Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 301108 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 608 AM EST FRI JAN 30 2015 .SYNOPSIS... LOW PRESSURE WILL WEAKEN OVER SOUTHERN QUEBEC AS A SECONDARY LOW DEVELOPS ALONG THE SOUTHERN NEW ENGLAND COAST THIS AFTERNOON. THIS LOW WILL INTENSIFY OVER THE GULF OF MAINE BY TONIGHT BRINGING PERIODS OF SNOW. BLUSTERY AND VERY COLD CONDITIONS ARE EXPECTED THIS WEEKEND. LOW PRESSURE WILL PASS SOUTH OF NEW ENGLAND SUNDAY NIGHT AND MONDAY...POSSIBLY BRINGING ANOTHER ACCUMULATING SNOWFALL. COLD CONDITIONS WILL CONTINUE THROUGH MOST OF NEXT WEEK. YET ANOTHER LOW MAY DEVELOP AROUND NEXT WED OR THU WITH A THREAT FOR SNOW...THOUGH LOW CONFIDENCE. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AREA OF LIGHT SNOW MOVING ACROSS SNE EARLY THIS MORNING. PRECIP NOT VERY ORGANIZED AND ASSOCD WITH WEAK OVERRUNNING AHEAD OF PARENT LOW ACROSS THE EASTERN LAKES. AMPLIFYING MID LEVEL TROF ACROSS THE GT LAKES BECOMES NEG TILTED AS IT REACHES THE COAST LATE TODAY. ASSOCD HEIGHT FALL CENTER AND SHORTWAVE ENERGY WILL RESULT IN PARENT LOW FILLING ACROSS NORTHERN NEW ENG WITH CYCLOGENESIS NEAR OR SOUTH OF CAPE COD LATER THIS AFTERNOON. EXPECT A PERIOD OF MAINLY LIGHT SNOW TODAY AHEAD OF THE OPEN MID LEVEL WAVE WHICH SHOULD TAPER OFF THIS AFTERNOON ACROSS THE CT VALLEY TO THE RI COAST. WARMING BOUNDARY LAYER ALONG THE IMMEDIATE SE NEW ENG COAST WILL RESULT IN RAIN OR MIXED RAIN/SNOW FOR THE CAPE AND ISLANDS. USED A BLEND OF MODEL QPF WHICH RESULTS IN SNOW ACCUM THROUGH TODAY OF 1-2 INCHES AWAY FROM THE COAST...WITH UP TO 3 INCHES NORTH CENTRAL AND NW MA. ALONG THE S COAST...EXPECT LESS THAN AN INCH. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... TONIGHT INTO SATURDAY... NEG TILT TROF EVOLVES INTO A CLOSED MID LEVEL OVER SOUTHERN NEW ENGLAND THIS EVENING THEN IT JUMPS TO THE GULF OF MAINE LATER TONIGHT. THE SFC LOW DEEPENS RAPIDLY TONIGHT IN THE GULF OF MAINE BUT LIKELY REMAINS A BIT TOO FAR OFFSHORE TO ROTATE HEAVY SNOW BACK ACROSS SNE AS THE HEAVIER PRECIP WILL REMAIN TO THE NORTH OVER MAINE. HOWEVER...A ROBUST COMMA HEAD WILL DEVELOP TO THE WEST OF THE MID LEVEL LOW TONIGHT AND EXTEND ACROSS EASTERN NEW ENG WHICH WILL LIKELY BRING BANDS OF SNOW TO THE REGION. THE WESTWARD EXTENT OF THE SNOW TONIGHT WILL LIKELY BE ACROSS CENTRAL MA AND RI WITH THE MAIN FOCUS ACROSS E MA INCLUDING THE CAPE/ISLANDS. MAINLY DRY WEATHER EXPECTED IN THE CT VALLEY. MODELS BACKED OFF A BIT ON THE QPF SO WE HAVE LOWERED SNOW ACCUM A TAD...BUT HAVE TO WATCH