Area Forecast Discussion
Issued by NWS Boston, MA

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462 FXUS61 KBOX 162329 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 729 PM EDT SAT MAY 16 2015 .SYNOPSIS... A WARM FRONT MOVES NORTH OF THE REGION EARLY TONIGHT. WARMER AND MORE HUMID WEATHER FOLLOWS SUNDAY. MARITIME HIGH PRESSURE BRINGS COOLER MARINE AIR IN FROM THE EAST LATER SUNDAY INTO MONDAY. ANOTHER COLD FRONT WILL BRING SCATTERED SHOWERS TO THE REGION MON NIGHT INTO TUE FOLLOWED BY DRY WEATHER MID TO LATE NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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730 PM UPDATE... OVERALL TREND IS ON TRACK. SCT SHOWERS BREAKING OUT OVER UPSTATE NY ARE STRUGGLING TO MAKE IT INTO SOUTHERN NEW ENGLAND. BELIEVE THIS IS DUE TO LOW K VALUES...AND STEERING FLOW WHICH IS MORE IN A SSE DIRECTION. CT AND SOUTHERN RI MAY SEE SOME SHOWERS BUT HAVE A LOW CONFIDENCE. THEREFORE MENTIONED ONLY ISO OR SCT SHOWERS. ONCE PRECIP OR CHC THERE OF PASSES AND THE FRONT MOVES THROUGH COULD SEE SOME PATCHY FOG IN VALLEY LOCATIONS. TONIGHT... UPPER RIDGE BUILDS OVER THE NORTHEAST USA WHILE A SHORTWAVE MOVES THROUGH. THIS SHORTWAVE WILL DRIVE THE WARM FRONT NORTH OF US...AND ALSO PUSH SURFACE LOW AND COLD FRONT THROUGH OVERNIGHT. EXPECT SCATTERED SHOWERS THROUGH THE FIRST HALF OF THE NIGHT. THEN ONCE THE SHORTWAVE AXIS PASSES AND THE COLD FRONT IS DRIVEN THROUGH...EXPECT SHOWERS TO SUPPRESS SOUTH OFFSHORE AT THAT TIME. DEWPOINTS WILL LINGER 55-60 THROUGH THE NIGHT...SO MIN TEMPS SHOULD BE NO LOWER THAN THAT.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
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SUNDAY...MARITIME HIGH PRESSURE BUILDS IN FROM DOWNEAST. INITIALLY OUR WINDS WILL BE FROM THE NORTH...WHICH WILL BRING IN SOMEWHAT DRIER AIR. THIS WILL MEAN A MOSTLY SUNNY DAY. TEMPS AT 850 MB WILL BE 10-12C...TEMPS AT 800 MB WILL BE 10C /EQUIV TO 15C AT 850MB/. FULL MIXING WOULD BRING MAX SFC TEMPS IN THE UPPER 70S AND LOWER 80S...STRONGER MIXING PAST 850 MB WOULD MOVE US TOWARD A MID 80S POTENTIAL. AS THE RIDGE AXIS BUILDS OVER SOUTHERN NEW ENGLAND THE SURFACE WINDS WILL SHIFT TO EAST AND BRING COOLER AIR ASHORE. FYI...WATER TEMPS EAST OF MASS ARE 50-52. SO COASTAL AREAS MAY BE HELD IN THE 70S WHILE THE INTERIOR EAST REACHES THE U70-L80S. THE CT RIVER VALLEY...BETTER SHIELDED FROM THE EFFECTS OF THE WIND SHIFT...MAY REACH THE L-M80S. SUNDAY NIGHT...THE MARINE FLOW BECOMES BETTER ESTABLISHED ACROSS ALL OF OUR AREA. THIS WILL INCREASE LOW LEVEL MOISTURE VALUES AND INCREASE THE CHANCE OF SOME FOG/DRIZZLE LATE AT NIGHT. WITH DEW POINTS IN THE 50S...EXPECT MIN TEMPS IN THAT SIMILAR RANGE.
