Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 022253 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 653 PM EDT MON MAY 2 2016 .SYNOPSIS...
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DRY WEATHER GIVES WAY TO A FAST MOVING LOW PRESSURE SYSTEM OVERNIGHT. THE LOW WILL BRING A PERIOD OF RAIN OVERNIGHT INTO TUESDAY MORNING...ESPECIALLY SOUTH OF THE MASSACHUSETTS TURNPIKE. THE RAIN SHOULD BE OVER FOR MOST BY TUESDAY AFTERNOON...BUT IT WILL REMAIN RATHER CLOUDY AND COOL. ONE OR MORE WAVES OF LOW PRESSURE PASS SOUTH OF THE REGION WEDNESDAY BRINGING MORE SHOWERS. A CLOSED UPPER LOW DEVELOPS OVER THE APPALACHIANS THURSDAY AND DRIFTS SOUTH OF NEW ENGLAND FRIDAY AND SATURDAY. A COLD FRONT SWINGS THROUGH NEW ENGLAND SUNDAY...FOLLOWED BY HIGH PRESSURE AND DRIER WEATHER MONDAY.
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&& .NEAR TERM /UNTIL 1 AM TUESDAY MORNING/...
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LOTS OF CLOUDS AND PATCHY DRIZZLE IN PLACE. THIS SHOULD CONTINUE THROUGH THE NIGHT DUE TO LOW LEVEL MOISTURE REMAINING TRAPPED BENEATH AN INVERSION. LOW TEMPS WILL BE IN THE 40S AND AREAS OF FOG ARE EXPECTED ESPECIALLY ON THE COAST. MINOR CHANGES MADE AT THE EVENING UPDATE BUT OTHERWISE THE FORECAST REMAINS ON TRACK.
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&& .SHORT TERM /1 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... ***PERIOD OF STEADY RAIN EXPECTED ALONG AND SOUTH OF MA TURNPIKE AFTER MIDNIGHT INTO TUESDAY MORNING PARTICULARLY NEAR THE SOUTH COAST*** OVERNIGHT INTO TUESDAY MORNING... ANOTHER WAVE OF LOW PRESSURE OVER THE MID ATLANTIC STATES WILL LIFT NORTHEAST AND PASS SOUTH OF SOUTHERN NEW ENGLAND OVERNIGHT INTO TUESDAY MORNING. BOTH THE GFS/NAM SHOW A DECENT BAND OF MID LEVEL FRONTOGENESIS/OMEGA SOUTH OF THE MA TURNPIKE AND PARTICULARLY NEAR THE SOUTH COAST. WITH ALL THAT SAID...EXPECT A BAND OF RAIN TO OVERSPREAD AREAS ALONG AND SOUTH OF THE MA TURNPIKE TOWARD DAYBREAK. THE RAIN MAY BRIEFLY BE HEAVY AT TIMES...ESPECIALLY NEAR THE SOUTH COAST WHERE THE BEST FORCING/LIFT WILL BE LOCATED. ALONG THE SOUTH COAST...RAINFALL AMOUNTS OF 0.50+ INCHES ARE POSSIBLE. MEANWHILE...NORTH OF THE MA TURNPIKE AND ESPECIALLY NEAR THE NH BORDER...A PERIOD OF SHOWERS IS POSSIBLE BUT RAINFALL AMOUNTS WILL BE MUCH LIGHTER. TUESDAY AFTERNOON... LOW PRESSURE WILL HAVE PASSED WELL TO OUR EAST TUE AFTERNOON...SO MAINLY DRY WEATHER OTHER THAN PERHAPS A FEW LINGERING SHOWERS ACROSS THE FAR SOUTHEAST NEW ENGLAND COAST. HOWEVER...LOW LEVEL MOISTURE TRAPPED BENEATH THE INVERSION WILL HANG TOUGH WITH LIGHT NORTH TO NORTHEAST WINDS. THE RESULT WILL BE ANOTHER DREARY DAY WITH HIGHS IN THE 50S AND ITS POSSIBLE PORTIONS OF THE EASTERN MA COAST STAY IN THE UPPER 40S. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... BIG PICTURE... LONGWAVE SCALE SHOWS TROUGH EAST/RIDGE WEST FOR MUCH OF THE FORECAST PERIOD. PROGRESSIVE NORTHERN STREAM STAYS ACROSS CANADA MUCH OF THE WEEK WHILE FLOW ACROSS THE USA REMAINS BLOCKY WITH CLOSED LOWS OVER THE PACIFIC AND ATLANTIC COASTS AND A WEAKER RIDGE OVER THE PLAINS. SHORTWAVES MOVE THROUGH THE EASTERN USA CLOSED LOW. THEN OVER THE WEEKEND A SHORTWAVE IN THE NORTHERN STREAM DIGS INTO THE LONGWAVE TROUGH. THIS KICKS OUT THE ATLANTIC CLOSED LOW AND ESTABLISHES A NEW CLOSED LOW OVER THE MARITIMES. THIS REMAINS AN UNSETTLED PATTERN FOR NEW ENGLAND THROUGH THE WEEKEND A TREND TO DRIER WEATHER EARLY NEXT WEEK. THE DAILIES... TUESDAY NIGHT-WEDNESDAY... SOUTHWEST UPPER FLOW WITH SEVERAL JET STREAKS MOVING OVERHEAD OF NEW ENGLAND. STATIONARY FRONT REMAINS OFFSHORE. THIS IS THE RECIPE FOR ONE OR MORE SURFACE LOWS RIPPLING UP THE FRONT AND PASSING TO OUR SOUTH. LOW LEVEL