Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 260259 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 959 PM EST SUN JAN 25 2015 .SYNOPSIS... CHILLY AND BLUSTERY CONDITIONS EXPECTED THROUGH MONDAY. A MAJOR AND POTENTIALLY HISTORIC WINTER STORM WILL AFFECT THE REGION MONDAY NIGHT INTO TUESDAY NIGHT...TRAVEL MAY BECOME IMPOSSIBLE AND LIFE THREATENING. DRIER WEATHER FOLLOWS WEDNESDAY INTO EARLY THURSDAY...BUT WILL HAVE TO WATCH FOR ANOTHER CHANCE OF SNOW BY THE END OF THE WORK WEEK. && .NEAR TERM /THROUGH MONDAY/...
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10 PM UPDATE... ASIDE FROM MORE INCREASING HIGH CLOUDS AHEAD OF THE CLIPPER SYSTEM AND SLOWLY DEEPENING LOW PRES NEAR N. CAROLINA MOST FORECAST PARAMETERS ARE ON TRACK LATE THIS EVENING. THEREFORE...ONLY MINOR ADJUSTMENTS WERE MADE TO ENSURE THAT TIMING/HOURLY TEMPS AND DWPTS WERE IN LINE WITH CURRENT TRENDS. PREVIOUS DISCUSSION... TONIGHT...HIGH PRESSURE IN QUEBEC WILL BUILD SOUTHWARD INTO SOUTHERN NEW ENGLAND ALLOWING WINDS TO CALM AND CLEAR SKIES CONTINUE. THIS WILL ALLOW FOR DECENT RADIATIONAL COOLING. HOWEVER...INCREASING CLOUDS FROM THE SOUTH IN ADVANCE OF LOW PRESSURE MOVING OFF THE COAST MAY PUT A STOP TO RADIATIONAL COOLING EARLY. THEREFORE...NOT DROPPING TEMPERATURES AS LOW AS THEY COULD BE IF SKIES REMAINED CLEAR. FORECASTING LOWS IN THE SINGLE DIGITS TO TEENS FOR MOST LOCATIONS. MONDAY...HIGH PRESSURE MOVES NORTHEASTWARD INTO THE MARITIMES AS LOW PRESSURE MOVES OFFSHORE THE DELMARVA PENINSULA BEFORE APPROACHING SOUTHERN NEW ENGLAND MONDAY NIGHT. MOSTLY DRY/QUIET WEATHER EXPECTED FOR MUCH OF MONDAY BUT DEFINITELY A DETERIORATING TREND. INCREASING CLOUDS THROUGH THE DAY WITH MOSTLY CLOUDY TO OVERCAST SKIES THROUGH THE DAY. THE GFS IS THE QUICKEST MOVING SNOW OVER SOUTHERN NEW ENGLAND AROUND MIDDAY. HOWEVER...THE NAM/ECMWF ARE THE PREFERRED SOLUTIONS FOR THE NOREASTER/BLIZZARD. THESE SOLUTIONS KEEP THE AREA DRY THROUGH MUCH OF THE DAY WITH SNOW MOVING IN FROM THE SOUTH LATE MONDAY AFTERNOON. BECAUSE OF THIS...ONLY EXPECT A FEW INCHES OF SNOW AT MOST PRIOR TO 00Z TUESDAY /7 PM MONDAY/. TEMPERATURES ARE EXPECTED TO BE IN THE 20S TO MID 30S ACROSS SE MA.
