AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 207 PM EDT WED MAY 11 2011 .SYNOPSIS... AN OCEAN STORM WELL OFFSHORE WILL BRING GUSTY NORTHEAST WINDS... AREAS OF DRIZZLE AND UNSEASONABLY COOL TEMPERATURES TO EASTERN MASSACHUSETTS AND RHODE ISLAND THROUGH TONIGHT WITH SLOW IMPROVEMENT THURSDAY. WEAKENING HIGH PRESSURE WILL BUILD OVER THURSDAY NIGHT THROUGH FRIDAY WITH DRY AND SEASONABLE CONDITIONS. A SLOW MOVING LOW PRESSURE SYSTEM MAY BRING UNSETTLED CONDITIONS LATER THIS WEEKEND THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... INTERESTING FEATURES SEEN ON LATEST VISIBLE SATELLITE IMAGERY WITH A BREAK IN THE CLOUD COVER OVER COASTAL ME AND EXTENDING JUST OFFSHORE INTO MA BAY. THIS AREA OF CLEARING WAS SLIDING TOWARD EASTERN MA AT EARLY AFTERNOON. APPEARS THIS AREA OF CLEARING IS ASSOCIATED WITH SUBSIDENCE SANDWICHED BETWEEN TWO VORT LOBES...ONE OVER NEW ENGLAND AND THE OTHER MOVING ACROSS NOVA SCOTIA. IN ADDITION A STRONG JET STREAK IS ASSOCIATED WITH THE NEW ENGLAND VORT LOBE WITH ITS REAR LEFT QUAD OVER COASTAL ME AND JUST OFFSHORE...ENHANCING THE SUBSIDENCE ACROSS THIS AREA. BOTH THE 12Z NAM AND GFS BUFKIT SUGGEST THIS AREA OF CLEARING WILL OVERSPREAD EASTERN MA AND POSSIBLY INTO RI THIS AFTERNOON AND EVENING. ALTHOUGH AREAL COVERAGE OF CLEARING IS TRICKY AS MOIST NE FLOW SHOULD YIELD CLOUDS JUST INLAND FROM THE COAST GIVEN MOIST UPSLOPE COMPONENT ESPECIALLY INTO THE WORCESTER HILLS. THEREFORE HIGHEST PROBABILITY OF ANY PARTIAL CLEARING/SUNSHINE SHOULD BE ACROSS NORTHEAST MA. CLOUDS SHOULD REMAIN ENTRENCHED ALONG WITH SOME LIGHT RAIN/DRIZZLE ACROSS SOUTHEAST MA AS STRONG LOW LEVEL NE JET MOVES ACROSS THIS AREA LATER THIS AFTERNOON INTO THE EARLY EVENING. THIS AREA OF WET WEATHER MAY EXTEND INTO SE RI LATER THIS AFTERNOON AND EARLY EVENING. FARTHER WEST ACROSS THE CT RVR VLY CLOUDS SHOULD CONTINUE TO SLOWLY LIFT ALONG WITH A FEW BREAKS IN THE OVERCAST. GIVEN THE STRENGTH OF THIS LOW LEVEL JET AND BOUNDARY LAYER MIXING WILL CONTINUE WITH WIND ADVISORY ACROSS NANTUCKET AND KEEP SPEEDS JUST BELOW ADVISORY ACROSS CAPE COD AS ALL MODEL DATA SUPPORTS THIS AT THE MOMENT. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... THURSDAY... THIS WILL BE OUR TRANSITION DAY AS OCCLUDED LOW OFFSHORE BEGINS TO DRIFT FARTHER SEAWARD WITH MID LEVEL FLOW TRANSITIONING SLOWLY FROM CYCLONIC TO ANTICYCLONIC WITH MODELS VARYING ON SPEED OF TRANSITION. HOWEVER SUBSIDENCE INVERSION WILL LIKELY TRAP LOW LEVEL MOISTURE IN THE FORM OF LOW CLOUDS DURING THE MORNING HOURS BUT SHOULD LIFT AND ERODE SOMEWHAT DURING THE AFTERNOON YIELDING PARTIAL SUNSHINE FOR MOST OF THE AREA EXCEPT CAPE COD AND THE ISLANDS WHERE CLOUDS MAY REMAIN DOMINATE. NAM AND GFS BUFKIT SHOW THIS NICELY. AS FOR TEMPS SIDED WITH THE WARMER GFS MOS GIVEN THE EXPECTED PARTIAL SUNSHINE FOR MOST OF THE AREA THU AFTERNOON. WINDS WILL FINALLY SLACKEN TOMORROW ESPECIALLY AWAY FROM THE CAPE AND ISLANDS AS PRES GRADIENT RELAXES. THU NIGHT... QUIET WEATHER AS DEEP LAYER RIDGE WEST OF NEW ENGLAND BUILDS CLOSER TO THE AREA. EXPECTING MOSTLY CLEAR SKIES...LIGHT WINDS AND SEASONABLY COOL TEMPS. && .LONG TERM /FRIDAY THROUGH TUESDAY/... * DRY AND SEASONABLE WEATHER THROUGH LATE IN THE WORK WEEK. * UNSETTLED CONDITIONS RETURN FOR THE WEEKEND AND EARLY NEXT WEEK. PREFERENCES... MODELS HAVE DIVERGED IN SOLNS SOMEWHAT FROM THE LAST FEW RUNS...AND ARE GENERALLY HAVING A DIFFICULT TIME RESOLVING THE HIGHLY AMPLIFIED PATTERN OVER MUCH OF THE CONUS. ECMWF HAS SHOWN SIGNIFICANT RUN TO RUN INCONSISTENCY WITH THE PATTERN...ESPECIALLY IN COMPARISON TO ITS TRADITION OF BEING THE MOST CONSISTENT OF LATE. WHILE A GENERAL BLEND OF MODELS WILL WORK WELL FOR THU NIGHT INTO FRI NIGHT...WITH ALL MODELS SUGGESTING LONGWAVE RIDGING...FROM THEN ON CHANGES IN PROGRESSIVENESS ARE CAUSING LOW CONFIDENCE IN ANY ONE SOLN. GFS AND ITS GEFS MEMBERS ARE INTERESTINGLY THE LEAST PROGRESSIVE MODEL...AND HAVE SOME SUPPORT FROM THE TAIL END OF THE NAM. THE ECMWF IS THE MOST PROGRESSIVE...SUGGESTING THAT TROF ENERGY DIGGING S INTO THE RIDGE SAT IS ENOUGH TO CREATE MORE ZONAL FLOW. WHILE THE 00Z GFS IS SOMEWHAT CLOSER TO THIS SUGGESTION...IT REMAINS THE MORE MERIDIONAL MODEL...WHICH GIVEN THE PATTERN IS FAVORED. USING THIS PREFERENCE AT LEAST FOR THE WEEKEND...WILL TREND TIMING OF THE BACKDOOR COLD FRONT SAT TOWARD THE GFS TIMING. THEN WITH SIGNIFICANT MODEL DIFFERENCES AFTERWARD WITH A SECOND APPROACHING CUTOFF...WILL GENERALLY TREND TOWARD A BLEND OF SOLNS BEGINNING NEXT WEEK. THIS WILL YIELD SOMEWHAT UNSETTLED CONDITIONS WHICH GIVEN THE USUAL IMPACTS OF A CUTOFF ALOFT IS NOT A BAD SUGGESTION. DETAILS... THU NIGHT THRU FRI NIGHT... HIGH AMPLITUDE LONGWAVE RIDGING ALOFT AND ITS ATTENDANT SFC HIGH WILL CREST OVER THE REGION DURING THE DAY FRI. THIS WILL YIELD DRY AND GENERALLY WEAK