Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 182341 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 741 PM EDT SAT APR 18 2015 .SYNOPSIS... MILDER WEATHER THIS AFTERNOON AHEAD OF A DRY COLD FRONT. CANADIAN HIGH PRESSURE BRINGS MUCH COOLER WEATHER TONIGHT AND SUNDAY. THEN A COASTAL LOW DELIVERS A WIND SWEPT SOAKING RAIN TO THE REGION MON AFTERNOON AND NIGHT. MILD WEATHER TUE ALONG WITH A DRYING TREND. THEN MID TO LATE WEEK THE TREND WILL BE TOWARD MUCH COOLER WEATHER ALONG WITH THE RISK OF SCATTERED SHOWERS...MAINLY IN THE AFTERNOON AND EVENING. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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7PM UPDATE... BULK OF THE SHOWERS ASSOCIATED WITH DEVELOPING LOW PRES ARE CURRENTLY EXITING OFF THE COAST OF ESSEX CO MA THIS EVENING. THIS WILL LIKELY BE THE END OF IMPACTS FOR THIS FEATURE AS ASSOCIATED CLOUD COVER IS EXPECTED TO FOLLOW NOT FAR BEHIND. THEREFORE...A MAINLY CLEAR NIGHT WITH JUST A FEW UPPER LVL CLOUDS TO CONTEND WITH. MINS MAINLY FALLING BACK INTO THE LOW 40S AFTER THE CLOUDS DISSIPATE. PREVIOUS DISCUSSION... TEMPERATURES HAVE SOARED INTO THE MID 70S SOUTH OF THE MASS PIKE AND AWAY FROM THE COAST. THE COASTAL SEABREEZE HAS MOVED ALMOST AS FAR INLAND AS 495. BETWEEN THE SEABREEZE AND THE COAST...TEMPERATURES ARE IN THE UPPER 50S TO LOWER 60S. THE COLD FRONT IS CURRENTLY DRAPED ACROSS EASTERN NEW YORK STATE. AS IT MOVES INTO SOUTHERN NEW ENGLAND LATE THIS AFTERNOON WINDS WILL BECOME GUSTY AND SHIFT TO THE NORTHWEST. THERE MAY BE A FEW SHOWERS POSSIBLE ACROSS NORTHEASTERN MASSACHUSETTS LATE THIS AFTERNOON ASSOCIATED WITH A SHORTWAVE CROSSING NORTHERN NEW ENGLAND. HOWEVER...DRY AIR ACROSS MUCH OF THE AREA AND A LACK OF INSTABILITY WILL KEEP MOST OF SOUTHERN NEW ENGLAND DRY THIS AFTERNOON AND TONIGHT. TONIGHT...HIGH PRESSURE BUILDS IN FROM QUEBEC BRINGING COOLER AND DRIER AIR INTO SOUTHERN NEW ENGLAND. BEHIND THE FRONT...WINDS WILL STAY UP ENOUGH TO INHIBIT RADIATIONAL COOLING. TEMPERATURES WILL MOSTLY BE IN THE LOW 40S...WITH A FEW MID TO UPPER 30S IN THE HIGHER TERRAIN OF NORTHWESTERN MASSACHUSETTS.