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&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... * HISTORIC AND POTENTIALLY CRIPPLING BLIZZARD MON NIGHT INTO TUE NIGHT * UP TO 2 FEET OF SNOW FOR MANY AREAS WITH HIGHER AMOUNTS POSSIBLE * DAMAGING WINDS LIKELY COAST ESP CAPE/ISLANDS...GUSTS 60 TO 75 MPH * POCKETS OF MAJOR COASTAL FLOODING POSSIBLE ALONG THE EASTERN MA COAST OVERVIEW... OVERALL MULTI-MODEL AGREEMENT ON SFC AND UPPER AIR PATTERN LEADS US TO HIGH CONFIDENCE OF A HISTORIC WINTER STORM AND POTENTIALLY CRIPPLING BLIZZARD FOR SNE. POTENT NEG TILT SHORTWAVE DIVING TO SE US COAST WILL RESULT IN SFC REDEVELOPMENT OFF THE MID ATLC COAST AND EXPLOSIVE CYCLOGENESIS SOUTH OF NEW ENGLAND MON NIGHT AS MID LEVEL LOW CLOSES OFF. HIGH PRES WILL SET UP ACROSS EASTERN CANADA PROVIDING A SOURCE OF COLD AIR AND ENHANCING BAROCLINIC ZONE ALONG THE COAST. THE STORM EVENTUALLY GETS CAPTURED WHICH WILL ALLOW FOR VERY SLOW MOVEMENT NWD FROM NEAR THE BENCHMARK AND LONG DURATION STORM. THERE ARE SOME DIFFERENCES IN THE TRACK OF THE 850/700 MB LOWS AND HOW QUICKLY IT EXITS THE AREA WHICH WILL IMPACT EXACTLY WHERE BEST BANDING SETS UP...POTENTIAL DRY SLOT EASTERN NEW ENG AS WELL AS PTYPE FOR CAPE/ISLANDS. WE THINK GFS IS TOO PROGRESSIVE AND A BIT TOO FAR NORTH AND WEST WITH MID LEVEL LOW AND WE ARE LEANING TOWARD ECMWF/NAM BLEND WHICH ARE REASONABLY CLOSE. DESPITE DIFFERENCES IN MID LEVEL LOW TRACK...QPF IS PRETTY SIMILAR WITH 1.5 TO 2.5 INCHES ACROSS SNE WITH LOCALLY UP TO 3 INCHES. PROBABLY LOOKING AT NEAR CLIMO SNOW LIQUID RATIOS WHICH ARE CLOSE TO 10:1 IN THE COASTAL PLAIN AND NO MORE THAN 12-15:1 INTERIOR AS MID LEVEL TEMPS IN THE SNOW PRODUCTION ZONE ARE NEAR CLIMATOLOGY. HIGH CONFIDENCE ON BLIZZARD IN EASTERN NEW ENG SO WE ARE UPGRADING WATCHES TO BLIZZARD WARNINGS. WE ARE ALSO EXPANDING THE BLIZZARD WARNINGS TO N CT...PORTIONS OF CENTRAL MA AND CAPE COD AND MVY. WINTER STORM WARNINGS FOR WESTERN MA AS WE ARE NOT CONFIDENT WIND CRITERIA WILL BE MET. AND FINALLY FOR ACK...WE KEPT THE WINTER STORM WATCH AS WE ARE NOT CONFIDENT IN 6 INCHES OF SNOW DUE TO PTYPE ISSUES AND WE ALSO UPGRADED TO A HIGH WIND WARNING. 1) PRECIP TYPE... THERMAL PROFILE COLD ENOUGH FOR ALL SNOW FOR MOST OF THE AREA...BUT WE ARE STILL CONCERNED ABOUT ENOUGH WARMING FOR A POSSIBLE CHANGE TO RAIN OVER ACK LATE MON NIGHT INTO TUE...WITH THIS WARMING POSSIBLY REACHING THE OUTER CAPE FOR A TIME DURING TUE. ECMWF IS PRETTY BULLISH ON THIS WARMING AND NAM ALSO SHOWS IT BUT TO A LESSER EXTENT. 