Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 112100 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 500 PM EDT FRI APR 11 2014 .SYNOPSIS...
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A WEAK COLD FRONT WILL STALL ALONG THE SOUTH COAST TONIGHT... BRINGING A ROUND OF SHOWERS AS WEAK LOW PRESSURE PASSES SOUTH OF THE REGION. DRY AND PROGRESSIVELY MILDER CONDITIONS ARE EXPECTED OVER THE WEEKEND AND MONDAY. A SLOW MOVING FRONT WILL BRING A SOAKING RAIN TUESDAY INTO WEDNESDAY.
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HIGHLIGHTS... * ABOVE AVERAGE TEMPERATURES EXPECTED SUNDAY AND MONDAY * STRONG COLD FRONTAL PASSAGE NEXT TUE/WED...THEN POSSIBLY STALLING JUST OFFSHORE LATE NEXT WEEK * BELOW NORMAL TEMPERATURES RETURN FOR THE REMAINDER OF THE WORK WEEK OVERVIEW AND MODEL PREFERENCES/CONFIDENCE... HIGHLY AMPLIFIED UPPER LEVEL PATTERN SETS UP FROM THE EASTERN PACIFIC INTO THE ATLC BY EARLY NEXT WEEK...WITH LARGE RIDGE OVER THE WESTERN ATLC AND UP THE EASTERN PACIFIC INTO ALASKA AND STRONG LONG WAVE TROUGH DIGGING OVER THE CENTRAL U.S. HAVE RATHER HIGH CONFIDENCE IN THE SLOW PROGRESSION OF SURFACE SYSTEMS INTO AT LEAST THE MIDDLE OF NEXT WEEK. BEYOND THIS...OP MODEL RUNS SPLIT ON HOW QUICKLY THE BLOCKING PATTERN ACROSS THE ATLC BREAKS DOWN. NOTING THE 00Z ECMWF RUN HAS A REX BLOCK SET UP IN THE CENTRAL ATLC...WHICH APPEARS TO STALL THE FRONT JUST OFF THE COAST...WHILE THE 12Z GFS TRIES TO FLATTEN OUT THE PATTERN ACROSS THE NORTHERN TIER...THOUGH STILL STALLS THE FRONT BUT FURTHER OFFSHORE. MODEL ENSEMBLES IN BETTER AGREEMENT THOUGH STILL HAVING ISSUES BEYOND WEDNESDAY AS TO THE CONTINUATION OF ATLC BLOCKING VS. SOME PROGRESSION. CONTINUED HIGH CONFIDENCE WITH THE WARMING TREND EARLY NEXT WEEK...ESPECIALLY DURING MONDAY WITH INCREASING SW WINDS. MODERATE CONFIDENCE CONTINUES FOR THE SLOW PROGRESSION OF THE STRONG SURFACE FRONT ACROSS THE REGION THOUGH TIMING SEEMS A BIT BETTER ON MODEL RUNS...AT LEAST BRINGING THE SYSTEM INTO THE REGION. WILL SEE PERIODS OF MODERATE TO HEAVY RAINFALL AS THE FRONT SLOWLY MOVES ACROSS...THOUGH STILL PROBLEMS WITH EXACT PLACEMENT AND TIMING. LOOKS LIKE OVERALL TIMING OF THE SLOW FRONTAL PASSAGE AROUND THE MIDDLE OF NEXT WEEK LOOKS OK FOR NOW. HOWEVER...BIG ISSUES AND DIFFERENCES WITH THE EXIT OF THE FRONT AND HOW CLOSE TO THE E COAST IT STALLS. HIGH PRES LOOKS TO SETTLE IN ACROSS NORTHERN NEW ENGLAND INTO THE MARITIMES...WITH A DEVELOPING ONSHORE FLOW WHICH MEANS COOLER THAN NORMAL TEMPS ESPECIALLY ALONG THE COAST LATE NEXT WEEK. AM LEANING TOWARD A BLEND OF PREVIOUS FORECAST /FOR CONTINUITY/ ALONG WITH THE EC ENS AND NAEFS...WHICH IS CLOSE TO THE WPC