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... SUNDAY...HIGH PRESSURE AND AN UPPER LEVEL RIDGE WILL MOVE OVER SOUTHERN NEW ENGLAND BRINGING BEAUTIFUL...BUT COOLER WEATHER TO THE REGION. HIGH TEMPERATURES WILL BE IN THE UPPER 50S TO LOW 60S MUCH OF THE AREA. EXCEPTIONS WILL BE THE CONNECTICUT VALLEY WHERE IT WILL BE A LITTLE WARMER AND THE EAST COAST WHERE IT WILL BE A LITTLE COOLER. SUNDAY NIGHT...THIS WILL BE A TRANSITION PERIOD AS HIGH PRESSURE MOVES OFFSHORE AND CLOUDS START TO BUILD INTO THE REGION. LOW TEMPERATURES WILL FALL INTO THE MID 30S TO AROUND 40. && .LONG TERM /MONDAY THROUGH SATURDAY/... HIGHLIGHTS... * MON/MON NGT...WIND SWEPT SOAKING RAIN * TUE...DRYING TREND AND MILD * WED-FRI...COOLER WITH PERIODS OF SHOWERS MID TO LATE NEXT WEEK OVERVIEW AND MODEL PREFERENCES... AAH...SPRINGTIME IN NEW ENGLAND. AFTER MANY DAYS OF RELATIVELY PLEASANT WEATHER THE DAMPER ON MANY A GREAT PLAN...A SLOW MOVING CUTOFF WILL DEVELOP JUST UPSTREAM OF SRN NEW ENGLAND. THE PERSISTENT CUTOFF OVER THE SW WILL FINALLY GET PHASED WITH NRN STREAM ENERGY TO FORM THIS DEEP MEANDERING CUTOFF BY LATE MON. NEGATIVE TRENDING AO/NAO SUGGESTS A BLOCKED FLOW REGIME...SO THIS CUTOFF WILL BE TAKING ITS TIME GOING ANYWHERE. IN FACT...IT/S PROGGED TO START IN THE GREAT LAKES BY LATE MON...AND ONLY BE ACROSS CENTRAL AND NRN NEW ENGLAND BY SAT. IN SPITE OF THIS HIGHLY AMPLIFIED AND BLOCKED FLOW PATTERN...THERE IS FAIRLY GOOD AGREEMENT BETWEEN MODELS. THEREFORE...A BLEND OF OPERATIONAL GUIDANCE SHOULD WORK WELL AS A BASELINE FOR THIS FORECAST. DETAILS... MON INTO TUE... THE FIRST IN A SERIES OF SHORTWAVES WILL BE DEVELOPING IN DIFFLUENT FLOW ACROSS NEW ENGLAND DURING THE MORNING HOURS ON MON. MOISTURE LOADING IS FROM THE TOP DOWN HOWEVER AND MOVING IN FROM THE SW. THE INITIAL SFC REFLECTION MON IS AN APPROACHING WARM FRONT...VEERING WIND PROFILE THROUGH THE LAYER AND A BUILDING LLJ ALL POINT TOWARD DECENT LIFT MOVING IN FROM THE W. PWATS OF 2 STD DEVIATIONS FROM NORMAL WILL COMBINE WITH THE S LLJ OF 60-70KT TO YIELD MODERATE RAINFALL BY THE AFTERNOON...WITH THE POSSIBILITY OF POCKETS OF HEAVIER RAIN THANKS TO MODERATE LAPSE RATES ABOVE H7. IT MAY TAKE UNTIL THE MID MORNING HOURS FOR ERN PORTIONS OF THE FA ON MON TO SEE PRECIP AT THE SFC AS THERE IS A VERY ROBUST DRY LAYER NEAR THE SFC TO OVERCOME...BUT SUSPECT ALL AREAS WILL SEE A SOAKING RAIN DURING THE DAY-EVENING MON. ALTHOUGH A MODEST BREAK IS POSSIBLE LATE MON NIGHT...AN APPROACHING COLD