Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 270842 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 342 AM EST TUE JAN 27 2015 .SYNOPSIS...
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A CRIPPLING AND HISTORIC WINTER STORM / BLIZZARD WILL IMPACT THE REGION INTO TONIGHT. DRIER WEATHER FOLLOWS WEDNESDAY AFTERNOON INTO EARLY THURSDAY...BUT LOW PRESSURE WILL BRING ANOTHER CHANCE FOR SNOW THURSDAY NIGHT AND FRIDAY. VERY COLD AIR LIKELY FOLLOWS FOR NEXT WEEKEND.
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&& .NEAR TERM /THROUGH TONIGHT/...
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HIGHLIGHTS... * CRIPPLING AND POTENTIALLY HISTORIC BLIZZARD WITH 1 TO 2 FT OF SNOW WITH LOCALLY HIGHER AMOUNTS * STRONG TO DAMAGING WINDS / HURRICANE FORCE ACROSS SE NEW ENGLAND * MODERATE TO MAJOR COASTAL FLOODING / SEVERE BEACH EROSION WV LOOP SHOWS DEEPENING MID LEVEL LOW SOUTH OF LONG ISLAND WITH WELL DEFINED COMMA HEAD WITH WARM CONVEYOR BELT/TROWAL LIFTING NWD INTO NEW ENG. RAPID CYCLOGENESIS IN PROGRESS WITH SFC LOW DOWN TO 984 MB. THERE ARE SUBTLE DIFFERENCES IN THE TRACK...BUT GENERAL AGREEMENT OF A TRACK CLOSE TO THE BENCHMARK AS A SUB 980 MB STORM AROUND 12Z. ONLY SLOW MOVEMENT NORTH DURING TODAY AS THE LOW GETS CAPTURED BY THE UPPER LEVEL SYSTEM WHICH WILL PROLONG OCCASIONAL HEAVY SNOW THROUGH TODAY. SNOWFALL / BANDING / BLIZZARD... VERY INTENSE MESOSCALE BAND SETTING UP ACROSS N CT THROUGH CENTRAL/NE MA ASSOCD WITH THE STRENGTHENING MID LEVEL FRONTOGENESIS WITH THE DEEPENING MID LEVEL LOW PRODUCING STRONG OMEGA THROUGH THE DENDRITIC GROWTH ZONE. PROBABLY SEEING 2-4"/HR SNOWFALL RATES IN THIS BAND. MEANWHILE...PULSES OF HEAVIER SNOW BANDS WHICH ARE CONVECTIVE IN NATURE CONTINUE TO MOVE FROM THE OCEAN ACROSS SE MA. VERY HEAVY CLUSTER OVER THE ISLANDS WILL BE MOVING UP ACROSS SE MA NEXT 1-2 HOURS. MID LEVEL LAPSE RATES OVER 6 C/KM ACROSS SE NEW ENG SUGGESTING POTENTIAL FOR UPRIGHT CONVECTION AND THUNDER SNOW. SNOWFALL RATES 2-3"/HOUR WILL BE DEVELOPING IN SE MA AND PORTIONS OF CAPE COD. HOW THESE BANDS EVOLVE TODAY WILL BE CRITICAL TO THE SNOWFALL FORECAST AND THIS WILL BE TRICKY. GFS/ECMWF KEEP THE BEST MID LEVEL FRONTOGENESIS ACROSS E MA WHILE NAM IS FURTHER WEST ACROSS CENTRAL MA INTO CT. NAM SEEMS TO BE HANDLING THIS THE BEST AND KEEP THIS BAND IN THE SAME GENERAL AREA BEFORE WEAKENING AND MOVING EAST. MEANWHILE...LOW LEVEL CONVERGENCE AND FRONTOGENESIS ASSOCD WITH THE COASTAL FRONT ACROSS SE MA WILL RESULT IN A SECONDARY MAX IN EASTERN MA INCLUDING CAPE COD WITH OCCASIONAL HEAVY SNOW. WE HAVE