2) HEAVY SNOW/BLIZZARD CONDITIONS/WIND SNOW WILL BE RAMPING UP QUICKLY MON EVENING...WITH VERY HEAVY SNOW LIKELY DEVELOPING AFTER MIDNIGHT INTO TUE MORNING FROM SOUTH TO NORTH AS VERY IMPRESSIVE BANDING SIGNATURE DEVELOPS AND LIFTS N ACROSS THE REGION. THIS OCCURS AS THE MID LEVEL LOW CLOSES OFF TO THE SOUTH WITH TIGHTENING THERMAL GRADIENT ENHANCING FRONTOGENETICAL FORCING. VERY STRONG OMEGA THROUGH THE FAVORABLE DENDRITIC GROWTH ZONE COMBINED WITH -EPV SUGGESTS POTENTIAL FOR 2-3"/HR SNOWFALL RATES AND POCKETS OF THUNDER SNOW 06-15Z AS THE BAND LIFTS TO THE N. MODELS SHOW BANDING SIGNATURE MOVING INTO THE INTERIOR WEST OF I-95 CORRIDOR DURING TUE AND PIVOTING FROM E-W TO NE-SW CONFIGURATION...WHILE POSSIBLE DRY SLOT MOVES INTO PORTIONS OF E MA. FORECASTING THE EXACT LOCATION OF THE BANDING...WHERE IT PIVOTS AND LOCATION OF THE DRY SLOT TUESDAY IS VERY CHALLENGING AND WILL DETERMINE WHERE AXIS OF HEAVIEST SNOW SETS UP. THIS WILL DEPEND ON THE TRACK OF THE MID LEVEL LOW. ECMWF PUSHES THIS BAND ALL THE WAY INTO WESTERN NEW ENG WHILE NAM IS CLOSER TO THE I-95 CORRIDOR. WE THINK IT WILL SET UP A LITTLE WEST OF I-95 ON THE COLD SIDE OF THE COASTAL FRONT AND THIS IS WHERE WE THINK HEAVIEST SNOW ACCUM WILL BE. POTENTIAL FOR 2-3 FEET OF SNOW IN THIS ZONE NEAR AND WEST OF I-95... UP TO 2 FEET FAR W MA AND ALSO SE MA WHERE DRY SLOT MAY CUT BACK ON SNOW ACCUM A TAD DESPITE HEAVIER QPF HERE. IT IS NOT UNCOMMON TO FIND THE HEAVIEST SNOW A BIT NW OF MAX QPF AXIS BECAUSE OF WHERE THE BANDING SETS UP. FOR THE CAPE AND MVY WE ARE LOOKING AT 10-18" WITH HEAVIEST NEAR THE CANAL. LOW CONFIDENCE FORECAST FOR ACK AND WE HAVE UP TO 6 INCHES HERE BUT WILL DEPEND ON TIMING OF CHANGEOVER. HIGHEST PROBABILITY OF HEAVY WET SNOW WILL BE ACROSS SE MA AND CAPE COD WHERE THERE IS ENHANCED POTENTIAL FOR DOWN TREES AND POWER OUTAGES...ESPECIALLY GIVEN THE STRONG WINDS. DRIER SNOW IN THE INTERIOR. VERY STRONG WINDS ARE LIKELY ALONG THE COAST AS IMPRESSIVE LOW LEVEL JET DEVELOPS N OF THE DEEPENING LOW PRES. NAM SOUNDINGS SHOW POTENTIAL FOR HURRICANE FORCE WIND GUSTS 70-80 MPH FOR THE OUTER CAPE AND ISLANDS...ESPECIALLY LATE MON NIGHT INTO TUE MORNING WHEN STRONGEST WINDS WILL OCCUR. GUSTS TO 50-60 MPH POSSIBLE ACROSS REST OF SE MA EAST OF THE I95 CORRIDOR...AND 30-40 MPH ACROSS THE INTERIOR. COMBINATION OF HEAVY SNOW AND VERY STRONG WINDS WILL RESULT IN BLIZZARD CONDITIONS WITH BLOWING AND DRIFTING SNOW AND NEAR ZERO VISIBILITY LATER TONIGHT INTO TUE...ESPECIALLY EASTERN NEW ENG. THIS IS A SERIOUS AND LIFE THREATENING STORM AND TRAVEL IS HIGHLY DISCOURAGED TONIGHT INTO TUE. IT LOOKS LIKE THE WORST OF THE STORM WILL BEGIN TO WIND DOWN LATE TUE AND ESPECIALLY TUE NIGHT AS THE LOW BECOMES VERTICALLY STACKED AND BANDING BECOMES FRACTURED...BUT LIGHT SNOW WILL PERSIST MOST OF THE NIGHT GIVEN PROXIMITY OF MID LEVEL LOW NEAR THE COAST...WITH SNOW FINALLY ENDING WEDNESDAY MORNING. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... WHILE THE FOCUS OF THE FORECAST REMAINS ON THE BLIZZARD...WE WILL UPDATE THIS PORTION OF THE FORECAST AS TIME PERMITS. SNOW COMES TO AN END WEDNESDAY MORNING AS HIGH PRESSURE STARTS BUILDING OVER SOUTHERN NEW ENGLAND. THEN ANOTHER WINTER STORM IS POSSIBLE SOMETIME THURSDAY INTO FRIDAY /ECMWF IS SLOWER THAN GFS/ AS LOW PRESSURE MOVES EASTWARD FROM THE GREAT LAKES OVER SOUTHERN NEW ENGLAND. HIGH PRESSURE EXPECTED TO BUILD IN NEXT WEEKEND. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. TONIGHT...HIGH CONFIDENCE. VFR. NW WINDS 10 TO 15 KTS. MONDAY...HIGH CONFIDENCE IN TRENDS. MODERATE CONFIDENCE IN TIMING. START OFF VFR WITH DETERIORATING CONDITIONS THROUGHOUT THE DAY. IFR CONDITIONS AND SNOW WILL NOT OCCUR UNTIL LATE IN THE DAY...LIKELY AFTER 21Z. HOWEVER...THEY COULD OCCUR AS EARLY AS 18Z. KBOS TAF...HIGH CONFIDENCE IN TAF. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK /MONDAY NIGHT THROUGH FRIDAY/... MONDAY NIGHT THROUGH TUESDAY NIGHT...WIDESPREAD LIFR IN HEAVY SNOW AND BLOWING SNOW. STRONG NE WINDS DEVELOPING NEAR THE COAST WITH GUSTS 50-65 KTS EXPECTED. WEDNESDAY...IMPROVING CONDITIONS EXPECTED AS HIGH PRESSURE BUILDS IN. THURSDAY AND FRIDAY...DETERIORATING CONDITIONS WITH ANOTHER POTENTIAL WINTER STORM. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH MONDAY/...HIGH CONFIDENCE. SMALL CRAFT CONDITIONS WILL CONTINUE THROUGH MONDAY. HOWEVER... FOCUSING ON THE UPCOMING NOREASTER/BLIZZARD...AND ASSOCIATED STORM FORCE TO HURRICANE FORCE WINDS EXPECTED WITH THIS STORM...HAVE DROPPED THE SMALL CRAFT ADVISORIES. OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/... ***LIFE THREATENING STORM FOR MARINERS WITH SEAS BUILDING TO 30 FT AND WIND GUSTS TO 65 KNOTS MONDAY NIGHT THROUGH TUESDAY*** MONDAY NIGHT THROUGH TUESDAY NIGHT...RAPIDLY INTENSIFYING LOW PRESSURE MOVING ACROSS THE WATERS WILL RESULT IN NORTHEAST WIND GUSTS INCREASING TO 55 TO 65 KNOTS OVER THE OPEN WATERS WITH SEAS BUILDING TO 30 FT OVER EASTERN WATERS. HURRICANE FORCE WIND WARNINGS HAVE BEEN ISSUED FOR MOST OF THE OPEN WATERS WITH STORM WARNING ELSEWHERE. THIS IS DANGEROUS AND LIFE THREATENING STORM AND MARINERS SHOULD RETURN TO PORT BY MONDAY AFTERNOON. WEDNESDAY...MODERATE CONFIDENCE. SHOULD SEE AT LEAST LEFTOVER N-NW WIND GUSTS UP TO SMALL CRAFT CRITERIA DURING WED...THEN SHOULD DIMINISH WED NIGHT. THURSDAY AND FRIDAY...LOW CONFIDENCE. WINDS SHOULD REMAIN BELOW SMALL CRAFT CRITERIA. SEAS MAY LINGER AT AROUND 5 FT. && .TIDES/COASTAL FLOODING... SIGNIFICANT COASTAL