ESE FLOW OVER MUCH OF THE REGION. H85 TEMPS REBOUND UNDER THE HIGH TO AROUND 8 OR 9C WITH MIXING EXPECTED TO REACH CLOSE TO THIS LVL BUT NOT MUCH HIGHER. THIS WILL YIELD TEMPS IN THE UPPER 60S TO LOWER 70S FOR MAX TEMPS ON FRI. ONLY CAVEAT TO THIS WILL BE ALONG COASTAL REGIONS...WHICH UNDER ESE FLOW WILL HAVE A MARINE INFLUENCE KEEPING TEMPS MOSTLY IN THE UPPER 50S TO MID 60S. SAT... WEAKENING BACKDOOR COLD FRONT STILL PROGGED TO CROSS THE REGION DURING THE DAY SAT...BUT CONFIDENCE OVERALL LOW IN TIMING. GIVEN THE FRONTOLYTICAL FLOW ALOFT IN STRETCHING THE FRONT WITH TIME...EXPECT SLOWER MOVEMENT TO BE FAVORED. THIS ALSO SUGGESTS THAT THE FROPA COULD BE MOSTLY DRY. HOWEVER...MODEL SOUNDINGS DO SUGGEST SOME MID AND LLVL MOISTURE TO WORK WITH SO WILL CONTINUE SUGGESTING AT LEAST ISOLD POPS WITH THIS FROPA. WITH CLOUD COVER EXPECTED TO BE GENERALLY BKN TO OVC...EXPECT DIURNAL TEMP TREND TO BE LOW AMPLITUDE WITH COOLER HIGHS AND WARMER MINS. SUN INTO MON... WITH THE SLOW MOVING AND WEAKENING FRONT CONTINUING TO SAG SOMEWHERE OVER THE CWA...EXPECT THAT THE OVERALL TREND WILL BE TOWARD MORE UNSETTLED CONDITIONS WITH WEAK ISENTROPIC LIFT UNDER LLVL WAA THROUGH MUCH OF THE PERIOD. THE EXACT LOCATION ON THE LOW WILL HAVE THE FINAL IMPACT ON WHERE THE BEST -SHRA AND -RA ACTIVITY WILL BE...WITH ECMWF SUGGESTING THE COASTAL PLAIN AND GFS SUGGESTING NRN PORTIONS OF THE FA. HOWEVER...GENERALLY ISOLD TO CHANCE POPS AND MOSTLY CLOUD SKIES ARE EXPECTED. THIS WILL ALSO YIELD TEMPS SLIGHTLY BELOW NORMAL TO NEAR NORMAL. TUE INTO MID WEEK... CONTINUED EFFECTS OF SLOW MOVING CUTOFF ALOFT AND ATTENDANT SFC LOW WILL YIELD CONTINUED MOIST AND UNSETTLED CONDITIONS THROUGH THE PERIOD. CONFIDENCE IS LOW ATTM. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT MODERATE...30 PERCENT TO 60 PERCENT HIGH...GREATER THAN 60 PERCENT THROUGH 00Z... LOW CONFIDENCE FORECAST ON DETAILS BUT MODERATE TO HIGH CONFIDENCE ON TRENDS. CIGS WILL CONTINUE TO LIFT TO MVFR FOR MUCH OF THE REGION WITH VFR ACROSS WESTERN NEW ENGLAND...BUT ALSO ACROSS EXTREME EASTERN MA. THIS IMPROVING TREND WILL CONTINUE INTO THIS EVENING ALTHOUGH EXACT TIMING IS DIFFICULT. OTHER THAN SOME SPOTTY LIGHT DRIZZLE EARLY THIS AFTERNOON EXPECT MAINLY DRY RUNWAYS. LLWS POSSIBLE CAPE COD AND THE ISLANDS AS LOW LEVEL NE JET MOVES ACROSS THE AREA. AFTER 00Z... MVFR TO VFR CONDITIONS MUCH OF THE NIGHT WITH LOWEST CIGS OVER THE