Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 161445 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 945 AM EST TUE DEC 16 2014 .SYNOPSIS... A WAVE OF LOW PRESSURE WILL RESULT IN A PERIOD OF RAIN SHOWERS WORKING ACROSS THE REGION FROM WEST TO EAST TONIGHT. THE SHOWERS SHOULD COME TO AN END SOMETIME WEDNESDAY MORNING...BUT A FEW HIT AND MISS RAIN/SNOW SHOWERS WILL LINGER LATER WEDNESDAY INTO THURSDAY MORNING. A STRENGTHENING LOW PRESSURE CENTER IS EXPECTED TO PASS SOUTHEAST OF NEW ENGLAND LATE IN THE WEEKEND. IT IS UNCERTAIN AT THIS TIME IF THIS SYSTEM WILL PASS CLOSE ENOUGH TO PRODUCE PRECIPITATION ACROSS SOUTHERN NEW ENGLAND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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945 AM UPDATE... LOW CLOUDS LOCKED IN ACROSS REGION AND EXPECT IT TO REMAIN THAT WAY THROUGH AFTERNOON. NOT SEEING MUCH IN WAY OF DRIZZLE AS CLOUD BASES ARE STILL A BIT HIGH...BUT WE SHOULD BEGIN TO SEE PATCHY DRIZZLE DEVELOP DURING AFTERNOON WITH LIGHT ONSHORE FLOW. TEMPERATURES HAVE BEEN SLOWLY RISING THIS MORNING...AND SHOULD GET ABOVE FREEZING ACROSS INTERIOR BEFORE ANY DRIZZLE BEGINS. THEREFORE POTENTIAL FOR LIGHT ICING REMAINS VERY LOW. FORECAST HIGHS IN 30S/40S ON TRACK.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
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TONIGHT... INITIAL LOW PRESSURE WILL BE LIFTING ACROSS THE GREAT LAKES AS SECONDARY LOW DEVELOPS NEAR THE MID ATLANTIC COAST AND MOVES NORTHEAST. THE RESULT WILL BE AN AREA OF RAIN SHOWERS THAT WILL WORK INTO THE INTERIOR DURING THE EVENING...BUT LIKELY NOT REACH THE COASTAL PLAIN UNTIL AFTER MIDNIGHT WHEN BETTER FORCING ARRIVES. UNTIL THAT HAPPENS THOUGH...LOW CLOUDS/PATCHY FOG AND AREAS OF DRIZZLE WILL BE POSSIBLE. AS FOR PTYPE TONIGHT...THERMAL PROFILES WILL BE WARM ENOUGH FOR RAIN ACROSS THE ENTIRE REGION. LOW RISK FOR A BRIEF PERIOD OF SPOTTY FREEZING RAIN ACROSS FAR NORTHWEST MA BUT NOT TOO EXCITED ABOUT THAT OCCURRING. THERE IS A EVEN A LOW RISK FOR AN ISOLATED THUNDERSTORM OR TWO TOWARD DAYBREAK AS SHOWALTER VALUES APPROACH ZERO ACROSS EASTERN NEW ENGLAND. NOT ENOUGH CONFIDENCE TO INSERT INTO THE FORECAST AT THIS TIME...BUT SOMETHING LATER SHIFTS WILL HAVE TO KEEP AN EYE ONE. WEDNESDAY... SECONDARY LOW PRESSURE WILL LIKELY MOVE ACROSS SOUTHEAST NEW ENGLAND WED MORNING. RAIN SHOWERS WILL LIKELY LINGER ACROSS OUR EASTERN AND PARTICULARLY NORTHEAST ZONES INTO PART OF WED MORNING. OTHERWISE...MAY SEE A FEW SHOWERS WITH THE UPPER LEVEL SHORTWAVE WED AFTERNOON...BUT THE STEADY PRECIPITATION WILL HAVE ENDED. HIGH TEMPS WILL BE WELL UP INTO THE 40S...TO PERHAPS EVEN SOME LOWER 50S ON THE COASTAL PLAIN. A FEW PEEKS OF SUNSHINE WILL ALSO BE POSSIBLE ACROSS THE COASTAL PLAIN BY AFTERNOON...BUT STILL EXPECT PLENTY OF CLOUDS.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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HIGHLIGHTS... * SNOW SHOWERS ACROSS THE INTERIOR WED NIGHT INTO THURS * DRY WEATHER AND AT OR BELOW AVG TEMPS FRIDAY INTO SAT * POSSIBLE COASTAL SYSTEM SUNDAY INTO MONDAY OVERVIEW... OVERALL 12Z GUIDANCE IS IN AGREEMENT SYNOPTICALLY...HOWEVER THERE ARE MANY ISSUES REGARDING THE SPLIT FLOW ESP FOR THE WEEKEND. IT DOES LOOK LIKE A PATTERN CHANGE IS GOING TO OCCUR AS UPPER LEVEL RIDGING BUILDS INTO CALIFORNIA AND HIGH PRESSURE IN CENTRAL CANADA MOVES TO EASTERN CANADA. THIS SHOULD FAVOR TROUGHING