NE MA AND CAPE COD WHICH WILL BE CLOSEST TO THE BEST FORCING. SNOW LINGERS ACROSS E MA INTO SAT MORNING...BEFORE GRADUALLY MOVING OUT. THE OUTER CAPE WILL BE LAST TO DRY OUT AROUND MIDDAY. OTHERWISE...CLEARING SKIES WILL DEVELOP FROM WEST TO EAST LATE MORNING THROUGH THE AFTERNOON BUT WINDY AND VERY COLD SATURDAY WITH HIGHS MOSTLY IN THE TEENS. WE KEPT THE WINTER STORM WARNING FOR ESSEX COUNTY BUT DOWNGRADED MIDDLESEX COUNTY TO AN ADVISORY. EXPANDED THE ADVISORY TO CAPE COD WHICH SHOULD GET INTO A DECENT BAND OF SNOW TONIGHT. OTHERWISE...DROPPED THE ADVISORY FOR NE CT...N RI AND ADJACENT SE MA WHERE SNOW AMOUNTS SHOULD FALL SHY OF ADVISORY CRITERIA. TOTAL SNOW ACCUM OF 4-7 EXPECTED ACROSS NE MA WITH THE MAX AMOUNTS IN ESSEX COUNTY...WITH 2-4 INCHES CENTRAL MA TO E COASTAL MA INCLUDING CAPE COD. AN INCH OR 2 POSSIBLE NEAR THE S COAST. IN ADDITION TO THE SNOWFALL TONIGHT...NORTHWEST WINDS WILL INCREASE LATE TONIGHT INTO SAT WITH GUSTS TO 40 TO 45 MPH AS LOW INTENSIFIES EAST OF MA. LOW PROB WIND GUSTS COULD REACH 50 MPH NEAR THE S COAST AND WIND ADVISORIES MAY EVENTUALLY BE NEEDED. VERY COLD AIR MOVES IN TONIGHT INTO SATURDAY COMBINED WITH GUSTY NW WINDS WILL RESULT IN DANGEROUSLY COLD WIND CHILLS OF 10 TO 20 BELOW ZERO IN CENTRAL AND WESTERN MA AND PORTIONS OF N CT WHERE WIND CHILL ADVISORIES HAVE BEEN ISSUED. WIND CHILLS 5 TO 10 BELOW IN THE COASTAL PLAIN. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... HEADLINES... * COLD CONDITIONS THROUGH SUNDAY AS WINDS DIMINISH * LOW PRESSURE LOOKS TO PASS S OF NEW ENGLAND SUNDAY NIGHT AND MONDAY WITH ACCUMULATING SNOW POSSIBLE * COLD CONDITIONS CONTINUE THROUGH MOST OF NEXT WEEK * ANOTHER LOW IS POSSIBLE AROUND WED OR THU...LOW CONFIDENCE OVERVIEW... OVERALL...NOTING A RATHER PROGRESSIVE UPPER LEVEL PATTERN ACROSS THE LOWER 48 WHICH WILL KEEP WEATHER SYSTEMS MOVING...BUT THERE IS ALSO THE POTENTIAL FOR A COUPLE MORE SNOW EVENTS ON THE HORIZON. DETAILS... SATURDAY NIGHT-SUNDAY...HIGH PRES MOVES OFF THE MID ATLC COAST AS A RIDGE POKES N INTO THE REGION. NW WINDS WILL REMAIN BLUSTERY EARLY SAT NIGHT...THEN WILL DIMINISH. A DRY COLD FRONT WILL PUSH ACROSS THE REGION SUNDAY MORNING...BRINGING LARGE HIGH PRES OUT OF SOUTH CENTRAL CANADA INTO THE NORTHERN GREAT LAKES. NOTING A DIGGING H5 SHORT WAVE WORKING E OUT OF THE MID MISSISSIPPI VALLEY AS SURFACE LOW DEVELOPS. WILL LIKELY SEE CLOUDS PUSHING IN DURING SUNDAY. SUNDAY NIGHT-MONDAY...BIG QUESTIONS WITH LOW PRES PASSING S OF NEW ENGLAND. FIRST...MORE COLD ARCTIC AIR WORKS ACROSS THE