CAPE AND ISLANDS ALONG WITH PATCHY DRIZZLE. LLWS POSSIBLE ACROSS THIS REGION EARLY ON. FORECAST CONFIDENCE MODERATE. KBOS TERMINAL... VFR LIKELY LATE THIS AFTERNOON AND EARLY EVENING BEFORE POSSIBLY GOING BACK TO MVFR LATER THIS EVENING. DRY RUNWAYS SHOULD PREVAIL ALONG WITH A MODEST N-NE WIND. MVFR CIGS EARLY THU SHOULD BECOME VFR BY AFTN AND CONTINUE THU NIGHT. WINDS SLACKEN THU AS WELL. OUTLOOK...FRI THROUGH SUNDAY... FRI INTO FRI NIGHT... HIGH CONFIDENCE VFR WITH HIGH PRESSURE BUILDING OVER THE AREA. SOME MID AND HIGH CLOUDS BUILD OVER FROM THE NW DURING THE NIGHT FRI NIGHT. WINDS GENERALLY LIGHT. SAT... MEDIUM CONFIDENCE WITH VFR TO DOMINATE. CHANCE FOR MVFR ESPECIALLY IN -SHRA WITH A WEAKENING FROPA. LOW CONFIDENCE IN TIMING. SUN... LOW CONFIDENCE. MIX OF VFR AND MVFR AS SLOW MOVING LOW PRESSURE APPROACHES FROM THE W. BEST CHANCE FOR MVFR IN -SHRA AND -RA AS THE LOW APPROACHES. TIMING UNCERTAIN. && .MARINE... THIS EVENING AND OVERNIGHT... NE GALE LIKELY FOR THE CAPE COD AND NANTUCKET WATERS WITH SUB GALE ELSEWHERE. HOWEVER VSBY SHOULD BE FAIR. ROUGH SEAS ACROSS THE EASTERN MA WATERS CONTINUE. THU/THU NIGHT... OFFSHORE LOW MOVES SLOWLY SEAWARD WITH WINDS EASING ACROSS THE EASTERN NEW ENGLAND WATERS. HOWEVER LARGE NE SWELLS WILL PERSIST. OUTLOOK...FRI THROUGH SUNDAY... FRI.... WINDS GENERALLY DECREASING BELOW SCA OVERNIGHT. HOWEVER...STRONG NE SWELL REMAINS ABOVE 5 FT THROUGH THE PERIOD. THEREFORE...SCA FOR HAZ SEAS WILL LIKELY BE NEEDED. SEAS REMAIN HIGHEST LONGEST OVER ERN OUTER WATERS. SAT... SEAS CONTINUE TO DIMINISH TO BELOW SCA SAT...LOW CONFIDENCE IN TIMING. SUN... SE WINDS AS WELL AS SEAS REMAIN BELOW SCA LEVELS. && .TIDES/COASTAL FLOODING... PERSISTENT NORTH TO NORTHEAST WINDS AND LARGE SEAS OVER MULTIPLE TIDE CYCLES WILL RESULT IN SOME BEACH EROSION ON NORTH AND EAST FACING BEACHES ESPECIALLY ON THE OUTER CAPE AND NANTUCKET. SURGE VALUES WILL RANGE BETWEEN 1-1.5 FT /ADDED 0.5 FT TO STORM SURGE GUID/. HOWEVER TIDES REMAIN LOW ENOUGH TO PRECLUDE ANY COASTAL FLOODING. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR MAZ024. NH...NONE. RI...NONE. MARINE...GALE WARNING UNTIL 8 PM EDT THIS EVENING FOR ANZ232. SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR ANZ231- 233>235-237-250-251-256. SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ230- 236. GALE WARNING UNTIL 3 AM EDT THURSDAY FOR ANZ254-255. && $$ SYNOPSIS...NOCERA