IN THE SW CONUS MOVING EASTWARD WHICH COULD KEEP OUR PATTERN ACTIVE BEGINNING NEXT WEEKEND. GUIDANCE TENDS TO HAVE ISSUES WITH THE PATTERN SHIFT AS WELL AS PHASING SO TIMING ON ANY SYSTEMS MAY SLOW DOWN OR EVEN SPEED UP. WHILE WE ARE IN TRANSITION...DEPARTING UPPER LEVEL LOW WILL PUSH TOWARDS THE MARITIMES BY LATE THURSDAY WITH RIDGING TO MOVING IN FRIDAY INTO SATURDAY. DIGGING SHORTWAVE INTO THE SE CONUS WILL DEVELOP A LOW PRESSURE SYSTEM IN THE MID-ATLANTIC. THIS SYSTEM MAY MOVE ACROSS THE BENCHMARK...THE CANAL OR WELL EAST OF THE BENCHMARK. FOR NOW TRENDED TOWARDS THE ENSEMBLES FOR THIS FORECAST BECAUSE OF THE AMOUNT OF UNCERTAINTY. DETAILS... WEDNESDAY NIGHT INTO THURSDAY...HIGH CONFIDENCE. UPPER LEVEL LOW WILL SET UP OVER NEW ENGLAND WEDNESDAY NIGHT BEFORE EXITING OFF INTO THE MARITIMES LATE THURSDAY. A SECONDARY SHORTWAVE WILL MOVE THROUGH THE FLOW AND OVER THE REGION ALLOWING FOR PRECIP TO DEVELOP AND CONTINUE INTO THURSDAY MORNING. STRONG CAA WILL MOVE IN BEHIND THE FIRST SHORTWAVE SO ANTICIPATE PRECIP TO BE MORE IN THE FORM OF SNOW...ESP AWAY FROM THE COASTLINE. THESE SNOW SHOWERS WILL BE MORE SCATTERED IN NATURE WED NIGHT THEN BEGIN TO BECOME MORE ISOLATED BY THURSDAY AS SHORTWAVE MOVES THROUGH AND DRY AIR PUSHES INTO THE AREA. AM NOT EXPECTING MUCH IN THE WAY OF ACCUMULATIONS BUT COULD SEE AN QUICK INCH ACROSS THE HIGHER ELEVATIONS INTO THE NW ZONES. TEMPERATURES THROUGH THIS PERIOD WILL BE AT OR BELOW AVERAGE AS STRONG CAA MOVES THROUGH WITHIN THE NORTHWEST FLOW. FRIDAY INTO SATURDAY...HIGH CONFIDENCE. AS UPPER LEVEL LOW SPINS INTO THE MARITIMES...HIGH PRESSURE WILL BUILD INTO SOUTHERN NEW ENGLAND. THIS SILL ALLOW FOR QUIET AND DRY WEATHER. TEMPERATURES WILL HOVER NEAR AVERAGE DURING THIS TIME PERIOD. SUNDAY INTO MONDAY...LOW CONFIDENCE. MAIN FOCUS OF THE FORECAST WAS ON THIS TRICKY TIME PERIOD. THE MODELS/ENSEMBLES HAVE OFFERED A VARIETY OF SOLUTIONS OVER THE PAST FEW DAYS FROM A VERY LOW AMPLITUDE AND FLAT WAVE MOVING THROUGH THE SOUTHEAST TO A WRAPPED UP SFC LOW HUGGING THE COAST INTO NEW ENGLAND. THE ECMWF ENSEMBLE MEAN HAS OFFERED THE BEST CONSISTENCY WHILE THE DETERMINISTIC ECMWF HAS BEEN LESS STABLE IN ITS DETAILS. THE GFS IS SHOWING A SYSTEM...BUT IT MORE OF A WAVE FOCUSING ON THE NORTHERN STREAM. THE GEFS SPREAD IS QUITE LARGE...BUT THERE ARE A FEW MEMBERS AGREEING WITH THE ECMWF ENSEMBLES. BECAUSE OF THE AMOUNT OF SPREAD...HAVE A VERY LOW CONFIDENCE ON THE FORECAST BUT TRENDED TOWARDS WPC AN A BLEND OF THE ENSEMBLES. OVERALL APPEARS THAT PRECIP WILL MOVE INTO THE REGION AND IMPACT SOUTHERN NEW ENGLAND BETWEEN THE SAT NIGHT INTO MONDAY TIME FRAME. THERE MAY BE ENOUGH LINGERING COLD AIR FROM DEPARTING HIGH PRESSURE THAT THERE COULD BE SOME SNOW ACROSS THE INTERIOR. HOWEVER IF THE STORM IS WELL EAST OF THE BENCHMARK THEN NO SNOW WILL OCCUR ACROSS THE INTERIOR AND IT MAY BE ACROSS THE COAST. SO APPEARS THAT THERE WILL BE P-TYPE ISSUES AND PERHAPS SOME WIND ISSUES IF THE STORM TRACKS WEST OF THE BENCHMARK. TIDES FOR THE MASS EAST COAST WILL BE ASTRONOMICALLY HIGH WITH 11.0 SUNDAY MORNING AND 11.4 MONDAY MORNING AT BOS. IF NE FLOW STRENGTHENS THEN ANTICIPATE A BUILD UP IN SEAS AS WELL AS SURGE. SO THERE COULD BE COASTAL FLOODING CONCERNS WITH THE SYSTEM. AS MENTIONED BEFORE...THIS IS A LOW CONFIDENCE FORECAST WITH MUCH SPREAD ACROSS THE GUIDANCE. HOWEVER THIS STORM WILL NEED TO BE WATCH OVER THE COMING DAYS.
