BOF 000 FXUS61 KBOX 212352 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 652 PM EST SAT NOV 21 2009 .SYNOPSIS... HIGH PRESSURE WILL MOVE FROM THE GREAT LAKES INTO SOUTHEAST CANADA TONIGHT...THEN MOVE EAST OF NOVA SCOTIA MONDAY. LOW PRESSURE WILL BRING RAIN TO THE REGION LATE MONDAY INTO TUESDAY. WEAK HIGH PRESSURE WILL TEMPORARILY BUILD INTO THE REGION WEDNESDAY NIGHT AND THANKSGIVING DAY...BEFORE ANOTHER LOW PRESSURE THREATENS THE REGION WITH MORE RAIN VERY LATE THANKSGIVING NIGHT AND FRIDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... SKIES HAVE BECOME CLEAR ACROSS THE VAST MAJORITY OF SOUTHERN NEW ENGLAND...WITH JUST SOME LEFT OVER HIGH CLOUDS ACROSS THE CAPE/ISLANDS EARLY THIS EVENING. SKIES SHOULD GENERALLY REMAIN MOSTLY CLEAR OVERNIGHT WITH LIGHT WINDS. THIS WILL RESULT IN A GOOD NIGHT OF RADIATIONAL COOLING. TEMPERATURES ALREADY RUNNING A FEW DEGREES BELOW GUIDANCE VALUES EARLY THIS EVENING...SO HAVE UNDERCUT GUIDANCE A BIT OVERNIGHT. LOWS SHOULD FALL WELL DOWN INTO THE 30S ACROSS MOST OF THE REGION...WITH EVEN SOME UPPER 20S POSSIBLE ACROSS THE NORMALLY COLDEST SPOTS MAINLY IN SOUTHWEST NH/NORTHWEST MA. THE WARM SPOT SHOULD BE THE URBAN HEAT ISLAND OF BOSTON WITH LOWS AROUND 40 TO THE LOWER 40S. ISOLATED PATCHY GROUND FOG WILL LIKELY DEVELOP LATE IN THE TYPICALLY PRONE LOCATIONS...ESPECIALLY ACROSS SOUTHWEST NH/NORTHWEST MA. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... HIGH PRESSURE REMAINS ACROSS NORTHERN NEW ENGLAND AND SOUTHEAST CANADA. THIS SHOULD MEAN ANOTHER MOSTLY SUNNY DAY...BUT THIS TIME WITH ONSHORE WINDS BY AFTERNOON. THESE ONSHORE WINDS COULD LEAD MARINE STRATUS LATE IN THE DAY INTO SUNDAY NIGHT...PARTICULARLY SOUTH AND EAST OF I-95 IN MA AND RI. GIVEN THE EXPECTED TIMING OF THE WIND SHIFT THOUGH...THINKING THIS MAY BE MORE OF A CONCERN SUNDAY NIGHT. MOS TEMPERATURES LOOK REASONABLE ONCE AGAIN...SO USED A BLEND OF THE MAV/MET GUIDANCE. && .LONG TERM /MONDAY THROUGH SATURDAY/... MONDAY AND TUESDAY... PLENTY OF UNCERTAINTY REMAINS BUT CONFIDENCE IS GROWING THAT AT LEAST SOME RAIN WILL AFFECT THE REGION LATER MONDAY INTO TUESDAY. THE MAIN DILEMMA IS HOW CLOSE TO THE COAST A WAVE OF LOW PRESSURE TRACKS AND ALSO ITS INTENSITY. HOWEVER...LATEST MODELS ALONG WITH SREF ENSEMBLES SUGGEST THAT EVEN IF THE SOUTHERN AND WEAKEST SOLUTIONS VERIFY THERE WILL LIKELY BE AT LEAST SOME RAIN WITH PERSISTENT ONSHORE FLOW. THE MAIN QUESTION IS WILL A PERIOD OF HEAVIER RAIN EFFECT PORTIONS OF THE REGION. THE GEM/NAM CERTAINLY SHOW THIS POTENTIAL...WHILE THE GFS/UKMET ARE MUCH FURTHER SOUTH SUGGESTING MAINLY