579 FXUS61 KBOX 101113 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 713 AM EDT SAT AUG 10 2013 .SYNOPSIS... ONE COLD FRNT MOVES OFFSHORE THIS MORNING...A SECOND ONE MOVES THROUGH BY AFTERNOON. HIGH PRESSURE WILL BUILD INTO SOUTHERN NEW ENGLAND THROUGH THE WEEKEND WITH DRY PLEASANT SEASONABLE TEMPERATURES. MOISTURE INCREASES ACROSS THE AREA ON MONDAY NIGHT AND TUESDAY AHEAD OF AN APPROACHING COLD FRONT...WITH THE CHANCE FOR SHOWERS AND THUNDERSTORMS. THE COLD FRONT PUSHES THROUGH OUR AREA BY TUESDAY NIGHT. DRY WEATHER THEN RETURNS FOR THE REMAINDER OF THE WORK WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 7 AM UPDATE... HUMIDITY IS TRENDING LOWER AS A COLD FRONT MOVES OFFSHORE. AS OF 7 AM DEWPOINTS WERE 68-69 ACROSS CAPE COD AND NANTUCKET...BUT MID 60S EASTERN MASS/AROUND 60 WORCESTER/UPPER 50S BERKSHIRES. ANOTHER COLD FRONT IS LOCATED IN NORTHERN/WESTERN NY WITH TRUELY DRY AIR OVER ONTARIO WHERE DEWPOINTS ARE IN THE 40S. DRIER AIR WILL KEEP WORKING IN THROUGH THE DAY. MID AND HIGH CLOUDS OVER NY AND PA WILL MIX WITH THE SUN THIS MORNING...BUT TREND TO MOSTLY CLEAR SKIES ESPECIALLY IN THE AFTERNOON. THE UPDATE MAKES AJUSTMENTS TO SKY COVER AND TEMPS/DEWPOINTS...BUT NO REAL CHANGES TO THE THEME OF THE FORECAST. FROM PREVIOUS DISCUSSION... EXPECT SOME GUSTY W-NW WINDS LATE THIS MORNING AND AFTERNOON ACROSS INLAND AREAS AS DRIER AIR WORKS IN ALONG WITH GOOD MIXING AND MOSTLY SUNNY SKIES. STILL RATHER MILD ALOFT...ALONG WITH GOOD LAUNCHING PAD THIS MORNING...SO EXPECT HIGHS IN THE LOWER-MID 80S EXCEPT AROUND 80 ACROSS THE HIGHER TERRAIN. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... TONIGHT AND SUNDAY... HIGH PRES TAKES OVER WITH MOSTLY CLEAR SKIES TONIGHT. SOME MID AND HIGH CLOUDS MAY LINGER ALONG S COASTAL AREAS. OVERNIGHT LOWS WILL FALL BACK THROUGH THE 50S...WITH SOME READINGS IN THE UPPER 40S ACROSS THE HIGHER TERRAIN OF SW NH/W MA. ON SUNDAY...THE FRONT THAT CROSSES THE REGION THIS MORNING STALLS ACROSS THE MID ATLC...WITH SOME MID AND HIGH CLOUDS FILTERING INTO SOUTHERN AREAS AS LIGHT WINDS BECOME SW DURING THE DAY. SEA BREEZES WILL DEVELOP DURING THE DAY AS WELL. EXPECT HIGHS IN THE MID 70S TO LOWER 80S. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... BIG PICTURE/PREFERENCES... THE LARGE SCALE PATTERN WILL BE YOUR GENERAL ALL-PURPOSE RIDGE WEST/TROUGH NORTHEAST. THIS WILL SUPPORT WARMER THAN NORMAL TEMPS IN THE WESTERN USA AND COOLER THAN NORMAL IN THE NORTHEAST. THE GFS AND ECMWF CONTINUE RATHER SIMILAR FOR MOST OF THE WEEK. THE ECMWF IS A LITTLE DEEPER WITH THE SHORTWAVE MOVING THROUGH THE NORTHEAST TROUGH AND ABOUT 12 HOURS SLOWER WITH PASSAGE. THIS AGREEMENT IN MASS FIELDS ALOFT BREAKS DOWN BY 12Z