Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 280844 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 344 AM EST WED JAN 28 2015 .SYNOPSIS...
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STRONG LOW PRESSURE WILL MOVE ACROSS NOVA SCOTIA TODAY. OTHER THAN A FEW OCEAN EFFECT SNOW SHOWERS ACROSS THE CAPE AND NANTUCKET...IT WILL BE DRY AND COLD 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 PM THIS EVENING/...
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WV IMAGERY SHOWS COMMA HEAD LOSING ITS PUNCH ACROSS NEW ENG AS DRIER AIR MOVES IN FROM THE WEST. SNOW BANDS HAVE WEAKENED CONSIDERABLY ACROSS E MA AND LIGHT SNOW WILL COME TO AN END BEFORE DAYBREAK WITH EXCEPTION OF CAPE COD WHERE OCEAN EFFECT SNOW SHOWERS WILL DEVELOP. FOR TODAY...SCT OCEAN EFFECT SNOW SHOWERS WILL LIKELY CONTINUE INTO THE AFTERNOON OVER THE OUTER CAPE. STEEP LOW LEVEL LAPSE RATES OVER THE WATER WITH DELTA T FROM SST TO TOP OF THE MIXED LAYER EXCEEDING 20C WHICH IS QUITE UNSTABLE. HOWEVER...NW TRAJECTORY AND SHALLOW MIXED LAYER WILL LIMIT AREAL EXTENT SOMEWHAT. COULD SEE AN ADDITIONAL COATING TO AN INCH OVER THE OUTER CAPE. OTHERWISE...CLOUDS WILL GRADUALLY GIVE WAY TO PTSUNNY SKIES FROM WEST TO EAST DURING THE AFTERNOON...EXCEPT FOR THE CAPE/ISLANDS WHERE CLEARING WILL BE DELAYED UNTIL EVENING. HIGH TEMPS WILL REACH LOW/MID 20S...EXCEPT UPPER TEENS HIGHER TERRAIN IN NORTHERN AND WESTERN MA. NW WINDS GUSTING TO 20-25 MPH WILL RESULT IN WIND CHILLS IN THE SINGLE NUMBERS AND TEENS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
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HIGH PRES BUILDS IN FROM THE WEST TONIGHT WITH CLEARING SKIES AND LIGHT WINDS DEVELOPING. WITH DEEP FRESH SNOWPACK...THE STAGE WILL BE SET FOR IDEAL RADIATIONAL COOLING AND A VERY COLD NIGHT. LEANED TOWARD COLDER MOS GUIDANCE AND UNDERCUT BY 2-3F WHICH YIELDS MINS IN THE SINGLE NUMBERS ABOVE AND BELOW ZERO...EXCEPT TEENS CAPE/ISLANDS. COLDEST MINS WILL BE ACROSS W MA.
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&& .LONG TERM /THURSDAY 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 /08Z WEDNESDAY THROUGH SUNDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THROUGH TONIGHT...HIGH CONFIDENCE. THROUGH 12Z...AREAS OF MVFR/IFR IN SNOW ACROSS E MA WILL IMPROVE 08-09Z...EXCEPT LINGERING IN OCEAN EFFECT SNOW SHOWERS ACROSS CAPE COD. DIMINISHING WIND. TODAY...VFR CIGS MOST AREAS...BUT MVFR CIGS ALONG WITH SCT SNOW SHOWERS ACROSS OUTER CAPE COD AND ACK. NW GUSTS TO 20 KT. TONIGHT...VFR. WINDS BECOMING LIGHT. KBOS TAF...HIGH CONFIDENCE IN TAF. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK /THURSDAY THROUGH SUNDAY/...LOW TO MODERATE CONFIDENCE. THURSDAY...VFR WITH 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...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TONIGHT/...HIGH CONFIDENCE. GALE FORCE GUSTS HAVE DIMINISHED OVER E WATERS AND SCA IN EFFECT FOR ALL WATERS. WINDS WILL CONTINUE TO DIMINISH BELOW SCA LATER THIS MORNING INTO THE AFTERNOON...WITH GRADUAL SUBSIDING SEAS. FREEZING SPRAY DIMINISHING. DIMINISHING NW WINDS THROUGH TONIGHT. SEAS MOSTLY BELOW SCA THRESHOLDS...EXCEPT SUBSIDING TO NEAR 5 FT OVER E WATERS TOWARD DAYBREAK THU. OUTLOOK /THURSDAY THROUGH SUNDAY/...MODERATE CONFIDENCE. THURSDAY... 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.
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&& .TIDES/COASTAL FLOODING...
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ANTICIPATE POCKETS OF MINOR COASTAL FLOODING FOR THE EARLY MORNING HIGH TIDE ALONG NORTH AND NORTHEAST FACING SHORELINES AS WELL AS SOME ADDITIONAL EROSION. IMPACTS FOR THIS TIDE CYCLE WILL BE MUCH LESS THAN WHAT WE EXPERIENCED DURING TUESDAY/S HIGH TIDES.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...COASTAL FLOOD ADVISORY UNTIL 7 AM EST THIS MORNING FOR MAZ019- 022-024. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ232>235-237. FREEZING SPRAY ADVISORY UNTIL 8 AM EST THIS MORNING FOR ANZ231>235-237-251. SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR ANZ230. SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ231- 251-255-256. SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR ANZ236. SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR ANZ250-254.
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&& $$ SYNOPSIS...KJC NEAR TERM...KJC SHORT TERM...KJC LONG TERM...WTB AVIATION...WTB/KJC MARINE...WTB/KJC TIDES/COASTAL FLOODING...

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