GUIDANCE. DETAILS... SUNDAY AND MONDAY... WARM FRONT MOVES N OF THE REGION EARLY SUNDAY WITH INCREASING S-SW WIND FLOW. PRECIP LOOKS TO REMAIN WELL N OF THE REGION...BUT COULD SEE A FEW WIDELY SCT SHOWERS SNEAK INTO S NH SUN MORNING. CLOUDS WILL LINGER ACROSS S NH/N MA DURING THE DAY...BUT MOST AREAS WILL SEE MOSTLY SUNNY CONDITIONS. EXPECT LL JET /ON ORDER OF 40-45 KT AT H925/ TO MIX DOWN SOMEWHAT...SO WILL SEE S-SW WINDS GUSTING UP TO 20-25 KT DURING THE AFTERNOON. H85 TEMPS WILL RISE DURING THE DAY SUNDAY...SO INLAND LOCATIONS SHOULD SEE HIGHS REACHING CLOSE TO OR JUST OVER THE 70 DEGREE MARK...BUT MUCH COOLER ALONG THE SOUTH COAST. WITH THE MILDER AIR MOVING OVER THE COOLER OCEAN WATERS...EXPECT LOW CLOUDS AND PATCHY FOG TO DEVELOP MAINLY DURING THE LATE AFTERNOON THROUGH SUN NIGHT ACROSS S COASTAL AREAS. ANOTHER BATCH OF MILD AIR AT H925 WILL SHIFT NE ACROSS THE INTERIOR...WITH H85 READINGS UP TO +11C TO +14C...HIGHEST ACROSS S NH/N MA DURING MONDAY...ALONG WITH THE CONTINUED H925 LL JET AT 40- 50 KT. LOOKS LIKE AT LEAST A PORTION OF THIS WILL MIX DOWN...SO WILL SEE SW WINDS GUSTING UP TO AROUND 25 KT DURING THE AFTERNOON AGAIN ON MON. THIS...ALONG WITH THE MILDER AIR WHICH WILL MIX DOWN INLAND...SHOULD SEE TEMPS TOPPING OFF IN THE LOWER- MID 70S /A FEW SPOTS COULD BE EVEN MILDER THAN THAT/. BIG PROBLEM WILL BE CLOUDS AND PATCHY FOG LINGERING ALONG THE S COAST DURING THE DAY MON AS TEMPS WILL ONLY REACH TO LOWER-MID 50S. CLOUDS SHOULD INCREASE FROM W-E MON NIGHT AS FRONT PROGRESSES SLOWLY E TOWARD THE REGION. LOOKS LIKE SCT SHOWERS WILL MOVE INTO THE E SLOPES OF THE BERKSHIRES AND CT VALLEY BY AROUND MIDNIGHT...THEN WILL PUSH E OVERNIGHT. AT THIS POINT...SHOULD HOLD OFF ACROSS E MA UNTIL AFTER DAYBREAK. AS PRES GRADIENT INCREASES AS FRONT APPROACHES...S-SW WINDS WILL CONTINUE AT 10-15 MPH WITH SOME HIGHER GUSTS OVER THE CAPE AND ISLANDS POSSIBLE WITH TUESDAY AND WEDNESDAY.... MODELS AND ENSEMBLES CONTINUE TO SIGNAL BEST SHOT FOR PRECIP DURING THIS TIMEFRAME. LOOKS LIKE SOME HEAVIER RAINFALL WILL PUSH INTO WESTERN AREAS DURING TUE WITH THE SLOW MOVEMENT AND BETTER MOISTURE TRANSPORT DUE TO INCREASING LL JET /ON ORDER OF 60-70 KT AT H925 TUE AFTERNOON-EVENING/ IN VICINITY OF THE FRONT. WITH ANY HEAVY RAINFALL...COULD SEE AREAS OF URBAN AND POOR DRAINAGE FLOODING AND MAY SEE RIVER LEVELS RISE AS WELL ESPECIALLY ACROSS CENTRAL AND WESTERN AREAS. HAVE CARRIED CAT POPS DURING TUE INTO TUE NIGHT WITH CONTINUED RAINFALL SIGNAL. BIG PROBLEM WILL BE TIMING THE EXIT OFF THE FRONT OFFSHORE SOMETIME WED. AT THIS POINT...KEPT PRECIP GOING INTO WED... BUT SHOULD TAPER OFF FROM W-E WED AFTERNOON/EVENING. SHOWERS MAY