Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 272355 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 655 PM EST TUE JAN 27 2015 .SYNOPSIS...
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THE BLIZZARD CONTINUING TO WIND DOWN THIS EVENING...BUT IMPROVEMENT WILL TAKE THE LONGEST ACROSS THE FAR SOUTHEAST NEW ENGLAND COAST. OTHER THAN A FEW OCEAN EFFECT SNOW SHOWERS ON WEDNESDAY ACROSS THE CAPE AND NANTUCKET...IT WILL BE DRY AND COLD FOR THE REST OF THE REGION AS THE CLEANUP BEGINS. PLAINS LOW PRESSURE WILL BRING ANOTHER CHANCE FOR SNOW THURSDAY NIGHT AND FRIDAY. DRY BUT VERY COLD AIR LOOKS TO FOLLOW FOR THE WEEKEND. A THIRD STORM MAY AFFECT THE REGION SUNDAY NIGHT AND MONDAY.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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HIGHLIGHTS... * BLIZZARD ACROSS CAPE/ISLANDS WINDS DOWN BY LATE EVENING * STEADY SNOW BANDS ACROSS EASTERN NEW ENGLAND END BY 9 OR 10 PM * DRY AND COLD WEDNESDAY EXCEPT LINGERING SNOW SHOWERS CAPE/NANTUCKET 650 PM UPDATE... DOWNGRADED THE BLIZZARD WARNING FOR MOST OF THE REGION EXCEPT THE FAR SOUTHEAST NEW ENGLAND COAST. WHILE THERE WERE STILL MODERATE SNOW BANDS ACROSS EASTERN MA/RI...BLIZZARD CONDITIONS WERE NO LONGER OCCURRING. HOWEVER...A FEW INCHES OF ADDITIONAL SNOW REMAIN POSSIBLE ALONG WITH GUSTY WINDS RESULTING IN BLOWING AND DRIFTING SNOW. THEREFORE...HAVE REPLACED THE BLIZZARD WARNING WITH A WINTER STORM WARNING THROUGH 10 PM FOR THIS REGION. FURTHER BACK INTO THE INTERIOR...HAVE A WINTER WEATHER ADVISORY FOR SOME BLOWING AND DRIFTING OF THE POWDERY SNOW ALONG WITH SCATTERED SNOW SHOWERS. CAPE/ISLANDS AND EASTERN PLYMOUTH COUNTY... NORTHERLY WINDS STILL GUSTING BETWEEN 40 AND 55 MPH ALONG WITH BANDS OF HEAVY SNOW/BLIZZARD CONDITIONS AND NEAR ZERO VISIBILITY. BLIZZARD WARNING NOW UNTIL 10 PM ACROSS THIS REGION. AFTER THAT TIME...STEADY SNOW SHOULD TAPER OFF TO SCATTERED OCEAN EFFECT SNOW SHOWERS AND WILL PROBABLY BE ABLE TO DROP THE BLIZZARD WARNING. HOWEVER...CONSIDERABLE BLOWING AND DRIFTING SNOW WILL CONTINUE OVERNIGHT RESULTING IN POOR VISIBILITY AND VERY HAZARDOUS TRAVEL.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
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WEDNESDAY... SCATTERED OCEAN EFFECT SNOW SHOWERS WILL REMAIN POSSIBLE ACROSS THE CAPE/NANTUCKET INTO THE AFTERNOON WITH NNW WINDS AND AN 850T/OCEAN DIFFERENTIAL OF 20C. ANY ADDITIONAL ACCUMS WILL BE RATHER LIGHT IN THIS REGION. ACROSS THE REST OF THE REGION...HIGH PRESSURE WILL SLOWLY BUILD IN FROM THE WEST. PARTIAL SUNSHINE SHOULD DEVELOP FROM WEST TO EAST LATER IN THE MORNING AND INTO THE AFTERNOON. HIGH TEMPS WILL ONLY BE IN THE LOWER TO MIDDLE 20S AS THE CLEANUP BEGINS.