Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 032058 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 458 PM EDT SUN MAY 3 2015 .SYNOPSIS... SOUTHWEST WINDS BETWEEN HIGH PRESSURE OFF THE MID ATLANTIC COAST AND LOW PRESSURE NORTH OF NEW ENGLAND WILL LEAD TO A WARM AND DRY MONDAY. A COLD FRONT SWEEPS SOUTH ACROSS THE REGION TUESDAY. HIGH PRESSURE REBUILDS WITH DRY AND WARMING WEATHER THE REMAINDER OF THE WORK WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 430 PM UPDATE... SCATTERED SHOWERS WERE STILL OCCURRING ACROSS WESTERN AND NORTH CENTRAL MA LATE THIS AFTERNOON...TO THE NORTH AND WEST OF A PRONOUNCED SEA BREEZE FRONT THAT EXTENDED ALL THE WAY INTO WORCESTER COUNTY. THESE SHOWERS SHOULD COMPLETELY DIMINISH BY THIS EVENING WITH SUNSET. SKIES WILL GRADUALLY CLEAR OVERNIGHT. MINIMUM TEMPERATURES ARE FORECAST MAINLY FROM 45 TO 50. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
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SUNNY SKIES AND PROBABLY THE WARMEST DAY WE HAVE EXPERIENCED THIS YEAR. 850 MB TEMPS ARE FORECAST TO RISE TO +11-12C WITH 925 MB TEMPS OF +16-18C WHICH SHOULD TRANSLATE TO MANY INTERIOR SPOTS REACHING THE LOWER 80S. SOUTHWEST FLOW WILL KEEP IT COOLER ON THE SOUTH COAST...BUT STILL COULD REACH THE UPPER 60S TO MID 70S THERE. THERE COULD BE A SEA BREEZE BRIEFLY ALONG THE EAST COAST BEFORE SOUTHWEST WINDS INCREASE DURING THE AFTERNOON...THEN IT SHOULD WARM UP EVEN ON EAST COASTAL AREAS. GOOD MIXING MEANS THAT DRIER DEWPOINTS FROM ALOFT WILL COME DOWN AND MINIMUM RELATIVE HUMIDITIES WILL DROP TO 15 TO 30 PERCENT ACROSS MUCH OF THE AREA. THAT COMBINED WITH THE POTENTIAL FOR WIND GUSTS TO 25+ MPH LATE IN THE DAY HAS LED TO THE ISSUANCE OF A FIRE WEATHER WATCH...SEE FIRE WEATHER SECTION BELOW FOR CONCERNS. WINDS AT 925 MB ARE FORECAST TO INCREASE TO 35 KNOTS BETWEEN 4 PM AND 8 PM IN EASTERN CT...RI...AND EASTERN MA. SUSTAINED WINDS AT THAT TIME ARE FORECAST TO BE 10 TO 15 MPH. THE NAM SHOWS AN INVERSION AT 1000 FT WHICH PREVENTS GUSTS GREATER THAN 20 MPH FROM REACHING THE SURFACE BUT THE GFS HAS A SHORT WINDOW FROM 3 PM TO 6 PM IN WHICH THERE COULD BE GUSTS TO 20-30 MPH. CLOUDS WILL INCREASE LATE MONDAY NIGHT AHEAD OF AN ADVANCING COLD FRONT AND THERE IS A CHANCE OF SHOWERS IN NORTHERN AND WESTERN MA TOWARD DAYBREAK. THERE WILL BE A STRONG LOW LEVEL JET OF 40 KT AT 925 MB BUT CONVECTIVE INDICES ARE NOT THAT UNSTABLE...SO HAVE REMOVED THUNDER POTENTIAL FOR THE MONDAY NIGHT TIME FRAME.
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&& .LONG TERM /TUESDAY THROUGH SUNDAY/... * ABOVE NORMAL TEMPERATURES EXPECTED THROUGHOUT THE WEEK * COLD FRONT MOVES THROUGH TUESDAY WITH SHOWERS POSSIBLE * POTENTIAL FOR A BACK DOOR COLD FRONT SATURDAY A DECENT BLOCKING SYSTEM IS SETTING UP ACROSS THE UNITED STATES THIS WEEK WITH A TROUGH ACROSS THE WESTERN STATES AND A STRONG RIDGE OVER MUCH OF THE EASTERN HALF OF THE COUNTRY. MODELS ARE IN AGREEMENT THROUGH MUCH OF THE LONG TERM ON THIS BLOCK PERSISTING. HOWEVER... TOWARDS THE END OF THE WEEK...THE GFS IS QUICK TO BREAK DOWN THE BLOCK...WHILE THE ECMWF SUSTAINS IT THROUGH THE WEEKEND. THIS RESULTS IN A COUPLE OF DIFFERENCES...LARGELY WITH THE INTRODUCTION OF A BACK DOOR COLD FRONT IN THE ECWMF FOR SATURDAY. LOOKS PICTURE PERFECT FOR MUCH OF THE LONG TERM. THE TWO POTENTIAL EXCEPTIONS TO THIS ARE A COLD FRONT MOVING THROUGH TUESDAY AND A POSSIBLE BACK DOOR COLD FRONT MOVING INTO THE REGION SATURDAY. OTHERWISE...TEMPERATURES LOOK TO BE WELL ABOVE NORMAL WITH HIGHS MOSTLY IN THE 70S AWAY FROM SHORE WITH A POSSIBILITY OF NEAR 80 ON FRIDAY. THE COLD FRONT TUESDAY WILL LIKELY BRING SOME SHOWERS. INSTABILITY