Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 301926 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 326 PM EDT SAT APR 30 2016 .SYNOPSIS... HIGH PRESSURE OVER THE REGION TONIGHT WILL MOVE OFF TO THE EAST SUNDAY MORNING. LOW PRESSURE MOVING UP THE OHIO VALLEY WILL BRING TWO BURSTS OF RAIN TO SOUTHERN NEW ENGLAND...ONE ON SUNDAY AFTERNOON/EVENING AND THE SECOND ON MONDAY. A BRIEF DRYING TREND TUESDAY WHICH MAY LAST INTO WEDNESDAY...THEN MORE UNSETTLED WEATHER FOR LATE NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... HIGH-BASED DIURNAL CLOUDS OVER THE INTERIOR WHILE THE COASTAL PLAIN REMAINS MAINLY CLEAR. EXPECT THESE CLOUDS TO DIMINISH WITH THE SETTING SUN. COASTAL SEA BREEZES WILL ALSO DIMINISH WITH SUNSET. HIGH PRESSURE LINGERS OVER THE REGION TONIGHT WITH LIGHT WIND AND DRY AIR. MAIN CONCERN WILL BE HOW QUICKLY THE EVENING CLOUDS DISSIPATE. THIS WILL DETERMINE HOW MUCH RADIATIONAL COOLING WE GET BEFORE MID AND HIGH CLOUDS MOVE UP FROM THE SOUTHWEST. IF THE COOLING PERIOD IS SHORT...MIN TEMPS MAY BE A LITTLE MILDER THAN FORECAST. CURRENTLY STAYING WITH MIN TEMPS 40-45...WITH ENOUGH COOLING TIME THE COOLER SPOTS COULD REACH THE UPPER 30S. EXTRAPOLATION ON THE INCOMING CLOUD SHIELD WOULD BRING THICKER CLOUDS OVER WESTERN MA/CT AROUND 10 PM TO MIDNIGHT...CENTRAL HILLS MIDNIGHT TO 2 AM...AND COASTAL PLAIN 2 TO 4 AM. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... UPPER SHORTWAVE AND PROGRESSIVE FLOW WILL FEED FAVORABLE UPPER DYNAMICS FOR SURFACE SHORTWAVE TO MOVE NORTHEAST ACROSS THE EASTERN GREAT LAKES. THIS TRACK WILL ALLOW TWO STREAMS OF 1 INCH PRECIPITABLE WATER TO MOVE ACROSS SOUTHERN NEW ENGLAND...THE FIRST MOVING ACROSS LATE SUNDAY AND SUNDAY NIGHT. THE MODELS ALSO SHOW SHORTWAVE ENERGY TRANSFERRING TO THE COAST DURING SUNDAY NIGHT. THIS WOULD ALLOW FOR A COASTAL LOW TO SPIN UP...SETTING UP OVERRUNNING ESPECIALLY ACROSS RI/SE MASS. TOTAL TOTALS WILL ALSO CLIMB HIGH INTO THE 40S. THIS MAY ALLOW EMBEDDED THUNDER IN THE AREAS OF RAIN SUNDAY NIGHT. TIMING OF PCPN...ALL MODELS AGREE ON BRINGING PCPN INTO WESTERN MA/CT SUNDAY MORNING...AND REACHING EASTERN MASS BY EARLY AFTERNOON. THE MODELS ALSO HINT AT A BREAK IN THE PCPN LATE AT NIGHT ESPECIALLY ACROSS WESTERN MASS. WITH THE STEADY EAST- NORTHEAST FLOW ACROSS NEW ENGLAND...SUSPECT CLOUDS/DRIZZLE WILL BE A FACTOR IF THE RAIN DOES BRIEFLY DIMINISH. THE NORTHEAST FLOW SHOULD ALSO HOLD MAX TEMPS DOWN DURING SUNDAY. WATER TEMPERATURES ARE 45-50. WITH WIND COMING OFF THAT WATER IT WOULD SUGGEST MAX TEMPS WILL BE ONLY A LITTLE HIGHER...AROUND 50 OR THE LOWER 50S...WITH MIN TEMPS IN THE 40S. && .LONG TERM /MONDAY THROUGH SATURDAY/... HIGHLIGHTS... * PERIODS OF RAIN MONDAY * DRY AND SEASONABLE TUE...POSSIBLY LASTING INTO WEDNESDAY * MORE UNSETTLED WEATHER POSSIBLE LATE NEXT WEEK OVERVIEW... AMPLIFIED PATTERN DEVELOPS IN THE EXTENDED PERIOD AS ANOMALOUS MID LEVEL RIDGE BUILDS ACROSS NORTHERN ROCKIES AND WESTERN CANADA WITH DOWNSTREAM TROF OVER THE GT LAKES. MODELS IN AGREEMENT ON AMPLIFICATION OF THIS TROF LATE NEXT WEEK WITH CUTOFF LOW EVENTUALLY DEVELOPING...BUT LOW CONFIDENCE ON EVOLUTION AND LOCATION OF THIS CUTOFF AND SUBSEQUENT SFC LOW DEVELOPMENT SOMEWHERE ALONG THE EAST COAST WHICH WILL DETERMINE SENSIBLE WEATHER. GENERAL THEME WILL BE A RETURN TO UNSETTLED WEATHER LATE NEXT WEEK BUT DETAILS ARE VERY UNCERTAIN. DETAILS... MONDAY... OVERRUNNING OF WARM FRONT S OF NEW ENG WITH