSUS WARNING. HAVE INDICATED IN THE UPDATED COASTAL FLOOD STATEMENT OF THE POTENTIAL FOR SEVERE EROSION TONIGHT ALONG THE OUTER CAPE AND THE EAST SIDE OF NANTUCKET AS A CONSEQUENCE OF LARGE AND LONG PERIOD SWELLS BREAKING ONSHORE. LONG PERIOD SWELLS CAN CONTAIN CONSIDERABLE ENERGY AND HAVE A GREATER EROSION IMPACT THAN ONE MIGHT FIRST THINK. AND HAVE ADDED A STATEMENT TO INDICATE POCKETS OF MINOR COASTAL FLOODING FROM BOSTON NORTH TO SALISBURY...AGAIN DUE TO THE LARGE SWELLS AND THE DIFFICULTY OF THE WATER EVACUATING FROM THE HIGH TIDE EARLIER TODAY. IT DOES NOT LOOK WIDESPREAD ENOUGH AT THIS TIME TO WARRANT AN ADVISORY FOR THIS STRETCH OF COASTLINE. PRIOR DISCUSSION ISSUED THIS AFTERNOON... PRELIMINARY REPORTS SUGGEST FAIRLY WIDESPREAD MODERATE COASTAL FLOOD IMPACT FROM THE MONDAY LATE MORNING HIGH TIDE SOUTH OF BOSTON INCLUDING HULL...SCITUATE...MARSHFIELD AND NANTUCKET. LOOKING AHEAD...HAVE ISSUED A COASTAL FLOOD ADVISORY FOR EAST AND NORTH FACING SHORELINES SOUTH OF BOSTON...INCLUDING HULL TO PLYMOUTH...SANDWICH TO DENNIS...ORLEANS TO CHATHAM AND NANTUCKET. THERE APPEARS TO BE ENOUGH RESIDUAL SURGE AND WAVE ACTION FOR AREAS OF MINOR COASTAL FLOODING IN THE ADVISORY AREA AROUND THE TIME OF HIGH TIDE TONIGHT...AT OR A LITTLE AFTER MIDNIGHT IN MOST LOCATIONS ALONG THE MA EAST COAST. WE ANTICIPATE A SWELL OF 12 TO 16 FEET PROPAGATING INTO MASS BAY AND EXPOSED PORTIONS OF CAPE COD BAY AND 14 TO 18 FEET JUST OFF THE OUTER CAPE AND JUST EAST OF NANTUCKET AROUND MIDNIGHT. THE LONGER PERIODS OF PERHAPS 11 TO 13 SECONDS IMPLIES GREATER ENERGY WAVES MOVING ONTO THE SHORELINE...AND THIS IS REFLECTED IN THE EXPERIMENTAL WAVE RUNUP OUTPUT DEPICTING SPLASH OVER AT OUR SCITUATE EXPERIMENTAL LOCATION. WENT NEAR OR A LITTLE BELOW THE ETSS SURGE GUIDANCE BUT ABOVE THE ESTOFS GUIDANCE...WHICH CONTINUES TO HAVE A VERY SIGNIFICANT LOW BIAS. SURFACE WIND DIRECTION IS EXPECTED TO BE FROM THE NORTH AND CONSIDERABLY DIMINISHED IN SPEED FROM EARLIER TODAY. THE ASTRONOMICAL HIGH TIDE TONIGHT RUNS ABOUT A HALF FOOT TO A FOOT LOWER THAN THE MON LATE MORNING TIDE...DEPENDING UPON LOCATION. TOTAL WATER LEVELS LOOK TO BE HIGH ENOUGH FOR SOME MINOR COASTAL FLOODING IN EAST FACING PROTECTIVE BAYS/HARBORS AND SPLASHOVER FROM THE LONG PERIOD SWELLS ALONG THE OPEN SHORELINE. SOME EROSION IS LIKELY AROUND THE TIME OF HIGH TIDE...MOST NOTABLY ALONG THE OUTER CAPE AND EAST SIDE OF NANTUCKET. A FEW ESPECIALLY VULNERABLE SPOTS MAY EXPERIENCE MINOR COASTAL FLOODING AROUND THE TIME OF THE PARTICULARLY HIGH ASTRONOMICAL TIDE AROUND MIDDAY/EARLY AFTERNOON TUE DUE TO A RESIDUAL LONG PERIOD SWELL AND POSSIBLE SURGE NEAR ONE FOOT. CONFIDENCE IS TOO LOW...HOWEVER...TO EXTEND THE ADVISORY HEADLINE AT THIS TIME. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...COASTAL FLOOD ADVISORY UNTIL 2 AM EST EARLY THIS MORNING FOR MAZ019-022-024. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST EARLY THIS MORNING FOR ANZ231>234. SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ235- 237-250-251-254>256. && $$ SYNOPSIS...NOCERA/RLG NEAR TERM...FRANK SHORT TERM...NOCERA LONG TERM...RLG AVIATION...FRANK/RLG MARINE...FRANK/NOCERA/RLG TIDES/COASTAL FLOODING...THOMPSON

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.