Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 031944 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 344 PM EDT TUE MAY 3 2016 .SYNOPSIS... CLOUDY...DREARY AND COOL WEATHER CONTINUES THROUGH FRIDAY WITH PERIODS OF RAIN AS WEAK WAVES OF LOW PRESSURE PASS SOUTH OF OUR REGION. SOME SHOWERS ARE STILL POSSIBLE AT TIMES THIS WEEKEND...BUT TEMPERATURES WILL BEGIN TO MODERATE. SIGNIFICANT IMPROVEMENT WILL LIKELY OCCUR EARLY NEXT WEEK AS HIGH PRESSURE BUILDS IN WITH MUCH MILDER TEMPERATURES. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... SCATTERED SHOWERS WILL COME TO AN END EARLY THIS EVENING AS DRIER MID LEVEL AIR WORKS INTO THE REGION. STILL AN ABUNDANCE OF LOW LEVEL MOISTURE...SO CLOUDS WILL PERSIST OVERNIGHT AND CAN NOT RULE OUT A SPOT SHOWER OR TWO AND PERHAPS SOME PATCHY DRIZZLE. LOW TEMPS WILL BE IN THE 40S. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... ***NEXT BAND OF STEADY RAIN AFFECTS MOST OF THE REGION LATE WEDNESDAY AFTERNOON/EVENING PARTICULARLY EASTERN MA/RI*** WEDNESDAY AND WEDNESDAY NIGHT... MOIST EAST TO NORTHEAST FLOW WILL DOMINATE INTO EARLY WEDNESDAY AFTERNOON WITH LOW CLOUDS TRAPPED BENEATH THE SUBSIDENCE INVERSION. FORCING WILL BE LIMITED THROUGH THAT TIME...BUT GIVEN THE DEEP LOW LEVEL MOISTURE A FEW SHOWERS ARE EXPECTED. HIGH TEMPS WILL MAINLY BE IN THE 50S. PORTIONS OF THE EASTERN MA COAST MAY STRUGGLE TO GET PASSED THE 50 DEGREE MARK. THINGS BECOME MORE INTERESTING LATE WEDNESDAY AFTERNOON AND EVENING. CLOSED UPPER LEVEL LOW PRESSURE DIGGING ACROSS THE OHIO VALLEY WILL BACK THE MID LEVEL FLOW AND INCREASE THE FORCING FOR ASCENT. STEADY RAIN SHOULD OVERSPREAD MOST OF THE REGION LATE WEDNESDAY AFTERNOON/EARLY EVENING. APPEARS MOST OF THE GUIDANCE INDICATES BETTER MID LEVEL FORCING/LIFT ACROSS EASTERN MA/RI...SO EXPECT THE HIGHER RAINFALL TOTALS IN THESE LOCATIONS. THERE IS SOME MARGINAL ELEVATED INSTABILITY...SO A LOW RISK FOR A FEW EMBEDDED THUNDERSTORMS EXISTS ACROSS THE SOUTHEAST NEW ENGLAND COAST WEDNESDAY EVENING. THE BULK OF THE HEAVIER RAIN SHOULD BE OVER BY MIDNIGHT...BUT MOIST NORTH NORTHEAST LOW LEVEL FLOW WILL RESULT IN SOME SCATTERED SHOWERS AND AREAS OF DRIZZLE PERSISTING...ESPECIALLY NEAR THE COAST. LOW TEMPS WILL BE IN THE 40S. && .LONG TERM /THURSDAY THROUGH TUESDAY/... BIG PICTURE... LONGWAVE SCALE HAS A TROUGH OVER THE EASTERN USA WITH AXIS CENTERED OVER THE GREAT LAKES. LONGWAVE RIDGE OVER THE WEST COAST. CLOSED UPPER LOW WITHIN THE LONGWAVE TROUGH LINGERS OVER THE EAST COAST THURSDAY THROUGH SATURDAY. NORTHERN STREAM SHORTWAVE THEN DIVES SOUTHEAST INTO THE NORTHEAST USA SUNDAY...KICKING THE OFFSHORE LOW OUT TO SEA. THE SHORTWAVE FORMS A NEW CUTOFF LOW THAT MIGRATES FROM NORTHERN NEW ENGLAND