ONLY MADE SLIGHT MODIFICATIONS TO THE SNOW ACCUM...LOWERING SLIGHTLY IN THE BERKSHIRES AND INCREASING ACROSS CAPE COD...ESPECIALLY NEAR THE CANAL. STILL LOOKING FOR MAX SNOWFALL ACROSS NE CT THROUGH CENTRAL MA...WITH SECONDARY MAX ACROSS E MA TO THE CAPE COD CANAL. AROUND 2 FT EXPECTED IN THIS AREA...LOCALLY 30-36 INCHES POSSIBLE WHERE PERSISTENT BANDS SET UP. LESSER AMOUNTS IN BETWEEN BANDS. COMBINATION OF HEAVY SNOW AND STRONG WIND WILL RESULT IN BLIZZARD CONDITIONS...ESPECIALLY ACROSS EASTERN HALF NEW ENG WITH CONSIDERABLE BLOWING AND DRIFTING. IN ADDITION...WIND CHILLS WILL BE DOWN INTO THE SINGLE NUMBERS ABOVE AND BELOW ZERO ADDING TO THE SEVERITY AND LIFE THREATENING ASPECT OF THE STORM. TRAVEL WILL BE NEAR IMPOSSIBLE. WIND... CORE OF STRONGEST WINDS WILL BE OCCURRING THROUGH ABOUT 18Z FOR THE CAPE/ISLANDS TO COASTAL SE MA AS LOW PRES DEEPENS NEAR THE BENCHMARK. LOW LEVEL JET AROUND 75 KTS PERSISTS IN THIS REGION. SOUNDINGS SHOW POTENTIAL FOR NEAR HURRICANE FORCE GUSTS TO 75 MPH IN THIS REGION...WITH GUSTS TO 50-60 BACK TO THE I-95 CORRIDOR AND 30-40 FURTHER IN THE INTERIOR. EXPECT WIND DAMAGE AND WIDESPREAD POWER OUTAGES ACROSS PORTIONS OF SE MA AND ESPECIALLY THE CAPE/ISLANDS WHERE HEAVY WET SNOW WILL ADD TO LOAD. TEMPS... COASTAL FRONT CURRENTLY ACROSS SE MA WITH TEMPS IN THE TEENS WEST OF THE FRONT AND 20S TO LOWER 30S TO THE EAST. EXPECT TEMPS TO REMAIN IN THE TEENS TO NEAR 20 TODAY FOR MOST OF THE REGION...AND EVENTUALLY FALLING INTO THE TEENS AND LOWER 20S SE COASTAL MA THIS AFTERNOON AS THE COASTAL FRONT MOVES THROUGH.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... DISCUSSION CONTINUES BELOW. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... HIGHLIGHTS... * COLDER WEATHER ARRIVES LATE THIS WEEK * CLIPPER LOW MAY BRING MORE MEASURABLE SNOW THU NIGHT INTO FRI * MUCH COLDER EARLY NEXT WEEK OVERVIEW... 26/12Z GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THEIR OVERALL SYNOPTIC HANDLING FOR THIS PORTION OF THE FORECAST. THERE ARE STILL SOME CRUCIAL DETAILS TO BE WORKED OUT THOUGH. WILL FAVOR A CONSENSUS APPROACH. DETAILS... WEDNESDAY...LINGERING SNOW SHOWERS SHOULD COME TO AN END DURING THE MORNING ACROSS MOST OF EASTERN NEW ENGLAND AS POWERFUL LOW PRESSURE LIFTS INTO THE CANADIAN MARITIMES. A FEW OCEAN-EFFECT SNOW SHOWERS MAY LINGER INTO THE AFTERNOON OR PERHAPS EARLY EVENING ACROSS THE CAPE AND ISLANDS. OTHERWISE...PARTIAL SUNSHINE DEVELOPS AS THE DAY WEARS ON ACROSS THE REGION. WEDNESDAY NIGHT AND THURSDAY...HIGH PRESSURE BUILDS IN WEDNESDAY NIGHT. WITH A FRESH...DEEP SNOWPACK IN PLACE