Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 281029 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 529 AM EST WED JAN 28 2015 .SYNOPSIS... 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. CLIPPER TYPE SYSTEM MOVES OUT OF THE PLAINS STATES...BRINGING ANOTHER CHANCE FOR SNOW THURSDAY NIGHT INTO FRIDAY NIGHT. DRY...BLUSTERY AND FRIGID CONDITIONS MOVE IN FOR THIS WEEKEND. A THIRD STORM MAY AFFECT THE REGION SUNDAY NIGHT AND MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 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. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... 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. && .LONG TERM /THURSDAY THROUGH TUESDAY/... OVERVIEW... ACTIVE BUT PROGRESSIVE NORTHERN AND SOUTHERN STREAMS ACROSS THE LOWER 48 THROUGH THIS LONG TERM PERIOD. FIRST NORTHERN STREAM SHORT WAVE WORKS OUT OF THE NORTHERN ROCKIES TODAY...CROSSING INTO THE REGION THURSDAY NIGHT AND FRIDAY...POSSIBLY LINGERING ALONG THE E COAST FRIDAY NIGHT. THIS WILL USHER IN ARCTIC AIR FOR THIS WEEKEND ALONG WITH BLUSTERY WINDS AND FRIGID WIND CHILLS. A PAIR OF H5 SHORT WAVES MAY MERGE AS THEY APPROACH THE E COAST SUNDAY NIGHT AND MONDAY. WHILE OPERATIONAL MODELS DID SHOW TIMING AND TRACK DIFFERENCES ESPECIALLY WITH THE POSSIBLE LATE WEEKEND SYSTEM...USED AN OVERALL MODEL BLEND INCLUDING ENSEMBLES. THIS GAVE GOOD CONTINUITY WITH THE PREVIOUS FORECAST. DETAILS... THURSDAY... HIGH PRES RIDGE BUILDS ACROSS IN FAST UPPER FLOW. WILL SEE MOSTLY CLEAR SKIES AND LIGHT WINDS. THE RIDGE WILL PUSH OFFSHORE DURING THE AFTERNOON WITH A LIGHT S-SW WIND FLOW SETTING UP. CLOUDS WILL ALSO INCREASE AHEAD OF NEXT APPROACHING SYSTEM. EXPECT HIGHS MAINLY IN THE UPPER 20S TO MID 30S. THURSDAY NIGHT-FRIDAY NIGHT... PRETTY VIGOROUS H5 SHORT WAVE WITH CLIPPER TYPE SYSTEM WORKING E OUT OF THE EASTERN GREAT LAKES/OHIO VALLEY. LOOKS LIKE THIS SYSTEM WILL REDEVELOP OFF THE NEW ENGLAND COAST AS THE SHORT WAVE BEGINS TO NEGATIVE TILT AND CUTOFF...BUT THIS LOOKS LIKE IT WILL HAPPEN ACROSS CENTRAL NEW ENGLAND. THE LOW DOES NOT DEEPEN UNTIL LATER FRIDAY...WHICH WILL BE INTO THE GULF OF MAINE BY THEN. HOWEVER... THE LOW LOOKS TO SPIN THERE FRI NIGHT AS IT DEEPENS...WHICH MAY KEEP MOISTURE ACROSS EASTERN AREAS. WITH MILDER AIR WORKING INTO THE DEVELOPING LOW FRIDAY...LOOKS LIKE THERE MAY BE A PERIOD OF MIXED RAIN/SNOW OR EVEN A BRIEF CHANGE TO RAIN ALONG THE S COAST...CAPE COD AND THE ISLANDS. OTHERWISE...LOOKS LIKE ANOTHER SHOT OF SNOWFALL FOR THE REGION THOUGH NOT NEARLY AS HIGH AS THE BLIZZARD. TOTAL QPF LOOKS TO BE FROM 0.15 TO 0.25 INCHES ACROSS MOST AREAS...BUT WILL SEE SOME ENHANCEMENT ACROSS E COASTAL AREAS AS THE LOW FORMS WITH QPF POSSIBLY UP TO 0.40 INCHES. WITH THE COLD AIR IN PLACE...WILL LIKELY SEE SNOWFALL TOTALS FROM 2-4 INCHES BUT COULD SEE A BIT MORE ACROSS NE MA CLOSER TO THE DEVELOPING LOW WITH SOME SNOW LINGERING FRI NIGHT. WITH STRONG PRESSURE FALLS AS THE LOW DEVELOPS OFFSHORE...EXPECT TIGHTENING PRES GRADIENT BRINGING INCREASING NW WINDS BEHIND THE STORM LATER FRIDAY NIGHT. WILL LIKELY SEE GUSTS UP TO 25-35 KT AROUND OR AFTER MIDNIGHT...BRINGING IN ARCTIC AIR AS WELL AS LOW WIND CHILL READINGS. LOWS FRIDAY NIGHT PLUNGE TO BELOW ZERO ACROSS THE HIGHER INLAND TERRAIN AS WELL AS