LOOKS FAIRLY MARGINAL AT THIS POINT BUT CANNOT COMPLETELY RULE OUT THUNDER SO HAVE KEPT THE SLIGHT CHANCE OF THUNDER CARRIED BY THE PREVIOUS FORECAST. THE BACK DOOR COLD FRONT SATURDAY IS CONFINED TO THE ECMWF SOLUTION WITH NO SIGN OF IT IN THE GFS. SO SATURDAY IS A SOMEWHAT LOW CONFIDENCE FORECAST. IF THE ECMWF IS RIGHT...COOLER AND CLOUDIER WEATHER WITH SOME RAIN POSSIBLE. IF THE GFS VERIFIES...ONE MORE BEAUTIFUL SPRING DAY...BEFORE A POTENTIAL COLD FRONT. ALL THAT SAID...TYPICALLY THE ECMWF HANDLES THESE BLOCKING SCENARIOS A BIT BETTER THAN THE GFS SO WILL LEAN TOWARDS THE ECMWF AT THIS TIME. && .AVIATION /21Z SUNDAY THROUGH FRIDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. INTO THIS EVENING...HIGH CONFIDENCE. VFR. SEA BREEZES GRADUALLY GIVE WAY TO PREVAILING LIGHT S TO SW FLOW. SCATTERED SHOWERS IN NORTHERN AND WESTERN MA AND NORTHERN CT WILL DISSIPATE AROUND SUNSET. TONIGHT AND MONDAY...HIGH CONFIDENCE. VFR. WINDS BECOME SW OVERNIGHT AND CONTINUE MON. GUSTS OF 20-25 KT ARE POSSIBLE LATE MON AFTERNOON AND EVENING. MONDAY NIGHT...HIGH CONFIDENCE. VFR. CHANCE OF SHOWERS IN NW MA LATE. KBOS TAF...HIGH CONFIDENCE IN TAF. SLIGHT RISK OF A SHOWER UNTIL 00Z. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...TUESDAY THROUGH FRIDAY... HIGH CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF BRIEF MVFR/IFR CONDITIONS IN SCT -SHRA/ISOLD -TSRA TUESDAY.
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&& .MARINE...
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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 MONDAY/... THROUGH TONIGHT...HIGH CONFIDENCE. MAINLY QUIET BOATING WEATHER EXPECTED WITH HIGH PRES SLIDING SE OF THE WATERS. ANY ONSHORE SEA BREEZES NEAR THE COAST WILL GIVE WAY TO PREVAILING S TO SW FLOW OVERNIGHT. MONDAY...MODERATE CONFIDENCE. SW FLOW MAY APPROACH 25 KT NEAR THE SE COAST OF MA...BUT REMAIN 20 KT OR LESS ON THE OPEN OCEAN. MONDAY NIGHT...MODERATE CONFIDENCE. COULD HAVE SEAS BUILDING TO 5 FT OVER THE OUTER WATERS. SW WINDS GUSTING TO NEAR 20 KT AT TIMES. OUTLOOK...TUESDAY THROUGH FRIDAY...HIGH CONFIDENCE. TUESDAY...WINDS AND SEAS DIMINISH AS HIGH PRESSURE BUILDS IN BEHIND THE COLD FRONT CROSSING THE WATERS EARLY. WEDNESDAY THROUGH FRIDAY...QUIET BOATING WEATHER WITH HIGH PRESSURE OVER THE WATERS.
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&& .FIRE WEATHER...
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A FIRE WEATHER WATCH IS IN EFFECT FROM 2 PM TO 8 PM MONDAY FOR MUCH OF OUR FORECAST AREA. THIS WAS BASED ON COORDINATION WITH STATE FIRE WEATHER MANAGERS. TEMPERATURES IN THE LOWER 80S WITH MINIMUM RELATIVE HUMIDITIES IN THE 25-30 PERCENT RANGE WILL BE THE RULE OVER MUCH OF THE INTERIOR AWAY FROM THE COAST. HOWEVER... MODELS SHOW THAT IN PORTIONS OF FRANKLIN AND NORTHERN WORCESTER COUNTIES...THE HUMIDITY COULD DROP AS LOW AS 15-20 PERCENT MONDAY AFTERNOON. THE PARAMETER MOST IN QUESTION THOUGH IS THE WINDS. IDEALLY...WIND GUSTS TO 25 MPH WOULD BE REQUIRED BUT IN MASSACHUSETTS...GUSTS TO 15 TO 20 MPH COULD RAISE SOME CONCERN ON MONDAY. WE ARE EXPECTING SUSTAINED WINDS OF 10 TO 15 MPH BUT A SMALL WINDOW MAINLY BETWEEN 3 PM AND 6 PM IN WHICH WIND GUSTS COULD GUST TO BETWEEN 20 AND 30 MPH.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING FOR CTZ002>004. MA...FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING FOR MAZ002>021-026. RI...FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING FOR RIZ001>005. MARINE...NONE. && $$ SYNOPSIS...RLG/GAF NEAR TERM...GAF SHORT TERM...GAF LONG TERM...RLG AVIATION...RLG/GAF MARINE...RLG/GAF FIRE WEATHER...GAF

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