FLOODING IS EXPECTED DURING THE EARLY TUESDAY MORNING HIGH TIDE ALONG THE MASSACHUSETTS EAST COAST. HIGH TIDE OCCURS BETWEEN 4 AND 6 AM ALONG MOST OF THE COASTLINE. IN BOSTON HIGH TIDE IS AT 430 AM. HAVE UPGRADED TO A COASTAL FLOOD WARNING FOR THE TUESDAY AM HIGH TIDE AND HAVE KEPT THE WATCH IN PLACE FOR THE TUESDAY LATE AFTERNOON HIGH TIDE. FOR THE TUESDAY AM HIGH TIDE...ANTICIPATE THE STORM SURGE TO BE 3 TO 3.5 FEET AND STILL RISING TO POSSIBLY 3.5 TO 4 FEET BY THE TIME OF THE LATER TUESDAY MORNING LOW TIDE. BY THE TUESDAY EARLY AM HIGH TIDE...ANTICIPATE SEAS TO HAVE BUILT TO BETWEEN 20 AND 25 FEET JUST OFFSHORE...HIGHEST EAST OF CAPE COD AND NANTUCKET. NE SURFACE WINDS ANTICIPATED TO BE GUSTING BETWEEN 50 AND 60 KT BY THE TIME OF THE EARLY TUESDAY AM HIGH TIDE. THESE SEAS WILL BE HIGH ENOUGH FOR OVERWASH TO BE AN ISSUE IN THOSE PLACES TYPICALLY PRONE TO IT. SEVERE BEACH EROSION IS LIKELY IN A FEW SPOTS GIVEN THE ELEVATED WATER LEVELS AND STRONG WAVE ACTION. THIS IS A STORM THAT COULD PRODUCE ONE OR MORE NEW INLETS ALONG EXPOSED EAST AND NORTHEAST FACING BARRIER BEACHES. THE TUESDAY LATE AFTERNOON HIGH TIDE IS SOMEWHAT LOWER ASTRONOMICALLY BUT THE SURGE COULD BE ABOUT THE SAME OR EVEN A FEW TENTHS HIGHER THAN AT THE TUESDAY AM HIGH TIDE. ALSO SEAS COULD BE STILL 25 TO 30 FEET JUST OFFSHORE AT THE TIME OF THE TUESDAY LATE AFTERNOON HIGH TIDE. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...BLIZZARD WARNING FROM 7 PM MONDAY TO 1 AM EST WEDNESDAY FOR CTZ002>004. MA...BLIZZARD WARNING FROM 7 PM MONDAY TO 1 AM EST WEDNESDAY FOR MAZ005>007-012>021. COASTAL FLOOD WARNING FROM 3 AM TO 7 AM EST TUESDAY FOR MAZ007- 015-016-019-022>024. COASTAL FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY EVENING FOR MAZ007-015-016-019-022-024. WINTER STORM WARNING FROM 7 PM MONDAY TO 1 AM EST WEDNESDAY FOR MAZ002>004-008>011-026. HIGH WIND WARNING FROM 7 PM MONDAY TO 1 AM EST WEDNESDAY FOR MAZ024. WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY AFTERNOON FOR MAZ024. BLIZZARD WARNING FROM 7 PM MONDAY TO NOON EST TUESDAY FOR MAZ022-023. RI...BLIZZARD WARNING FROM 7 PM MONDAY TO 1 AM EST WEDNESDAY FOR RIZ001>008. MARINE...HURRICANE FORCE WIND WARNING FROM 7 PM MONDAY TO 7 PM EST TUESDAY FOR ANZ231>235. STORM WARNING FROM 11 PM MONDAY TO 7 PM EST TUESDAY FOR ANZ230- 236. STORM WARNING FROM 7 PM MONDAY TO 7 PM EST TUESDAY FOR ANZ237- 251. HURRICANE FORCE WIND WARNING FROM 1 AM TO NOON EST TUESDAY FOR ANZ250-254>256. && $$ SYNOPSIS...KJC/RLG NEAR TERM...DOODY/RLG SHORT TERM...KJC LONG TERM...RLG AVIATION...KJC/RLG MARINE...KJC/RLG TIDES/COASTAL FLOODING...

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