WITH DIMINISHING WIND...SOME OUTLYING LOCATIONS SHOULD FALL BELOW ZERO. MODEL GUIDANCE IS STILL LIKELY TOO HIGH. WILL MAKE FURTHER ADJUSTMENTS LATER THIS WEEK TO DIAL THIS IN. THURSDAY NIGHT AND FRIDAY...ANOTHER LOW PRESSURE QUICKLY MOVES IN FROM THE WEST. THIS SYSTEM WON/T COMPARE TO WHAT WE WILL SEE INTO WEDNESDAY...BUT SHORTWAVE LOOKS FAIRLY IMPRESSIVE. THE PRIMARY TRACK OF A CLIPPER LOW SHOULD BE TO THE NORTH OF SOUTHERN NEW ENGLAND. THIS SHOULD RESULT IN MORE SCATTERED SNOWFALL. PLOWABLE AMOUNTS ARE POSSIBLE...EVEN WITH THE MORE NORTHERN TRACK. THIS WEEKEND INTO MONDAY...A SHOT OF VERY COLD AIR APPROACHES SOUTHERN NEW ENGLAND THIS WEEKEND INTO EARLY NEXT WEEK. THERE IS SOME QUESTION IF ANOTHER COASTAL LOW PRESSURE CAN DEVELOP AND GET CLOSE ENOUGH TO OUR REGION. 29/12Z ECMWF HAS COME CLOSER TO THE GFS SOLUTION...BOTH IN TRACK AND TIMING. AT PRESENT...WILL PLACE A CHANCE OF SNOW IN THE FORECAST LATE SUNDAY INTO MONDAY. THERE IS STILL TOO MUCH UNCERTAINTY AT THIS POINT TO SAY MORE THAN THAT AT THIS TIME. && .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...THROUGH TUESDAY NIGHT... TONIGHT... SIGNIFICANT SNOWSTORM IS MOVING INTO THE REGION. HEAVY SNOW WILL MOVE UP AFTER MIDNIGHT WITH 1-3 INCH PER HOUR RATES...AND LOCAL 4 INCH PER HOUR RATES POSSIBLE. NORTH NORTHEAST SURFACE WINDS WILL INCREASE THROUGH THE NIGHT WITH GUSTS 30-40 KNOTS IN THE CT VALLEY AND CENTRAL MASS...40-50 KNOTS IN THE BOS-PVD COASTAL PLAIN AREA...AND 50-70 KNOTS CAPE/ISLANDS/SOUTH COAST. EVEN STRONGER WINDS ALOFT MOVE IN AT 2000 FEET AGL LEADING TO LOW LEVEL WIND SHEAR. TUESDAY AND TUESDAY NIGHT... SIGNIFICANT SNOWSTORM CONTINUES THROUGH THE PERIOD WITH SNOWFALL RATES OF 1-3 INCHES PER HOUR. ISOLATED THUNDER POSSIBLE. MOST AIRPORTS ARE EXPECTED TO BE AT OR BELOW MINIMUMS DURING THIS PERIOD WITH LIFR/VLIFR CONDITIONS. VERY STRONG WIND CONTINUE WITH GUSTS 70-80 KNOTS CAPE AND ISLANDS AND PARTS OF SOUTHEAST MASS. LOW LEVEL WIND SHEAR CONTINUES THROUGH TUESDAY AND DIMINISHES TUESDAY NIGHT. KBOS TAF...HIGH CONFIDENCE IN TAF TRENDS...LOWER CONFIDENCE IN EXACT TIMING. KBDL TAF...HIGH CONFIDENCE IN TAF TRENDS...LOWER CONFIDENCE IN EXACT TIMING. OUTLOOK /WEDNESDAY THROUGH SATURDAY/... WEDNESDAY...HIGH CONFIDENCE IN TRENDS...MODERATE CONFIDENCE IN TIMING. CONDITIONS IMPROVE TO VFR FROM WEST TO EAST...ALTHOUGH MVFR CIGS MAY LINGER CAPE/ISLANDS. NORTHWEST WIND GUSTS TO 25 KNOTS. THURSDAY AND FRIDAY...MODERATE CONFIDENCE. ANOTHER ROUND OF MVFR- IFR CONDITIONS IN SOME SNOW SOMETIME THU NIGHT INTO FRI. SATURDAY...MODERATE CONFIDENCE VFR. GUSTY NORTHWEST WINDS.