DEEP MOISTURE AND MODEST FORCING FOR ASCENT WILL LEAD TO PERIODS OF RAIN SUN NIGHT. MORE COMPLEX SCENARIO UNFOLDING MON AS APPROACHING SHORTWAVE LEADS TO A PRIMARY LOW MOVING TO THE WEST WHILE SECONDARY LOW DEVELOPS OVER OR SOUTH OF NEW ENG. NAM IS OVERDONE WITH HEAVY RAINFALL MON DUE TO ITS DEPICTION OF A STRONG LOW LEVEL JET WHICH SEEMS UNLIKELY. EXPECT MAINLY LIGHT RAIN TO LINGER INTO MON...THEN TAPERING OFF MON AFTERNOON AS BEST FORCING LIFTS TO THE NE. TRICKY TEMP FORECAST FOR MON WHICH WILL DEPEND ON EXACTLY WHERE SECONDARY LOW DEVELOPS AS THERE WILL BE A SURGE OF MILDER AIR TO THE SOUTH OF THE LOW. THERE WILL LIKELY BE A SHARP NORTH TO SOUTH TEMP GRADIENT ACROSS SNE. TUESDAY INTO WEDNESDAY... DRY WEATHER SHOULD RETURN TUE AS THE COLUMN DRIES WITH TEMPS REBOUNDING TO NEAR SEASONABLE NORMS AWAY FROM THE IMMEDIATE COAST. DRY WEATHER MAY PERSIST INTO WED BUT NOT AS CONFIDENT AS MID LEVEL TROF WILL BE AMPLIFYING TO THE WEST WITH SFC WAVE LURKING TO THE SOUTH. LOW CONFIDENCE TEMP FORECAST FOR WED AS GFS INDICATING SW FLOW AND TEMPS ABOUT 10 DEGREES MILDER THAN ECMWF WHICH HAS EASTERLY FLOW. THURSDAY AND FRIDAY... LOOKS LIKE AN UNSETTLED PERIOD WITH CUTOFF LOW WEST OR SW OF NEW ENG AND SFC LOW SOMEWHERE NEAR THE EAST COAST. HOWEVER...LOW CONFIDENCE ON DETAILS AS THERE IS CONSIDERABLE SPREAD AMONG THE DETERMINISTIC AND ENSEMBLE GUIDANCE REGARDING INTENSITY AND PLACEMENT OF THE SFC LOW WHICH WILL IMPACT TEMPS AND SENSIBLE WEATHER. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH SUNDAY NIGHT/...HIGH CONFIDENCE. THROUGH TONIGHT...VFR. ONSHORE SEA BREEZE WINDS AROUND 10 KNOTS DIMINISHING THIS EVENING. EAST-NORTHEAST WIND CAPE COD AND ISLANDS DIMINISHING THIS EVENING. SUNDAY AND SUNDAY NIGHT...RAIN MOVES INTO W MA/CT BETWEEN 11-14Z SUNDAY REACHING THE EAST COAST BETWEEN 15-18Z. INITIAL VFR IN LIGHT RAIN DETERIORATES TO MVFR CIGS/VSBYS IN RAIN SUNDAY EVENING WITH AREAS OF IFR. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK /MONDAY THROUGH THURSDAY/... MONDAY...OVERALL HIGH CONFIDENCE WITH MVFR/IFR CONDITIONS IN PERIODS OF RAIN. TUESDAY AND WEDNESDAY...MODERATE CONFIDENCE. MAINLY VFR WITH LIGHT WINDS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH SUNDAY NIGHT/...HIGH CONFIDENCE. HIGH PRESSURE OVERHEAD TONIGHT AND SUNDAY WILL KEEP WINDS BELOW 20 KNOTS AND SEAS BELOW 5 FEET. RAIN MOVES IN FROM WEST TO EAST DURING SUNDAY...ENTERING THE WATERS LATE MORNING OR EARLY AFTERNOON. LOWERING VSBYS IN RAIN AND FOG DURING THE AFTERNOON/EVENING. SUNDAY NIGHT...EAST-NORTHEAST WINDS WILL INCREASE WITH SPEEDS AROUND 20 KNOTS. BEST CHANCE WILL BE ALONG THE WATERS NEAR CAPE ANN/NORTH SHORE. THE INCREASING WINDS WILL BUILD SEAS DURING THE NIGHT WITH 5 FOOT HEIGHTS ON THE OUTER WATERS. A SMALL CRAFT ADVISORY MAY BE NEEDED. REDUCED VSBYS IN RAIN AND PATCHY FOG. OUTLOOK /MONDAY THROUGH THURSDAY/... MONDAY...LOW CONFIDENCE ON WINDS DUE TO UNCERTAINTY IN TRACK OF LOW PRES. ROUGH SEAS...ESPECIALLY EASTERN WATERS. VSBYS REDUCED AT TIMES IN RAIN AND FOG. TUESDAY...HIGH CONFIDENCE. LIGHT WINDS BUT LEFTOVER ROUGH SEAS WILL SLOWLY SUBSIDE. WEDNESDAY...LOW CONFIDENCE WIND FORECAST. LOW PRESSURE TO THE SOUTH MAY RESULT IN WINDS BEING MORE EASTERLY THAN WHAT IS CURRENTLY FORECAST. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...WTB/KJC NEAR TERM...WTB SHORT TERM...WTB LONG TERM...KJC AVIATION...WTB/KJC MARINE...WTB/KJC

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