Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 141357 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 957 AM EDT SUN SEP 14 2014 .SYNOPSIS... HIGH PRESSURE OVER THE GREAT LAKES BUILDS INTO NEW ENGLAND TODAY AND MONDAY...BRINGING DRY WEATHER ALONG WITH MILD AFTERNOONS AND CHILLY NIGHTS. A COLD FRONT WILL LIKELY BE ACCOMPANIED BY A PERIOD OF SHOWERS LATE MONDAY NIGHT INTO TUESDAY. MAINLY DRY BUT COOLER THAN NORMAL WEATHER FOLLOWS NEXT WEDNESDAY THROUGH FRIDAY. TEMPERATURES THEN LIKELY MODERATE TO NEAR NORMAL BY NEXT WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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10 AM UPDATE...A CHILLY MORNING WITH MANY LOCATIONS SEEING LOW TEMPERATURES IN THE MID 40S HAS MEANT A SLOW REBOUND THIS MORNING WITH TEMPERATURES STILL IN THE UPPER 40S ACROSS THE NORTHWESTERN ZONES TO AROUND 60 ON THE CAPE. OTHERWISE...MOSTLY SUNNY SKIES AND GUSTY WINDS THIS MORNING. MADE SOME MINOR UPDATES TO THE FORECAST TO ACCOUNT FOR CURRENT TRENDS...OTHERWISE THE FORECAST IS ON TRACK. PREVIOUS DISCUSSION... WINDS WILL BRIEFLY BECOME BREEZY AFTER SUNRISE AS BLYR WARMS AND ERODES INVERSION RESULTING IN STRONGER WINDS ALOFT MIXING TO THE SURFACE. HOWEVER BY 15Z PGRAD RELAXES AND WINDS DIMINISH WITH AFTERNOON SEABREEZES POSSIBLE. POST FRONTAL AIRMASS IS SLIGHTLY COOLER THAN NORMAL WITH 925 MB TEMPS AROUND +10C...-1 STD FROM CLIMO. MODEL SOUNDINGS SUGGEST SUBSIDENCE INVERSION LIMITS MIXING TO ABOUT 900 MB. THIS WILL LIMIT HIGH TEMPS THIS AFTERNOON TO 65 TO 70...LOW 60S HIGHER TERRAIN. THIS IS ABOUT 5-8 DEGS COOLER THAN NORMAL. HOWEVER ABUNDANT SUNSHINE AND DIMINISHING WINDS WILL HELP OFFSET THE COOLER TEMPS...YIELDING A VERY PLEASANT DAY BY MID SEP STANDARDS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... TONIGHT...IDEAL RADIATIONAL COOLING WITH CLEAR SKIES...LIGHT WINDS AND A DRY ATMOSPHERE. GIVEN THESE CONDITIONS SIDED WITH THE COOLER MOS TEMPS COMPARED TO THE WARMER MODEL BLEND. MOST LOCATIONS DIP INTO THE 40S TONIGHT BUT AS COLD AS THE M30S OVER NORTHWEST MA AND SOUTHWEST NH. M30S APPEAR MORE WIDESPREAD IN SOUTHWEST NH SO HAVE ISSUED A FROST ADVISORY FOR CHESHIRE COUNTY. MONDAY...MORE OF THE SAME...CHILLY START TO THE DAY BUT SHORT WAVE RIDGING WILL PROVIDE MOSTLY SUNNY SKIES AND LIGHT WINDS WITH HIGH PRES OVERHEAD. TEMPS A FEW DEGS WARMER THAN TODAY WITH AFTERNOON HIGHS IN THE U60S TO L70S. LIGHT PGRAD SHOULD SUPPORT ANOTHER ROUND OF AFTERNOON SEABREEZES. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... HIGHLIGHTS... * A PERIOD OF SHOWERS LIKELY LATE MON NIGHT/TUE * DRY WEATHER AND BELOW NORMAL TEMPS NEXT WED-FRI * PATTERN CHANGE FOR NEXT WEEKEND OVERVIEW... OVERALL MODEL GUIDANCE IS IN AGREEMENT WITH A BROAD TROUGH OVER THE EASTERN HALF OF THE CONTINENT AND A FULL-LATITUDE RIDGE OVER WESTERN NORTH AMERICA. THUS FAR A VERY PROGRESSIVE PATTERN TO START...THEN THE FLOW DOES BEGIN TO BECOME MORE AMPLIFIED AS A DEEP TROUGH INVADES SOUTHERN NEW ENGLAND. HIGH CONFIDENCE THIS WILL OCCUR THANKS TO A VERY NEGATIVE AO. OVER THE WEEKEND...A TROUGH WILL DIG OVER THE EASTERN PACIFIC LEADING TO A RIDGE IN THE CENTRAL CONUS....ABOUT WHEN THE NAO BECOMES MORE NEUTRAL. ANTICIPATE A POSSIBLE CHANGE IN THE PATTERN BY NEXT WEEKEND/OR EARLY NEXT WEEK. ONLY MAJOR WEATHER MAKER TO WATCH FOR IS THE SHORTWAVE PASSING THROUGH MONDAY NIGHT/TUESDAY BRINGING SHOWERS TO THE REGION. LOW CONFIDENCE ON EXACT SPECIFICS BUT CONFIDENCE IS INCREASING THAT PRECIP WILL OCCUR. OTHERWISE HIGH PRESSURE WILL PREVAIL WITH TEMPS AT OR BELOW AVERAGE FOR THIS TIME OF YEAR. IN FACT MID TO LATE NEXT WEEK MAY NEED TO