LINGER ACROSS CAPE COD AND THE ISLANDS WED NIGHT AS FRONT SLOWS ITS EASTWARD PROGRESS. IF WINDS INCREASE AT H925 HIGHER THAN CURRENTLY FORECAST AND MIX DOWN AHEAD AND BEHIND THE FRONT...COULD SEE ADVISORY LEVEL WINDS. ALSO...WITH THE STRONG SW WIND FLOW...MIGHT SEE SOME PROBLEMS ALONG THE S COAST WITH SPLASHOVER AROUND THE TIME OF HIGH TIDE TUESDAY EVENING/LATE NIGHT. ON THE BACKSIDE OF THE FRONT...STRONG COLD AIR ADVECTION WORKS IN CAUSING TEMPS TO FALL QUICKLY. COULD SEE SOME MIXED PRECIP OR EVEN LIGHT SNOW AS PRECIP BEGINS TO END ACROSS S NH/W MA MAINLY OVER THE HIGHER TERRAIN. COULD SEE SOME LIGHT ACCUMULATIONS...BUT WILL DEPEND UPON HOW QUICKLY THE PRECIP MOVES E. WHILE THERE IS STILL SOME UNCERTAINTY WITH THIS SYSTEM...WILL CONTINUE TO MONITOR THE EVOLUTION AS COULD POTENTIALLY BECOME A POTENT SPRING SYSTEM FOR THE REGION. THURSDAY AND FRIDAY... TIMING ISSUES DUE TO HANDLING OF BREAKDOWN OF OVERALL BLOCKING PATTERN OVER THE ATLC...LOW CONFIDENCE FOR SENSIBLE WEATHER DURING THIS TIMEFRAME. FOR NOW...LOOKS LIKE HIGH PRES BUILDS ACROSS N NEW ENGLAND INTO THE MARITIMES...SETTING UP A COOL EASTERLY FLOW. CURRENT FORECAST HIGHS ONLY EXPECTED IN THE UPPER 40S TO LOWER 50S BUT WILL FEEL RAW ESPECIALLY ALONG THE COAST WITH THE ONSHORE WIND.
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&& .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
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LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH SATURDAY NIGHT/...HIGH CONFIDENCE. AREA OF RAIN SHOWERS ARRIVES IN WESTERN NEW ENGLAND 19-21Z AND REACHES COAST 21-23Z. MOST OF SHOWERS ARE LIGHT AND CIGS/VSBYS SHOULD REMAIN VFR. WEAK SEA BREEZE EXPECTED ALONG E MA COAST AROUND 20Z OR SO. IFR CIGS/VSBYS ARRIVE THIS EVENING NEAR S COAST DUE TO S FLOW AND MAY REACH UP E MA COAST INTO BOS LATER TONIGHT. ELSEWHERE AREAS MVFR CIGS/VSBYS IN SHOWERS/FOG. SHOULD SEE RAPID IMPROVEMENT TO VFR BY 12Z SAT...EXCEPT ON CAPE COD AND ISLANDS WHERE IT MAY TAKE UNTIL 16Z. WINDS DIMINISH SAT AFTERNOON AND SHOULD ALLOW FOR SEA BREEZES ALONG BOTH E AND S COASTS. POTENTIAL FOR MVFR/IFR CIGS TO RETURN LATE SAT NIGHT DUE TO MORE OF A S/SW FLOW...ESPECIALLY NEAR S COAST. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. STILL FORECASTING WEAK SEA BREEZE AFTER 20Z BUT WINDS COULD REMAIN MORE S/SE. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...SUNDAY THROUGH WEDNESDAY... SUNDAY...MODERATE CONFIDENCE. MAINLY VFR. LOCAL MVFR-IFR CIGS/VSBYS ALONG S COAST IN LOW OCEAN CLOUDS AND PATCHY FOG WHICH SHOULD IMPROVE BY MIDDAY. EXPECT S WINDS TO INCREASE DURING THE AFTERNOON...GUSTING TO AROUND 25 KTS. MAY SEE LOW CLOUDS/PATCHY FOG MOVE IN AROUND OR AFTER MIDNIGHT ALONG S COAST WITH MVFR-IFR CONDITIONS. MONDAY...MODERATE CONFIDENCE. LOCAL MVFR-IFR CIGS/VSBYS ALONG S COAST EARLY MON SHOULD IMPROVE...OTHERWISE VFR. S-SW WINDS GUSTING UP 25-30 KTS. TUESDAY-WEDNESDAY...LOW CONFIDENCE. EXPECT MVFR CONDITIONS TO DEVELOP FROM W-E DURING TUE IN RAIN SHOWERS. PERIODS OF HEAVY RAIN POSSIBLE TUE AFTERNOON/EVENING ACROSS CENTRAL AND WESTERN AREAS WITH AREAS OF IFR. PRECIP MAY MIX WITH LIGHT SNOW AND/OR SLEET ACROSS S NH/W MA BEFORE ENDING LATE TUE NIGHT OR WED MORNING. CONDITIONS SHOULD IMPROVE TO VFR FROM W-E DURING WED. WINDS SHIFT TO W-NW FROM W-E OVERNIGHT TUE INTO WED MORNING.
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&& .MARINE...
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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 SATURDAY NIGHT/...HIGH CONFIDENCE. SCA REMAINS POSTED FOR OUTER WATERS DUE TO LEFTOVER 5-7 FT SEAS. OTHERWISE WINDS DIMINISH AS WEAK FRONT APPROACHES TONIGHT AND EXITS WATERS SAT MORNING. SHOWERS MOST LIKELY TO OCCUR LATER TONIGHT AND END BEFORE DAYBREAK SAT. MAY SEE PULSE OF 20KT GUSTS ON E MA WATERS BEHIND SYSTEM SAT MORNING...THEN WINDS SUBSIDE SAT AFTERNOON ALLOWING FOR SEA BREEZES ALONG E AND ESPECIALLY S COASTS. LIGHT S/SW FLOW DEVELOPS SAT NIGHT AND THIS MAY RESULT IN PATCHY FOG BEFORE DAYBREAK SUN... MAINLY ON S COASTAL WATERS. OUTLOOK...SUNDAY THROUGH WEDNESDAY... SUNDAY...MODERATE CONFIDENCE. LIGHT/VRBL WINDS SHIFT TO SE-S DURING SUNDAY. EXPECT GUSTS TO AROUND 25 KT WITH BUILDING SEAS. VSBY RESTRICTIONS IN PATCHY FOG. MONDAY-TUESDAY...MODERATE CONFIDENCE. EXPECT S-SW WINDS TO GUST UP TO 30 KT WITH SEAS INCREASING IN RESPONSE ESP ON THE SOUTHERN OUTER WATERS. EXPECT VSBY RESTRICTIONS IN PATCHY FOG THROUGH MIDDAY MONDAY...THEN AGAIN LATE MON AFTERNOON THROUGH TUE MORNING. WEDNESDAY...LOW CONFIDENCE...MAINLY DUE TO TIMING. WINDS SHOULD DIMINISH...THEN SHIFT TO W-NW AS COLD FRONT PASSES DURING THE DAY. LEFTOVER SEAS DURING WEDNESDAY SHOULD SUBSIDE.
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&& .HYDROLOGY... LATEST NERFC FORECASTS BRING LOWER CT RIVER FROM HARTFORD THROUGH MIDDLE HADDAM JUST INTO MINOR FLOOD BEGINNING SUN EVENING...BASED UPON WATER BEING ROUTED DOWNSTREAM. THOSE WITH INTERESTS ALONG LOWER REACHES OF CT RIVER SHOULD PAY ATTENTION TO THE LATEST FORECASTS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR ANZ235-237- 254>256. SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ250. && $$ SYNOPSIS...EVT/JWD NEAR TERM...JWD SHORT TERM...JWD LONG TERM...DUNTEN AVIATION...EVT/JWD MARINE...EVT/JWD HYDROLOGY...JWD

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