Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 011955 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 355 PM EDT MON JUN 1 2015 .SYNOPSIS... STALLED FRONT SOUTH OF THE REGION WILL KEEP UNSEASONABLY COOL AND DAMP CONDITIONS THROUGH TUESDAY ACROSS SOUTHERN NEW ENGLAND. EXPECT PERIODS OF RAIN...HEAVY AT TIMES TO MOVE ACROSS THE AREA TONIGHT AND TUESDAY. HIGH PRESSURE RETURNS WITH DRIER WEATHER WEDNESDAY AND THURSDAY. SHOWERS ARE POSSIBLE FRIDAY INTO SATURDAY...AS ANOTHER COLD FRONT MOVES THROUGH THEN HIGH PRESSURE FOLLOWS FOR SUNDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 4 PM UPDATE... *** PERIODS OF HEAVY RAIN LIKELY TONIGHT INTO TUESDAY *** COOL SEASON PRECIP EVENT UNDERWAY WITH COOL AIR DAMMING SETUP AS 1030+ MB ANTICYCLONE SETTLES OVER SOUTHEAST QUEBEC AND NEW BRUNSWICK...MAINTAINING SHALLOW COOL AIRMASS INTO SOUTHERN NEW ENGLAND. THIS HAS RESULTED IN A SHARP BAROCLINIC ZONE AT 925 MB AND 850 MB OVER THE REGION. MEANWHILE DEEP LAYER MID LEVEL TROUGH WEST OF NEW ENGLAND CONTINUES TO STREAM SUBTROPICAL AIRMASS UP AND OVER THIS BOUNDARY WITH PWATS UP TO 1.5 INCHES ENTERING CT AND RI EARLY THIS EVENING. THESE VALUES ARE AROUND +2 STANDARD DEVIATIONS ABOVE CLIMO. HENCE DEEP LAYER MOISTURE AVAILABLE FOR HEAVY DOWNPOURS. AS FRONTAL WAVE TRACKS SOUTH OF NEW ENGLAND TONIGHT LOW TO MID LEVEL FGEN BECOMES ENHANCED ACROSS CT/RI AND MA THIS EVENING AND OVERNIGHT. THUS PERIODS OF HEAVY RAINFALL. SOME INSTABILITY ALOFT...PERHAPS NOT SUFFICIENT FOR THUNDER BUT SUFFICE TO ENHANCE RAINFALL RATES. BEST CHANCE OF EMBEDDED THUNDER WILL BE ACROSS CT/RI AND SOUTH OF THE MASS PIKE. AS FOR TIMING...AREAS OF DRIZZLE AND SCATTERED SHOWERS EARLY THIS EVENING BECOME MORE WIDESPREAD LATER THIS EVENING AND ESPECIALLY OVERNIGHT. TEMPS...NOT MUCH CHANGE GIVEN COOL ONSHORE FLOW. GOOD CHANCE WE BREAK THE RECORD FOR COLDEST HIGH TEMPS. DON`T SEE MUCH IF ANY TEMP INCREASE BETWEEN NOW AND MIDNIGHT. SEE CLIMATE SECTION BELOW FOR MORE DETAILS. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... *** HEAVY RAIN AND FLOOD THREAT CONTINUES INTO TUE *** BAROCLINIC WAVE TRAVERSES SOUTH OF NEW ENGLAND WITH MODEST LOW TO MID LEVEL FGEN SAGGING SOUTHWARD INTO CT/RI AND SOUTHEAST MA IN THE MORNING. FORCING FOR ASCENT BECOMES ENHANCED AS ANOMALOUS RRQ OF UPPER LEVEL JET STREAK DESCENDS SOUTHWARD FROM THE ST. LWRNC RVR VLY. THIS WILL YIELD PERIODS OF HEAVY RAINFALL ESPECIALLY OVER CT/RI ALONG AND SOUTH OF THE MASS PIKE. GOOD AGREEMENT AMONG ALL GUID SOURCES WITH BOTH THE HI RES ARW...NMM...4KM NAM AND EVEN THE GLOBAL EC AND GFS HAVING THE AXIS OF HEAVIEST RAINFALL ACROSS CT EXTENDING NORTHEAST INTO RI AND CENTRAL-EASTERN MA. MODELS ALSO IN GOOD AGREEMENT ON MAGNITUDE OF QPF RANGING FROM 1.5 TO 2.5 INCHES WITH ISOLATED 3+ AMOUNTS POSSIBLE IN THE AREA MENTIONED ABOVE. THESE AMOUNTS COMBINED WITH HEAVY RAINS FROM YESTERDAY/LAST NIGHT WILL INCREASE THE RISK FOR ADDITIONAL FLOODING TONIGHT INTO TUE. THUS HAVE EXPANDED THE