Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 040651 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 151 AM EST WED MAR 4 2015 .SYNOPSIS...
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A COLD FRONT WILL PUSH ACROSS THE REGION THIS MORNING...THEN WILL STALL SOUTH OF THE REGION WITH LINGERING LIGHT PRECIPITATION ACROSS SOUTH COASTAL AREAS THROUGH THE DAY. WEAK LOW PRESSURE WILL PUSH ALONG THE STALLED FRONT WITH ANOTHER ROUND OF SNOW TONIGHT INTO THURSDAY. HIGH PRESSURE WILL BUILD IN FOR FRIDAY THROUGH THIS WEEKEND...BRINGING DRY CONDITIONS WITH COLDER THAN NORMAL TEMPERATURES. A WEAKENING FRONT MAY BRING SOME LIGHT SNOW SHOWERS ON MONDAY.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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225 AM UPDATE... BACK EDGE OF PRECIP AHEAD OF APPROACHING COLD FRONT HAS MOVED ACROSS N MA MAINLY N OF THE MASS PIKE AT 06Z. WHERE PRECIP IS LINGERING...MAINLY NEAR AND S OF THE MASS PIKE...IT IS MAINLY LIGHT RAIN. NOTING A COUPLE OF SPOTS WITH LINGERING MIXED PRECIP MAINLY ACROSS NE MA...BUT SHOULD END IN THE NEXT HOUR OR TWO. TEMPS AT 06Z MAINLY IN THE 30S...THOUGH A FEW SPOTS HAVE HIT 40 /41 AT KBID AND 40 AT KTAN/. VERY STRONG LOW LEVEL JET PASSING ACROSS SOUTHERN AND EASTERN AREAS AS SEEN ON 00Z KCHH AND KOKX SOUNDINGS AS WELL AS SHORT RANGE MODELS /SW WINDS AT 45-60 KT AT H925...UP TO 70 TO 80 KT AT H85/. SHOULD SEE THESE WINDS SLOWLY DIMINISH AND SHIFT TO W AS THE JET MOVES E WITH THE FRONTAL PASSAGE THIS MORNING. STRONG PRES FALLS CONTINUE AT 06Z... GENERALLY FROM 4-7 MB/3 HR WHICH HELPS TO MIX DOWN SOME OF THE SW WINDS ESPECIALLY ACROSS RI/SE MA AND THE HIGHER INLAND TERRAIN. SHORT RANGE MODELS /NAM AND HRRR/ SEEM TO BE HANDLING THE ENDING PRECIP EARLY THIS MORNING SO LEANED TOWARD THESE ALONG WITH RADAR TRENDS FOR THIS UPDATE. REMAINDER OF FORECAST IN PRETTY GOOD SHAPE BUT HAVE UPDATED TO BRING CONDITIONS CURRENT.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... COLD FRONT MOVES THROUGH SOUTHERN NEW ENGLAND DURING THE MORNING. THAT SHOULD END MOST OF THE PCPN. THE BEST CHANCE OF PCPN WOULD BE ALONG THE SOUTH COAST...WITH TEMPS WARM ENOUGH FOR RAIN. UPPER FLOW WILL BE WEST-TO-EAST AHEAD OF ANOTHER UPPER TROUGH SWINGING ACROSS THE GREAT LAKES. THE WEDNESDAY COLD FRONT WILL LINE UP WITH THAT UPPER FLOW...STALLING THE FRONT SOUTH OF NEW ENGLAND. MEANWHILE THE UPPER JET IN THE FLOW MOVES ACROSS NEW ENGLAND AND PLACES US IN ITS RIGHT ENTRANCE REGION. THIS WILL GENERATE SUPPORT FOR A WAVE ON THE FRONT PUSHING PCPN NORTH AGAIN WEDNESDAY NIGHT. AT THE SAME TIME...WINDS SHIFTING TO NORTH WILL DRAW COLDER AIR SOUTH ACROSS THE REGION AGAIN. SO ANY DEVELOPING PCPN WOULD CHANGE TO FREEZING RAIN AND THEN SNOW. QUESTION REMAINS AS TO WHETHER