TO NEWFOUNDLAND EARLY NEXT WEEK. THE DAILIES... THURSDAY-FRIDAY... CLOSED UPPER LOW AND ASSOCIATED COLD POOL OVER THE APPALACHIANS SHIFT EAST. UPPER FLOW OVER NEW ENGLAND IS SOUTHERLY AND DIFLUENT. GFS INDICATES ONE DEPARTING JET STREAK IN THIS FLOW AT 12Z THURSDAY...A SECOND STREAK APPROACHING FROM THE SOUTH MIDDAY. ADDITIONAL STREAKS MOVE PAST US DURING FRIDAY AS WELL. MEANWHILE COLD ADVECTION FROM THE ADVANCING COLD POOL WILL FURTHER DESTABILIZE THE AIRMASS. THIS WILL MAINTAIN A CHANCE OF SHOWERS BOTH DAYS...WITH FOG AND DRIZZLE IN BETWEEN ANY SHOWERS. EAST-NORTHEAST LOW LEVEL FLOW OFF THE GULF OF MAINE/MASS BAY WILL MAINTAIN COOL MOIST AIR NEAR THE SURFACE WITH DAY TEMPS IN THE UPPER 40S AND 50S WHILE DEW POINTS IN THE 40S WILL ALLOW MIN TEMPS IN THE 40S. WE WILL TREND A COUPLE OF DEGREES COOLER THAN GUIDENCE ON FRIDAY MAX TEMPS. SATURDAY-SUNDAY... UPPER TROUGH AND COLD POOL STILL OVERHEAD BUT JET SUPPORT MOVES OFF FARTHER EAST. PROBABILITY OF SHOWERS WILL BE LESS...BUT STILL A LOT OF LOW LEVEL MOISTURE SO LINGERING SCATTERED TO WIDELY SCATTERED SHOWERS. WITH THE EAST-NORTHEAST FLOW DIMINISHING...DAYTIME TEMPS SHOULD REACH A LITTLE MILDER. MIXING DEPTHS SUPPORT MAX SFC TEMPS MID 60S EACH DAY. NORTHERN STREAM SHORTWAVE PUSHES SOUTHEAST FROM ONTARIO SUNDAY. THIS WILL BRING A BETTER CHANCE OF SHOWERS AS A COLD FRONT SWINGS THROUGH NEW ENGLAND. SOME SIGNS OF NORTHWEST GUSTS TO 30 KNOTS IN COLD ADVECTION BEHIND THE COLD FRONT. MONDAY-TUESDAY... HIGH PRESSURE BUILDS OVER THE REGION. LINGERING COLD POOL MOISTURE ALOFT MAY BRING DIURNAL CLOUDS MONDAY...OTHERWISE A FAIR PERIOD. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY NIGHT/... TONIGHT...MODERATE CONFIDENCE. MVFR CONDITIONS WILL PROBABLY DOMINATE WITH LOW CLOUDS TRAPPED BENEATH THE SUBSIDENCE INVERSION. HOWEVER...SOME LOCATIONS NORTH OF THE PIKE AND ESPECIALLY NORTHEAST MA MAY IMPROVE TO VFR FOR A TIME AS DRIER AIR TEMPORARILY TRIES TO WORK INTO THIS REGION. MEANWHILE...MAINLY IFR CONDITIONS PROBABLY PERSIST ACROSS THE CAPE AND ISLANDS. WEDNESDAY...MODERATE CONFIDENCE. MVFR CONDITIONS AGAIN EXPECTED TO BE THE RULE FOR MUCH OF THE DAY...BUT SOME MARGINAL VFR CONDITIONS MAY OCCUR. MEANWHILE...IFR CONDITIONS MAY PERSIST ACROSS THE CAPE/ISLANDS GIVEN NORTHEAST FLOW. A FEW SHOWERS POSSIBLE THROUGH MID AFTERNOON...BUT A BAND OF STEADY RAIN WILL LIKELY MOVE INTO THE REGION FROM SOUTHWEST TO NORTHEAST LATE IN THE AFTERNOON/EVENING. LOW RISK OF AN EMBEDDED THUNDERSTORM OR TWO ACROSS SOUTHEAST NEW ENGLAND WEDNESDAY EVENING. WEDNESDAY NIGHT...MODERATE CONFIDENCE. LOW END MVFR TO IFR CONDITIONS EXPECTED. STEADY RAIN FOR MUCH OF THE REGION DURING THE EVENING DIMINISHES TO SCATTERED SHOWERS AND AREAS OF DRIZZLE AFTER MIDNIGHT. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. MVFR CONDITIONS MAY IMPROVE TO VFR FOR A TIME TONIGHT. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. OUTLOOK...THURSDAY THROUGH SUNDAY...MODERATE CONFIDENCE THURSDAY-FRIDAY...MIXED IFR/MVFR IN SHOWERS AND FOG. LOW LEVEL EAST- NORTHEAST FLOW UP THROUGH 3000 FEET WITH GUSTS TO 25 KNOTS ALONG THE EAST MASS SHORE. SATURDAY-SUNDAY... MIXED MVFR/IFR SATURDAY. WINDS BECOMING SOUTH WITH IMPROVEMENT TO VFR BY SUNDAY...THEN SCATTERED MVFR/IFR IN SHOWERS AS A COLD FRONT MOVES THROUGH. WINDS TURN FROM THE NORTHWEST SUNDAY AFTERNOON WITH GUSTS 20 TO 25 KNOTS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY NIGHT/...HIGH CONFIDENCE. TONIGHT AND WEDNESDAY...PERSISTENT NORTHEAST FLOW WILL BUILD SEAS TO BETWEEN 3 AND 5 FEET ACROSS OUR SOUTHERN OUTER-WATERS. SO WHILE WIND SPEEDS WILL GENERALLY NOT EXCEED 20 KNOTS THROUGH MIDDAY WEDNESDAY...WILL STILL NEED SMALL CRAFT HEADLINES FOR SOME 5 FOOT SEAS. PATCHY FOG POSSIBLE AT TIMES AS WELL. WEDNESDAY NIGHT...PRESSURE GRADIENT INCREASES AS WAVE OF LOW PRESSURE APPROACHES FROM THE SOUTH AND COMBINES WITH HIGH PRESSURE OVER THE CANADIAN MARITIMES. NORTHEAST WIND GUSTS TO 25 KNOTS MAY DEVELOP ACROSS A GOOD CHUNK OF OUR WATERS ALONG WITH SEAS BUILDING TO BETWEEN 4 AND 7 FEET. ADDITIONAL SCA HEADLINES WILL LIKELY BE NEEDED...BUT SINCE ITS 3RD PERIOD WILL WAIT UNTIL THE NEXT SHIFT GETS A LOOK AT IT. OUTLOOK...THURSDAY THROUGH SUNDAY...MODERATE CONFIDENCE... NORTHEAST WIND GUSTING 20 TO 25 KNOTS THURSDAY...BEST CHANCE ALONG THE WATERS EAST OF MASS. WINDS TURN FROM SOUTH SATURDAY AND SUNDAY MORNING...THEN FROM NORTHWEST SUNDAY AFTERNOON AFTER A COLD FRONT MOVES THROUGH. NORTHWEST GUSTS BEHIND THE COLD FRONT MAY REACH 25 KNOTS. SEAS 5 TO 7 FEET MUCH OF THE PERIOD. SMALL CRAFT ADVISORY MAY BE NEEDED. && .TIDES/COASTAL FLOODING... HIGH ASTRONOMICAL TIDES ARE EXPECTED...WITH PRIME CONCERN ON THE HIGHER OF THE TWO HIGH TIDE CYCLES THURSDAY NIGHT AND FRIDAY NIGHT. ASTRO HEIGHTS ARE PROJECTED JUST BELOW 12 FEET AT BOSTON BOTH NIGHTS. ASTRO HEIGHTS NEAR PROVIDENCE ARE PROJECTED AT 6 FEET THURSDAY NIGHT AND 6.5 FEET FRIDAY NIGHT. IT WON/T TAKE MUCH OF A SURGE ON TOP OF THOSE ASTRO HEIGHTS TO CAUSE SOME SPLASHOVER OR EVEN POSSIBLY SOME MINOR COASTAL FLOODING. PERSISTANT NORTHEAST WINDS AGAINST THE EAST MASSACHUSETTS COAST WILL ADD TO POTENTIAL FOR SURGE ALONG THAT COASTLINE. THIS WILL NEED TO BE MONITORED. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR ANZ254>256. && $$ SYNOPSIS...WTB/FRANK NEAR TERM...FRANK SHORT TERM...FRANK LONG TERM...WTB AVIATION...WTB/FRANK MARINE...WTB/FRANK TIDES/COASTAL FLOODING...

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