FLOOD WATCH. MID LEVEL TROUGH IS SOMEWHAT PROGRESSIVE SO EXPECTING BACK EDGE OF RAIN AND CLOUD SHIELD TO MOVE NW TO SE TOMORROW WITH SOME PARTIAL CLEARING FOR MOST OF THE AREA LATE IN THE DAY AND ESPECIALLY TOWARD SUNSET. THE EXCEPTION WILL BE OVER SOUTHEAST MA WHERE ANY CLEARING WILL LIKELY HOLD OFF UNTIL TUE EVENING. UNSEASONABLY COOL TEMPS CONTINUE WITH STIFF NE WINDS OFF THE CHILLY OCEAN WATERS ALONG WITH OVERCAST CONDITIONS AND RAIN. TUE NIGHT... IMPROVING/DRYING CONDITIONS FROM NW TO SE. CHILLY CONDITIONS CONTINUE. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGHLIGHTS... * MAINLY DRY WITH BELOW NORMAL TEMPS WED AND THU * A FEW SHOWERS POSSIBLE FRI INTO SAT AS A COLD FRONT APPROACHES * DRY AND SEASONABLE SUN THEN THREAT OF SHOWERS RETURNS MON OVERVIEW... MODELS IN GOOD AGREEMENT ON OVERALL PATTERN INTO THE WEEKEND. CLOSED LOW WILL MEANDER OVER THE SOUTHERN APPALACHIANS THROUGH THU BEFORE WEAKENING AND MOVING TO THE MID ATLC COAST. DOWNSTREAM RIDGING TO THE NE OVER THE WESTERN ATLC WILL PROVIDE A FEW DRY DAYS...THEN THE RIDGE WILL BREAK DOWN BY FRI INTO THE WEEKEND AS NORTHERN STREAM ENERGY APPROACHES FROM THE NW WITH POLAR JET SHIFTING S. NORTHERN STREAM TROF DELIVERS A COLD FRONT FRI NIGHT INTO SAT WITH SOME SHOWERS POSSIBLE. NEXT TROF AMPLIFIES ACROSS GT LAKES BY EARLY NEXT WEEK WITH DEEPER MOISTURE MOVING BACK IN FROM THE SW. WEDNESDAY AND THURSDAY... HIGH PRESSURE BUILDS S ACROSS SNE BRINGING DRY WEATHER BUT BELOW NORMAL TEMPS UNDER LOW LEVEL EASTERLY FLOW. COOLEST TEMPS IN E MA AND WARMEST IN CT VALLEY. MOSTLY SUNNY SKIES EXPECTED WED...BUT CLOUDS WILL BE INCREASING THU AS THE HIGH SHIFTS TO THE E AND MOISTURE TO THE SW TRIES TO MOVE BACK IN. THERE IS A LOW PROB OF A FEW SHOWERS ACROSS W NEW ENG BUT RIDGING SHOULD KEEP THIS TO THE WEST. FRIDAY... HIGH MOVES OFFSHORE AS COLD FRONT APPROACHES N NEW ENG. MODELS SHOW CONSIDERABLE LOW LEVEL MOISTURE DEVELOPING IN LOW LEVEL SOUTHERLY FLOW SO MOCLDY SKIES EXPECTED AND CANT RULE OUT A FEW SHOWERS...BUT MAIN FOCUS WILL BE TO THE N CLOSER TO THE FRONT. FRIDAY NIGHT INTO SATURDAY... COLD FRONT MOVES S ACROSS WHICH MAY BRING A PERIOD OF SHOWERS FRI NIGHT...POSSIBLY LINGERING INTO SAT DEPENDING ON TIMING OF THE FRONT. GFS IS QUICKER MOVING FRONT OFFSHORE AND HAS A MAINLY DRY DAY SAT...WHILE SLOWER ECMWF HAS SHOWERS LINGERING SAT ESPECIALLY SOUTHERN AREAS. SUNDAY INTO MONDAY... MAINLY DRY SUNDAY AS HIGH PRES RETURNS...THEN MODEL CONSENSUS FAVORS MOISTURE AND THE THREAT OF SHOWERS RETURNING MONDAY. GFS SHOWING TROPICAL SYSTEM MOVING N ACROSS W ATLC BUT CONFIDENCE IN THIS SOLUTION IS QUITE LOW. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. THROUGH 00Z...MODERATE TO HIGH CONFIDENCE...PERSISTENCE WILL BE A GOOD FORECAST REGARDING CIGS AND VSBYS. THUS IFR AND LIFR EXPECTED. WIDESPREAD DRIZZLE WILL CONTINUE. SHOWERS FOCUSED ALONG THE MA/NH BORDER AT 2 PM WILL CONTINUE MOVING NORTHEAST. NEXT ROUND OF SHOWERS OVER LOWER HUDSON VALLEY/NYC/LONG ISLAND WILL MOVE NORTHEAST AND SHOULD BLOSSOM IMPACTING THE TERMINALS 21Z-00Z. MODEST NE WINDS CONTINUE. TONIGHT...MORE OF THE SAME IFR/LIFR WITH RAIN BECOMING STEADY AND HEAVY AT TIMES. NE WINDS CONTINUE. LOW RISK OF ISOLATED THUNDER MAINLY CT/RI AND MUCH OF MA EXPECT NORTHWEST SECTIONS. TUESDAY...IFR/LIFR IN PERIODS OF HEAVY RAIN WITH LOW RISK OF EMBEDDED THUNDER CT/RI AND SOUTH OF THE MASS PIKE. IMPROVING CONDITIONS IN THE AFTERNOON FROM NW TO SE BUT NOT REACHING SOUTHEAST MA UNTIL SUNSET OR SO. TUE NIGHT...FURTHER IMPROVEMENT CONTINUES WITH RAIN EXITING CAPE COD AND ISLANDS EARLY IN THE EVENING. MODEST NNE WIND. IFR TRENDING TOWARD MVFR AND VFR TOWARD MORNING. KBOS TERMINAL...HIGH CONFIDENCE IN CIGS AND VSBYS BUT LOWER IN TIMING OF RAIN. GUSTY NE WINDS. SHOWERS BECOME HEAVY WITH A LOW PROB OF ISOLATED THUNDER TONIGHT INTO TUE MORNING. KBDL TERMINAL...HIGH CONFIDENCE IN CIGS AND VSBYS BUT LOWER IN TIMING OF RAIN. GUSTY NE WINDS. SHOWERS BECOME HEAVY WITH A LOW PROB OF ISOLATED THUNDER TONIGHT INTO TUE MORNING. OUTLOOK...WEDNESDAY THROUGH SATURDAY... WEDNESDAY...HIGH CONFIDENCE. AREAS OF MVFR/IFR STRATUS IN THE MORNING...OTHERWISE VFR. SEABREEZES LIKELY. THURSDAY...HIGH CONFIDENCE. VFR CIGS. SEABREEZES LIKELY. FRIDAY...MODERATE CONFIDENCE. VFR/MVFR CIGS. LOW PROB OF A FEW SHOWERS. SATURDAY...LOW CONFIDENCE. CIGS AND WEATHER DEPEND ON TIMING OF A COLD FRONT WHICH IS UNCERTAIN. AREAS OF MVFR AND SHOWERS MAY LINGER INTO SAT IF FRONT IS SLOWER. VFR IF FRONT MOVES THROUGH QUICKER. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH TUESDAY NIGHT/...MODERATE TO HIGH CONFIDENCE. TONIGHT AND TUE...NE WINDS CONTINUE 15-20 KT WITH GUSTS UP TO 25 KT AS WEAK WAVES OF LOW PRES TRACK SOUTH OF NEW ENGLAND. PERIOD OF RAIN...HEAVY AT TIMES POSSIBLE. LOW RISK OF ISOLATED THUNDER. TUE NIGHT...DRYING TREND AS HIGH PRES BUILDS INTO NEW ENGLAND. WINDS DIMINISH AND BECOME MORE NORTHERLY. OUTLOOK...WEDNESDAY THROUGH SATURDAY... WEDNESDAY AND THURSDAY...HIGH CONFIDENCE. MAINLY EASTERLY WINDS UNDER 20 KT. FRIDAY...HIGH CONFIDENCE. WINDS BECOMING S WITH SPEEDS LESS THAN 15 KT. SATURDAY...MODERATE CONFIDENCE. WINDS BECOMING NORTHERLY BEHIND A COLD FRONT WITH SPEEDS BELOW SCA. && .CLIMATE... HIGH TEMPERATURES TODAY RUNNING ABOUT 20-25 DEGS BELOW NORMAL! NORMAL HIGH TODAY IS 70-75. BELOW ARE THE RECORDS FOR THE COLDEST HIGHS ON THIS DATE. BOS...53...1992 PVD...56...1984 BDL...57...1992 ORH...52...2004 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...FLASH FLOOD WATCH THROUGH TUESDAY EVENING FOR CTZ002>004. MA...FLASH FLOOD WATCH THROUGH TUESDAY EVENING FOR MAZ003>007- 010>021-026. RI...FLASH FLOOD WATCH THROUGH TUESDAY EVENING FOR RIZ001>007. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR ANZ230>235-237- 250-251-254>256. && $$ SYNOPSIS...KJC/NOCERA NEAR TERM...NOCERA SHORT TERM...NOCERA LONG TERM...KJC AVIATION...KJC/NOCERA MARINE...KJC/NOCERA CLIMATE...JWD

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