000 FXUS61 KBOX 260613 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 113 AM EST THU NOV 26 2009 .SYNOPSIS... WEAK HIGH PRESSURE WILL REMAIN ACROSS NEW ENGLAND TONIGHT AND THURSDAY. HOWEVER CLOUDS...DRIZZLE AND FOG WILL PERSIST. LOW PRESSURE WILL RAPIDLY DEVELOP THURSDAY NIGHT SOUTHEAST OF NANTUCKET. THE LOW WILL INTENSIFY AS IT PASSES NEAR NANTUCKET EARLY FRIDAY...THEN MOVE NORTHEAST THROUGH THE MARITIMES FRIDAY NIGHT AND SATURDAY BRINGING STRONG NORTHWEST WINDS. HIGH PRESSURE WILL THEN BRING DRIER WEATHER FROM SATURDAY AFTERNOON INTO SUNDAY. MILD BUT SHOWERY WEATHER RETURNS EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... LOWERED POPS OVERNIGHT AS MID LEVEL SHORTWAVE HAS PUSHED NWD INTO CANADA WITH MID LEVEL DRY SLOT MOVING IN. SHOWER ACTIVITY HAS PRETTY MUCH ENDED ACCORDING TO RADAR. HOWEVER...ABUNDANT LOW LEVEL MOISTURE BELOW THE INVERSION WILL PROMOTE AREAS OF DRIZZLE AND FOG...LOCALLY DENSE IN SPOTS. RH TIME SECTIONS INDICATE SOME THINNING/DECREASE OF THE LOW LEVEL MOISTURE TOWARD 12Z ACROSS E MA WHICH MAY RESULT IN SOME IMPROVEMENT TOWARD MORNING. NOT MUCH TEMPERATURE CHANGE TONIGHT GIVEN OVERCAST CONDITIONS AND ABSENCE OF ANY THERMAL ADVECTION. MIN TEMPS MAINLY 40-45 DEGREES. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... THU... MODELS IN GOOD AGREEMENT HERE WITH WEAK SURFACE RIDGE REMAINING ACROSS THE REGION. THIS WILL LIKELY KEEP THE LOW LEVEL INVERSION IN TACT. IN ADDITION...THE LACK OF ANY SURFACE GRADIENT WILL PRECLUDE LOW LEVEL MOISTURE FROM BEING SCOURED OUT. RH TIME SECTIONS FROM BOTH THE NAM AND GFS INDICATE LOTS OF LOW CLOUDS. THERE COULD BE SOME BREAKS OF SUNSHINE BUT GIVEN THE REASONS ABOVE COMBINED WITH THE LOW SUN ANGLE...THINK CLOUDS WILL DOMINATE. HOWEVER ANY FOG AND DRIZZLE SHOULD BE CONSIDERABLY LESS IN COVERAGE THAN TODAY. AS FOR TEMPS...BLENDED THE COOLER METNAM WITH THE WARMER GFS MOS GIVEN THE ABUNDANT CLOUD COVER. THU NIGHT... SIGNIFICANT TROF AMPLIFICATION ACROSS THE EASTERN GREAT LAKES AS NORTHERN STREAM SHORT WAVES MERGE FORMING A CLOSED MID LEVEL LOW OVER PA BY 12Z FRIDAY. THIS INDUCES THE BEGINNING OF SIGNIFICANT CYCLOGENESIS EAST OF NANTUCKET LATE THU NIGHT. LOOKS LIKE WARM ADVECTION RAINS WILL OVERSPREAD THE REGION FROM SOUTH OF NORTH DURING THE EVENING HOURS WITH RAIN BECOMING WIDESPREAD BY MIDNIGHT. THERMAL PROFILES AND SOUNDINGS SUGGEST COLUMN IS WARM ENOUGH TO SUPPORT ALL RAIN ACROSS THE ENTIRE REGION. THERE IS A LOW PROB OF THUNDER TOWARD MORNING AS SIGNIFICANT HEIGHT FALLS YIELDS STEEPENING MID LEVEL LAPSE RATES. ALTHOUGH DID NOT INCLUDE THUNDER IN THE FORECAST YET GIVEN THE TIME RANGE AND LOW PROBABILITY. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... AGREEMENT AMONG THE MODELS THAT LOW PRESSURE MOVES PAST NANTUCKET FRIDAY AND INTO THE MARITIMES FOR SATURDAY. SOME DIFFERENCES IN TIMING THE END OF PRECIPITATION FRIDAY. WITH A CLOSED UPPER LOW AND ITS COLD POOL MOVING OVERHEAD AT THE TIME...WE WILL NOT BE TOO QUICK TO END IT. RATHER WE WILL START WITH CATEGORICAL POPS AND WIND DOWN FROM SOUTH TO NORTH DURING THE AFTERNOON AND EVENING. COLDER AIR MOVING IN CHANGES THE PROFILES ENOUGH TO CHANGE LINGERING SHOWERS OVER TO SNOW SHOWERS IN THE NORTHWEST...MOSTLY THE HIGHER ELEVATIONS. SUFFICIENT MOISTURE TO SUPPORT AN INCH OR TWO OF SNOW IN THOSE AREAS FRIDAY NIGHT. SURFACE PRESSURES FALL AS THE LOW PASSES US FRIDAY. THIS TIGHTENS THE PRESSURE GRADIENT AND SHOULD BRING INCREASING WINDS FRIDAY AFTERNOON AND NIGHT. THE COLDER AIR TRAILING THE LOW ALSO ENHANCES MIXING OF STRONGER WINDS FROM ALOFT. THE GFS SHOWS A POTENTIAL FOR WEST WIND GUSTS AROUND 45 KNOTS WHILE THE NAM FAVORS GUST POTENTIAL FOR 35 TO 40 KNOTS. WE MAY NEED TO CONSIDER A WIND ADVISORY...MAINLY FOR THE CAPE AND ISLANDS AND SOUTH COAST BUT POTENTIALLY FOR HIGHER ELEVATIONS INLAND. UPPER TROF OVER MAINE AND GULF OF MAINE SATURDAY MORNING...SHOULD REMAIN SUFFICIENTLY MOIST AND UNSTABLE TO KEEP SCATTERED RAIN/SNOW SHOWERS DURING THE MORNING. THE LOW MOVES OFF INTO THE MARITIMES AFTERNOON WHICH SHOULD ALLOW CLEARING AND AN END TO ANY SHOWERS. HIGH PRESSURE BRINGS GENERAL CLEARING/DRY WEATHER FOR SUNDAY. LOW COMING OUT OF THE MIDWEST/GREAT LAKES AREA WILL PUSH CLOUDS OUR WAY MONDAY. MODELS DISAGREE ON TIMING OF THE SUBSEQUENT COLD FRONT PASSAGE WITH THE GFS AND GLOBAL SAYING MONDAY NIGHT WHILE THE ECMWF SAYS TUESDAY. WE WILL GO WITH THE GFS/GLOBAL CONSENSUS FOR NOW WITH CHANCE POPS MONDAY AFTERNOON AND NIGHT AND DRY WEATHER TUESDAY. WEDNESDAY WEATHER STILL UNCERTAIN WITH DIFFERENCES BETWEEN THE OPERATIONAL MODELS AND THEIR ENSEMBLES. WE WILL START WITH CHANCE POPS CONNECTED WITH LOW PRESSURE MOVING UP FROM THE SOUTHEAST USA...BUT WITH LOW CONFIDENCE AT THIS TIME. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... HIGH CONFIDENCE ON LOW CIGS/VSBYS WITH IFR/LIFR CONDITIONS THROUGH MID MORNING. SOME IMPROVEMENT EXPECTED INTO THE AFTERNOON WITH VSBYS IMPROVING TO MVFR/VFR AND CIGS LIFTING TO MVFR...ESPECIALLY BDL-BAF- MHT. FROM BOS-PVD SE TO CAPE/ISLANDS...ONLY A BRIEF PERIOD OF MVFR CIGS EXPECTED THIS AFTERNOON BEFORE FALLING BACK TO IFR. SOME DRIZZLE POSSIBLE BUT MAINLY DRY TODAY. TONIGHT...WIDESPREAD IFR/LIFR CONDITIONS WITH RAIN OVERSPREADING THE REGION FROM SOUTH TO NORTH. OUTLOOK /FRIDAY THROUGH MONDAY/... FRIDAY...WIDESPREAD IFR CIGS AND VSBYS IN RAIN AND FOG. FLIGHT CONDITIONS IMPROVING TO MVFR IN THE AFTERNOON. FRIDAY NIGHT AND SATURDAY...MVFR CONDITIONS IMPROVE TO VFR. STRONG SURFACE WINDS WITH W WIND GUSTS 35-40 KT AND ASSOCIATED MECHANICAL TURBULENCE. WINDS DIMINISH LATE SATURDAY/SATURDAY NIGHT. SUNDAY AND MONDAY...VFR. && .MARINE... TONIGHT... PATCHY DENSE FOG WILL REDUCE VSBY TO LESS THAN A 1/2 MILE AT TIMES ESPECIALLY ACROSS EASTERN MA WATERS. ALSO...HAZARDOUS SEAS WITH EAST SWELLS OF 5-7 FT EVERY 10 SECONDS ACROSS THE OCEAN WATERS. THURSDAY... VSBY SHOULD IMPROVE ESPECIALLY BY MIDDAY. EAST SWELLS WILL SUBSIDE AS WELL. WINDS WILL BE LIGHT AND VARIABLE. THURSDAY NIGHT... LOW PRES DEVELOPS SOUTHEAST OF NANTUCKET TOWARD MORNING. VSBY WILL LOWER IN RAIN. LOW PROB OF AN EASTERLY GALE TOWARD DAYBREAK FRI ACROSS THE EASTERN MA WATERS. MORE LIKELY SCENARIO WILL BE FOR EAST WINDS 20-30 KT...LESS WIND ALONG THE SOUTH COAST OF NEW ENGLAND. OUTLOOK /FRIDAY THROUGH MONDAY/... FRIDAY...WINDS SHIFT TO WEST AND INCREASE IN THE AFTERNOON. FRIDAY NIGHT AND SATURDAY...WEST WINDS STRENGTHEN TO GALE FORCE BEHIND THE DEPARTING LOW. GUSTS TO 40 KT POSSIBLE. SATURDAY NIGHT-SUNDAY...DIMINISHING WEST WINDS WITH LINGERING SEAS AND WIND GUSTS AT SCA LEVELS...ESPECIALLY ON THE OUTER WATERS. MONDAY...LINGERING ROUGH SEAS ON THE OUTER WATERS. PERSISTENT ONSHORE FLOW AND 6 TO 8 FOOT EAST SWELLS COULD LEAD TO MINOR BEACH EROSION ACROSS THE EASTERN MASSACHUSETTS COAST EARLY FRIDAY. WE COULD SEE A SURGE OF 1.0 TO 1.5 FT DURING THE TIMES OF HIGH TIDE FRIDAY BUT ASTRONOMICAL TIDES ARE QUITE LOW. && .CLIMATE... IT IS INTERESTING TO NOTE THAT BOSTON/S LOGAN AIRPORT HAS NOT GOTTEN DOWN TO THE FREEZING MARK SO FAR THIS SEASON. THE LATEST IN THE SEASON THAT BOS HAS GONE WITHOUT HITTING 32F WAS DEC 2ND 1975. IT/S POSSIBLE WE BREAK THAT RECORD...BUT IT WILL BE CLOSE SUNDAY NIGHT...AND NOT COMPLETELY OUT OF THE QUESTION SATURDAY NIGHT...BUT LOWER PROBABILITY THEN. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 AM EST THIS MORNING FOR ANZ250-251-254>256. && $$ SYNOPSIS...WTB/NOCERA NEAR TERM...KJC/NOCERA SHORT TERM...NOCERA LONG TERM...WTB AVIATION...WTB/KJC MARINE...WTB/NOCERA CLIMATE...