THE E SLOPES OF THE BERKSHIRES TO 10-15 ALONG THE S COAST...CAPE COD AND THE ISLANDS. THE COMBINATION OF THE LOW TEMPS AND BLUSTERY WINDS MAY MEAN VERY LOW WIND CHILL READINGS. ADVISORIES MAY BE NEEDED FOR PORTIONS OF THE INTERIOR. SATURDAY-SUNDAY... HIGH PRES BEGINS TO SHIFT E DURING SAT...BUT THE DEPARTING STORM INTO THE MARITIMES WILL CAUSE BLUSTERY CONDITIONS TO CONTINUE. ARCTIC AIRMASS ENTRENCHES ITSELF ACROSS THE REGION WITH H85 TEMPS DROPPING TO -11C TO -16C. THIS TRANSLATES TO TEMPS ONLY RECOVERING TO THE TEENS TO AROUND 20 ON SAT...THOUGH WIND CHILLS WILL MAKE IT FEEL MUCH COLDER. WINDS WILL DIMINISH SAT NIGHT...BUT MAY REMAIN HIGH ENOUGH WITH THE DROPPING TEMPS TO SEE POSSIBLE WIND CHILL ADVISORIES. LOWS WILL BOTTOM OUT FROM ZERO TO 5 BELOW WELL INLAND TO THE MID TEENS ON THE OUTER CAPE AND NANTUCKET. ANOTHER LOW BEGINS TO MOVE NE ACROSS THE MISSISSIPPI VALLEY DURING SUNDAY AS HIGH PRES CRESTS ACROSS THE REGION. NW WINDS DIMINISH AND BEGIN TO BACK TO W LATE IN THE DAY. CLOUDS WILL ALSO INCREASE DURING THE AFTERNOON. SUNDAY NIGHT-MONDAY... PAIR OF UPPER LEVEL SYSTEMS BEGIN TO APPROACH. LOW CONFIDENCE ON THE TIMING AND TRACK OF THESE SYSTEMS...AS WELL AS HOW SURFACE LOW PRES FORMS AS IT APPROACHES. OF CONCERN IS THE TRACK OF THIS LOW ON THE 00Z ECMWF...WHICH TAKES THE LOW S OF THE REGION MEANING ANOTHER SHOT FOR MORE SNOW. THE 00Z GFS AND GGEM MODELS KEEP THE LOW FURTHER INLAND...WITH POSSIBLE MIXTURE OR A CHANGE TO RAIN FOR SOME LOCATIONS. MAY ALSO SEE DECENT RAINFALL WITH SOME INFUSION OF SOUTHERN STREAM MOISTURE WITH THIS LOW. SOMETHING TO KEEP A CLOSE EYE ON...THOUGH AGAIN CONFIDENCE REMAINS LOW. TUESDAY...DEPENDING UPON THE DEPARTURE OF THE LOW...LOOKS LIKE MORE COLD AIR WORKS IN AS ANOTHER HIGH APPROACHES. && .AVIATION /10Z 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/... THURSDAY...MODERATE CONFIDENCE. MAINLY VFR. WINDS BECOMING LIGHT S. MID AND HIGH CLOUDS APPROACH DURING THE AFTERNOON. THURSDAY NIGHT-FRIDAY NIGHT...LOW TO MODERATE CONFIDENCE. EXPECT CIGS LOWER TO MVFR WITH MVFR-IFR VSBYS IN SNOW. CONDITIONS IMPROVE TO VFR FRIDAY AFTERNOON BUT NW WINDS INCREASE WITH GUSTS UP TO 25-30 KT...POSSIBLY HIGHER ALONG THE E COAST. SATURDAY-SUNDAY...LOW TO MODERATE CONFIDENCE. VFR. GUSTY NORTHWEST WINDS 25-35 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 /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... THOUGH S WINDS MAY GUST UP TO 20 KT THU NIGHT. FRIDAY... LOW PRES WILL CROSS THE WATERS. EXPECT REDUCED VSBYS IN SNOW. EXPECT WINDS TO SHIFT TO NW BY FRI NIGHT...INCREASING TO 25-35 KT...SO GALES WILL LIKELY BE NEEDED. SEAS ALSO BUILD UP TO 6-8 FT OVER THE OPEN WATERS. FREEZING SPRAY WILL LIKELY DEVELOP FRI 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. WINDS WILL BEGIN TO DIMINISH SAT NIGHT. SUNDAY...WINDS AND SEAS AT SMALL CRAFT ADVISORY LEVELS EARLY SUNDAY...BUT WILL DIMINISH THROUGH THE DAY. && .TIDES/COASTAL FLOODING... 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. && .BOX WATCHES/WARNINGS/ADVISORIES... 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. && $$ SYNOPSIS...KJC/EVT NEAR TERM...KJC SHORT TERM...KJC LONG TERM...EVT AVIATION...KJC/EVT MARINE...KJC/EVT TIDES/COASTAL FLOODING...KJC

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