FRONT ASSOCIATED WITH LOW PRES SHIFTING INTO QUEBEC AHEAD OF THE CUTOFF WILL LIKELY YIELD A CONTINUATION OF THE PRECIP INTO THE DAY ON TUE. DRY SLOT WILL BE WORKING ITS WAY AROUND THE SYSTEM AND INTO THE REGION BY LATE DAY TUE SO SUSPECT WITH COLD ADVECTION AN END TO PRECIP BY TUE AFTERNOON. FINAL TOTALS ARE LIKELY TO APPROACH 1.0 TO 1.5 INCHES ALTHOUGH SLIGHTLY HIGHER AMOUNTS ARE POSSIBLE IN SPOTS. TUE NIGHT INTO WED... DRIER AIR AND RIDGING BETWEEN SHORTWAVES SHOULD ALLOW FOR A PERIOD OF AT LEAST RELATIVELY DRY WX ACROSS THE REGION. HOWEVER...WITH UPPER LVL CUTOFF SLOWLY SHIFTING E WITH TIME...WILL LIKELY SEE A FAIR AMOUNT OF CLOUDS IN A REGION WHERE ANY LEFTOVER MOISTURE IS OBSERVED. TEMPS MAINLY NEAR NORMAL. THU AND FRI... ANOTHER TWO SHORTWAVES WILL SHIFT THE UPPER LVL CUTOFF THE E THROUGH THE PERIOD SETTLING JUST TO THE N. THE COMBINATION OF COLD AIR ALOFT YIELDING MODEST UPPER LVL INSTABILITY...INCREASING MOISTURE AND BETTER FOCUS FOR LEFT AS SFC LOW PRES DEVELOPS...EXPECT A PERIOD OF -SHRA ACROSS THE REGION BOTH DAYS. HOWEVER...NOT A WASHOUT THIS PERIOD AS THERE WILL LIKELY BE PERIOD DRY SPELLS. OVERALL COLUMN MOISTURE NOT AS ROBUST AS THE EARLY WEEK SYSTEM. SAT... CUTOFF SHIFTS E ALLOWING STACKED NW FLOW AND COLD ADVECTION TO DEVELOP OVER THE REGION. THE COLD ADVECTION ALOFT MAY BE SUCH THAT LOW TOPPED CONVECTIVE SHOWERS ARE OBSERVED IN SPITE OF THE DRIER AIR SHIFTING INTO THE REGION. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. THROUGH SUNDAY NIGHT...HIGH CONFIDENCE. OVERNIGHT... WINDS WILL BEGIN TO SHIFT MAINLY TO THE NW OVER THE NEXT COUPLE OF HOURS AS SEA BREEZES DISSIPATE AND HIGH PRES SLOWLY BUILDS IN. OTHERWISE VFR. TOMORROW AND TOMORROW NIGHT... MAINLY VFR. N WINDS WILL SHIFT DUE TO SEA BREEZES BY ABOUT LATE MORNING. CONDITIONS REMAIN MOSTLY VFR OVERNIGHT...BUT MAY BEGIN TO SEE LOW VFR CLOUDS AND SOME SHOWERS IN THE W BY EARLY MON MORNING. OUTLOOK...MONDAY THROUGH THURSDAY... MON AND TUE...HIGH CONFIDENCE. PERIOD OF RAIN/FOG UNDER E WINDS WHICH MAY GUST AROUND 20 KT NEAR THE EAST COAST. EXPECT CONDITIONS DETERIORATING THROUGH THE FROM VFR TO IFR. WED AND THU...MODERATE CONFIDENCE. CONDITIONS IMPROVE ON WED...SUCH THAT A PERIOD OF VFR CONDITIONS SHOULD OCCUR NW FLOW. SHOWERS ON THU COULD YIELD PERIODIC MVFR/IFR CONDITIONS.