SATURDAY. THERMAL FIELDS SHOW A SIMILAR PATTERN BUT WITH THE ECMWF 2C COOLER THAN THE GFS SUNDAY-MONDAY AND AGAIN WEDNESDAY THROUGH FRIDAY. TEMPS AT 850 MB START AROUND 10C...WARM A COUPLE DEGREES AHEAD OF THE TUESDAY COLD FRONT...THEN COOL SEVERAL DEGREES FOR WEDNESDAY THROUGH FRIDAY. SO EXPECT TEMPS NEAR SEASONABLE TO START THE WEEK BUT TRENDING COOLER MID WEEK. ALTHOUGH WITH SOUTHERN NEW ENGLAND NORMAL HIGHS/LOWS STILL AT L-M80S AND L-M60S...COOLER THAN NORMAL IS STILL QUITE TOLERABLE. WE FAVORED A BLEND OF HPC/GMOS GRIDS WHERE AVAILABLE AND GFS/ECMWF OTHERWISE. THE DAILIES... SUNDAY NIGHT-MONDAY... THE UPPER FLOW COULD BE LOOSELY CONSIDERED ZONAL AS TWO SHORTWAVES ROTATE THROUGH THE NORTHEAST TROUGH. IN THIS WE HAVE TWO JET MAXES...ONE ALONG THE CANADIAN BORDER AND A SECOND PASSING SOUTH OF NEW ENGLAND. AN EAST-WEST FRONT IS STALLED ACROSS THE MID ATLANTIC AND ADJACENT OCEAN. THE RIGHT ENTRANCE TO THE SOUTHERN JET MAY GENERATE A WAVE ALONG THE STALLED FRONT...TOO FAR SOUTH TO BRING RAIN TO SOUTHERN NEW ENGLAND BUT CLOSE ENOUGH TO SPREAD SOME CLOUDS UP THE COAST. BOTH THE 00Z NAM AND GFS TRY TO BRING SHOWERS TO THE SOUTH COAST REGION...AND THE GFS SUCCEEDS AS IT DOES TOO OFTEN. WE OPTED FOR 10 PERCENT POPS ALONG THE SOUTH COAST...IN EFFECT A DRY FORECAST WITH PARTLY CLOUDY SKIES. DEWPOINTS IN THE UPPER 40S AND 50S SHOULD ALLOW MIN TEMPS IN THE 50S...A FEW OF THE TRADITIONAL COOL SPOTS MAY BREAK 50 BUT IF THERE ARE ENOUGH CLOUDS THEN LIKELY NOT. TEMPS AT 800 MB AROUND 10C MEAN A FULL MIXING POTENTIAL IN THE MID 80S...BUT CLOUDS MAY HOLD THIS BACK A FEW DEGREES SO MONDAY MAX TEMPS IN THE UPPER 70S AND LOWER 80S. SURFACE FLOW WILL BE WESTERLY BUT LIGHT...SO COASTAL LOCATIONS COULD BE OPEN TO AN AFTERNOON SEA BREEZE. TUESDAY... UPPER SHORTWAVE DRIVES THROUGH THE NORTHEAST TROUGH...CROSSING THE GREAT LAKES MONDAY AND NEW ENGLAND TUESDAY. THE DEEPER/SLOWER ECMWF BRINGS THE TROUGH ACROSS NEW ENGLAND TUESDAY NIGHT. IN EITHER CASE...THE TROUGH PUSHES A SURFACE COLD FRONT THROUGH OUR AREA. WE WILL BE IN THE RIGHT ENTRANCE REGION OF A 110 KNOT JET LEADING THE TROUGH WHICH WILL GENERATE UPPER LIFT/VENTING FOR ANY CONVECTION THAT FIRES ALONG/AHEAD OF THE FRONT. THE MODEL DATA SHOWS SIGNS OF A PRE-FRONTAL TROUGH/LEE TROUGH OVER OUR AREA DURING THE DAY...WHICH WOULD PROVIDE A FOCUS FOR LOW LEVEL CONVERGENCE. SBCAPE FORECAST 1000-1500 J/KG. SIGNS OF A DEVELOPING THETA-E RIDGE IN THE GFS...LESS SO IN THE ECMWF. PRECIP WATER VALUES CLIMB TO 1.5 INCHES. WILL FORECAST CHANCE POPS FOR SHOWERS/TSTMS. HOLDING OFF ON HEAVY DOWNPOUR WORDING FOR NOW...BUT WILL NEED TO MONITOR. WEDNESDAY THROUGH FRIDAY... SURFACE HIGH PRESSURE BUILDS OVER THE REGION AND SHOULD PROVIDE DRY WEATHER MID TO LATE WEEK. TEMPS AT 800 MB COOL 4-5C FROM MONDAY TO WEDNESDAY WITH SLIGHT SUBSEQUENT MODERATION BY FRIDAY. SO EXPECT MAX TEMPS IN THE 70S MIDWEEK MODERATING TO NEAR 80 AT THE END OF THE WEEK. DEWPOINTS IN THE UPPER 40S AND 50S WITH LIGHT WINDS WILL ALLOW MIN TEMPS IN THIS RANGE EACH NIGHT...EXCEPT AROUND 60 IN BOSTON AND ALONG THE SOUTH COAST. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW THROUGH SUNDAY...HIGH CONFIDENCE. TODAY...SCATTERED TOP BROKEN MID AND HIGH CLOUDS THIS MORNING BUT OTHERWISE VFR EXPECTED WITH A TREND TO MOSTLY CLEAR SKIES. WEST WINDS THIS MORNING WILL SHIFT TO NORTHWEST THIS AFTERNOON WITH GUSTS TO 25 KNOTS. TONIGHT AND SUNDAY...VFR. MAY SEE SOME LATE NIGHT/EARLY MORNING FOG IN THE NORMALLY SUSCEPTIBLE LOCALES. SEA BREEZES DEVELOP DURING SUNDAY. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. WEST WINDS THIS MORNING WILL TREND TO WEST-NORTHWEST DIRECTION BY AFTERNOON WITH GUSTS 20 TO 25 KNOTS POSSIBLE. THESE WINDS WILL DIMINISH BY SUNSET. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY... OVERALL...MODERATE CONFIDENCE TUESDAY. HIGH CONFIDENCE FOR THE REMAINING PERIODS. SUNDAY NIGHT-MONDAY...VFR. AREAS OF IFR POSSIBLE IN EARLY MORNING FOG. LIGHT WEST TO SOUTHWEST WINDS...WITH POSSIBLE SEABREEZE ALONG THE COASTS. TUESDAY...A COLD FRONT MOVES THROUGH THE REGION BRINGING A PERIOD OF SHOWERS/SCATTERED TSTMS. LOW CONFIDENCE ON TIMING...BUT LIKELY TO BE CONCENTRATED IN THE AFTERNOON/EVENING. BRIEF MVFR/IFR CIGS/VSBYS IN SHOWERS/TSTMS. WEDNESDAY...VFR WITH LIGHT NORTH WINDS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW THROUGH SUNDAY...HIGH CONFIDENCE. HAVE KEPT SMALL CRAFTS GOING FOR THE OUTER WATERS AS WELL AS BI AND RI SOUNDS THROUGH AROUND MID DAY TODAY...MAINLY FOR SEAS UP TO 5-6 FT. WINDS HAVE LOWERED BELOW SMALL CRAFT FOR THE MOST PART...BUT MAY SEE GUSTS UP TO 20 KT ON THE OUTER WATERS THROUGH EARLY AFTERNOON. EXPECT WINDS AND SEAS BELOW SMALL CRAFT CRITERIA TONIGHT AND SUNDAY AS HIGH PRES TAKES OVER. OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY... MODERATE CONFIDENCE. SUNDAY NIGHT-MONDAY...WINDS AND SEAS BELOW SMALL CRAFT THRESHOLDS. TUESDAY...A COLD FRONT MOVES ACROSS THE WATERS WITH SHOWERS AND SCATTERED TSTMS. SOUTHWEST WINDS LEADING THE FRONT MAY GUST TO 20 KNOTS. LIGHTER NORTH WINDS TRAIL THE FRONT TUESDAY NIGHT. SEAS LESS THAN 5 FEET. WEDNESDAY...NORTH WINDS GUSTING TO 20 KNOTS. SEAS CONTINUE LESS THAN 5 FEET. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ254>256. SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR ANZ235- 237. && $$ SYNOPSIS...WTB/EVT NEAR TERM...WTB/EVT SHORT TERM...EVT LONG TERM...WTB AVIATION...WTB/EVT MARINE...WTB/EVT