Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 061820 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 220 PM EDT MON JUL 6 2015 .SYNOPSIS... DRY AND ABOVE-SEASONABLE CONDITIONS PREVAIL BENEATH HIGH PRESSURE INTO TUESDAY MORNING. A SERIES OF FRONTS WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS TUESDAY AND WEDNESDAY. DRY WEATHER SHOULD PREVAIL INTO NEXT WEEKEND...ALTHOUGH A STALLED FRONT SOUTH OF NEW ENGLAND MAY TRIGGER A FEW SHOWERS FROM TIME TO TIME. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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230 PM UPDATE... MID-LEVEL RIDGE AXIS IS CURRENTLY OVER HEAD KEEPING DRY AIR ACROSS THE REGION. HOWEVER...WAA AND ASSOCIATED UPPER LEVEL WARM FRONT IS APPROACHING FROM THE SW AND WE COULD SEE A POP UP SHOWER MAINLY ACROSS WESTERN CT AND MA. OTHERWISE TEMPERATURES CONTINUE TO CLIMB INTO THE LOW TO MID 80S. COULD SEE A FEW SITES REACHING THE UPPER 80S TO LOW 90S. YET WITH HIGH LEVEL CIRRUS PUSHING IN FROM THE SOUTH...WILL LIMIT DIURNAL HEATING. SEA BREEZES ARE PLAYING A ROLL ALONG THE COASTLINE WITH BOS ONLY AT 74F YET NORWOOD IS AT 86F. HIGH LEVEL CLOUDS WILL CONTINUE TO STREAM INTO THROUGH THE REMAINDER OF THE AFTERNOON.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... HIGH PRESSURE MOVES SOUTHEAST OF NEW ENGLAND TONIGHT. THIS WILL PLACE OUR REGION INTO A FAVORABLE AREA FOR ISENTROPIC LIFT. THIS WILL MEAN THICKER CLOUDS LATER TONIGHT. A WARM FRONT SHOULD APPROACH THE SOUTH COAST LATE TONIGHT. DESPITE THE SURFACE HUMIDITY...DRIER AIR ALOFT SHOULD KEEP RAINFALL CHANCES AT A MINIMUM. ANOTHER NIGHT OF PATCHY DENSE FOG NOT OUT OF THE QUESTION. WARM FRONT LIFTS MOVES THROUGH TUESDAY. MARGINAL INSTABILITY DURING THE MORNING HOURS...SO THINKING CHANCES FOR THUNDERSTORMS WILL BE SMALL. ONCE WE GET INTO THE WARM SECTOR THOUGH...WE SHOULD SEE CAPE VALUES BETWEEN 700-1200 J/KG DURING THE AFTERNOON ACROSS THE INTERIOR. 0-6 KM SHEAR REMAINS WEAK...SO THE SEVERE WEATHER THREAT IS LOW. HOWEVER...THAT SHOULD BE ENOUGH INSTABILITY FOR SCATTERED THUNDERSTORMS. PROJECTED STORM MOTIONS COULD BE QUITE SLOW. WITH PRECIPITABLE WATER VALUES APPROACHING 2.0 INCHES... THERE IS POTENTIAL FOR LOCALIZED HEAVY RAINFALL...LEADING TO A RISK FOR LOCALIZED FLOODING. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... HIGHLIGHTS... * SHOWERS/STORMS WED * HIGH UNCERTAINTY LATER IN WEEK BUT MAINLY DRY OVERVIEW AND MODEL PREFERENCES... LITTLE CHANCE IN THE SYNOPTIC SCALE PATTERN AMONGST OPERATIONAL AND ENSEMBLE GUIDANCE AT 00Z. AMPLIFIED RIDGING GIVES WAY TO ZONAL FLOW BENEATH DEEP CUTOFF LOW PRES ACROSS CENTRAL CANADA. THIS ZONAL FLOW IS WHAT LEADS TO THE UNCERTAINTY IN TIMING OF ANY POTENTIAL SHORTWAVES/MCS IMPACTING SRN NEW ENGLAND. WITH A