WATCH FOR FROST HEADLINES ACROSS THE DISTANT INTERIOR. DETAILS... MONDAY NIGHT INTO TUESDAY... THE NEXT SHOT FOR PRECIPITATION WILL BE LATE MONDAY NIGHT INTO TUESDAY AS A SHORTWAVE MOVES THROUGH THE FLOW. OVERALL GUIDANCE HAS TRENDED TO BE ON THE WETTER SIDE SO CONFIDENCE IS INCREASING THAT PRECIP WILL OCCUR. RIGHT NOW IT LOOKS AS IF DROUGHT STRICKEN RI AND SE MASS HAVE THE BETTER SHOT FOR THE HIGHER QPF AMOUNTS. ALTHOUGH THE EC CONTINUES TO SHOW A QPF BULLS-EYE FOR THE REGION...NOTICED THAT THE GFS HAS TICKED UP. OVER 0.25 TO 0.5 INCHES OF RAIN IS NOT OUT OF THE QUESTION...ESPECIALLY SINCE PWAT VALUES DO NOSE IN AT ABOUT 1.5 INCHES. THIS IS ALSO ALONG THE SAME THINKING OF HPC. INSTABILITY LOOKS FAIRLY LIMITED...SO WILL NOT INCLUDE THUNDER IN THE FORECAST AT THIS TIME. HIGHS SHOULD BE IN THE 60S TO AROUND 70. END OF THE WORK WEEK... A LARGE AREA OF HIGH PRESSURE THEN BUILDS SE FROM CENTRAL CANADA THROUGH THE END OF THE WEEK. A DRY COLD FRONTAL PASSAGE WED NIGHT INTO THU MORNING WILL REINFORCE THE DRY...COOL AIR ALREADY IN PLACE. THERE IS STILL SOME UNCERTAINTY ON EXACT TIMING OF THE FRONT BUT EITHER WAY...BELOW AVERAGE TEMPERATURES ARE ANTICIPATED. APPEARS THAT WE MAY NEED TO BEGIN TO WATCH FOR THE RISK FOR SOME FROST IN SOUTHWEST NH/NORTHWEST MA...WHERE WINDS CAN DECOUPLE. NEXT WEEKEND... GUIDANCE AS WELL AS THE TELECONNECTIONS ARE SHOWING THAT A CHANGE IN THE PATTERN IS POSSIBLE BEGINNING NEXT WEEKEND. THIS MAY LEAD TO A MORE AMPLIFIED PATTERN AND TEMPS BACK TO NORMAL. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. HIGH CONFIDENCE THRU MONDAY. TODAY...VFR. NNW WINDS MAY GUSTS UP TO 25 KT FROM 09Z TO 15Z THEN DIMINISH WITH AFTERNOON SEABREEZES POSSIBLE. TONIGHT...VFR ALONG WITH LIGHT WINDS. LOW RISK OF PATCHY MVFR INLAND IN FOG. MONDAY...VFR WITH LIGHT WINDS INTERIOR AND SEABREEZES ALONG THE COAST. KBOS TERMINAL...HIGH CONFIDENCE IN TAF EXCEPT FOR AFTERNOON WINDS. SEABREEZE MAY DEVELOP THIS AFTERNOON BUT LOW CONFIDENCE. KBDL TERMINAL...HIGH CONFIDENCE IN TAF FOR VFR CONDITIONS. OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...HIGH CONFIDENCE. MONDAY NIGHT...VFR CONDITIONS EXPECTED. TUESDAY...SHOWERS BEGIN IN THE EARLY MORNING HOURS WITH MVFR CONDITIONS EXPECTED. THEN BECOMING VFR AS SHOWERS EXIT IN THE MID AFTERNOON HOURS. WEDNESDAY AND THURSDAY...VFR. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. FORECAST CONFIDENCE IS HIGH THROUGH MONDAY. TODAY...NNW WINDS GUSTING UP TO 25 FROM ABOUT 5 AM TO 11 AM THEN DIMINISHING THEREAFTER. GOOD VSBY AS WELL. TONIGHT AND MONDAY...LIGHT WINDS AND GOOD VSBY. OUTLOOK...MONDAY NIGHT THROUGH THURSDAY... MONDAY NIGHT INTO TUE MORNING...MODERATE TO HIGH CONFIDENCE. HIGH PRESSURE NEARBY WILL RESULT IN A WEAK PRESSURE GRADIENT KEEPING WINDS/SEAS BELOW SCA THRESHOLDS. TUESDAY AFTERNOON INTO WEDNESDAY...MODERATE CONFIDENCE. SWELLS BEGIN TO BUILD TO BETWEEN 5 AND 7FT BEHIND THE DEPARTING LOW PRESSURE SYSTEM AND COLD FRONT. THIS IS ABOVE SCA LEVELS AND THEREFORE A SCA MAY BE NEED. THURSDAY...AS NEXT HIGH PRESSURE SYSTEM APPROACHES WITH WEAKER PRESSURE GRADIENT...EXPECT SWELLS TO DIE DOWN DURING THE DAY TO BELOW SCA THRESHOLD. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...FROST ADVISORY FROM 3 AM TO 7 AM EDT MONDAY FOR NHZ011. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR ANZ231- 232-251-255. SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR ANZ250- 254. && $$ SYNOPSIS...NOCERA/DUNTEN NEAR TERM...NOCERA/RLG SHORT TERM...NOCERA LONG TERM...DUNTEN AVIATION...NOCERA/DUNTEN MARINE...NOCERA/DUNTEN

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