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... BIG PICTURE... NORTHERN AND SOUTHERN STREAMS WILL PUSH SHORTWAVES ACROSS THE USA. ONE NORTHERN STREAM SHORTWAVE ENTERED THE PACIFIC NORTHWEST TODAY AND WILL REACH NEW ENGLAND THURSDAY NIGHT/FRIDAY. A SOUTHERN STREAM SHORTWAVE FROM CALIFORNIA MAY MERGE WITH IT WEDNESDAY OR THURSDAY. ANOTHER PAIR OF SHORTWAVES DIG OVER THE PLAINS OVER THE WEEKEND AND APPROACH THE EAST COAST SUNDAY NIGHT/MONDAY. THE VARIOUS MODELS ARE SIMILAR IN THE BROAD PORTRAIT OF WEATHER SYSTEMS THESE NEXT SEVEN DAYS BUT DIFFER ON DETAILS SUCH AS TIMING. WE OPTED FOR A BLEND OF MODEL DATA FOR THIS FORECAST. THE DAILIES... WEDNESDAY NIGHT-THURSDAY...HIGH CONFIDENCE HIGH PRESSURE MOVES ACROSS THE REGION AND SHOULD PROVIDE A PERIOD OF CLEAR SKIES AND LIGHT WINDS. DEW POINTS WILL BE IN THE SINGLE NUMBERS BELOW ZERO WHICH SHOULD ALLOW THE COLDER LOCATIONS TO A SIMILAR RANGE OVERNIGHT. IF THERE ARE POTENTIAL PROBLEMS IN THE FORECAST...IT WOULD BE THAT MINS MAY BE 2-4F TOO WARM IN THE NORMAL COLD SPOTS OF THE EAST IF THEY RADIATE MORE EFFECTIVELY. THE HIGH WILL SHIFT OFFSHORE THURSDAY BUT STILL PROVIDE PLENTY OF DRY AIR FOR NEW ENGLAND. AS IT SHIFTS OFFSHORE...A SOUTHWEST FLOW ALOFT WILL BRING IN INCREASING MOISTURE ALOFT AND THUS INCREASING MID AND HIGH CLOUDS. ANY PCPN SHOULD HOLD OFF UNTIL AFTER DARK. THURSDAY NIGHT-FRIDAY...LOW-MODERATE CONFIDENCE CLIPPER AND SUPPORTING SHORTWAVE RACE EAST TO THE GREAT LAKES THURSDAY AND THEN REDEVELOP ALONG THE NEW ENGLAND COAST. THE GFS HAS THE REDEVELOPMENT IN THE GULF OF MAINE WHILE THE ECMWF AND GGEM SHOW THIS CLOSER TO 40N/70W. THE SOUTHERN SOLUTION IS CLOSER TO THE DYNAMICALLY FAVORED LEFT EXIT REGION OF THE UPPER JET...AND MAY RESULT IN MORE PCPN IF IT OCCURS. TEMPERATURE PROFILES FAVOR SNOW ALTHOUGH SOME WARM INTRUSION MAY WARM THE CAPE/ISLANDS INTO THE UPPER 30S AND PROVIDE A BRIEF CHANGE TO RAIN. THIS WILL NEED TO BE MONITORED. THE DIFFERENCES IN MODEL PLACEMENT OF THE SURFACE LOW LEAD TO THE REDUCED CONFIDENCE IN THIS PART OF THE FORECAST. SURFACE PRESSURE FALLS AS THE STORM DEEPENS OFFSHORE. THIS WILL TIGHTEN THE PRESSURE GRADIENT AND BRING INCREASING NORTHWEST WINDS ON THE TRAILING SIDE OF THE STORM. COLD AIR THEN GETS DRAWN IN ACROSS NEW ENGLAND FRIDAY. TEMPS ALOFT WILL SUPPORT MAX TEMPS IN THE 30S DURING THE MORNING-MIDDAY AND 20S BY SUNSET. FRIDAY NIGHT-SATURDAY-SUNDAY... STRONG WINDS TRAILING THE STORM BRING INCOMING COLD AIR WITH AIRMASS TEMPS REACHING THE SINGLE NUMBERS. THIS WILL BRING WIND CHILLS BELOW ZERO. NORTHERN AND WESTERN WIND CHILLS SHOULD GO BELOW 10 BELOW ZERO AND MAY REQUIRE A WIND CHILL ADVISORY. HIGH PRESSURE BUILDS OVER THE REGION ON