Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 171107 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 707 AM EDT THU APR 17 2014 .SYNOPSIS... HIGH PRESSURE WILL BRING DRY...BUT SEASONABLY COOL WEATHER TO THE REGION TODAY AND TOMORROW. DRY AND SLOWLY WARMING WEATHER IS EXPECTED THROUGH MONDAY. THE ONLY EXCEPTION WILL BE A PERIOD OF CLOUDINESS AND POSSIBLE DRIZZLE ALONG THE SOUTHEAST MA COAST FRIDAY NIGHT. SLOW MOVING LOW PRESSURE COULD BRING SHOWERS FROM LATE MONDAY NIGHT INTO WEDNESDAY OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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7 AM UPDATE.... VISIBLE SATELLITE IMAGERY SHOWS SCATTERED LOW CLOUDS AFFECTING PARTS OF EAST COASTAL MA EARLY THIS MORNING. OTHERWISE...SUNSHINE WILL BE THE RULE THIS MORNING. WE WERE OFF TO A VERY CHILLY START WITH 7 AM TEMPERATURES STILL IN THE 20S TO LOWER 30S EXCEPT MID TO UPPER 30S ON CAPE COD AND THE ISLANDS. STRONG HIGH PRESSURE TO OUR NORTHEAST WAS CAUSING AN INCREASINGLY TIGHT GRADIENT OVER SOUTHEASTERN MA. WINDS WERE ALREADY GUSTING TO 30 MPH ON NANTUCKET. PREVIOUS DISCUSSION FOR TODAY... HIGH PRESSURE WILL MOVE TOWARDS THE MARITIMES RESULTING IN A MORE ONSHORE FLOW ACROSS THE MA COASTLINE. THIS EASTERLY FLOW WILL PUSH THE COOL MARITIME AIR ONSHORE RESULTING IN TEMPERATURES ALONG THE COASTLINE IN THE LOW 40S. A FEW SCATTERED CLOUDS MAY MOVE ONSHORE AS WELL AS THE MOISTURE INCREASING WITHIN THE COLUMN. OTHERWISE ACROSS THE INTERIOR...TEMPS WILL WARM INTO THE UPPER 40S TO LOW 50S...WHICH IS STILL BELOW NORMAL.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... THURSDAY NIGHT INTO FRIDAY... SOUTHERN NEW ENGLAND`S WEATHER WILL STILL BE INFLUENCED BY THE OFFSHORE HIGH PRESSURE OVER THE MARITIMES WHILE A STALLED FRONT SOUTH OF THE REGION WILL STAY SUPPRESSED. THIS SET-UP WILL CONTINUE THE EASTERLY FLOW KEEPING THE MARITIME AIR ONSHORE. THROUGHOUT THE NIGHT ON THURSDAY AND INTO FRIDAY MOISTURE WILL INCREASE IN THE LOW LEVELS AS CROSS SECTIONS SHOW MOISTURE BEING TRAPPED UNDER THE INVERSION. FRIDAY ESPECIALLY LOOKS TO BE A COLD AND DREARY DAY FROM THE NORTH SHORE DOWN TO THE CAPE...INCLUDING BOSTON...DUE TO THE INCREASE OF CLOUD COVER AND DRIZZLE. OTHERWISE ACROSS THE INTERIOR...TEMPS WILL RADIATE OUT ON THURSDAY NIGHT DUE TO CLEAR SKIES AND LIGHT WINDS. TEMPS WILL DIP AGAIN BELOW THE FREEZING MARK BUT WILL HOLD OFF ON ANY HEADLINES AS THE GROWING SEASON BEGINS ON THE 20TH OF APRIL. ON FRIDAY THE INTERIOR WILL WARM UP WELL INTO THE MID TO UPPER 50S WITH THE CT VALLEY BEING THE WARM SPOT WHICH COULD MAKE A RUN TO 60F. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... HIGHLIGHTS... * CLOUDS/POSSIBLE DRIZZLE SOUTHEAST AREAS FRI NIGHT * DRY AND SEASONABLE THROUGH MONDAY * SHOWERS A GOOD BET FOR TUE INTO WED IN GENERAL THERE IS VERY GOOD MODEL AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. FROM LATE IN THE WEEK THROUGH EARLY NEXT WEEK...UPPER LEVEL SPLIT FLOW EXISTS ACROSS THE EASTERN USA. SOUTHERN NEW ENGLAND IS INFLUENCED BY THE NORTHERN STREAM AND A CUTOFF LOW OVER THE SOUTHEAST STATES SNEAKING HARMLESSLY OUT TO SEA WELL TO OUR SOUTH. ON TUE...A NEW UPPER TROUGH OVER THE GREAT LAKES DEEPENS...FORMING A CUTOFF LOW OFF OF CAPE COD BY WED. DETAILS... FRIDAY NIGHT AND SATURDAY... A STORM SYSTEM WILL BE PASSING VERY FAR TO THE SOUTHEAST OF NEW ENGLAND FRIDAY NIGHT. ITS PRECIPITATION SHIELD WILL REMAIN SOUTH OF OUR WATERS. HOWEVER THE ONSHORE FLOW BETWEEN THAT SYSTEM AND AN APPROACHING WEAK SURFACE TROUGH WILL LIKELY KEEP LOW CLOUDINESS AND PERHAPS FOG AND DRIZZLE OVER CAPE COD AND THE ISLANDS AND PERHAPS AS FAR NORTH AS MARSHFIELD MA FRI NIGHT...BEST INDICATED BY THE NAM LOW LEVEL RH FIELDS BUT ALSO SEEN ON THE GFS. OTHERWISE EXPECT PARTLY TO MOSTLY CLOUDY SKIES FARTHER INLAND WITH LOWS IN THE 30S. A WEAK SURFACE TROUGH WILL PASS ACROSS SOUTHERN NEW ENGLAND EARLY SAT. WHILE A SHOWER CANNOT BE RULED OUT...ITS MAIN IMPACT WILL BE TO PUT AN END TO THE ONSHORE FLOW...WITH LIGHT WEST TO NORTHWEST WINDS BECOMING ESTABLISHED AND SUNSHINE RETURNING FOR MOST OF THE DAY. THIS WILL ALLOW HIGHS TO REACH THE UPPER 50S TO NEAR 60. SUNDAY AND MONDAY... HIGH CONFIDENCE OF REMAINING DRY THROUGH SUNDAY AND MONDAY. VERY STRONG HIGH PRESSURE BECOMES CENTERED OVER NEW ENGLAND SUNDAY AND MOVES OFFSHORE MONDAY. SUNDAY WILL BE BRIGHT AND SUNNY WITH HIGHS AGAIN IN THE UPPER 50S TO LOWER 60S...COOLER NEAR THE COAST THOUGH. LIGHT SOUTHWEST FLOW AROUND THE DEPARTING HIGH ON MONDAY WILL GIVE TEMPERATURES ANOTHER BOOST. 925 MB TEMPS ARE FORECAST TO REACH +8C TO +10C BY MONDAY EVENING. HAVE INCREASED FORECAST MAX TEMPERATURES A FEW DEGREES ABOVE GUIDANCE...REACHING THE MID TO PERHAPS UPPER 60S EXCEPT 50S AT THE IMMEDIATE COAST. SUNSHINE WILL FADE BEHIND INCREASING MID AND HIGH LEVEL CLOUDINESS MONDAY AFTERNOON. HOWEVER THERE NO LONGER IS ANY RISK FOR PRECIPITATION DURING THE DAY. MONDAY NIGHT THROUGH WEDNESDAY... THIS IS AN UNSETTLED PERIOD. MODELS AGREE THAT ANOTHER UPPER LEVEL TROUGH IN THE NORTHERN STREAM MOVES FROM THE GREAT LAKES EASTWARD AND AMPLIFIES TUE...EVENTUALLY BECOMING A CUTOFF UPPER LOW SOMEWHERE OFF THE NEW ENGLAND COAST. MODEL CONSENSUS IS THAT THIS OCCURS EAST OF CAPE COD/NANTUCKET ON WED ALTHOUGH THE GFS OPERATIONAL RUN IS FARTHER NORTH OFF OF NEW HAMPSHIRE. MILD WITH SHOWERS A GOOD BET FROM LATE MON NIGHT THROUGH AT LEAST TUE NIGHT. HAVE EXTENDED THIS CHANCE OF SHOWERS THROUGH WED BASED ON THE 00Z ECMWF MODEL RUN. THERE IS A CHANCE THAT THIS COULD TURN INTO A SOAKING RAIN... ESPECIALLY TUE INTO TUE NIGHT...BUT THIS FAR OUT IN TIME OUR PROBABILITIES ONLY REFLECT 30-40 PERCENT CHANCES OF RAIN. MODEL GUIDANCE SHOWS HIGHS IN THE MID 60S TUE AND UPPER 50S TO NEAR 60 WED. HAVE GONE WITH THIS...HOWEVER THE ECMWF 850 MB TEMPS ARE ONLY +4C...WHICH IS COLDER THAN THE GFS +8C...SO IT IS POSSIBLE THE WED MAX TEMPS MAY NEED TO BE ADJUSTED DOWNWARD. && .AVIATION /12Z THURSDAY THROUGH MONDAY/...
