Area Forecast Discussion
Issued by NWS Boston, MA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBOX 202002 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 401 PM EDT SAT SEP 20 2014 .SYNOPSIS...
-- Changed Discussion --
SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM OR TWO ARE EXPECTED VERY LATE TONIGHT INTO SUN MORNING...WITH MOST AREAS DRY AND RATHER MILD BY SUN AFTERNOON. A COLD FRONT CROSSES THE REGION BY DAYBREAK MONDAY WITH HIGH PRESSURE BRINGING DRY WEATHER FOR THE REST OF NEXT WEEK. TEMPS START OFF COOL EARLY NEXT WEEK...BUT MODERATE TO ABOVE NORMAL BY THE END OF THE WEEK.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
-- Changed Discussion --
THIS EVENING WILL FEATURE DRY WEATHER WITH PLEASANT TEMPERATURES. MOST LOCATIONS WILL SEE TEMPS IN THE UPPER 50S AND 60S THIS EVENING...AS SURFACE WINDS WILL NOT DECOUPLE WITH A DEVELOPING LOW LEVEL JET.
-- End Changed Discussion --
&& .SHORT TERM /MIDNIGHT TONIGHT THROUGH SUNDAY NIGHT/...
-- Changed Discussion --
OVERNIGHT INTO SUNDAY AFTERNOON... A SHORTWAVE/LOW PRESSURE SYSTEM OFF THE CAROLINA COAST WILL BE LIFTING NORTHEAST OVERNIGHT. THIS WILL INDUCE A 30 TO 40 KNOT SOUTHERLY LOW LEVEL JET...TRANSPORTING DEEPER MOISTURE NORTHWARD INTO SOUTHERN NEW ENGLAND. THIS WILL RESULT IN A BURST OF INSTABILITY AND A BAND OF SCATTERED SHOWERS MOVING FROM WEST TO EAST. TIMING LOOKS TO BE AFTER MIDNIGHT INTO SUNDAY MORNING...APPROXIMATELY BETWEEN 6Z AND 15Z. INSTABILITY PARAMETERS ARE MARGINAL...BUT THERE MIGHT BE ENOUGH ELEVATED CAPE FOR A FEW EMBEDDED THUNDERSTORMS. THIS RISK FOR SEVERE WEATHER IS EXTREMELY LOW SUNDAY MORNING. HOWEVER...WITH 0 TO 6 KM SHEAR OF 25 TO 30 KNOTS/0 TO 1 KM HELICITY AROUND 100...AND A FEW HUNDRED J/KG OF CAPE....CAN/T COMPLETELY RULE OUT AN ISOLATED STRONG STORM NEAR THE SOUTH COAST SUNDAY MORNING. AGAIN THOUGH...THAT APPEARS TO BE A VERY LOW PROBABILITY BUT SOMETHING WILL NEED TO WATCH. THE STEADY AND HEAVIEST RAIN WILL LIKELY REMAIN OFF THE COAST WITH THE SURFACE LOW PRESSURE SYSTEM GIVEN LIMITED BAROCLINICITY/FRONTOGENESIS. HOWEVER...IT STILL MAY SCRAPE THE FAR SOUTHEAST NEW ENGLAND COAST FOR A TIME WHERE PWATS APPROACH 2 INCHES SO BRIEF HEAVY RAIN IS POSSIBLE. IN A NUTSHELL...SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS ARE EXPECTED MAINLY SUNDAY MORNING. WE ARE NOT EXPECTING A SOAKING RAIN BY ANY MEANS...BUT A PERIOD OF HEAVY RAIN IS POSSIBLE NEAR THE FAR SOUTHEAST NEW ENGLAND COAST IF THE PLUME OF TROPICAL MOISTURE CAN MAKE IT THAT FAR NORTHWEST. OTHERWISE...MOST OF SUNDAY AFTERNOON SHOULD BE DRY WITH JUST A LOT OF CLOUDS AROUND THE REGION...EXCEPT PERHAPS THE FAR SOUTHEAST NEW ENGLAND COAST WHERE SHOWERS MAY LINGER A BIT LONGER. LOW TEMPS OVERNIGHT WILL BE MUCH MILDER THAN LAST NIGHT WITH A DEVELOPING LOW LEVEL JET NOT ALLOWING WINDS TO DECOUPLE. LOWS WILL MAINLY BE IN THE UPPER 50S AND LOWER 60S BY DAYBREAK SUNDAY. HIGHS ON SUNDAY WILL BE IN THE MIDDLE TO UPPER 70S AND IT WILL FEEL A BIT HUMID WITH DEWPOINTS WELL INTO THE 60S! LATE SUNDAY AFTERNOON AND SUNDAY NIGHT... A COLD FRONT WILL APPROACH FROM THE WEST LATE SUNDAY AFTERNOON AND SLOWLY MAKE ITS WAY THROUGH THE REGION BY DAYBREAK MONDAY. A LOT OF MID LEVEL DRY AIR AND A LACK OF INSTABILITY WILL LIMIT PRECIPITATION POTENTIAL ALONG THE FRONT. THERE STILL MAY BE A FEW SPOT SHOWERS AND PERHAPS A THUNDERSTORM ACROSS THE INTERIOR LATE SUN AFTERNOON INTO THE EVENING ACROSS THE INTERIOR...BUT THAT IS ABOUT IT. MOST OF SUNDAY NIGHT SHOULD BE DRY IN A GIVEN LOCATION. LOW TEMPS WILL MAINLY IN THE UPPER 50S AND LOWER 60S BY DAYBREAK MONDAY.