SATURDAY WITH DRY WEATHER AND GUSTY NORTHWEST WINDS. TEMPS AT 925 MB WILL BE -13C TO -17C...SO MAX TEMPS SATURDAY WILL BE CHALLENGED TO REACH THE 20S MOST PLACES...BEST CHANCE WILL BE IN RI AND SOUTHEAST MASS. THE HIGH MOVES OFFSHORE ON SUNDAY...AGAIN CREATING INCREASING MOISTURE ALOFT WHILE DRY NEAR THE SURFACE. THIS WILL MEAN INCREASING CLOUDS DURING THE DAY WITH TEMPS A LITTLE LESS COLD THAN ON SATURDAY. SUNDAY NIGHT-MONDAY... NEXT PAIR OF SHORTWAVES APPROACH. THE SOUTHERN STREAM SHORTWAVE GENERATES AN INVERTED TROUGH IN THE WESTERN GULF/MISSISSIPPI VALLEY REGION. THE NORTHERN SHORTWAVE HELPS GENERATE LOW PRESSURE IN THIS TROUGH AND SWINGS IT NORTHEAST TOWARD NEW ENGLAND. ALL MOVE PCPN INTO NEW ENGLAND AND CONSENSUS KEEPS TEMPS COLD ENOUGH FOR SNOW. BUT DIFFERENCES IN TRACK RANGING FROM ACROSS THE BERKSHIRES /ECMWF/ TO ACROSS THE 40N/70W BENCHMARK /GGEM/. AND THIS IS A DAY 5 FORECAST. SO CONFIDENCE REMAINS LOW. TUESDAY... HIGH PRESSURE BUILDS OVER THE REGION WITH 925 MB TEMPS AGAIN FALLING TO AROUND -15 TO -17C. ANOTHER CHILLY DRY WEATHER DAY. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THROUGH TUESDAY NIGHT... THIS AFTERNOON AND TONIGHT... RADAR SHOWS MOST OF THE SNOW IS NOW EAST OF THE CT VALLEY. THE HEAVIEST SNOW IS CONCENTRATED IN EASTERN MASS AND TO A LESSER EXTENT IN RHODE ISLAND. MOST CIGS AND VSBYS WITHIN THIS SNOW BAND SHOULD BE AT OR BELOW 1000 FEET AND BELOW 1 MILE. BASED ON THE LOCATION OF THE STORM CENTER EAST OF NANTUCKET...EXPECT THE SNOW BAND WILL LINGER OVER EASTERN MASS/RI THROUGH THE AFTERNOON WITH AN IMPROVING TREND AFTER 22Z. STRONG WIND GUSTS CONTINUE IN THE EAST WITH 50-60 KNOT GUSTS CAPE COD AND ISLANDS. LOW LEVEL WIND SHEAR CONTINUES THIS AFTERNOON ON THE CAPE AND ISLANDS BEFORE SHIFTING OFFSHORE. EXPECT CIGS AND VSBYS TO IMPROVE WEST TO EAST THE FIRST PART OF TONIGHT. WESTERN AREAS REMAIN VFR THROUGH THE NIGHT WHILE EASTERN AREAS BECOME VFR AFTER MIDNIGHT. MVFR CIGS MAY LINGER ON CAPE COD AND NANTUCKET. NORTHWEST WINDS WILL DIMINISH WITH ALL AREAS UNDER 30 KNOTS AFTER MIDNIGHT. WEDNESDAY...VFR MOST AREAS. SOME LINGERING MVFR CIGS OUTER CAPE COD AND NANTUCKET. NORTHWEST WINDS CONTINUE TO DIMINISH UNDER 20 KNOTS. KBOS TAF...HIGH CONFIDENCE IN TAF TRENDS...LOWER CONFIDENCE IN EXACT TIMING. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK /WEDNESDAY NIGHT THROUGH SUNDAY/...LOW TO MODERATE CONFIDENCE. WEDNESDAY NIGHT-THURSDAY...VFR WITH LIGHT NORTHWEST WIND BECOMING LIGHT SOUTH ON THURSDAY. THURSDAY NIGHT-FRIDAY...CIGS LOWER TO MVFR WITH MVFR-IFR VSBYS IN SNOW. CONDITIONS IMPROVE TO VFR FRIDAY AFTERNOON. WINDS ALSO SHIFT TO NORTHWEST WITH GUSTS OF AT LEAST 25 KNOTS. SATURDAY-SUNDAY...VFR. GUSTY NORTHWEST WINDS 25-30 KNOTS SATURDAY...LIGHTER WINDS SUNDAY. && .