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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 SUNDAY/... HIGH CONFIDENCE. QUIET BOATING WEATHER EXPECTED THROUGH MUCH OF THE PERIOD. WINDS AND SEAS WILL COME UP BRIEFLY OVERNIGHT TONIGHT AS THE COLD FRONT PASSES OVER THE WATERS. THEN LATE SUNDAY NIGHT... THEY WILL COME UP AGAIN AS LOW PRESSURE APPROACHES THE WATERS. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR ALL WATERS FOR LATE SUNDAY NIGHT THROUGH MONDAY. OUTLOOK...MONDAY THROUGH THURSDAY... MON INTO TUE...MODERATE CONFIDENCE. S FLOW WILL BUILD ACROSS THE REGION THROUGH MUCH OF THE PERIOD. GUSTS UP TO 30 KT WITH A FEW GUSTS TO AROUND 35 KT POSSIBLE. NOT CONFIDENT ENOUGH IN WIDESPREAD 34+ GUSTS TO ISSUE A GALE WATCH AT THIS TIME...BUT IT WILL BE CLOSE. WILL RUN SMALL CRAFT ADVISORY FOR LATE SUN NIGHT INTO TUE NIGHT AS THAT LOOKS LIKELY. HOWEVER...SEAS ARE LIKELY TO REACH ABOUT 10-13 FT BY MON EVENING ON THE OCEAN WATERS. LOW VSBYS IN RAIN/FOG. WED INTO THU...MODERATE CONFIDENCE. CONDITIONS IMPROVE SOMEWHAT BY WED...SUCH THAT NO HEADLINES MAY BE NEEDED FOR A PERIOD. HOWEVER...A SLOWLY BUILDING SWELL AND 20 KT WINDS MAY YIELD ANOTHER ROUND OF SMALL CRAFT ADVISORIES BY THU. && .FIRE WEATHER... THERE IS THE POTENTIAL FOR ELEVATED FIRE WEATHER CONDITIONS LATE THIS AFTERNOON AND THIS EVENING ACROSS THE INTERIOR. FOCUS IS ALONG A COLD FRONT WHICH SWEEPS ACROSS THE REGION. EXPECTING NW WINDS SUSTAINED AROUND 15 MPH WITH GUSTS AROUND 30 MPH /STRONGER ACROSS THE HIGH TERRAIN/ IMMEDIATELY BEHIND THE COLD FRONT AS THE RELATIVE HUMIDITY DROPS CLOSE TO 20 PERCENT. HIGH PRESSURE MOVES IN ON SUNDAY KEEPING THE WIND GUSTS AT BAY... BUT ALLOWING FOR RH/S TO DROP TO 30 TO 40 PERCENT. CONDITIONS WILL TURN MORE WET BY NEXT WEEK WITH SEVERAL CHANCES OF SHOWERS AND COOLER WEATHER THROUGHOUT THE WORK WEEK. && .TIDES/COASTAL FLOODING... SPRING TIDES OF 11.5-12.1 FT ARE EXPECTED STARTING LATE SUN ON THE E COAST. THE HIGHEST FOR BOS HARBOR OCCURS AROUND MIDNIGHT SUN NIGHT AT 12.1 FT...HOWEVER WINDS WILL BE OUT OF THE S-SE AND SEAS WILL HAVE NOT YET BUILT OFFSHORE. THEREFORE...NOT EXPECTING TOO MUCH IN THE WAY OF ISSUES WITH THIS PARTICULAR TIDE. HOWEVER...FOLLOWING HIGH TIDES MON AFTERNOON OF 11.8 FT...SURGE MAY BE A FOOT OR MORE BY THIS POINT WITH 14 FT SEAS AND E FLOW GUSTING NEAR 25-30 KT. THEREFORE...MAY NEED TO MONITOR FOR A PERIOD OF SPLASHOVER DURING THIS TIDE CYCLE. NOT CONFIDENT ENOUGH TO ISSUE STATEMENTS AT THIS TIME...BUT IT IS WORTH WATCHING. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...RED FLAG WARNING UNTIL 9 PM EDT THIS EVENING FOR CTZ002>004. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 8 AM EDT SUNDAY FOR ANZ231>235-237-250-251-254>256. SMALL CRAFT ADVISORY FROM 5 AM TO 8 PM EDT MONDAY FOR ANZ230>237-250-251-254>256.
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&& $$ SYNOPSIS...DOODY/RLG NEAR TERM...DOODY/RLG SHORT TERM...RLG LONG TERM...DOODY AVIATION...DOODY/RLG MARINE...DOODY/RLG FIRE WEATHER... TIDES/COASTAL FLOODING...

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