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LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH FRIDAY/...HIGH CONFIDENCE. TODAY...HIGH CONFIDENCE...VFR. INCREASING NORTHEAST TO EAST WINDS...STRONGEST ON THE CAPE AND ISLANDS. THERE IS A RISK OF CIGS IN THE 3000-3500 FT RANGE ACROSS EASTERN MA COAST. TONIGHT...HIGH CONFIDENCE...VFR TO START. CIGS MAY BUILD AND DROP TO MVFR CONDITIONS ACROSS THE EAST COASTLINE INCLUDING THE CAPE AND THE ISLANDS DUE TO ONSHORE FLOW. FRIDAY...MODERATE CONFIDENCE...ONSHORE FLOW WILL CONTINUE DROPPING THE CIGS ACROSS BOTH COASTLINES TO MVFR. THERE IS A LOW PROB OF LOCALLY IFR AS WELL AS FOG AND DRIZZLE. KBOS TERMINAL...HIGH CONFIDENCE. KBDL TERMINAL...HIGH CONFIDENCE. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... FRIDAY NIGHT INTO EARLY SATURDAY MORNING...LOW TO MODERATE PROBABILITY OF IFR CONDITIONS IN LOW CLOUDS AND FOG OVER CAPE COD AND THE ISLANDS. VFR EXPECTED INLAND WITH A LOW PROBABILITY OF MVFR IN AN ISOLATED SHOWER. LATE SATURDAY MORNING THROUGH MONDAY...HIGH CONFIDENCE VFR.
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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 FRIDAY/...HIGH CONFIDENCE. WINDS WILL CONTINUE TO BE GUSTY THROUGHOUT THE DAY AND TONIGHT BEFORE DISSIPATING BY FRIDAY. BECAUSE OF THE GUSTY WINDS...THE SEAS WILL TAKE A BIT TO RELAX BELOW 5 FT. THEREFORE HAVE EXTENDED SCA ACCORDINGLY. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... FRI NIGHT THROUGH SAT MORNING...LIGHT BUT PERSISTENT EAST TO NORTHEAST FLOW WILL KEEP SEAS ELEVATED ABOVE SMALL CRAFT ADVISORY THRESHOLDS FOR WATERS SOUTH AND EAST OF NEW ENGLAND. SAT AFTERNOON AND NIGHT...A BRIEF PERIOD OF NW FLOW BEHIND A WEAK LOW PRES TROUGH. SEAS MAY SUBSIDE BRIEFLY TO BELOW 5 FT OVER THE OUTER WATERS. SUNDAY...HIGH PRESSURE AND A RETURN OF NORTHEAST WIND FLOW. SEAS ONCE AGAIN BUILDING TO JUST ABOVE THE 5 FT THRESHOLD. MONDAY...AS THE HIGH MOVES OFFSHORE...WINDS SHIFT TO THE SOUTHWEST AND BECOME GUSTY...ESPECIALLY OVER THE WATERS EAST OF MA. THEY COULD REACH 20 TO 25 KT AT TIMES. SEAS EXPECTED TO REMAIN ON THE ORDER OF 3 TO 5 FT. && .HYDROLOGY... SEVERAL POINTS ALONG THE CT RIVER ARE FLOODING OR WILL BE IN MINOR FLOOD SOON. WARNINGS CONTINUE FOR THE CT RIVER AT... THOMPSONVILLE HARTFORD MIDDLE HADDAM MONTAGUE NORTHAMPTON RAINFALL ON TUESDAY AND SNOWMELT OVER THE LAST FEW DAYS HAS THE MAINSTEM CT RIVER IN MINOR FLOOD...ALTHOUGH PROJECTED TO GO INTO MODERATE FLOOD AT MIDDLE HADDAM. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 3 AM EDT FRIDAY FOR ANZ231>235-237. SMALL CRAFT ADVISORY UNTIL 8 PM EDT FRIDAY FOR ANZ250-254-255. SMALL CRAFT ADVISORY UNTIL 2 PM EDT FRIDAY FOR ANZ256. && $$ SYNOPSIS...DUNTEN/FIELD NEAR TERM...FIELD/DUNTEN SHORT TERM...DUNTEN LONG TERM...FIELD AVIATION...DUNTEN/FIELD MARINE...DUNTEN/FIELD HYDROLOGY...STAFF

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