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. ***GRADUAL IMPROVEMENT TONIGHT BUT CONDITIONS WILL REMAIN DANGEROUS FOR MARINERS UNTIL WEDNESDAY*** POWERFUL STORM SLOWLY PULLS AWAY FROM THE REGION AND FINALLY LIFTS INTO THE CANADIAN MARITIMES ON WEDNESDAY. STORM FORCE WIND GUSTS CONTINUE FOR THE FIRST PART OF THE NIGHT...BUT SHOULD SEE THINGS LOWER TO GALES NEAR MIDNIGHT. GALES THEN LOWER TO SCA HEADLINES WED MORNING AS PRESSURE GRADIENT SLOWLY WEAKENS. 25 TO 30 FOOT SEAS ACROSS THE THE EASTERN WATERS WILL GRADUALLY DIMINISH TONIGHT AND FINALLY DROP BELOW 10 FEET SOMETIME WEDNESDAY AFTERNOON. OUTLOOK /WEDNESDAY NIGHT THROUGH SUNDAY/...MODERATE CONFIDENCE. WEDNESDAY NIGHT-THURSDAY... DIMINISHING NORTHWEST WINDS THROUGH THE NIGHT. COULD BE SOME 25 KNOT GUSTS IN THE EVENING BUT OTHERWISE WINDS SHOULD BE LESS THAN THAT THRESHOLD. LINGERING 5 TO 7 FOOT SEAS ON MASSACHUSETTS BAY AND THE OUTER WATERS WILL DIMINISH OVERNIGHT. CONDITIONS REMAIN BELOW SMALL CRAFT THRESHOLDS ON THURSDAY. FRIDAY... COLD FRONT MOVES THROUGH WITH AREAS OF REDUCED VISIBILITY IN SNOW. ONCE THE FRONT MOVES ACROSS THE WATERS...WINDS SHIFT TO NORTHWEST AND INCREASE TO 30-35 KNOTS. THIS IS CLOSE ENOUGH TO THE GALE THRESHOLD SO THAT LOW-END GALES ARE A POSSIBILITY. THIS WILL BE MONITORED. SEAS WILL ALSO INCREASE TO 5 TO 8 FEET ON THE EXPOSED WATERS. THE NORTHWEST WINDS WILL BRING IN PLENTY OF COLD AIR. THIS WILL CAUSE OCEAN EFFECT SNOW SHOWERS OFF OUTER CAPE COD...AND FREEZING SPRAY WILL AGAIN DEVELOP FRIDAY NIGHT. SATURDAY...NW GALES EXPECTED WITH POTENTIAL FOR A LIGHT FREEZING SPRAY. SEAS REMAIN HIGH...POSSIBLY UP TO 7-9 FT ON THE EXPOSED WATERS. SUNDAY...WINDS AND SEAS AT SMALL CRAFT ADVISORY LEVELS BUT DIMINISHING THROUGH THE DAY. && .TIDES/COASTAL FLOODING... *** LATE AFTERNOON HIGH TIDE WILL LIKELY PRODUCE COMPARABLE IMPACTS TO EARLY MORNING HIGH TIDE IN MANY AREAS EXCEPT PROBABLY HIGHER IMPACTS NORTH SIDE OF CAPE COD AND NANTUCKET *** FORECAST FOR LATE AFTERNOON HIGH TIDE IS TRICKY WHEN IT COMES TO THE DETAILS. THE SURGE SHOULD BE SUBSIDING BUT NOT FAST ENOUGH TO PRECLUDE PROBLEMS. THE ISSUE IS HOW FAST THE SURGE SUBSIDES. BELIEVE WAVES WILL BE HIGHER THAN AT THE TIME OF THE EARLY MORNING HIGH TIDE BUT ALSO STARTING TO SUBSIDE. THERE ARE A COUPLE OF OTHER FACTORS TO CONSIDER. SOME SHORELINE DEFENSES MAY HAVE BEEN COMPROMISED WITH THE EARLY MORNING HIGH TIDE AND THUS INCREASING VULNERABILITY FOR AT LEAST A FEW SPOTS. ALSO...WAVE PERIODS HAVE INCREASED TO THE 13 TO 15 SECOND RANGE AND SUGGEST GREATER ENERGY IN THE BREAKING SURF THIS AFTERNOON COMPARED WITH EARLY THIS MORNING. AND THERE ARE SOME AREAS