Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 301944 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 344 PM EDT THU APR 30 2015 .SYNOPSIS... CONTINUED MID- TO UPPER-LEVEL DISTURBANCES WILL RESULT IN CLOUDS AND A FEW SHOWERS AROUND THROUGH THE END OF THE WEEK. MAINLY DRY CONDITIONS ARE EXPECTED THROUGH THE WEEKEND...BUT A SERIES OF WEAK DISTURBANCES MAY BRING A FEW SHOWERS FROM TIME TO TIME. COASTAL LOW PRESSURE WILL PASS WELL SOUTH OF NEW ENGLAND FRIDAY AND SATURDAY. WHILE COOL WEATHER WILL CONTINUE INTO SATURDAY...A WARMING TREND IS EXPECTED SUNDAY INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... REST OF TODAY... CLOUDS WILL FILL IN ACROSS THE REGION AHEAD OF THE ONCOMING BACK- DOOR COLD FRONT PRESENTLY SWEEPING SW OUT OF CANADA. WITH THE INCREASING CLOUD COVER FEEL TEMPERATURES WILL BE SLOW TO MODERATE DOWNWARD. E ONSHORE FLOW CONTINUING POTENTIALLY ENHANCING AHEAD OF THE ONCOMING BOUNDARY. TONIGHT... LIGHT SHOWERS / SPRINKLES PREVAIL AHEAD OF A BACKDOOR COLD FRONT SWEEPING S/SW ACROSS THE REGION OVERNIGHT. FORECAST GUIDANCE STILL POORLY HANDLING THE LIGHT EVENT. WILL FOCUS ON WHERE FORECAST GUIDANCE CONSENSUS IS DERIVING BROKEN TO OVERCAST CLOUDS. SLIGHT CHANCE POPS. DO HAVE HIGHER CONFIDENCE OF OUTCOMES CONSIDERING ASCENT OF AVAILABLE MOISTURE AHEAD OF THE FRONT THROUGH A FAVORABLE ENVIRONMENT ALOFT. UPSTREAM BANDING OF SHOWERS AND COLDER CLOUD TOPS HAS BEEN EVIDENT ACROSS MAINE PER SATELLITE AND RADAR. BELIEVE THE GREATER FOCUS OF ACTIVITY WILL BE ALONG NE-SLOPES OF HIGHER TERRAIN WITH OROGRAPHIC TENDENCIES AS SOME OF THE NEAR-TERM HIGH- RES GUIDANCE SUGGESTS. E-ONSHORE FLOW AHEAD OF THE FRONT BACKING NW WITH PASSAGE BECOMING BLUSTERY WITH GUSTS AROUND 20-25 MPH POSSIBLE. COOL AIRMASS OFF THE OCEAN MAINTAINED...BUT ALSO A PRONOUNCED CLOUD DECK. LOWS AROUND THE LOW- TO MID-40S. BELIEVE BLANKETING CLOUDS WILL PREVENT LOCALES FROM FALLING INTO THE UPPER-30S AS WAS THE CASE LAST NIGHT. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... FRIDAY... WILL KEEP THE FOCUS OF LIGHT SHOWERS/SPRINKLE ACTIVITY ACROSS SW- AREAS OF NEW ENGLAND AHEAD OF THE BACKDOOR COLD FRONT AS IT SLIDES S AND BECOMES DIFFUSE UP AGAINST A PRONOUNCED OFFSHORE LOW DEVELOPS OFF THE MID-ATLANTIC COAST. HIGH PRESSURE OVER THE GULF OF MAINE BUILDS INTO THE REGION. CLOUDS DISSIPATING E TO W EVER SLOWLY. A LIGHT WIND PROFILE...AS WELL AS A COLDER AIRMASS IN PLACE ALOFT...SHOULD MAKE FOR AN UNSEASONABLY COOL DAY. LOOKING AT HIGHS IN THE 50S ACROSS THE INTERIOR...COOLER WITH ONSHORE SEA-BREEZE FLOW ACROSS E MA. FRIDAY NIGHT... AS THE OFFSHORE LOW DEEPENS...N-STREAM MID-LEVEL ENERGY IS USURPED ACROSS THE REGION REARWARD INTO THE POSITIVELY-TILTED TROUGH. MID- LEVEL CLOUD DECKS NOT OUT OF THE QUESTION...BUT SOME THOUGHT AS TO WHETHER WE WILL SEE ONE LAST SHOT OF SPRINKLE ACTIVITY BEFORE WE CLEAR OUT. MOISTURE DOES BECOME FOCUSED AHEAD OF THE WAVE AND THERE IS FAVORABILITY WITH RESPECT TO THE LOCAL ENVIRONMENT SUPPORTIVE FOR LIFT...ALBEIT MID-LEVEL