-- End Changed Discussion --
&& .LONG TERM /MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
HEADLINES... *LOW CHANCE SHOWERS MON. THEN DRY THE REST OF THE WEEK *COOL TEMPERATURES DURING THE WEEK...MODERATING BY WEEKEND OVERVIEW... THE PERIOD STARTS OFF WITH GOOD AGREEMENT ON A TROUGH DRAPED OVER THE EAST COAST AND A RIDGE OVER THE WEST COAST. THE RIDGE SLOWLY MOVES EAST AS TIME GOES ON AND THE UPPER LEVEL MOVES NORTH INTO CANADA. GOOD AGREEMENT IN THE ENSEMBLE NAO AND AO TELECONNECTION FORECASTS TO STAY IN THE POSITIVE PHASES. THE PNA LOOKS TO START POSITIVE AND GO NEUTRAL AS TIME GOES ON...BUT THEN MODELS DIVERGE IN THEIR OUTPUTS AS A WEAKNESS IN THE RIDGE ALLOWS FOR SOME SPREAD. DAILIES... MONDAY...THE MORNING BEGINS WITH A DEPARTING COLD FRONT THAT IS FIGHTING WITH SOME DRY MIDLEVELS ALLOWING SOME OF THE PRECIP TO DRY UP. MOST OF THE PRECIPITATION SHOULD FALL IN NORTHWESTERN PORTIONS OF THE AREA AND OFFSHORE. BEHIND THE FRONT...STRONG MIXING OCCURS UP TO AROUND 850 MB WHERE 20 TO 25 KT WINDS EXIST SO GUSTS UP TO 25 KTS IS NOT OUT OF THE QUESTION. 850 MB TEMPS AHEAD OF THE FRONT ARE AROUND 10C SO MID TO UPPER 70S ARE NOT OUT OF THE QUESTION THERE. NORTHWESTERN SECTIONS WON/T GET THAT HIGH AS THE FRONT CROSS THROUGH TOO EARLY. TUESDAY THROUGH FRIDAY...BEHIND THE COLD FRONT...A STRONG 1035 MB HIGH PRESSURE SYSTEM COMES INTO THE REGION WITH COOLER TEMPERATURES...BUT NOT AS COLD AS THE PREVIOUS COLD FRONT. DRY WEATHER WILL ALSO PREVAIL DURING THIS PERIOD. SOME MODEL DISAGREEMENT AS TO THE PLACEMENT OF THE UPPER LEVEL JET APPROACHING THE REGION FROM THE SOUTH TOWARDS THE END OF THE PERIOD. THINK THE ECMWF MAY HAVE IT TOO FAR NORTH WHILE THE 6Z GFS HAS IT FURTHER SOUTH. THE EXACT PLACEMENT OF THIS JET WILL GIVE US WHEN CIRRUS CLOUDS MOVE NORTH FROM MOISTURE OFF OF THE SOUTHEAST US. WINDS WILL BE LIGHT DURING THIS PERIOD WITH THE UPPER JET UP NORTH SO BETTER CHANCE FOR COOLING TEMPS AT NIGHT ESPECIALLY WITH THE RECENT DRY SPELL WE/VE BEEN HAVING. IN PERIODS OF ONSHORE WINDS...FOG COULD OCCUR. SATURDAY...A COLD FRONT APPROACHES THE REGION FROM SOUTHEAST CANADA
-- End Changed Discussion --