THE COLD AIR WILL BE DRY ENOUGH TO SUPPRESS THE PCPN SHIELD FARTHER SOUTH. THIS MAY LIMIT ANY SIGNIFICANT PCPN TO THE SOUTH COAST OR EVEN JUST OFFSHORE. WE WILL GO WITH CATEGORICAL POPS ALONG THE SOUTH COAST...LIKELY POPS ACROSS CT-RI-SE MASS...AND CHANCE POPS FARTHER NORTH. BASED QPF ON HPC VALUES. DUE TO THE COMBINATION OF EXPECTED PCPN AND EXPECTED TEMPS...WE HAVE ISSUED A WINTER STORM WATCH ALONG THE SOUTH COAST INCLUDING CAPE COD AND ALL THE ISLANDS. THIS WILL ALSO INCLUDE KENT COUNTY RI. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... OVERVIEW... UPPER LEVEL PATTERN SHOWING A FEW SIGNS OF CHANGE WITH THE CHANGING SEASON...THOUGH DOES LOOK A COLD PATTERN REMAINS FOR MUCH OF THE NORTHEAST U.S. THROUGH A GOOD PORTION OF THIS LONG TERM TIMEFRAME. ONE NOTICEABLE CHANGE IS THE DRYING OF THE SAME PATTERN. USED A BLEND OF AVAILABLE GUIDANCE FOR THIS FORECAST...WHICH CONTINUED TO HAVE GOOD CONTINUITY TO THE PREVIOUS PACKAGE. DETAILS... THURSDAY... THE WINTER STORM WATCH CONTINUES INTO THURSDAY FOR SOUTHERN RI/BI AND SOUTH COASTAL MA INCLUDING THE CAPE AND ISLANDS. LOW PRESSURE ALONG THE SURFACE FRONT IS WELL SOUTH OF OUR AREA...12Z RUNS SHOWING IT OFF THE CAROLINA COAST...BUT PRECIPITATION SHOULD STILL GET INTO OUR AREA TO SOME EXTENT. FORECAST SURFACE TEMPS AND THICKNESSES INDICATE THE AIRMASS IN OUR AREA ON THURSDAY IS COLD ENOUGH FOR ALL SNOW. THERE MAY BE A FAIRLY SHARP CUTOFF WITHIN OR JUST SOUTH OF OUR AREA WITH RESPECT TO ACCUMULATING SNOWS VS. MORE MINIMAL SNOWFALL. AT THIS TIME THE BEST CHANCE FOR AN INCH OF SNOW OR GREATER DURING THURSDAY LOOKS TO BE IN THE VICINITY OF AND SOUTH OF THE MASS PIKE...WITH THE POTENTIAL FOR AN ADDITIONAL FEW INCHES OF SNOW IN SOUTHERN RI/FAR SOUTHEAST MA...IN THE WATCH AREA. THURSDAY NIGHT... UPPER TROUGH SHIFTS EAST...PUSHING THE FRONT FURTHER OFFSHORE. THERE MAY BE SOME LINGERING LIGHT SNOW EARLY THURSDAY EVENING IN EXTREME SOUTHEAST MA...BUT ANY SNOWFALL AT THIS TIME IS EXPECTED TO BE LESS THAN AN INCH. OTHERWISE ANOTHER SHOT OF ARCTIC AIR WORKS INTO SOUTHERN NEW ENGLAND...WITH WEAKENING WINDS AND CLEARING SKIES. SO ANOTHER NIGHT OF GOOD RADIATIONAL COOLING. OVERNIGHT LOWS IN THE SINGLE DIGITS FOR MOST AREAS EXCEPT TEENS ALONG THE SOUTH COAST. CANT RULE OUT A FEW SUB-ZERO LOWS IN THE TYPICAL COLDER SPOTS OF THE FAR INTERIOR. FRIDAY THROUGH MONDAY... BROAD UPPER TROUGH PERSISTS ACROSS CENTRAL AND EASTERN CANADA... KEEPING THE REGION IN BELOW NORMAL TEMPS THROUGH THIS TIMEFRAME. FAST FLOW ALOFT ALSO BRINGS WEAK SYSTEMS TOWARD THE REGION...THOUGH LOOKS LIKE ONLY LIGHT PRECIP WITH W-NW FLOW IN PLACE WITH THESE CLIPPER TYPE SYSTEMS. AN AREA OF HIGH PRESSURE BUILDS TO THE SW OF OUR AREA ON FRIDAY. DAYTIME HIGHS IN THE 20S ARE EXPECTED...15 TO 20 DEGS