Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBOX 312022 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 422 PM EDT SUN MAY 31 2015 .SYNOPSIS... A COLD FRONT WILL MOVE SOUTH OFF THE COAST THIS EVENING...THEN STALL SOUTH OF NEW ENGLAND THROUGH TUESDAY AS LOW PRES TRACKS ALONG THE FRONT MONDAY NIGHT INTO TUESDAY. THIS WILL BRING PERIODS OF HEAVY RAIN TO THE REGION THROUGH TUESDAY. HIGH PRESSURE RETURNS FOR WEDNESDAY AND THURSDAY. CHANCE OF SHOWERS RETURNS FOR FRIDAY AND SATURDAY AS ANOTHER COLD FRONT MOVES THROUGH ON SATURDAY. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... SHOWERS AND EMBEDDED TSTMS WITH HEAVY RAINFALL PRODUCING LOCALIZED FLOODING ACROSS NE MA...WITH ADDITIONAL HEAVY RAINFALL MOVING ACROSS N CT AND SW MA. SPC MESOANALYSIS INDICATING SBCAPES 1000-1500 J/KG ACROSS N CT INTO RI AND ADJACENT AREAS OF MA. CLUSTER OF SHOWERS AND THUNDERSTORMS ARE MOVING NE FROM SE NY AND N NJ AND EXPECT SOME OF THIS ACTIVITY TO HOLD TOGETHER AS IT MOVES INTO CT GIVEN SOMEWHAT FAVORABLE INSTABILITY. FOCUS FOR HEAVIEST RAIN MAY END UP CLOSER TO THE CT COAST WHERE BETTER SFC INSTABILITY. HIRES-WRF SHOWING LOCALIZED 3-4" QPF BETWEEN 18-00Z ACROSS PORTIONS OF CT WITH AXIS OF RAINFALL EXTENDING INTO MA AND MUCH OF THIS RAINFALL COULD OCCUR IN A SHORT TIME. AS A RESULT WILL ISSUE A SHORT TERM FLASH FLOOD WATCH THROUGH THIS EVENING FOR N CT AND ADJACENT AREAS OF MA. COLD FRONT MOVING S ACROSS THE REGION AND APPROACHING RI AND SE MA. TEMPS WILL FALL SHARPLY THROUGH THE 60S AND INTO THE UPPER 50S BEHIND THE FRONT WHICH WILL REACH THE S COAST LATE AFTERNOON AND EARLY EVENING. NE WIND GUSTS TO 30 MPH WILL CONTINUE INTO EARLY EVENING ACROSS NE MA. TONIGHT...EXPECT CONVECTION TO WEAKEN THIS EVENING WITH JUST OCCASIONAL LIGHT SHOWERS ACROSS THE REGION...FOCUSED MORE IN THE INTERIOR. LATER TONIGHT...ANOTHER ROUND OF HEAVY RAINFALL WILL LIKELY SET UP ACROSS UPSTATE NY AND VT ASSOCD WITH STRONG LOW LEVEL CONVERGENCE AND FRONTOGENESIS WITH THE 850 MB FRONT TO THE NORTH. HOWEVER...MODELS ARE SHOWING AN AREA OF ENHANCED MID LEVEL OMEGA MOVING INTO SNE LATE TONIGHT WHICH WILL LIKELY BRING ANOTHER PERIOD OF RAIN. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... MONDAY... A BAND OF RAIN WILL LIKELY BE MOVING ACROSS SNE IN THE MORNING ASSOCD WITH AREA OF MID LEVEL LIFT. OTHERWISE...850 MB FRONT WILL REMAIN TO THE NORTH WHILE SFC FRONT IS TO THE S. WITH DECENT E/NE INFLOW AT 950 MB AND SOUTHERLY FLOW AT 850 MB ALONG WITH DEEP MOISTURE IN PLACE WITH PWATS NEAR 1.5" WILL SEE PERIODS OF COOL OVERRUNNING RAIN THROUGH MUCH OF THE DAY WHICH MAY BE LOCALLY HEAVY AT TIMES. ELEVATED INSTABILITY PARAMETERS ARE MARGINAL SO ONLY A LOW PROB FOR AN ISOLD TSTM. A VERY COOL DAY WITH TEMPS AVERAGING 15-20 DEGREES BELOW NORMAL...RANGING FROM NEAR 50 IN THE HIGHER TERRAIN TO MID/UPPER 50S NEAR THE S COAST. IN ADDITION...NE WINDS WILL GUST TO 25-30 MPH ACROSS NE MA. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... MONDAY NIGHT-TUESDAY... IMPRESSIVE OVERRUNNING SITUATION SETTING UP WITH THE POTENTIAL FOR RATHER WIDESPREAD HEAVY RAINFALL. THE SURFACE COLD FRONT REMAINS STALLED JUST SOUTH OF NEW ENGLAND WHILE THE FRONT AT 850 MB IS PARKED IN SOUTHERN NEW ENGLAND ROUGHLY NEAR THE MASS PIKE. LOW PRESSURE WILL TRAVEL ALONG THE FRONT FROM NEW JERSEY MON NIGHT TO THE GULF OF MAINE TUE AFTERNOON. BETWEEN 06Z AND 12Z TUE THE NAM SHOWS ENE WINDS AT 20-30 KT AT 925 MB ACROSS NORTHERN MA WHILE S-SW WINDS INCREASE TO 30-40 KT AT 850 MB ACROSS THE ENTIRE FORECAST AREA BRINGING IN +13-14C 850 MB AIR INTO CT/RI/SE MA ABOVE THE COOL MOIST SURFACE ENVIRONMENT. GFS WINDS ARE LESSER BUT STILL SHOW OVERRUNNING. PRECIPITABLE WATER VALUES ARE 1.6 TO 1.7 WHICH IS QUITE HIGH. EXPECT WIDESPREAD 1-2 INCHES OF RAIN WITH LOCALIZED AREAS OF 2-3 INCHES. MAINLY RAIN BUT COULD SEE SOME EMBEDDED ISOLATED THUNDERSTORMS ESPECIALLY IN RI AND SOUTHEAST MA WHERE THE SHOWALTER INDICES ARE DOWN TO 0.5...STILL POSITIVE BUT A MINIMUM AREA. IT IS TOO EARLY TO PIN DOWN AREAS MOST AT RISK FOR ANY FLOODING. IT MAY BE DEPENDENT ON WHERE THE HEAVIEST CONVECTION ENDS UP LATE THIS AFTERNOON AND EVENING. THUS LATER SHIFTS WILL NEED TO MONITOR THE POTENTIAL FOR A FLOOD OR FLASH FLOOD WATCH FOR A PORTION OF THE AREA. RAINFALL TAPERS OFF FROM WEST TO EAST TUE AFTERNOON. ECMWF MUCH SLOWER AT MOVING OUT THE CLOUDINESS SO WILL ERR ON THE CAUTIOUS SIDE AND KEEP IT MAINLY CLOUDY FOR THE AFTERNOON. UNSEASONABLY COOL TUE WITH HIGHS MAINLY 55 TO 60. WEDNESDAY AND THURSDAY...HIGH PRESSURE BUILDS OVER THE NORTHEAST STATES BOTH AT THE SURFACE AND ALOFT. BY THU EVENING THE HIGH BECOMES CENTERED EAST AND SOUTH OF NANTUCKET. SKIES WILL BE MOSTLY SUNNY AND THERE WILL BE A WARMING TREND. FORECASTING HIGHS IN THE 60S TO NEAR 70 WED AND IN THE MID AND UPPER 70S THU...COOLER ON CAPE ANN...CAPE COD...AND THE ISLANDS. FRIDAY...RETURN FLOW AROUND THE HIGH PRESSURE LEADS TO AN INCREASE IN MOISTURE AND SOME CLOUDINESS. THERE IS A CHANCE OF SHOWERS... ESPECIALLY IN WESTERN AND CENTRAL AREAS IN THE AFTERNOON AND EVENING. HIGHS MAINLY 75 TO 80...COOLER AT THE IMMEDIATE COAST AND 60S ON NANTUCKET. SATURDAY...MODELS ALL INDICATE A COLD FRONT MOVING THROUGH NEW ENGLAND. THE ECMWF IS MOST EMPHATIC. IN ADDITION TO THE FRONT...IT IS FARTHER NORTH THAN THE GFS WITH AN UPPER LEVEL LOW PRESSURE SYSTEM OVER THE MID ATLANTIC/SOUTHEAST STATES. RIGHT NOW HAVE INDICATED A LOW CHANCE OF SHOWERS...25 TO 30 PERCENT. HOWEVER...IF THE ECMWF IS RIGHT THE PROBABILITY WOULD BE GREATER. COULD ALSO BE THUNDER...BUT TOO FAR OUT NOW TO INCLUDE WITH ANY CONFIDENCE. HIGHS AGAIN MAINLY 75 TO 80. SUNDAY...ASSUMING FRONT HAS PASSED THROUGH...EXPECTING PARTLY SUNNY SKIES AND TEMPS IN THE 70S. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. THROUGH 00Z...MODERATE CONFIDENCE. WIDESPREAD SHOWERS WITH SCT TSTMS WILL CONTINUE TO DEVELOP ACROSS SNE. LOCALLY VERY HEAVY RAINFALL POSSIBLE ACROSS CT. WIDESPREAD MVFR CONDITIONS DEVELOPING WITH LOCALIZED IFR. NE WIND GUSTS TO 25-30 KT DEVELOPING ACROSS NE MA. WIND SHIFT TO N/NE WILL OCCUR LATE AFTERNOON/EARLY EVENING ALONG THE S COAST. TONIGHT AND MONDAY...MODERATE CONFIDENCE. WIDESPREAD MVFR/IFR CONDITIONS. OCCASIONAL SHOWERS AND PERHAPS AN EMBEDDED TSTM WILL PERSIST...WITH GREATEST COVERAGE ACROSS INTERIOR. NE WIND GUSTS TO 25 KT NE MA IN THE EVENING...THEN DIMINISHING OVERNIGHT BUT ANOTHER PULSE TO GUSTS TO 25 KT POSSIBLE MONDAY. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. AREAS OF IFR LIKELY DEVELOP THIS AFTERNOON ALONG WITH NUMEROUS SHOWERS AS WINDS SHIFT TO NE BEHIND THE FRONT. NE WIND GUSTS TO 25 KT DEVELOPING THIS AFTERNOON INTO EARLY EVENING. KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. OUTLOOK...MONDAY NIGHT THROUGH FRIDAY...MODERATE CONFIDENCE MONDAY NIGHT AND TUE. HIGH CONFIDENCE WED THROUGH FRI. MONDAY NIGHT AND TUESDAY...GUSTY EAST TO NORTHEAST FLOW AT THE SURFACE INCREASING TO 30 KT AT 2000 FT...THEN SHIFTING TO SOUTH- SOUTHWEST AND INCREASING TO 40 KT BY 5000 FT. A SMALL DEGREE OF LOW LEVEL WIND SHEAR WITH THIS OVERRUNNING SETUP. MVFR/IFR CIGS AND VSBYS... HEAVY RAIN EXPECTED MON NIGHT INTO TUE MORNING. ISOLATED TSTMS POSSIBLE MAINLY S RI AND SE MA. RAIN ENDING FROM W TO E TUE AFTERNOON WITH IMPROVING CONDITIONS. WEDNESDAY...VFR. LIGHT NORTHERLY WIND. THURSDAY...VFR. LIGHT SOUTHERLY WIND. LOCAL SEABREEZES POSSIBLE. PATCHY FOG POSSIBLE ALONG THE SOUTH COAST. FRIDAY...VFR. LIGHT SOUTHWEST WIND. CHANCE OF SHOWERS WEST LATE. LOCAL SEA BREEZES STILL POSSIBLE. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TODAY THROUGH MONDAY/...HIGH CONFIDENCE. NE GUSTS TO 30 KT WILL CONTINUE INTO THIS EVENING ACROSS NE COASTAL WATERS. EXPECT A BRIEF LULL OVERNIGHT..THEN ANOTHER PULSE OF NE GUSTS TO 30 KT IS EXPECTED DURING MONDAY...AGAIN MAINLY FOCUSED OVER NE COASTAL WATERS. ELSEWHERE...SW WINDS OVER S COASTAL WATERS WILL SHIFT TO NE THIS EVENING AND PERSIST THOUGH MONDAY WITH GUSTS TO 20 KT AT TIMES. SEAS WILL BUILD TO 5-8 FT OVER NE MA COASTAL WATERS. OCCASIONAL SHOWERS AND PATCHY FOG WILL REDUCE VSBYS. OUTLOOK...MONDAY NIGHT THROUGH FRIDAY...MODERATE CONFIDENCE. MONDAY NIGHT-TUESDAY NIGHT...SMALL CRAFT ADVISORIES HAVE BEEN EXTENDED THROUGH MONDAY NIGHT AS ROUGH SEAS FROM 5 TO 7 FT WILL CONTINUE OVER THE COASTAL WATERS EAST OF MASSACHUSETTS. SMALL CRAFT ADVISORIES MAY BE NEEDED ACROSS THE SOUTHERN OUTER COASTAL WATERS AS WELL ON TUE. NORTHEAST WINDS MAY BE GUSTING TO NEAR 25 KT MON EVENING BUT WILL GRADUALLY DIMINISH BY TUE. EXPECTING SEAS TO SUBSIDE TO BELOW SMALL CRAFT ADVISORY THRESHOLDS TUE NIGHT. WEDNESDAY AND THURSDAY...QUIET BOATING WEATHER WITH HIGH PRESSURE OVERHEAD WED AND THEN SLIDING OFF THE COAST LATE THU. FRIDAY...SOUTHERLY WINDS INCREASE TO 10 TO 15 KT BEHIND DEPARTING HIGH PRESSURE. STILL NO HEADLINES EXPECTED. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...FLASH FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR CTZ002>004. MA...FLASH FLOOD WATCH UNTIL 11 PM EDT THIS EVENING FOR MAZ009-011- 012. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT MONDAY FOR ANZ230. SMALL CRAFT ADVISORY UNTIL 2 AM EDT MONDAY FOR ANZ231. SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ250-251-254. SMALL CRAFT ADVISORY UNTIL 2 PM EDT MONDAY FOR ANZ255-256. && $$ SYNOPSIS...KJC/GAF NEAR TERM...KJC SHORT TERM...KJC LONG TERM...GAF AVIATION...KJC/GAF MARINE...KJC/GAF

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.