WHICH REMAIN INUNDATED FROM THE EARLY MORNING HIGH TIDE WITH THE WATER UNABLE TO DRAIN...AN UNSETTLING SITUATION FOR SURE. GREATEST CONCERN IS THE POTENTIAL IMPACT FOR CAPE COD AND NANTUCKET. VERY STRONG ONSHORE WINDS WILL JUST BE STARTING TO DIMINISH AS WE APPROACH THE TIME OF HIGH TIDE AND SO THINK THE SURGE WILL REMAIN NEAR 4.5 FEET ALONG THE NORTH SIDE OF CAPE COD AND NEAR 4 FEET IN NANTUCKET HARBOR. THESE VALUES ARE WELL ABOVE THOSE FROM BOTH THE ETSS AND ESTOFS GUIDANCE. EXPECT A WORSE IMPACT FOR THE NORTH SIDE OF CAPE COD AND PROBABLY AT LEAST A LITTLE WORSE FOR NANTUCKET. BEACH EROSION IS EXPECTED TO BE SEVERE IN THESE SAME AREAS AS WELL AS THE OCEAN SIDE OF CAPE COD FROM TRURO TO CHATHAM. ELSEWHERE ALONG THE MASSACHUSETTS EAST COAST...ANTICIPATE COMPARABLE COASTAL FLOOD IMPACT FOR THE SHORELINE FROM HULL TO PLYMOUTH WITH RUNUP AND OVERWASH AS BIG OR PERHAPS EVEN BIGGER FACTOR DUE TO THE LARGE WAVES. WE ARE ALSO THINKING A COMPARABLE IMPACT FOR THE SHORELINE FROM SALISBURY TO ROCKPORT WITH LARGE WAVES AND EROSION PLAYING A ROLE THERE AS WELL. IN CONTRAST...THE SHIFT IN THE WIND TO BE FROM THE N OR NNW IS EXPECTED TO RESULT IN LESS IMPACT ALONG THE NORTH SHORE FROM BOSTON TO GLOUCESTER. LOOKING AHEAD TO THE EARLY WEDNESDAY MORNING HIGH TIDE CYCLE...GENERALLY BETWEEN 530 AM AND 630 AM...ANTICIPATE POCKETS OF MINOR COASTAL FLOODING ALONG NORTH AND NORTHEAST FACING SHORELINES AS WELL AS SOME ADDITIONAL EROSION. IMPACTS FOR THE EARLY WEDNESDAY HIGH TIDE WILL BE MUCH LESS THAN WHAT WE HAVE EXPERIENCED OR WILL HAVE EXPERIENCED DURING THE HIGH TIDES TODAY. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR CTZ002>004. MA...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR MAZ004>007-012>018-020-021-026. COASTAL FLOOD WARNING UNTIL 8 PM EST THIS EVENING FOR MAZ007- 015-016-019-022-024. BLIZZARD WARNING UNTIL 10 PM EST THIS EVENING FOR MAZ019-022- 023. WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR MAZ002-003-008>011. HIGH WIND WARNING UNTIL 1 AM EST WEDNESDAY FOR MAZ024. WINTER STORM WARNING UNTIL 1 AM EST WEDNESDAY FOR MAZ024. RI...WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR RIZ001>008. MARINE...STORM WARNING UNTIL 10 PM EST THIS EVENING FOR ANZ231>234-250- 254-255. FREEZING SPRAY ADVISORY UNTIL 8 AM EST WEDNESDAY FOR ANZ231>235-237-251. SMALL CRAFT ADVISORY UNTIL 7 PM EST WEDNESDAY FOR ANZ230-236. GALE WARNING UNTIL 1 AM EST WEDNESDAY FOR ANZ235-237-251-256.
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&& $$ SYNOPSIS...FRANK/WTB NEAR TERM...FRANK SHORT TERM...FRANK LONG TERM...WTB AVIATION...WTB MARINE...WTB/FRANK TIDES/COASTAL FLOODING...THOMPSON

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