Issued by NWS Boston, MA
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-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --000 FXUS61 KBOX 210430 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1130 PM EST FRI NOV 20 2009 .SYNOPSIS... DRY AND PLEASANT WEATHER WILL RETURN OVER THE WEEKEND WITH HIGH PRESSURE IN PLACE. COASTAL LOW PRESSURE MAY STAY FAR ENOUGH TO THE SOUTH TO JUST CLIP THE REGION MONDAY INTO TUESDAY. A FRONTAL SYSTEM AND LOW PRESSURE MAY AFFECT SOUTHERN NEW ENGLAND TOWARD THE END OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...-- Changed Discussion --IR SATELLITE SHOWING A THIN VEIL OF HIGH CIRRUS CLOUDS CROSSING THE REGION IN THE UPPER LEVEL W FLOW AT 04Z. NOTING MORE CIRRUS CLOUDS WORKING OUT OF PA/OHIO VALLEY THAT WILL WORK E OVERNIGHT. HIGH PRES WILL WORK OUT OF WV/MD/VA REGION INTO NY STATE BY SAT MORNING. WINDS HAVE DIMINISH ACROSS MANY LOWLAND AREAS...WITH SOME WIND STILL ACROSS THE HIGHER TERRAIN. DEWPTS DOWN TO THE 30S TO AROUND 40 AS TEMPS HAVE FALLEN TO THE 40S AT 04Z...EXCEPT AROUND 50 ON THE ISLANDS. HAVE KEPT MINS IN THE MID 30S TO MID 40S TOWARD SUNRISE...BUT WILL DEPEND UPON IF HIGH CLOUDS BREAK UP ENOUGH TO ALLOW TEMPS TO DROP.-- End Changed Discussion --&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...-- Changed Discussion --HIGH PRESSURE CONTINUES TO BUILD INTO SOUTHERN NEW ENGLAND THROUGH SATURDAY...MOVING OVER NORTHERN NEW ENGLAND SATURDAY NIGHT. CLEAR SKIES...LIGHT WINDS...AND ABOVE NORMAL TEMPERATURES WILL BE THE RULE. SATURDAY NIGHT...TEMPERATURES WILL DROP INTO THE 30S /RIGHT AROUND NORMAL/. USED A BLEND OF AVAILABLE GUIDANCE FOR THE GRIDS.-- End Changed Discussion --&& .LONG TERM /SUNDAY THROUGH FRIDAY/... HIGH PRESSURE WILL GRADUALLY SHIFT TO THE NE SUN INTO SUN NIGHT...BUT SFC RIDGING WILL REMAIN IN CONTROL ACROSS SNE. THIS WILL KEEP ANY MOISTURE TO THE SOUTH THROUGH SUN NIGHT...SO DRY FORECAST. MOSUNNY SKIES EXPECTED SUNDAY ACROSS MUCH OF THE REGION...BUT SHALLOW LOW LEVEL MOISTURE IN DEVELOPING NE FLOW MAY BRING MORE CLOUDINESS NEAR THE COAST. USED A MAV/MET BLEND FOR TEMPS. NOT MUCH CHANGE IN CLOUD COVER EXPECTED SUN NIGHT WITH MOST CLOUDS NEAR THE COAST. WE LEANED TOWARD COOLER MET GUIDANCE FOR TEMPS AS GFS IS TOO FAST BRINGING IN MOISTURE. MODELS STILL SHOW CONSIDERABLE SPREAD IN THEIR HANDLING OF COASTAL LOW PRESSURE SYSTEM MON AND TUE SO FORECAST CONFIDENCE REMAINS BELOW NORMAL. GFS/GGEM ARE FURTHEST NW AND BRING RAIN TO SNE MON/MON NIGHT. GGEM REALLY HITS THE QPF HARD MON NIGHT. NAM/EC/UK ALL KEEP RAIN TO THE SOUTH WITH COASTAL LOW REMAINING WELL OFFSHORE. MAJORITY OF GEFS ENSEMBLES ALSO SOUTH WITH COASTAL LOW AND SUPPORT DRIER SOLUTION SO WE WILL TREND IN THIS DIRECTION AND SCALE BACK THE POPS WITH