&& .AVIATION /20Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... TONIGHT...MODERATE CONFIDENCE. VFR CONDITIONS THROUGH 4Z. INCREASING LOW LEVEL MOISTURE SHOULD ALLOW MVFR-IFR CIGS/VSBYS TO OVER SPREAD THE REGION VERY LATE THIS EVENING AND INTO THE OVERNIGHT HOURS. SCATTERED SHOWERS AND PERHAPS A FEW EMBEDDED THUNDERSTORMS MAY WORK INTO THE REGION AFTER 6Z. SUNDAY...MODERATE CONFIDENCE. MAINLY IFR CONDITIONS EXPECTED IN THE MORNING WITH SCATTERED SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM OR TWO. CONDITIONS SHOULD IMPROVE TO MVFR AND PERHAPS EVEN VFR DURING THE AFTERNOON ACROSS THE INTERIOR. HOWEVER...LOWER CIGS/VSBYS MAY HANG TOUGH THOUGH ALONG THE SOUTHEAST NEW ENGLAND COAST. SUNDAY NIGHT...LOW TO MODERATE CONFIDENCE. SCATTERED LOW CLOUDS AND FOG PATCHES ARE POSSIBLE ESPECIALLY ACROSS EASTERN NEW ENGLAND. KBOS TERMINAL...HIGH CONFIDENCE IN TAF THROUGH 6Z. MODERATE CONFIDENCE AFTER 6Z. KBDL TERMINAL...MODERATE TO HIGH CONFIDENCE IN TAF THROUGH 4Z. MODERATE CONFIDENCE AFTER 4Z. OUTLOOK...MONDAY THROUGH THURSDAY... HIGH CONFIDENCE THROUGHOUT THE PERIOD VFR THRU THE PERIOD EXCEPT FOR ANY SHOWERS ON MONDAY IN THE NORTHWESTERN AREAS WHERE MVFR COULD BE NEEDED. WINDS AROUND 10KTS DURING THE DAY MONDAY WITH GUSTS TO 20 OR 25KTS IN PLACES. THESE WINDS DIE OFF ON TUESDAY AND FOR THE REST OF THE WEEK.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... TONIGHT...MODERATE CONFIDENCE. SOUTH WINDS OF 10 TO 15 KNOTS WITH HIGH PRESSURE WELL OFF THE COAST. THERE IS A LOW PROBABILITY THAT 5 FOOT SEAS COULD DEVELOP FOR A TIME ACROSS THE OUTER-WATERS...BUT DECIDED TO KEEP WAVES JUST BELOW FOR NOW. LATER SHIFTS WILL HAVE TO KEEP A CLOSE EYE ON THIS POTENTIAL AND PERHAPS THE NEED FOR A SHORT FUSED SCA ADVISORY. SUNDAY AND SUNDAY NIGHT...MODERATE CONFIDENCE. SOUTHEAST WINDS AT 10 TO 15 KNOTS ON SUNDAY WILL SHIFT TO THE SOUTHWEST SUNDAY NIGHT AHEAD OF A COLD FRONT. HOWEVER...SWELL FROM LOW PRESSURE NEAR THE BENCHMARK WILL LIKELY RESULT IN SCA SEAS ACROSS THE OUTER-WATERS BY SUNDAY NIGHT. SINCE ITS MAINLY 3RD PERIOD...WILL DEFER THE ISSUANCE OF HEADLINES TO THE NEXT SHIFT. SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM MAY AFFECT THE WATERS THIS MORNING. THERE MAY ALSO BE SOME VISIBILITY RESTRICTIONS IN PATCHY FOG...ESPECIALLY DURING THE SUNDAY MORNING. OUTLOOK...MONDAY THROUGH THURSDAY... HIGH CONFIDENCE... SEAS FROM 5 TO 8FT ON MONDAY AND INTO TUESDAY WITH THE PASSAGE OF A LOW TO THE SOUTHEAST OF THE REGION. EVEN WITH WINDS BELOW SCA THRESHOLDS...AN SCA MAY BE NEEDED FOR THIS PERIOD FOR THE SWELLS.
-- End Changed Discussion --
&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...FRANK/HR NEAR TERM...FRANK SHORT TERM...FRANK LONG TERM...HR AVIATION...FRANK/HR MARINE...FRANK/HR

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