BELOW NORMAL. AS THE HIGH SHIFTS S OF THE REGION SATURDAY AND SUNDAY...TEMPERATURES DO REBOUND A BIT. THEY LOOK REMAIN BELOW NORMAL BUT ANTICIPATING HIGHS IN THE 30S SAT AND SUN WITH WINDS FROM THE SW. A WEAK LOW/COLD FRONT PASSES NORTH OF OUR AREA LATE SAT INTO SUN... MOST OF THE ENERGY AND PRECIP LOOKS TO REMAIN ACROSS NORTHERN NEW ENGLAND. MIGHT SEE SOME CLOUDS OTHERWISE ANTICIPATING MAINLY DRY CONDITIONS FOR SOUTHERN NEW ENGLAND DURING THIS TIMEFRAME. ANOTHER CLIPPER SYSTEM QUICKLY MOVES N OF THE GREAT LAKES BY MONDAY MORNING...ONLY HAVE A SLIGHT CHANCE POPS FOR SNOW IN OUR AREA WITH THIS FEATURE. MAY SEE PRECIP MAY WASH OUT AS IT APPROACHES IN THE DRY W-NW FLOW. TUESDAY LOOKS UNCERTAIN WITH DIFFERENCES IN THE MODELS AS TO WHETHER HIGH PRESSURE KEEPS OUR AREA FAIRLY DRY...OR IF WE ARE CLIPPED BY A NORTHERN OR SOUTHERN STREAM LOW. AT THIS POINT HAVE DRY TO SLIGHT CHANCE POPS. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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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/... THROUGH 12Z...CIGS MAINLY IFR-LIFR WITH VLIFR ALONG THE S COAST. PRECIP ENDING MAINLY ACROSS THE CT VALLEY AND N OF THE MASS PIKE WITH VFR VSBYS...BUT PATCHY FOG DEVELOPING WITH VSBYS RANGING FROM MVFR TO IFR WITH PATCHY LIFR. S-SW WINDS AT 15-20 KT GUSTING TO 25 KT MAINLY ACROSS E MA/RI WHERE STRONG LOW LEVEL JET LINGERS. LLWS LIKELY AT 2KFT THERE. LIGHT RAIN LINGERS MAINLY S OF THE MASS PIKE. TODAY...MODERATE CONFIDENCE. N OF MASS PIKE...SHOULD SEE GENERALLY VFR CONDITIONS. S OF MASS PIKE...VFR WITH PATCHY MVFR CIGS/VSBYS ALONG S COASTAL AREAS WITH LINGERING LIGHT RAIN. TONIGHT...MODERATE CONFIDENCE. N OF MASS PIKE...MAINLY VFR CIGS THOUGH MAY LOWER TO MVFR ALONG THE PIKE AFTER MIDNIGHT. S OF THE MASS PIKE...CONDITIONS DETERIORATE TO MVFR BY 05Z IN MIXED PRECIP CHANGING OVER TO SNOW FROM N-S. WILL VSBYS LOWER TO IFR-LIFR ACROSS N CT/RI/SE MA IN PERIODS OF SN/+SN AFTER 05Z. KBOS TAF...HIGH CONFIDENCE IN OVERALL TRENDS...LOWER CONFIDENCE IN EXACT TIMING. KBDL TAF...HIGH CONFIDENCE IN OVERALL TRENDS...LOWER CONFIDENCE IN EXACT TIMING. OUTLOOK...THURSDAY THROUGH SUNDAY... THURSDAY...MODERATE CONFIDENCE. EXPECT MVFR CONDITIONS OVERALL...LOCALIZED CIGS/VSBYS LOWER TO IFR- VLIFR ACROSS N CT/RI/SE MA IN PERIODS OF SN/+SN THROUGH THU MORNING. CONDITIONS SHOULD SLOWLY IMPROVE FROM N-S DURING THU AFTERNOON...BUT LOWER CIGS/VSBYS CONTINUE ALONG S COAST INTO THU EVENING. NW WINDS COULD GUST TO 20-25 KT ALONG THE COAST. THURSDAY NIGHT...MODERATE CONFIDENCE. MAINLY VFR ACROSS MOST AREAS. RI/SE MA...IFR CONDITIONS EARLY IN LEFTOVER -SN...THEN IMPROVING TO VFR. N-NW GUSTING TO 20-25 KT ALONG THE COAST...DIMINISHING AFTER MIDNIGHT. FRIDAY THROUGH SUNDAY...MODERATE CONFIDENCE. VFR.