BEST CHC OF RAIN/SHOWERS NEAR THE COAST MON/MON NIGHT. TUE...HELD ON TO CHC POPS SE COAST BASED ON EC SOLUTION WHICH CONTINUED MOIST NE FLOW WITH OFFSHORE COASTAL LOW. FORECAST CONFIDENCE REMAINS LOW FOR THE MIDDLE AND END OF THE WEEK GIVEN THE CONSIDERABLE MODEL SPREAD IN HANDLING THE TIMING/EVOLUTION OF SHORTWAVE ENERGY EJECTING FROM THE MIDWEST. WE GENERALLY FOLLOWED ECMWF SOLUTION WHICH SHOWS AMPLIFYING MID LEVEL TROF APPROACHING THE NE BY THE END OF THE WEEK...SO CHC SHOWERS THU INTO FRI. BOTH GFS/ECMWF INDICATE THIS WILL BE A DYNAMIC SYSTEM BUT DIFFER ON TIMING AND THE EXTENT OF PHASING. POTENTIAL IS THERE FOR HEAVY PRECIP. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...-- Changed Discussion --OVERNIGHT...VFR. SAT AND SAT NIGHT... VFR WITH LIGHT W-NW WINDS. OUTLOOK /SUNDAY THROUGH WEDNESDAY/... SUN...VFR...WITH LOW PROB OF MVFR CIGS DEVELOPING NEAR THE COAST. MON...MVFR POSSIBLE NEAR THE COAST WITH CHC RAIN. VFR NORTH OF THE PIKE. TUE...MVFR CIGS POSSIBLE...ESPECIALLY NEAR THE COAST. WED...VFR.-- End Changed Discussion --&& .MARINE...-- Changed Discussion --OVERNIGHT...HAVE TAKEN DOWN THE SMALL CRAFT ON BOTH BLOCK ISLAND AND RHODE ISLAND SOUNDS. NOTED SEAS HAVE SUBSIDED TO 3-4 FEET WELL OFFSHORE. CONTINUE THE SMALL CRAFT THROUGH THE OVERNIGHT ACROSS THE FAR OUTER WATERS AS SEAS REMAIN AT 5-6 FEET. SOME GUSTS UP TO 25 KT WILL ALSO CONTINUE UNTIL AROUND 06Z-07Z ACROSS THE WATERS EAST OF THE MASSACHUSETTS COAST. SATURDAY...W-NW WINDS UP TO 20 KT. SEAS MAY LINGER AT AROUND 5 FEET ON THE OUTER WATERS THROUGH MID TO LATE MORNING. WAVE GUIDANCE HAS INITIALIZED HIGH SO AM NOT CONFIDENT THAT SEAS WON/T DROP A BIT FASTER THAN FORECAST. SO HAVE OPTED TO NOT EXTEND THE SMALL CRAFT YET. SATURDAY NIGHT...HIGH PRESSURE BUILDS OVERHEAD WITH WINDS AND SEAS DIMINISHING. OUTLOOK /SUNDAY THROUGH WEDNESDAY/... SUN-SUN NIGHT...DEVELOPING NE FLOW SLOWLY INCREASES THROUGH SUN NIGHT BUT CONDITIONS EXPECTED TO REMAIN BELOW SCA. MON-TUE...A PERIOD OF SCA E/NE WINDS LIKELY...ESPECIALLY ACROSS SOUTH COASTAL WATERS AS COASTAL LOW PASSES OFFSHORE. LOWERED WNAWAVE GUIDANCE DUE TO ITS RELIANCE ON THE GFS...BUT STILL HAVE SEAS BUILDING TO 5-7 FT. WED...DIMINISHING WINDS AND SEAS WED AS GRADIENT RELAXES.-- End Changed Discussion --&& .EQUIPMENT... THE FAA TERMINAL DOPPLER WEATHER RADAR /TDWR/ S OF BOSTON IS OUT OF SERVICE UNTIL FURTHER NOTICE. && .BOX WATCHES/WARNINGS/ADVISORIES...-- Changed Discussion --CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EST SATURDAY FOR ANZ250-256. SMALL CRAFT ADVISORY UNTIL 9 AM EST SATURDAY FOR ANZ254-255.-- End Changed Discussion --&& $$ SYNOPSIS...KJC/RLG NEAR TERM...EVT SHORT TERM...RLG LONG TERM...KJC AVIATION...KJC/NOCERA/EVT MARINE...KJC/EVT/RLG EQUIPMENT...