REGION...SO TEMPS WILL BE RATHER COLD. HOWEVER...MOST MODELS AND SEVERAL ENSEMBLES SIGNALING LOW PRES WILL PASS CLOSE TO JUST S OF 40N LATITUDE...POSSIBLY PASSING NEAR THE 40N/70W BENCHMARK. NOTING THE 00Z GFS AND ECMWF WERE MORE IN LINE THIS MORNING IN SPREADING A SWATH OF QPF ACROSS THE REGION WHILE HIGH PRES EXTENDS INTO QUEBEC. LOOKS LIKE A SET UP FOR MORE ACCUMULATING SNOWFALL. CURRENT FORECAST SUGGESTS AROUND 0.3 TO 0.5 INCHES QPF AND...WITH THE COLD AIR IN PLACE...COULD SEE SNOW TO LIQUID RATIOS OF AROUND 15:1. EXACT TIMING IS STILL IN QUESTION THOUGH AS THE PATTERN REMAINS PROGRESSIVE...BUT WILL BE MONITORING THIS DEVELOPMENT VERY CLOSELY. TUESDAY...ANOTHER HIGH CROSSES THE REGION DURING TUESDAY WITH MORE COLD AIR WORKING IN. WEDNESDAY-THURSDAY...MODELS AND ENSEMBLES CONTINUE TO SIGNAL LOW PRES AND COLD FRONT MOVING OUT OF THE GREAT LAKES WED NIGHT...THEN MOVING OFFSHORE THU MORNING. LOW PRES MAY DEVELOP ALONG THIS FRONT...POSSIBLY BRINGING MORE SOUTHERN STREAM MOISTURE UP THE COAST. WAY TOO EARLY TO TELL HOW THE NORTHERN AND SOUTHERN STREAMS WILL INTERACT...LOW CONFIDENCE. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM.../THROUGH SATURDAY/...MODERATE CONFIDENCE. THROUGH 12Z...LIGHT SNOW OVERSPREADING THE REGION WITH CONDITIONS LOWERING TO MVFR/IFR. SNOW MIXING WITH OR CHANGING TO RAIN CAPE/ISLANDS TOWARD DAYBREAK. TODAY...MVFR/IFR IN AREAS OF SNOW...WITH RAIN CAPE/ISLANDS. SNOW TAPERS OFF AND ENDS CT VALLEY TO THE RI COAST DURING THE AFTERNOON WITH MAINLY MVFR CIGS...BUT PERIODS OF SNOW CONTINUE CENTRAL AND E MA. GUSTY NW WINDS TO 25 KT DEVELOPING CT VALLEY BY LATE AFTERNOON. TONIGHT...MAIN FOCUS FOR AREAS OF SNOW AND MVFR/IFR CONDITIONS WILL BE ACROSS E MA...WITH VFR CT VALLEY. GUSTY NW WINDS DEVELOP FROM WEST TO EAST IN THE EVENING WITH GUSTS TO 30-40 KT AFTER MIDNIGHT. SATURDAY...LINGERING MVFR/IFR IN AREAS OF LIGHT SNOW ACROSS E MA AND CAPE/ISLANDS EARLY...OTHERWISE IMPROVING TO VFR WITH CLEARING SKIES FROM WEST TO EAST. GUSTY NW WINDS TO 35-40 KT. KBOS TAF...MODERATE CONFIDENCE. KBDL TAF...MODERATE CONFIDENCE. OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/... SATURDAY NIGHT-SUNDAY...HIGH CONFIDENCE. VFR. NW WINDS GUSTING TO 25-35 KNOTS SATURDAY...HIGHEST ALONG THE COAST. LIGHTER WINDS SUNDAY. SUNDAY NIGHT-MONDAY...LOW CONFIDENCE. DEVELOPING LOW PRES LOOKS TO PASS S OF NEW ENGLAND WITH ACCUMULATING SNOW POSSIBLE. COULD SEE IFR CONDITIONS FOR A TIME...ESPECIALLY S OF THE MASS PIKE. CONDITIONS MAY IMPROVE EARLY MON NIGHT TUESDAY...MODERATE CONFIDENCE. MAINLY VFR. MAY SEE GUSTY NW WINDS EARLY. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH SATURDAY/...HIGH CONFIDENCE. TODAY...SOUTHERLY WINDS WILL SHIFT TO W THEN NW DURING FRI AFTERNOON...WITH GUSTS TO 25 KT DEVELOPING ACROSS RI COASTAL WATERS BY LATE AFTERNOON. TONIGHT AND SATURDAY...AS LOW PRES INTENSIFIES OVER WESTERN GULF OF MAINE...GALE FORCE NW WINDS WILL DEVELOP. GUSTS TO 40-45 KT EXPECTED LATE TONIGHT INTO SAT. THE GUSTY WINDS AND ROUGH SEAS COMBINED WITH ARCTIC AIR MOVING INTO THE REGION WILL RESULT IN AREAS OF MODERATE FREEZING SPRAY OVER THE NEARSHORE WATERS SO FREEZING SPRAY ADVISORIES WERE ISSUED. SNOW REDUCES VSBY OVER EASTERN WATERS TONIGHT INTO SAT MORNING. OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/...MODERATE CONFIDENCE THROUGH SUNDAY...THEN LOW CONFIDENCE SUN NIGHT-TUESDAY. SATURDAY NIGHT...NW WINDS GUSTING TO 35-40 KT EARLY...THEN SHOULD START TO DIMINISH AROUND OR AFTER MIDNIGHT. SEAS UP TO 10-14 FT ON THE OUTER WATERS EARLY...THEN SLOWLY SUBSIDING BUT REMAINING WELL ABOVE 5 FT. LIGHT TO MODERATE FREEZING SPRAY. SUNDAY...EXPECT WINDS AND SEAS REMAIN AT SMALL CRAFT LEVELS. LIGHT FREEZING SPRAY LIKELY. SUNDAY NIGHT-TUESDAY...HIGHLY DEPENDENT ON STRENGTH AND TRACK OF DEVELOPING LOW PRESSURE SOUTH OF THE REGION. WORSE CONDITIONS WOULD BE MONDAY WITH SLOW IMPROVEMENT ON TUESDAY. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...WIND CHILL ADVISORY FROM 1 AM TO 9 AM EST SATURDAY FOR CTZ002- 003. MA...WINTER WEATHER ADVISORY UNTIL 8 AM EST SATURDAY FOR MAZ004-005- 012>016-018-019-026. WIND CHILL ADVISORY FROM 1 AM TO 9 AM EST SATURDAY FOR MAZ003- 004-010-011. WIND CHILL ADVISORY FROM 11 PM THIS EVENING TO 11 AM EST SATURDAY FOR MAZ002-008-009. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 8 AM EST SATURDAY FOR MAZ022. WINTER STORM WARNING UNTIL 8 AM EST SATURDAY FOR MAZ006-007. RI...NONE. MARINE...FREEZING SPRAY ADVISORY FROM 11 PM THIS EVENING TO 6 PM EST SATURDAY FOR ANZ231>235-237-250-251. GALE WARNING FROM 11 PM THIS EVENING TO 6 PM EST SATURDAY FOR ANZ232-250-254-255. GALE WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST SATURDAY FOR ANZ230-231-233-234-251. GALE WARNING FROM 1 AM TO 1 PM EST SATURDAY FOR ANZ236. GALE WARNING FROM 9 PM THIS EVENING TO 6 PM EST SATURDAY FOR ANZ235-237. GALE WARNING FROM 7 PM THIS EVENING TO 6 PM EST SATURDAY FOR ANZ256. && $$ SYNOPSIS...KJC/EVT NEAR TERM...KJC SHORT TERM...KJC LONG TERM...EVT AVIATION...KJC/EVT MARINE...KJC/EVT

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