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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 TONIGHT/...HIGH CONFIDENCE. *** POWERFUL STORM PRODUCE LIFE THREATENING CONDITIONS *** EXPECT NE WIND GUSTS OF 55-65 KT WITH SEAS 30-35 FT OVER THE E WATERS AS WELL. HURRICANE FORCE WIND WARNINGS CONTINUE FOR THE OPEN WATERS...WITH STORM WARNINGS CLOSER TO THE SHORE. CONDITIONS IMPROVE SOMEWHAT LATER TODAY INTO TONIGHT...ALTHOUGH A PERIOD OF GALES ARE POSSIBLE UNTIL CONDITIONS DROP DOWN TO SMALL CRAFT ADVISORY THRESHOLDS. OUTLOOK /WEDNESDAY THROUGH SATURDAY/... WEDNESDAY...HIGH CONFIDENCE. ANY LEFTOVER GALE FORCE NORTHWEST WIND GUSTS EARLY IN THE MORNING WILL QUICKLY DIMINISH TO SMALL CRAFT ADVISORY LEVELS. SEAS WILL CONTINUE TO SUBSIDE...BUT STILL REMAIN WELL ABOVE SMALL CRAFT THRESHOLDS ACROSS THE EASTERN WATERS. THURSDAY AND FRIDAY...MODERATE CONFIDENCE. HIGH PRESSURE NEARBY WILL KEEP WINDS/SEAS BELOW SMALL CRAFT THRESHOLDS THU INTO EARLY FRI. DEPENDING ON THE TRACK OF AN APPROACHING LOW PRESSURE...WE COULD SEE SMALL CRAFT ADVISORY CONDITIONS DEVELOP LATER FRI OR FRI NIGHT. SATURDAY...PRESSURE GRADIENT BETWEEN AN OFFSHORE LOW PRESSURE AND A HIGH PRESSURE OVER THE NORTHEAST INTENSIFIES. THIS COULD RESULT IN GALE FORCE WIND GUSTS WITH ROUGH SEAS...ESPECIALLY ACROSS THE OUTER COASTAL WATERS.
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&& .TIDES/COASTAL FLOODING...