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY/... OVERNIGHT... S-SW WINDS CONTINUE TO INCREASE AS PRES GRADIENT TIGHTENS...WHICH WILL CONTINUE TO SUPPORT WINDS GUSTING TO 25-30 KT AT TIMES. SEAS ALSO BUILDING...AND WILL INCREASE TO 6-8 FT ON THE OUTER WATERS. SMALL CRAFT ADVISORY CONTINUES FOR ALL WATERS. WEDNESDAY... COLD FRONT CROSSES THE WATERS. THIS WILL SHIFT THE WIND OUT OF THE WEST. WINDS WILL CONTINUE TO GUST AT TIMES TO 25 KNOTS...AND SEAS WILL CONTINUE AT 5 TO 8 FEET ON THE EXPOSED WATERS. SMALL CRAFT ADVISORY CONTINUES BUT MAY BE DROPPED ON SOME NEAR SHORE WATERS. WEDNESDAY NIGHT... WINDS BECOME NORTHWEST AND PULL COLDER AIR ACROSS THE WATERS...GUSTING 20-25 KNOTS LATER AT NIGHT. SEAS WILL LINGER AROUND 5-6 FEET OVERNIGHT. OUTLOOK...THURSDAY THROUGH SUNDAY... THURSDAY-THURSDAY NIGHT... NW WIND THURSDAY EXPECTED TO GUST TO 25-30 KT BY LATE IN THE DAY...LASTING MUCH OF THURSDAY NIGHT. SEAS BUILD UP TO 4-6 FT ON THE OUTER WATERS. VSBYS REDUCED IN SNOW THURSDAY INTO THURSDAY NIGHT...BUT DIMINISHING THURSDAY NIGHT. LIGHT FREEZING SPRAY LIKELY THURSDAY NIGHT. FRIDAY AND SATURDAY... NW GUSTS TO AROUND 25 KT CONTINUE ON THE OPEN WATERS INTO FRIDAY...THEN BACK TO SW BUT WILL STILL GUST UP TO 25-30 KT DURING SAT. SEAS SUBSIDING ON FRIDAY BUT THEN BUILD TO 3 TO 5 FEET ON THE OUTER WATERS DURING SAT. SUNDAY... W WINDS AND SEAS SHOULD DIMINISH BELOW SMALL CRAFT CRITERIA DURING THE MORNING. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR CTZ002>004. MA...WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR MAZ020>024. WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR MAZ002>022-026. RI...WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR RIZ003>008. WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR RIZ001>007. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EST TODAY FOR ANZ231>234. SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR ANZ230-236. SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR ANZ235-237- 250-254>256. SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ251.
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&& $$ SYNOPSIS...WTB/NMB NEAR TERM...EVT SHORT TERM...WTB LONG TERM...NMB AVIATION...EVT/NMB MARINE...WTB/EVT/NMB

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