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&& .AVIATION /15Z TUESDAY THROUGH SATURDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TODAY THROUGH WEDNESDAY/... MODERATE CONFIDENCE. MVFR CIGS THROUGH AFTERNOON...LOWERING TO IFR MAINLY ACROSS HIGHER TERRAIN LATER IN DAY AS PATCHY FOG/DRIZZLE DEVELOPS. LIGHT E/SE WINDS. TONIGHT...WIDESPREAD LOW END MVFR TO IFR CONDITIONS EXPECTED IN LOW CLOUDS AND FOG PATCHES. BAND OF SHOWERS WILL WORK ACROSS THE REGION FROM WEST TO EAST AS THE NIGHT WEARS ON. WEDNESDAY...MVFR-IFR CONDITIONS FOR THE FIRST PART OF THE DAY...BUT SHOULD SOME IMPROVEMENT DURING THE AFTERNOON FROM SOUTH TO NORTH. SHOWERS ALONG THE COASTAL PLAIN EARLY IN THE MORNING SHOULD DIMINISH TO A FEW HIT AND MISS SHOWERS BY WED AFTERNOON. KBOS TERMINAL...HIGH CONFIDENCE. MVFR CIGS PREVAIL THRU EVENING. LIGHT S WINDS WILL BACK TO SE EARLY THIS AFTERNOON. KBDL TERMINAL...MODERATE CONFIDENCE. MVFR CIGS PREVAIL THRU EVENING...POSSIBLY LOWERING TO IFR AFTER 18Z. OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY... WEDNESDAY NIGHT THROUGH THURSDAY...HIGH CONFIDENCE. MVFR CIGS IN SCATTERED SNOW SHOWERS. NORTHWEST WINDS NEAR 25 KTS. THURSDAY THROUGH SATURDAY...HIGH CONFIDENCE. VFR CONDITIONS EXPECTED.
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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 /TODAY THROUGH WEDNESDAY/...HIGH CONFIDENCE. TODAY...WEAK RIDGE OF HIGH WILL KEEP WINDS/SEAS WELL BELOW SMALL CRAFT ADVISORY THRESHOLDS. TONIGHT AND WEDNESDAY...LOW PRESSURE WILL MOVE ACROSS THE REGION VERY LATE TONIGHT INTO WEDNESDAY MORNING. SEAS MAY REACH MARGINAL SMALL CRAFT ADVISORY THRESHOLDS TOWARD DAYBREAK ACROSS OUR EASTERN OUTER-WATERS. HOWEVER...MAIN SMALL CRAFT CONDITIONS WILL ARRIVE WED AND ESPECIALLY WED AFTERNOON BEHIND LOW PRESSURE. WESTERLY WIND GUSTS OF 20 TO 30 KNOTS ARE EXPECTED TO DEVELOP AND SCA HEADLINES ARE POSTED FOR MOST OPEN WATERS. OUTLOOK...WEDNESDAY THROUGH SATURDAY...MODERATE TO HIGH CONFIDENCE. ANTICIPATE SMALL CRAFT ADVISORY WINDS IN NW FLOW BEHIND THE DEPARTING SYSTEM WED INTO THU. SEAS WILL LIKELY BE NEAR OR ABOVE 5 FEET ACROSS THE OPEN WATERS WED INTO THU. LOW CONFIDENCE OF GALES WED NIGHT THANKS TO STRONG CAA OVER THE RELATIVELY WARM WATER. WINDS DIMINISHING AND SEAS SUBSIDING THU NIGHT AND LIKELY BELOW SMALL CRAFT ADVISORY LEVELS FRI THROUGH SAT. ALTHOUGH JUST BEYOND THE OUTLOOK PERIOD...WE CONTINUE TO MONITOR A POTENTIAL COASTAL STORM FOR LATE SATURDAY NIGHT AND SUNDAY. THERE IS A LARGE UNCERTAINTY IN THE TRACK AND INTENSITY OF THIS SYSTEM AND ANY CORRESPONDING IMPACT ON WINDS AND SEAS IN THE COASTAL WATERS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 1 PM WEDNESDAY TO 7 AM EST THURSDAY FOR ANZ231>235-237. SMALL CRAFT ADVISORY FROM 4 AM WEDNESDAY TO 7 AM EST THURSDAY FOR ANZ250-254>256. && $$ SYNOPSIS...FRANK/DUNTEN NEAR TERM...JWD SHORT TERM...FRANK LONG TERM...DUNTEN AVIATION...FRANK/DUNTEN/JWD MARINE...FRANK/DUNTEN

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