Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 230553 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 153 AM EDT WED APR 23 2014 .SYNOPSIS... A COLD FRONT SWINGS THROUGH SOUTHERN NEW ENGLAND TONIGHT...ACCOMPANIED BY SHOWERS AND AN ISOLATED THUNDERSTORM. THE AIRMASS REMAINS WINDY AND UNSETTLED WEDNESDAY. HIGH PRESSURE THEN BUILDS IN WITH DRY WEATHER FOR THURSDAY AND FRIDAY. UNSETTLED WEATHER IS LIKELY FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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145 AM UPDATE... SHOWERS HAVE PUSHED OFFSHORE AND DRY CONDITIONS WILL PREVAIL OVERNIGHT. BUT HIGH DEWPOINTS AND PARTIAL CLEARING HAS LED TO DEVELOPMENT OF PATCHY STRATUS/FOG NEAR THE COAST. GIVEN THAT UPSTREAM DEWPOINTS REMAIN IN THE 40S EXPECT PATCHY FOG TO PERSIST OVERNIGHT. PREVIOUS DISCUSSION... NUMEROUS SHOWERS MOVING EAST ACROSS SNE THIS EVENING. BACK EDGE OF THE RAIN LINES UP FAIRLY WELL WITH THE COLD FRONT WHICH IS MOVING THROUGH THE BERKSHIRES. SHOWERS WILL EXIT THE COAST JUST AFTER MIDNIGHT AS THE FRONT MOVES TO THE EAST. ADJUSTED POPS SLIGHTLY FOR TIMING AND REMOVED ISOLD THUNDER AS ELEVATED INSTABILITY IS CONFINED TO EASTERN PA. TEMPERATURES COME FROM A MODEL BLEND...VALUES MAINLY IN THE 40S. THIS LINES UP WELL WITH EXPECTED DEWPOINTS IN THE 40S DURING THE NIGHT.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/... SUPPORTING UPPER LOW TRAILING THE SURFACE SYSTEM TAKES A NEGATIVE TILT AS IT MOVES OVER NEW ENGLAND. THIS WILL SLOW THE PROGRESS OF CLOUDS AND SHOWERS. UPPER COLD POOL MOVES OVER NEW ENGLAND DURING THE DAY AND PROVIDES DESTABILIZATION OF THE AIRMASS. EXPECT CLOUDS AND A CHANCE OF SHOWERS MOST AREAS WITH THE BEST CHANCE ALONG AND NORTH OF THE MASS PIKE. THE UPPER TROUGH MOVES EAST OF OUR AREA DURING THE EVENING WHICH WILL MAKE ROOM FOR CLEARING SKIES WEDNESDAY EVENING AND NIGHT. WINDS...THE DESTABILIZING OF THE AIRMASS WILL ALLOW MIXING UP TO AT LEAST 900 MB /GFS/ AND POSSIBLY 850 MB /NAM/. WINDS IN THIS LAYER ARE FORECAST TO REACH 30 KNOTS BY AFTERNOON AND POSSIBLY 35 KNOTS LATER IN THE DAY. WILL INCLUDE WIND GUSTS TO 30 KNOTS IN THE AFTERNOON. FORECAST ISALLOBARS SHOW PRESSURE RISES OF 3-5 MB/HOUR MOVING INTO OUR AREA IN THE AFTERNOON AND CONTINUING INTO THE NIGHT. SUSTAINED WINDS SHOULD MAINTAIN THEMSELVES WEDNESDAY NIGHT. TEMPS...MIXED LAYER WILL TAP 850-EQUIVALENTS OF 0 TO -3C WHICH WOULD SUPPORT MAX TEMPS IN THE MID 50S TO NEAR 60. NIGHTTIME TEMPS ARE A MODEL BLEND YIELDING 29 TO 41. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... HIGHLIGHTS... * GUSTY...DRY WEATHER DAY ON THURSDAY * UNSETTLED WEATHER THIS WEEKEND * SEASONABLE TEMPS THROUGH THE PERIOD MODELS AND CONFIDENCE... 12Z SYNOPTIC PATTERN IS IN GOOD AGREEMENT THROUGH THE PERIOD. HOWEVER CLOSER TO THE SURFACE...MODELS DIVERGE SIGNIFICANTLY...ESP FOR THIS WEEKENDS SYSTEM. SURFACE LOW WILL MOVE OFFSHORE BY THURSDAY AS UPPER LEVEL RIDGING MOVES INTO NEW ENGLAND. A STRONG TROUGH WILL DIG THROUGH THE FLOW OVER THE GREAT LAKES REGION BY FRIDAY RESULTING IN A LOW PRESSURE SYSTEM DEVELOPING. THIS IS WHERE THE MODELS DIVERGE AS THE LATEST EC IS MUCH WEAKER IN ITS SHORTWAVE AND DEVELOPS THE SURFACE LOW WELL INTO NORTHERN NEW ENGLAND WHILE THE GFS PUTS IT RIGHT OVER SNE. TRENDED THIS PORTION OF THE FORECAST TOWARDS THE ENSEMBLES WHICH KEEPS THE LOW OVER SOUTHERN NEW HAMPSHIRE. BECAUSE OF THE DIFFERENCES FOR THIS WEEKEND...MODELS CONTINUE TO DIVERGE FOR EARLY NEXT WEEK. OVERALL CONFIDENCE LEVEL IS MODERATE YET...WITH THIS WEEKENDS SYSTEM AND BEYOND HAVE A LOWER CONFIDENCE LEVEL DUE TO THE DIFFERENCES IN THE GUIDANCE. HOWEVER DO HAVE A HIGHER CONFIDENCE THAT SEASONABLE TEMPS WILL OCCUR THROUGH THE END OF THIS WEEK INTO THE WEEKEND. ALSO BELIEVE THAT RAIN WILL IMPACT SOUTHERN NEW ENGLAND ON FRIDAY NIGHT/SATURDAY...JUST A LOW CONFIDENCE ON AMOUNTS AND EXACT LOCATION. DETAILS... THURSDAY INTO FRIDAY... VERY TIGHT PRESSURE GRADIENT WILL OCCUR ON THURSDAY AS HIGH PRESSURE TRIES TO BUILD IN FROM THE WEST WITH A DEPARTING LOW TO THE EAST. THIS TIGHT PRESSURE GRADIENT WILL YIELD A 850MB LLJ BETWEEN 40-50 KTS. BUFKIT SOUNDINGS SUGGEST THAT THE REGION WILL MIX UP TO 850MB ALLOWING FOR GUSTY AND DRY CONDITIONS. THIS COULD PROMPT THE ISSUANCE OF BOTH FIRE WEATHER AND WIND ADV HEADLINES. MORE DETAILS ON THE FIRE WEATHER CONDITIONS BELOW. HIGH PRESSURE WILL BUILD INTO THE REGION BY THURSDAY NIGHT ALLOWING FOR THE WINDS TO RELAX AND SKIES TO BECOME MOSTLY CLEAR. TEMPERATURES