FLOW SOUTH OF THE FRONT REMAINS DIRECTED OUT TO SEA...BUT IF ONE OF THESE LOWS BECOMES A LITTLE STRONGER THAN DEPICTED THEN IT IS CONCEIVABLE THAT IT COULD BRIEFLY PULL THE LOW LEVEL FLOW OUT OF THE SOUTH AND GENERATE SOME LOW LEVEL LIFT/OVERRUNNING ACROSS SOUTHERN NEW ENGLAND AS IT PASSES. MEANWHILE THE JET STREAKS ALOFT WILL GENERATE SOME UPPER VENTING. AT A MINIMUM THIS WOULD INDICATE CHANCE POPS FOR SHOWERS IN SOUTHERN NEW ENGLAND. IF ONE LOW BECOMES FOCUSSED ALONG THE FRONT THEN HIGHER POPS VALUES /ABOVE THE 55 PCT LIKELY THRESHOLD/ WOULD BE REASONABLE ALONG THE SOUTH COAST AND ISLANDS. THURSDAY THROUGH SATURDAY... CLOSED UPPER LOW TAKES SHAPE OVER THE APPALACHIANS AND DRIFTS SOUTH OF NEW ENGLAND. COLD POOL ALOFT ASSOCIATED WITH THE LOW WILL ADVECT OVER OUR AREA AND DESTABILIZE THE AIRMASS. THIS WILL SUPPORT SCATTERED SHOWERS THROUGH THE PERIOD. SUNDAY-MONDAY... NORTHERN SHORTWAVE DIVES SOUTHEAST THROUGH NEW ENGLAND SUNDAY. THIS DRIVES THE CLOSED LOW OFF TO THE EAST AND BRINGS A COLD FRONT THROUGH OUR AREA ON SUNDAY. WE SHOULD BE UNDER THE LEFT EXIT REGION OF THE NORTHWEST UPPER JET...PROVIDING ENOUGH VENTING TO SUPPORT SCATTERED SHOWERS. HIGH PRESSURE THEN BUILDS IN WITH DRIER WEATHER FOR MONDAY. && .AVIATION /00Z TUESDAY 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/... TONIGHT...MODERATE CONFIDENCE. IFR/LIFR CONDITIONS LINGER IN RI/SOUTHEAST MASS DUE TO LOW CLOUDS/FOG/DRIZZLE. CONDITIONS FARTHER NORTH AND WEST MAY BRIEFLY IMPROVE TO MVFR. A BAND OF STEADY RAIN WILL MOVE INTO AREAS ALONG AND SOUTH OF MA TURNPIKE BETWEEN O6Z AND 12Z. SOME SHOWERS MAY REACH NEAR THE MA/NH BORDER...BUT THE HEAVIEST RAIN WILL BE NEAR THE SOUTH COAST. TUESDAY...MODERATE TO HIGH CONFIDENCE. BULK OF THE RAIN MOVES EAST OF THE REGION TUE MORNING. OTHERWISE...MAINLY DRY WEATHER FOR THE REST OF TUE AFTERNOON BUT MVFR-IFR CONDITIONS WILL LINGER BUT SHOULD SEE A GRADUAL IMPROVEMENT AT LEAST AWAY FROM THE COAST. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. IFR CONDITIONS MAY BRIEFLY IMPROVE TO MVFR AFTER 00Z THIS EVENING IF WINDS CAN TEMPORARILY SHIFT TO THE NORTHWEST. IF SO...IFR CONDITIONS PROBABLY RE-DEVELOP AFTER 8Z WITH THE NEXT BAND OF RAIN. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. IFR CONDITIONS PROBABLY IMPROVE TO LOW END MVFR THIS EVENING. OUTLOOK /TUESDAY NIGHT THROUGH SATURDAY/...MODERATE CONFIDENCE TUESDAY NIGHT-WEDNESDAY...AREAS OF MVFR/IFR IN SHOWERS AND LOW CIGS. NORTHEAST WIND 15 KNOTS OR LESS. THURSDAY THROUGH SATURDAY...VFR WITH AREAS OF MVFR/IFR IN SCATTERED SHOWERS.
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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 TUESDAY/...HIGH CONFIDENCE. MAIN CONCERN FOR MARINERS WILL BE AREAS OF FOG...MAINLY LATER TONIGHT INTO TUESDAY. RELATIVELY WEAK PRESSURE GRADIENT WILL KEEP MOST WATERS BELOW SMALL CRAFT ADVISORY THRESHOLDS THROUGH TUE AFTERNOON. HOWEVER...WILL MAINTAIN SCA FOR HAZARDOUS SEAS ACROSS OUR FAR EASTERN WATERS FOR THE FIRST PART OF THE NIGHT FOR MARGINAL 5 FOOT SEAS. WE MAY NEED ADDITIONAL SCA FOR MARGINAL 5 FOOT SEAS LATER TUE ACROSS OUR OUTER-WATERS AGAIN...SO SOMETHING LATER SHIFTS WILL HAVE TO EVALUATE. OUTLOOK /TUESDAY NIGHT THROUGH SATURDAY/...MODERATE CONFIDENCE OUTLOOK /TUESDAY NIGHT THROUGH SATURDAY/...MODERATE CONFIDENCE... NORTHEAST WINDS 15 KNOTS OR LESS. SEAS 5 TO 7 FEET THROUGH THE PERIOD. SMALL CRAFT ADVISORY FOR SEAS MAY BE NEEDED...MOSTLY ON THE OUTER WATERS.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 2 AM EDT TUESDAY FOR ANZ250-254-255. && $$ SYNOPSIS...WTB/FRANK NEAR TERM...WTB/FRANK SHORT TERM...FRANK LONG TERM...WTB AVIATION...WTB/FRANK MARINE...WTB/FRANK

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