RAIN/DRIZZLE. THE ECMWF IS NOT AS EXTREME AS THE VERY WET GEM/NAM BUT IT DOES LEAN IN MORE OF THEIR DIRECTION. THEREFORE...WE WILL LEAN IN THE ECMWF/S DIRECTION FOR NOW ESPECIALLY CONSIDERING ITS TRACK RECORD IN THIS TIMEFRAME. WILL RUN WITH A PERIOD OF LIKELY POPS ACROSS THE ENTIRE REGION MONDAY NIGHT/TUESDAY. A PERIOD OF HEAVY RAIN IS POSSIBLE DEPENDING ON HOW CLOSE TO THE COAST THE WAVE OF LOW PRESSURE TRACKS. THE BEST CHANCE FOR HEAVY RAIN WILL BE ACROSS THE SOUTHERN AND EASTERN SECTIONS. IN FACT...LATER SHIFTS MAY HAVE TO INCREASE POPS INTO CATEGORICAL LEVELS FOR SOME OF THE REGION. DESPITE PERSISTENT ONSHORE FLOW MONDAY/TUESDAY...ASTRONOMICAL TIDES ARE LOW AND THE SYSTEM DOES NOT APPEAR INTENSE ENOUGH TO RESULT IN ANY COASTAL FLOODING. HOWEVER...MINOR BEACH EROSION CERTAINLY IS POSSIBLE. AS FOR TEMPERATURES...CONFIDENCE IS HIGH THAT IT WILL BE RATHER COOL AND RAW DURING THE AFTERNOON. HIGHS MAINLY IN THE UPPER 40S AND THE LOWER 50S WITH THE ONSHORE FLOW. CONFIDENCE IS ALSO HIGH THAT WHAT EVER FALLS WILL BE IN THE LIQUID VARIETY. LOW TEMPERATURES SHOULD REMAIN IN THE 40 TO 45 DEGREE RANGE ACROSS MOST OF THE REGION. WEDNESDAY... LOW CONFIDENCE FORECAST OVER THIS TIME...BUT THE STEADIEST PRECIPITATION WILL LIKELY BE OVER. HOWEVER...WILL CONTINUE WITH THE CHANCE OF A FEW SHOWERS WITH WAVE OF LOW PRESSURE STILL SPINNING OFF THE COAST. PRECIPITATION CHANCES MAY DIMINISH LATER WEDNESDAY AFTERNOON AND EVENING AS DRIER AIR WORKS INTO THE REGION FROM THE WEST AND THE LOW FINALLY PULLS AWAY. HIGHS SHOULD MAINLY BE IN THE UPPER 40S TO MID 50S ACROSS THE REGION. WEDNESDAY NIGHT THROUGH FRIDAY... ALTHOUGH THE TIMING CAN CERTAINLY CHANGE SINCE WE ARE STILL 5 TO 6 DAYS OUT...AT THIS TIME IT APPEARS THAT MOST OF WEDNESDAY NIGHT THANKSGIVING DAY MAY TURN OUT DRY. A WEAK RIDGE OF HIGH PRESSURE LOOKS TO TEMPORARILY BUILD INTO THE REGION WEDNESDAY NIGHT AND THANKSGIVING DAY. HOWEVER...A VIGOROUS TROUGH DEVELOPING OVER THE GREAT LAKES MAY ALLOW ANOTHER LOW PRESSURE SYSTEM TO AFFECT THE REGION LATE THANKSGIVING NIGHT INTO FRIDAY. AGAIN...TIMING AND FORECASTS ARE SUBJECT TO SIGNIFICANT ERRORS THIS FAR IN ADVANCE. HOWEVER...THIS MAY BRING MORE RAIN TO THE REGION. TEMPERATURE PROFILES CONTINUE TO LOOK TOO WARM SUPPORT ANY FROZEN PRECIPITATION EVEN IN THE DISTANT INTERIOR FOR MOST OF THE POTENTIAL EVENT. SATURDAY... BLUSTERY AND CHILLY WEATHER LOOKS TO BE FILTERED INTO THE REGION BEHIND THE SYSTEM. MUCH OF THE DAY WILL BE DRY...BUT CAN NOT RULE OUT A FEW SPRINKLES/PASSING RAIN SHOWER SO WILL RUN WITH A SLIGHT CHANCE. ITS NOT OUT OF THE QUESTION THAT A FEW WET SNOWFLAKES FALL ACROSS THE INTERIOR HIGH TERRAIN BUT IT DOES NOT APPEAR TO BE A BIG DEAL. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... TONIGHT...VFR. THERE IS A LOW PROBABILITY THAT BRIEF MVFR VISIBILITIES IN PATCHY GROUND FOG COULD AFFECT THE BAF/BDL TERMINALS FOR A FEW HOURS AFTER MIDNIGHT. SUNDAY...VFR. MAY SEE PATCHY VFR TO LOCAL MVFR CIGS ALONG THE COAST DURING THE LATE MORNING AND AFTERNOON. SUNDAY NIGHT...VFR MOST LOCATIONS. GREATER RISK OF MVFR CIGS ALONG THE EAST COAST AND SOUTH AND EAST OF A LINE FROM KBOS-KPVD. CONFIDENCE ON THIS IS NOT HIGH AT THIS TIME. OUTLOOK /MONDAY THROUGH THURSDAY/... MONDAY AND TUESDAY...MVFR-IFR CONDITIONS IN LOW CLOUDS AND RAIN WILL OVERSPREAD THE REGION FROM SOUTH TO NORTH SOMETIME ON MONDAY AND PERSIST INTO TUESDAY. WEDNESDAY...LOW CONFIDENCE FORECAST BUT MVFR-IFR CONDITIONS MAY LINGER IN LOW CLOUDS/RAIN SHOWERS FOR A TIME. WEDNESDAY NIGHT AND THANKSGIVING...MAINLY VFR BUT CONDITIONS MAY DETERIORATE LATE THANKSGIVING NIGHT. && .MARINE... HIGH PRES BUILDING N OF THE WATERS TONIGHT. WINDS GRADUALLY SHIFTING N TONIGHT...THEN NE SUNDAY INTO SUNDAY NIGHT. SEAS BELOW 5 FT TONIGHT INTO EARLY SUNDAY. DO EXPECT SEAS TO BUILD OVER 5 FT ACROSS THE OUTER COASTAL WATERS SUNDAY AFTERNOON INTO SUNDAY NIGHT ONCE NE WINDS GET ESTABLISHED. THERE IS STILL A QUESTION ABOUT STRENGTH OF THESE WINDS...WHICH WILL BE ENTIRELY DEPENDENT UPON THE APPROACH OF A LOW PRESSURE FROM THE MID ATLANTIC COAST. BASED UPON THE BUILDING SEAS...WILL HOIST A SMALL CRAFT ADVISORY FOR THE OUTER COASTAL WATERS. OUTLOOK /MONDAY THROUGH THURSDAY/... MONDAY THROUGH WEDNESDAY...CANADIAN HIGH PRESSURE WITH LOW PRESSURE TO THE SOUTH WILL CREATE A PERSISTENT NORTHEAST FLOW AND GOOD GRADIENT. THIS WILL RESULT IN SCA ACROSS MOST OF OUR WATERS OVER THIS TIME. SEAS MAY BUILD TO BETWEEN 7 AND 12 FEET ACROSS THE OUTER-WATERS. THERE IS A LOW PROBABILITY OF A BRIEF MARGINAL GALE AT SOME POINT. THANKSGIVING...WINDS SHOULD TEMPORARILY DIMINISH AS WEAK RIDGE OF HIGH PRESSURE BUILDS IN DURING THE DAY. HOWEVER...SEAS WILL LIKELY REMAIN ABOVE SCA THRESHOLDS ACROSS THE OUTER-WATERS. WINDS AND SEAS MAY ONCE AGAIN INCREASE VERY LATE THANKSGIVING NIGHT IN ADVANCE OF OUR NEXT POSSIBLE SYSTEM && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 9 AM SUNDAY TO 6 AM EST MONDAY FOR ANZ250-254. SMALL CRAFT ADVISORY FROM NOON SUNDAY TO 6 AM EST MONDAY FOR ANZ255. SMALL CRAFT ADVISORY FROM 3 PM SUNDAY TO 6 AM EST MONDAY FOR ANZ256. && $$ SYNOPSIS...BELK/FRANK NEAR TERM...FRANK SHORT TERM...BELK LONG TERM...FRANK AVIATION...BELK/FRANK MARINE...BELK/FRANK EOF