OVERNIGHT MAY RADIATE OUT IF WINDS DECOUPLE ENOUGH RESULTING IN LOWS IN THE 30S WITH 40S IN THE METRO REGIONS. HIGH PRESSURE WILL DOMINATE ON FRIDAY ALLOWING FOR DRY WEATHER AND SUNNY SKIES TO START THE DAY. WINDS WILL BE RELATIVELY LIGHT WITH MAX TEMPS IN THE LOW TO MID 60S DUE TO RETURN FLOW FROM THE SOUTH. FRIDAY NIGHT INTO SATURDAY... UPPER LEVEL LOW WILL APPROACH THE REGION OVER THE WEEKEND RESULTING IN WET WEATHER. THERE IS STILL A LOT OF DISCREPANCIES REGARDING HOW MUCH...WHAT TIME AND WHERE THE PRECIP WILL FALL. OVERALL FEEL THAT THE NORTHERN HALF OF THE REGION HAS THE BEST SHOT IN PRECIP CHANCES. ALSO BELIEVE THIS EVENT WILL BE FAR FROM A SOAKER AS WE HAVE SEEN IN THE PAST COUPLE OF WEEKS IN FACT QPF AMOUNTS COULD REACH AROUND 0.25 INCHES. HOPEFULLY OVER THE NEXT FEW RUNS MODELS WILL BECOME MORE IN-LINE WITH ONE ANOTHER BUT FOR NOW TRENDED TOWARDS THE ENSEMBLES WHICH SEEM TO BE IN GOOD AGREEMENT. OTHERWISE WITH SOUTHERLY FLOW AHEAD OF THE APPROACHING SYSTEM EXPECT TEMPS TO WARM UP INTO THE LOW TO MID 60S ON SATURDAY. AS THE SYSTEM PASSES...WINDS WILL SWITCH MORE TO THE NORTH OR NORTHWEST RESULTING IN HIGHS BACK DOWN INTO THE MID TO UPPER 50S BY SUNDAY. EARLY NEXT WEEK... NORTHERLY FLOW WILL CONTINUE WITH A POSSIBLE WARM FRONT ACROSS THE MID-ATLANTIC THROUGH THE FIRST PART OF NEXT WEEK. THIS NORTHERLY FLOW WILL KEEP TEMPS MORE SEASONABLE...OR EVEN SLIGHTLY COOLER WITH HIGHS IN THE UPPER 50S TO LOWER 60S THROUGH THIS PERIOD. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THURSDAY/... THROUGH 12Z...PATCHY IFR STRATUS/FOG EXPECTED...ESPECIALLY NEAR THE COAST. TODAY...PATCHY IFR STRATUS/FOG POSSIBLE EARLY...OTHERWISE MAINLY VFR CIGS. SCT TO NUMEROUS SHOWERS DEVELOPING WITH BRIEF MVFR VSBYS IN ANY SHOWERS. ISOLD THUNDER POSSIBLE. INCREASING NORTHWEST WINDS IN THE AFTERNOON WITH GUSTS TO 30 KT POSSIBLE. TONIGHT AND THURSDAY...VFR WITH GUSTY NORTHWEST WINDS. GUSTS TO 25-30 KT TONIGHT AND 35-40 KT THURSDAY. KBOS TERMINAL...LOW CONFIDENCE ON ANY STRATUS OR FOG DEVELOPING THROUGH 12Z. OTHERWISE...VFR. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY... FRIDAY...HIGH CONFIDENCE. VFR. SATURDAY INTO SUNDAY...MODERATE CONFIDENCE. MAINLY VFR. BRIEF PERIODS OF MVFR IN SCT -SHRA.