ENERGY IS STRETCHED BECOMING WEAKER. WILL GO WITH SLIGHT CHANCE POPS FOR SPRINKLE ACTIVITY COINCIDENT WITH BROKEN TO OVERCAST CLOUD DECKS. SOME HINT WITH LONG-FETCH OF NE-FLOW OFF THE WATERS THAT MOISTURE- LOADING OCCURS BECOMING TRAPPED BENEATH THE DRY INVERSION ASSOCIATED WITH THE HIGH PRESSURE OVER THE GULF OF MAINE. COULD SEE A MIX OF LOW CLOUDS / FOG / DRIZZLE OVER E/SE NEW ENGLAND. NOT ALL FORECAST GUIDANCE IS ON BOARD...BUT IT IS SOMETHING WORTH MONITORING. WILL NOT PREVAIL WITH THIS FORECAST DUE TO UNCERTAINTY. OTHERWISE LIGHT WINDS WITH NE-FLOW ALONG THE SHORES OVERNIGHT. CLOUD DECKS LENDING TO A BLANKET EFFECT...BUT SHOULD ANY LOCALES CLEAR OUT WOULD EXPECT RADIATIONAL COOLING. LOWS AROUND THE UPPER-30S WITH COOLER TEMPERATURES DURING THE DAY AND EXPECTATION OF RADIATIONAL COOLING OVERNIGHT. && .LONG TERM /SATURDAY THROUGH THURSDAY/... HIGHLIGHTS... * COOL WITH A FEW SHOWERS FROM TIME TO TIME THU AND FRI * MODERATING TEMPS THIS WEEKEND BUT STILL A THREAT OF A FEW SHOWERS * MAINLY DRY AND WARM EARLY NEXT WEEK OVERVIEW... PATTERN FEATURES AN UPPER TROF ACROSS THE NE INTO THE WEEKEND WHICH RESULTS IN A CONTINUATION OF COOL WEATHER INTO THE FIRST HALF OF THE WEEKEND. A SERIES OF DISTURBANCES WILL BRING THE THREAT OF SHOWERS FROM TIME TO TIME ALTHOUGH IT WILL BE DRY MOST OF THE TIME. GFS IS MORE AGGRESSIVE THAN OTHER MEDIUM RANGE GUIDANCE WITH A CLOSED LOW PASSING S OF NEW ENGLAND. GFS IS AN OUTLIER AND ECMWF/UKMET/GGEM INDICATE MORE OF AN OPEN WAVE WITH COASTAL LOW TRACKING WELL TO THE SOUTH WITH RAIN SHIELD REMAINING TO THE S. PATTERN BEGINS TO CHANGE BY SUNDAY AND ESPECIALLY EARLY NEXT WEEK AS THE TROF LIFTS OUT WITH ZONAL FLOW DEVELOPING WITH POLAR JET SETTING UP ACROSS N CONUS. THIS WILL BRING A WARMING TREND INTO EARLY NEXT WEEK. THURSDAY AND FRIDAY... EXPECT LOTS OF CLOUDS DURING THIS PERIOD WITH THREAT OF SHOWERS FROM TIME TO TIME ALTHOUGH IT WILL BE DRY MOST OF THE TIME. SHORTWAVE ROTATING S AROUND MID LEVEL LOW IN THE GULF OF MAINE MAY TRIGGER A FEW SHOWERS THU...WITH BEST CHANCE IN THE INTERIOR WHERE LOW LEVEL LAPSE RATES AND INSTABILITY ARE MORE FAVORABLE. LAPSE RATES NOT AS STEEP ON FRI BUT LINGERING TROF AND SUFFICIENT MOISTURE IN THE COLUMN SUGGESTS THREAT OF A FEW SHOWERS WILL CONTINUE. WITH LOW LEVEL EASTERLY FLOW...TEMPS WILL BE BELOW NORMAL WITH 50S TO LOWER 60S THU COOLING TO UPPER 40S TO MID 50S FRIDAY. COOLEST E NEW ENG. SATURDAY AND SUNDAY... COASTAL LOW TRACKS WELL OFFSHORE SAT WITH RAIN SHIELD REMAINING TO THE S. JUST A LOW PROB FOR A FEW SHOWERS OVER THE OUTER CAPE/ACK SAT...OTHERWISE MAINLY DRY BUT CONTINUED COOL WITH BELOW NORMAL TEMPS. THEN ON SUNDAY...TEMPS MODERATE TO NEAR NORMAL OR EVEN A FEW DEGREES ABOVE NORMAL AS LOW LEVEL FLOW BECOMES W/NW...BUT A FEW SHOWERS POSSIBLE AS LAST SHORTWAVE IN THE FLOW MOVES IN FROM THE WEST. MONDAY AND TUESDAY... NICE WARMING TREND EXPECTED AS WEAK RIDGING ALOFT DEVELOPS WITH LOW LEVEL SW FLOW BRINGING MILDER TEMPS INTO SNE. HIGHS SHOULD REACH WELL INTO THE 70S MON AND TUE IN THE INTERIOR...BUT MUCH COOLER ALONG THE S COAST. ECMWF WOULD BRING TEMPS TO 80+ IN THE INTERIOR TUE AS 850 TEMPS WARM TO 12C. MAINLY DRY...BUT WILL HAVE TO WATCH TIMING OF NEXT FRONT WHICH COULD APPROACH TUE WITH SOME SHOWERS BUT TIMING UNCERTAIN THIS FAR OUT. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. .SHORT-TERM /THROUGH FRIDAY NIGHT/... INTO TONIGHT...HIGH CONFIDENCE. SCT-BKN LOW-END VFR CIGS BECOMING BKN-OVC AS WE PROGRESS TOWARDS EVENING. E-WINDS. TONIGHT...HIGH CONFIDENCE. COLD FRONT DROPS S. E-WINDS BACKING NE. GUSTS UP TO 20 KTS BEHIND THE FRONT POSSIBLE. CHANCE OF -SHRA WITH WIND SHIFT. LOW-END VFR DROPPING TO MVFR CIGS BEHIND THE FRONT. FRIDAY...HIGH CONFIDENCE. CONTINUED ONSHORE FLOW. WINDS RELAXING AS THEY TURN E. LOW-END VFR / MVFR CIGS LIFTING DURING THE MID-MORNING TO MIDDAY HOURS. -SHRA CHANCES DIMINISH. FRIDAY NIGHT...MODERATE CONFIDENCE. LOW-END VFR CIGS POSSIBLE ALONG WITH ANOTHER SHOT OF -SHRA. WINDS TURNING N. MAY SEE IFR CIGS AND DRIZZLE ACROSS E/SE-COASTAL TERMINALS WITH THE ONSHORE FLOW. VSBY ISSUES WITH FOG POSSIBLE. KBOS TAF...HIGH CONFIDENCE IN TAF. SHOULD SEE A MORE E-WIND PRIOR TO THE COLD FRONTAL PASSAGE LATER TONIGHT. KBDL TAF...HIGH CONFIDENCE IN TAF. .OUTLOOK /THURSDAY THROUGH SUNDAY/...MODERATE CONFIDENCE. THURSDAY AND FRIDAY...A MIX OF VFR/MVFR CIGS WITH A FEW SHOWERS FROM TIME TO TIME. SATURDAY...IMPROVING CONDITIONS TO VFR. SUNDAY...VFR. A FEW SHOWERS POSSIBLE. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. .SHORT-TERM /THROUGH FRIDAY NIGHT/... THROUGH FRIDAY...HIGH CONFIDENCE. E-FLOW PERSISTING OVER THE WATERS INTO TONIGHT WILL BACK NE AND PERHAPS BECOME BLUSTERY WITH GUSTS UP AROUND 20 KTS DURING THE OVERNIGHT HOURS AS A COLD FRONT /PRESENTLY ACROSS MAINE/ SWEEPS S ACROSS THE WATERS ALONG WITH THE CHANCE OF SHOWERS. SEAS COULD RISE EVER BRIEFLY TO 5-FEET ON THE OUTER WATERS... OTHERWISE MAJORITY OF THE TIMEFRAME HAS SUB-SMALL-CRAFT-ADVISORY CRITERIA. FRIDAY NIGHT...LOW CONFIDENCE. CONCERN TOWARDS SATURDAY MORNING OF LOW CLOUDS WITH A MIX OF FOG AND DRIZZLE RESULTING IN SOME VISIBILITY ISSUES. LOW CONFIDENCE AT THIS TIME. WINDS AND SEAS SHOULD BE BELOW SMALL-CRAFT ADVISORY CRITERIA. .OUTLOOK /THURSDAY THROUGH SUNDAY/... THURSDAY...HIGH CONFIDENCE. QUIET BOATING WEATHER WITH LIGHT EASTERLY WINDS AND SEAS BELOW SCA. FRIDAY AND SATURDAY...MODERATE CONFIDENCE. INCREASING NE WINDS AS LOW PRES DEVELOPS TO THE S. GUSTS TO 25-30 KT DEVELOPING... ESPECIALLY WATERS S OF NEW ENG AND E OF CAPE COD. SEAS BUILDING TO 8- 12 FT OVER OUTER WATERS. THERE IS STILL UNCERTAINTY IN THE TRACK AND WINDS/SEAS COULD BE HIGHER OR LOWER DEPENDING ON EXACT TRACK OF THE COASTAL LOW. SUNDAY...MAINLY LIGHT WINDS BUT LINGERING E SWELL WILL RESULT IN HAZARDOUS SEAS OVER E WATERS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...KJC/SIPPRELL NEAR TERM...SIPPRELL SHORT TERM...SIPPRELL LONG TERM...KJC AVIATION...KJC/SIPPRELL MARINE...KJC/SIPPRELL

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