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*** MODERATE TO MAJOR COASTAL FLOODING TODAY ALONG THE EASTERN MA COAST FOR BOTH THIS MORNING AND LATE AFTERNOON HIGH TIDE CYCLES *** POWERFUL WINTER STORM DEVELOPING NEAR THE 40N/70W BENCHMARK AND COMBINING WITH ARCTIC HIGH PRESSURE OVER SOUTHEAST QUEBEC TO YIELD HURRICANE FORCE WIND GUSTS THIS MORNING AND INTO MIDDAY ACROSS NANTUCKET...CAPE COD AND COASTAL PLYMOUTH COUNTY. TIDE GAUGES ALONG THE EASTERN MA COASTLINE AT 3 AM INDICATING STORM SURGE VALUES ALREADY 2.5 TO 3.0 FT! THIS WILL YIELD MODERATE TO MAJOR COASTAL FLOODING WITH THIS MORNING/S HIGH TIDE CYCLE. THE HIGHEST IMPACT AREAS WILL LIKELY BE NANTUCKET/CAPE COD BAY COMMUNITIES AND NORTHWARD ALONG THE COAST INTO PLYMOUTH COUNTY INCLUDING THE COMMUNITIES OF HULL/MARSHFIELD AND SCITUATE. COASTAL FLOODING WILL OCCUR FARTHER NORTHWARD INTO CAPE ANN HOWEVER THE MAGNITUDE OF THE FLOODING SHOULD BE SLIGHTLY LESS THAN THE SOUTH SHORE. THESE HIGH WATER LEVELS WILL RESULT IN SIGNIFICANT INUNDATION OF SEA WATER. STRUCTURAL DAMAGE IS LIKELY AS WELL GIVEN SEAS OFFSHORE HAVE ALREADY CLIMBED TO 18 TO 22 FT AND WILL ONLY CONTINUE TO INCREASE. COULD SEE OFFSHORE SEAS 25 TO 35 FT THIS AFTERNOON! THIS WILL RESULT LARGE WAVES BATTERING SEAWALLS AND OTHER SHORELINE STRUCTURES. IN ADDITION THE HIGH WATER LEVELS WILL COMBINE WITH THE LARGE WAVE ACTION TO YIELD SEVERE BEACH EROSION. AS FOR THE LATE AFTERNOON HIGH TIDE...WATER LEVELS MAY BE ABOUT A HALF A FOOT LOWER HOWEVER SEAS WILL BE AT LEAST AS LARGE AS THIS MORNING OR POSSIBLE A FEW FEET HIGHER. THUS IMPACTS WILL BE SIMILAR HOWEVER THE FOCUS WILL SHIFT TO COASTAL PLYMOUTH COUNTY SOUTHWARD TO CAPE COD BAY COMMUNITIES SUCH AS SANDWICH HARBOR. THUS LESS IMPACT FOR NANTUCKET THAN THIS MORNING. NEVERTHELESS AT LEAST MODERATE COASTAL FLOODING EXPECTED FOR NANTUCKET. SO IN A NUTSHELL...NO CHANGES TO ANY HEADLINES WITH COASTAL FLOOD WARNINGS REMAINING IN PLACE FOR THE NEXT TWO TIDE CYCLES. AS FOR RI...THE RISK FOR MINOR COASTAL FLOODING HAS COMMENCED WITH HIGH TIDE ALREADY OCCURRING. THEREFORE THE RISK HAS DIMINISHED AND THE ADVISORY WILL BE ALLOWED TO EXPIRE.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...BLIZZARD WARNING UNTIL 1 AM EST WEDNESDAY FOR CTZ002>004. MA...BLIZZARD WARNING UNTIL 1 AM EST WEDNESDAY FOR MAZ005>007- 012>021. COASTAL FLOOD WARNING UNTIL 7 AM EST THIS MORNING FOR MAZ007- 015-016-019-022>024. COASTAL FLOOD WARNING FROM 3 PM THIS AFTERNOON TO 7 PM EST THIS EVENING FOR MAZ007-015-016-019-022-024. WINTER STORM WARNING UNTIL 1 AM EST WEDNESDAY FOR MAZ002>004- 008>011-024-026. HIGH WIND WARNING UNTIL 1 AM EST WEDNESDAY FOR MAZ024. BLIZZARD WARNING UNTIL NOON EST TODAY FOR MAZ022-023. RI...COASTAL FLOOD ADVISORY UNTIL 2 AM EST EARLY THIS MORNING FOR RIZ006>008. BLIZZARD WARNING UNTIL 1 AM EST WEDNESDAY FOR RIZ001>008. MARINE...HURRICANE FORCE WIND WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ231>235. STORM WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ230-236-237- 251. HURRICANE FORCE WIND WARNING UNTIL NOON EST TODAY FOR ANZ250- 254>256. && $$ SYNOPSIS...KJC NEAR TERM...KJC SHORT TERM...SIPPRELL LONG TERM...BELK/99 AVIATION...WTB/BELK/EVT MARINE...BELK/SIPPRELL/THOMPSON TIDES/COASTAL FLOODING...

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