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&& .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH WEDNESDAY/...HIGH CONFIDENCE. INCREASING SOUTH TO SOUTHWEST WINDS LEAD A COLD FRONT WHICH WILL CROSS THE WATERS OVERNIGHT. WINDS THEN SHIFT TO WEST AND THEN NORTHWEST OVERNIGHT. THE FRONT WILL BE ACCOMPANIED BY SHOWERS AND POSSIBLY A THUNDERSTORM. COLD AIR AND STRONG PRESSURE RISES WILL BRING STRONG GUSTY WINDS WEDNESDAY...ESPECIALLY IN THE AFTERNOON AND AT NIGHT. NORTHWEST GALES WITH GUSTS 35-40 KNOTS ARE MOST LIKELY WEDNESDAY NIGHT. WE ARE CONVERTING THE PREVIOUS GALE WATCH TO A GALE WARNING WITH COVERAGE OF ALL WATERS. NORTHWEST GALES WEDNESDAY NIGHT WILL CONTINUE INTO THURSDAY. SEAS WILL BUILD TO 5 FEET ON THE SOUTHERN WATERS WEDNESDAY AFTERNOON AND THEN 5 TO 9 FEET ON THE EXPOSED WATERS WEDNESDAY NIGHT. OUTLOOK...THURSDAY THROUGH SUNDAY... THURSDAY...HIGH CONFIDENCE. GALE WATCH HAS BEEN ISSUED FOR STRONG GUSTS OVER THE WATERS. GUSTS COULD REACH BETWEEN 34-50 KNOTS OVER THE WATER ON THURSDAY. SEAS WILL BUILD TO 10 FEET IN RESPONSE. EXPECT BOTH WINDS AND SEAS TO SLOWLY DIMINISH BY THURSDAY NIGHT. FRIDAY...HIGH CONFIDENCE. QUIET BOATING WEATHER YET SEAS WILL STILL BE WILL SLOWLY RELAXING TO 5FT BY THE AFTERNOON. SCA MAY BE NEEDED. SATURDAY AND SUNDAY...LOW TO MODERATE CONFIDENCE. SW WINDS AND SEAS INCREASE AS A COLD FRONT APPROACHES THE WATERS. VISIBILITIES MAY BE REDUCED AT TIMES IN RAIN SHOWERS. AS THE COLD FRONT PASSES WINDS SWITCH TO THE NW RESULTING IN GUSTY CONDITIONS. SCA MAY BE NEEDED FOR THIS PERIOD. && .FIRE WEATHER... CONDITIONS ON THURSDAY ARE LOOKING FAVORABLE FOR THE POTENTIAL FOR FIRE WEATHER HEADLINES. LOW PRESSURE SYSTEM WILL SLOWLY EXIT THE REGION WED NIGHT/THURS MORNING FOLLOWED BY HIGH PRESSURE. THESE TWO FEATURES WILL RESULT IN A STRONG PRESSURE GRADIENT OVER THE REGION WITH A 40-50 KT LLJ AT 850KTS. ANTICIPATE THE ATMOSPHERE TO MIX UP TO 850MB ON THURSDAY RESULTING IN WINDY CONDITIONS AND DRY WEATHER. MIXING TO THIS LEVEL WILL BRING DOWN GUSTS CLOSE TO 40 KTS WITH THE POSSIBILITY OF A FEW 50 KTS GUSTS AS WELL. DEWPOINT LEVELS WILL ALSO DROP INTO THE TEENS ACROSS THE CT VALLEY WITH THE LOW 20S CLOSER TO THE COASTLINE. THE COMBINATION OF THESE LOW DEWPOINTS AND VERY GUSTY WINDS RESULTED IN MIN RH VALUES BETWEEN 15-25 PERCENT. WE DECIDED TO HOLD OFF ON ISSUING FIRE WEATHER HEADLINES TODAY AS A COLD FRONT PASSING THROUGH TONIGHT IS EXPECTED TO DROP AROUND 0.25 INCHES OF RAINFALL. ALSO WITH THE POTENTIAL FOR THUNDER...A FEW LOCATIONS MAY SEE HIGHER RAIN AMOUNTS. FINALLY ON WEDNESDAY THERE IS A POTENTIAL FOR CONVECTIVELY DRIVEN SHOWERS ON THE BACKSIDE OF THE LOW WHICH MAY NOT LET FUELS DRY OUT FAST ENOUGH PER DISCUSSION WITH OUR FIRE WEATHER PARTNERS. STAY TUNED TO THE LATEST FORECAST FOR UPDATES ON THE FIRE WEATHER POTENTIAL. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...GALE WARNING FROM 5 PM THIS AFTERNOON TO 8 PM EDT THURSDAY FOR ANZ230>237-250-251-254>256.
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&& $$ SYNOPSIS...WTB/DUNTEN NEAR TERM...KJC SHORT TERM...WTB LONG TERM...DUNTEN AVIATION...KJC/DUNTEN MARINE...WTB/DUNTEN FIRE WEATHER...

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