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&& .LONG TERM /MONDAY THROUGH SATURDAY/... HIGHLIGHTS... * COOL DOWN ON MONDAY THANKS TO PASSING BACKDOOR COLD FRONT * SCATTERED SHOWERS WITH AN ISO THUNDERSTORM ON TUESDAY WITH A PASSING COLD FRONT * DRY WEATHER AND MODERATING TEMPS WELL INTO NEXT WEEKEND OVERVIEW... FORECAST GUIDANCE CONTINUES TO BE IN GOOD AGREEMENT FOR MOST OF THE EXTENDED. HARDLY ANY BIG DISCREPANCIES SYNOPTICALLY...WITH JUST A FEW MINOR MESOSCALE DIFFERENCES. OVERALL HAVE MODERATE TO HIGH CONFIDENCE IN THE FORECAST. BACKDOOR COLD FRONT WILL SLIDE THROUGH SUNDAY NIGHT/MONDAY MORNING AS HIGH PRESSURE BUILDS OVER THE MARITIMES. UPPER LEVEL SHORTWAVE WILL FLATTEN THE BUILDING RIDGE ON TUESDAY AS COLD FRONT APPROACHES DURING THE DAY ON TUESDAY...WITH A SECONDARY COLD FRONT TUESDAY NIGHT. OTHERWISE NEW ENGLAND WILL BE IN A FLAT TO CYCLONIC FLOW ALOFT WITH THE CORE OF UPPER TROUGHING OVER ERN CANADA. DETAILS... * MONDAY...HIGH CONFIDENCE. BACK DOOR COLD FRONT SHOULD SLIDE THROUGH SOUTHERN NEW ENGLAND AS HIGH PRESSURE STRENGTHENS OVER THE MARITIMES. THIS FRONT WILL ALLOW FOR COOL MARITIME AIR TO FLOW ONSHORE KEEPING LOCATIONS ALONG THE EAST COASTLINE BELOW AVERAGE. STRATUS DECK SHOULD BREAK UP BY THE LATE MORNING/EARLY AFTERNOON ALLOWING FOR SOME SUNSHINE WHICH WILL HELP IN TEMPS REBOUNDING. COULD SEE LOW 70S ACROSS CT VALLEY AND MID 60S ACROSS THE CENTRAL HILLS. HOWEVER ALONG THE COASTLINE SHOULD STILL SEE UPPER 50S TO LOW 60S. * TUESDAY...HIGH CONFIDENCE. LOW PRESSURE SYSTEM WILL MOVE ACROSS SOUTHERN CANADA...DRAGGING A COLD FRONT WITH IT. THIS FRONT COULD BRING SOME MUCH NEEDED PRECIP TO THE AREA. 12Z MODEL SUITE HAS BEGUN TO AGREE ON TIMING...WITH PRECIP MOVING IN AROUND 12Z OUT WEST AND BY 18Z SHOULD BE ACROSS THE CENTRAL/EASTERN HALF OF THE REGION. PWAT VALUES ARE 1.5 INCHES TO THE ATMOSPHERE IS PRETTY MOIST. HOWEVER SEEMS TO BE MISSING A GOOD INFLOW JET AND THERE IS STILL A GOOD AMOUNT OF DRY AIR THAT NEEDS TO BE OVERCOME. SO ALTHOUGH ANTICIPATE PRECIP...SHOULD BE MORE SCATTERED IN NATURE. GUIDANCE ALSO INDICATED SOME INSTABILITY WITH K INDEX ABOVE 30 AND A FEW HUNDREDS OF CAPE...SO AN ISOLATED THUNDERSTORM IS POSSIBLE. A SECONDARY COLD FRONT WILL PASS THROUGH LATE TUESDAY/TUESDAY NIGHT WHICH WILL PUSH DRY COOLER AIR ACROSS THE REGION. * WEDNESDAY INTO NEXT WEEKEND...MODERATE CONFIDENCE. DRY WEATHER RETURNS BEGINNING ON WEDNESDAY LASTING INTO NEXT WEEKEND. DRY AIR AT THE SURFACE WILL MOVE INTO THE REGION ON THE BACKSIDE OF THE SECONDARY COLD FRONT. DESCENT WINDS ALOFT...SO WITH DOWNSLOPING COULD SEE WIND GUSTS INCREASE BETWEEN 20-30 MPH. ALSO EXPECT THE DOWNSLOPE FLOW TO OFFSET SOME OF THE COLD AIR ADVECTION...KEEPING HIGHS NEAR NORMAL ON WEDNESDAY. TEMPS ALOFT THEN WARM UP ON THURSDAY AND FRIDAY...WITH HIGHS WARMING UP EACH DAY. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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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 SUNDAY NIGHT/... EVENING...MODERATE CONFIDENCE. MVFR/VFR CIGS WILL CONTINUE. LOW CHC FOR ISO/SCT SHOWERS ACROSS WESTERN MASS AND SITES SOUTH OF THE PIKE. IF SHOWERS DO PASS CIGS MAY DROP QUICKLY...BUT OVERALL HAVE A LOW CONFIDENCE. OVERNIGHT...HIGH CONFIDENCE. WINDS SHIFT TO WEST/NORTHWEST. MAINLY VFR. LOW PROBABILITY OF MVFR CIGS/VSBYS IN PATCHY FOG. SUNDAY...HIGH CONFIDENCE. VFR. SEABREEZES DEVELOP ALONG THE EAST AND SOUTH COASTS ABOUT 14-15Z. SUNDAY NIGHT...MODERATE CONFIDENCE. EAST TO NORTHEAST FLOW OFF THE OCEAN. THIS MAY BRING AN INCREASE IN LOW CLOUDS AND POSSIBLY SOME FOG/DRIZZLE. BEST CHANCE WOULD BE IN THE COASTAL PLAIN...BOSTON- PROV- CAPE/ISLANDS. EXPECT IFR/LIFR IN ANY FOG/DRIZZLE. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...MONDAY THROUGH THURSDAY... MON...MODERATE CONFIDENCE. SKIES IMPROVING TO VFR MON AFTERNOON BUT MVFR CIGS MAY LINGER ALONG THE COAST. MON NIGHT AND TUE...MODERATE CONFIDENCE. AREAS OF MVFR/IFR REDEVELOPING WITH SCT TO NUMEROUS SHOWERS AND POSSIBLY A TSTM...ESPECIALLY TUE. WED INTO THURSDAY...MODERATE CONFIDENCE. VFR. DRY WEATHER LIKELY.
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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 SUNDAY NIGHT/...MODERATE-HIGH CONFIDENCE. A COLD FRONT SWEEPS ACROSS THE WATERS LATER TONIGHT BRINGING A FEW LIGHT SHOWERS. OTHERWISE QUIET BOATING WEATHER EXPECTED AS HIGH PRESSURE BUILDS OVER THE WATERS. SOUTH WINDS BECOME WEST TONIGHT...NORTH SUNDAY...AND EAST BY SUNDAY NIGHT. SPEEDS SHOULD REMAIN BELOW 20 KNOTS. SEAS WILL REMAIN AT 4 FEET OR LOWER THROUGH THE PERIOD. LOWER CONFIDENCE IN VISIBILITY SUNDAY NIGHT. THERE IS LOW-MODERATE CONFIDENCE IN AREAS OF FOG/DRIZZLE FORMING OVERNIGHT WITH VSBYS BELOW 1 MILE. OUTLOOK...MONDAY THROUGH WEDNESDAY... MON...HIGH CONFIDENCE. E WINDS MON AFTERNOON TURNING SOUTHERLY MON NIGHT. VSBYS MAY BE REDUCED IN PATCHY FOG. TUE...HIGH CONFIDENCE. PREFRONTAL S/SW WINDS INCREASING TO 15 KT INTO TUE EVENING. THEN SHIFTING TO NW LATE TUESDAY NIGHT BEHIND FROPA. SHOWERS AND PATCHY FOG WILL REDUCE VSBYS. WED...HIGH CONFIDENCE. W/NW WINDS WITH GUSTS TO 20-25 KT. MARGINAL SCA CONDITIONS POSSIBLE. THURSDAY...HIGH CONFIDENCE. WESTERLY WINDS WILL CONTINUE WITH GUSTS NEAR 15-20 KTS. SEAS SHOULD REMAIN BELOW 4 FEET.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...WTB/DUNTEN NEAR TERM...WTB/DUNTEN SHORT TERM...WTB LONG TERM...DUNTEN AVIATION...WTB/DUNTEN MARINE...WTB/DUNTEN

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