STALLED BAROCLINIC CONDUIT TO THE SOUTH IT/S A BATTLE BETWEEN THE ANTICYCLONIC SHEAR ACROSS NEW ENGLAND. AGREE WITH THE PREVIOUS FORECASTERS ASSESSMENT THAT THIS IS LIKELY TO LEND TO MAINLY DRY WX AT THE END OF THE WEEK FOLLOWING THE FRONTAL PASSAGE ON WED. HOWEVER...WILL NEED TO WATCH MAINLY UPSTREAM CONVECTIVE DEVELOPMENT FOR THEIR POTENTIAL IMPACT ON THE REGION. MODELS CONTINUE TO INDICATE THE REMNANTS OF AN MCS MOVING THROUGH AT SOME POINT. WITH THE E SHIFT IN THE NRN VORTEX LATE NEXT WEEK...A TRANSITION TOWARD A MORE DEFINITE UNSETTLED PATTERN IS POSSIBLE BEGINNING EARLY NEXT WEEK. WILL CONTINUE WITH THE ENSEMBLE BLEND PROPOSED EARLIER. DETAILS... TUE NIGHT INTO WED... WARM FRONT LIFTS N OVERNIGHT ALLOWING SRN NEW ENGLAND TO FULLY ENTER THE WARM SECTOR. THE COMBINATION OF THIS INCREASED WARMTH/MOISTURE MAY LEAD TO OVERNIGHT FOG/STRATUS DEVELOPMENT...THE EXTENT OF WHICH MAY DEFINE CONDITIONS FOR WED. THE COLD FRONT...WHICH WILL PASS THROUGH LATE DAY WED WILL PROVIDE A FOCUS FOR ANOTHER ROUND OF CONVECTION. INSTABILITY WILL BE DEPENDENT ON THE LEFTOVER STRATUS/FOG. LAPSE RATES AND SHEAR IS MARGINAL AT BEST WHILE PWATS REMAIN HIGH...NEARLY 2 STD DEVIATIONS ABOVE NORMAL. WITH SUNNY BREAKS...WHICH ARE POSSIBLE...SFC CAPE VALUES COULD REACH OR EXCEED 1500J/KG PARTICULARLY IF DWPTS REACH THE LOW 70S IN SPOTS AS POTENTIAL FORECAST. IN ANY CASE...THUNDER IS LIKELY ASSUMING LIFTING OF THE EARLY DAY LOW CLOUDS...WITH HEAVY RAIN THE MOST LIKELY THREAT...SVR THREAT IS LOW GIVEN THE LACKING SHEAR/ENHANCED LAPSE RATES...BUT WILL NEED TO MONITOR OVER THE NEXT 48 HOURS. HIGHS WILL BE DEPENDENT ON HOW QUICKLY ANY CLOUDS CLEAR...IF THEY DO...SOME TEMPS IN THE UPPER 80S TO NEAR 90 ARE POSSIBLE AS H85 TEMPS APPROACH +17C. THU INTO FRI.. COLD FRONT STALLS OFFSHORE AS UPPER LVL STEERING FLOW BECOMES MORE ZONAL. THIS WILL PROVIDE A FOCUS FOR LIFT WITHIN THE VICINITY AND A CONDUIT FOR UPSTREAM CONVECTION OR THE REMNANTS THERE TO FOLLOW AS LOW LVL WAVES DEVELOP. THE BULK OF THE INSTABILITY WILL REMAIN TO THE S...SO SOME STEERING TO THE S IS LIKELY AS WELL. THEREFORE...WILL MAINTAIN LOWER POPS ESPECIALLY FOCUSED ON THE SRN HALF OF THE REGION WHERE THE BETTER LIFT/MOISTURE RESIDES...BUT WILL NEED TO WATCH UPSTREAM DURING THIS PERIOD IN SPITE OF THE LOW END POPS AND MAINLY DRY WORDING. TEMPS NEAR TO POSSIBLY BELOW NORMAL. SAT AND SUN... A WEAK RIDGE WILL BUILD E AS THE CUTOFF LOW PRES TO THE NW MOVES E. THE COLD FRONT WILL CONTINUE A SHIFT OFFSHORE. THEREFORE...WILL BEGIN TO LEAN DRIER FOR THE WEEKEND AT THIS TIME...BUT THIS IS STILL A LOW CERTAINTY FORECAST GIVEN THE ZONAL FLOW AND UPSTREAM CUTOFF. H85 TEMPS OF +12C TO +14C SUGGEST TEMPS NEAR SEASONAL NORMALS. EARLY NEXT WEEK... AS MENTIONED ABOVE...WITH THE UPPER LVL CUTOFF SHIFTING E AND MOST GUIDANCE SHOWING A SLIGHT BAGGINESS TO MID-UPPER LVL HEIGHTS ACROSS THE REGION...WILL BE SEEING A SHIFT TOWARD WET/UNSETTLED CONDITIONS. TIMING WILL BE BETTER DEFINED ONCE THE KICKER WAVE THAT SHIFTS THE CUTOFF E IS BETTER SAMPLED. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THROUGH TUESDAY... BEFORE 00Z...HIGH CONFIDENCE. VFR. LIGHT AND VARIABLE WINDS. SEA BREEZES END BY SUNSET. TONIGHT...MODERATE CONFIDENCE. MAINLY VFR TO START WITH MVFR/IFR CIGS APPROACHING FROM THE SOUTH AFTER 06Z. CANT RULE OUT SOME FOG DEVELOPMENT AS LOW LEVEL MOISTURE INCREASES OVERNIGHT. TOMORROW...HIGH CONFIDENCE. LOWER CIGS/FOG GIVE WAY TO MAINLY HIGH END MVFR OR LOW VFR. A WARM FRONT WILL PUSH THROUGH THE REGION ALLOWING FOR SOME -SHRA/-TSRA ESP ACROSS WESTERN SITES BY THE AFTERNOON. SEA BREEZES IN THE MORNING WILL TURN MORE SOUTH BY THE AFTERNOON BEHIND THE FRONT. COULD SEE A FEW 25 KT WINDS ACROSS THE SOUTH COAST. TOMORROW NIGHT...MODERATE CONFIDENCE. ANY VFR/MVFR CIGS COULD DROP BACK DOWN TO MVFR/IFR AFTER SUNSET AS MOISTURE INCREASES AHEAD OF AN APPROACHING COLD FRONT. ANTICIPATE PATCHY FOG AS WELL ACROSS A FEW TERMINALS. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. SEA BREEZE SHOULD END AFTER SUNSET. MODERATE CONFIDENCE ON SEA BREEZE TOMORROW. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. PATCHY FOG IS POSSIBLE TONIGHT. LOW RISK OF A -TSRA TOMORROW AFTERNOON. OUTLOOK /TUESDAY NIGHT THROUGH FRIDAY/... WED...MODERATE CONFIDENCE. MVFR/IFR IN SCT SHOWERS/TSTMS...OTHERWISE VFR. PATCHY FOG AT NIGHT. THU AND FRI...LOW CONFIDENCE. MAINLY VFR. BUT OCCASIONAL SHOWERS/FOG MAY LEAD TO LOWER CATEGORIES PERIODICALLY.
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM /THROUGH TUESDAY/...HIGH CONFIDENCE. QUIET BOATING WEATHER. SEAS CONTINUE TO DIMINISH BENEATH HIGH PRESSURE. WINDS TURN SOUTH TODAY INTO TONIGHT WITH ANY GUSTS REMAINING BELOW 20 KTS. LIGHT WINDS WILL LEAD TO LOCAL SEABREEZES TODAY. PATCHY DENSE FOG POSSIBLE TONIGHT. OUTLOOK /TUESDAY NIGHT THROUGH FRIDAY/... NO CHANGE WITH THE OVERNIGHT FORECAST...MAINLY QUIET BOATING WEATHER PREVAILS WITH THE SLIGHT CHANCE OF SMALL CRAFT ADVISORY CONDITIONS LATE WED INTO THU. PREVIOUS DISCUSSION FOLLOWS... MODERATE CONFIDENCE. MAINLY LIGHT WINDS AND FLAT SEAS AS A SERIES OF WEAK FRONTS CROSS WATERS...BUT COULD SEE 4-5 FT SEAS ON SOUTHERN WATERS S OF ISLANDS BY WED OR THU DUE TO BUILDING SWELL. MAIN CONCERN IS FOR SCATTERED SHOWERS/STORMS TUE AND WED...AS WELL AS PATCHY LATE NIGHT/EARLY MORNING FOG. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...BELK/DUNTEN NEAR TERM...DUNTEN SHORT TERM...BELK LONG TERM...DOODY AVIATION...DOODY/DUNTEN MARINE...BELK/DOODY

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