Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 240540 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 140 AM EDT THU APR 24 2014 .SYNOPSIS... LOW PRESSURE MOVES OFF THROUGH THE MARITIMES AND DRAWS ANY LINGERING SHOWERS OUT OF SOUTHERN NEW ENGLAND. WINDY AND DRYING CONDITIONS FOLLOW FOR TONIGHT AND THURSDAY AS HIGH PRESSURE APPROACHES. WINDS THEN DIMINISHING THURSDAY NIGHT AND FRIDAY AS HIGH PRESSURE BUILDS OVERHEAD. UNSETTLED WEATHER IS LIKELY FOR A PORTION OF THE WEEKEND WITH SEASONABLE TEMPS AT THE START OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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140 AM UPDATE... DRIER AIR IS ADVECTING INTO THE REGION AS DEWPOINTS DROP INTO THE 20S AND THIS HAS RESULTED IN CLEARING SKIES. CLOUDS WILL LINGER ACROSS E COASTAL MA AND CAPE/ISLANDS. PREVIOUS DISCUSSION... MID LEVEL LOW JUST OFFSHORE WITH BACK EDGE OF RAIN SHIELD EAST OF THE CAPE. STILL LOTS OF CLOUD COVER ACROSS THE REGION BUT PARTIAL CLEARING DEVELOPING TO THE WEST IN NEW YORK STATE. THIS CLEARING WILL MOVE INTO SNE OVERNIGHT FROM WEST TO EAST...BUT CLOUDS WILL LIKELY LINGER THROUGH THE NIGHT OVER THE CAPE/ISLANDS AND POSSIBLY E COASTAL MA. COLD ADVECTION ALOFT WILL PROMOTE MIXING OF STRONGER WINDS ALOFT...WITH VALUES OF 30 KNOTS EXPECTED ALOFT OVERNIGHT. WE WILL FORECAST NORTHWEST GUSTS TO 30 KNOTS. THE WIND WILL KEEP THE AIRMASS MIXED. SO NO RADIATIONAL COOLING. DEWPOINTS FALLING INTO THE 20S WILL ALLOW ROOM FOR TEMPS TO FALL. BUT WITH WINDS STAYING UP...TEMPS SHOULD STAY A LITTLE HIGHER. EXPECTED MINS WILL BE MOSTLY IN THE 30S.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... HIGH PRESSURE SURFACE AND ALOFT WILL APPROACH FROM THE WEST ON THURSDAY AND BUILD OVER NEW ENGLAND THURSDAY NIGHT. EXPECT MOSTLY SUNNY SKIES. ANY LINGERING CLOUDS IN EASTERN MASS SHOULD QUICKLY MOVE OFF. FULL APRIL SUN SHOULD BE ABLE TO MIX TO AT LEAST 850 MB...THIS IS INDICATED IN THE MODEL FORECASTS. GIVEN THE MODEL CAPABILITY OF UNDERESTIMATING THE MIXING DEPTH...MIXING COULD REACH TO 825 MB OR 800 MB. EXPECT PRESSURE GRADIENT AND MIXING TO MAINTAIN STRONG GUSTY NORTHWEST WINDS. WINDS ALOFT IN THE MIXED LAYER WILL INCREASE TO 35 KNOTS...WITH POTENTIAL TO REACH 40 KNOTS. WE WILL FEATURE GUSTS TO 35 KNOTS/40 MPH AND MONITOR FOR STRONGER WINDS. TEMPS AT 850 MB WILL BE -2C TO -3C...SUPPORTING MID 50S. TEMPS AT 800 MB WILL BE AROUND -3C TO -4C...EQUIV TO 1-2C AT 850...AND WOULD SUPPORT LOWER 60S. FORECAST MAX TEMPS WILL BE IN THE 50S...BUT AROUND 60 IN A FEW WARM SPOTS. IF MIXING GOES DEEPER THAN 850 MB THEN TEMPS COULD BUMP UP 3-4 DEGREES. HIGH PRESSURE MOVES INTO NEW ENGLAND THURSDAY NIGHT. THIS WILL DIMINISH THE PRESSURE GRADIENT AND ALLOW WINDS TO DIMINISH INLAND. EXPECT MIN TEMPS AGAIN IN THE UPPER 20S AND 30S. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... HIGHLIGHTS... * UNSETTLED BUT SEASONABLE WEATHER LATE FRIDAY INTO SATURDAY * UNSEASONABLE TEMPS AND UNSETTLED WEATHER NEXT WEEK MODELS AND CONFIDENCE... 12Z SYNOPTIC PATTERN IS IN GOOD AGREEMENT...HOWEVER AT THE SURFACE THERE ARE MANY VARIABLES WHICH HAS CAUSED DIFFERENCE AMONGST THE MODELS. OVERALL CONTINUED FOCUSING THE FORECAST BASE ON THE ENSEMBLES AS THE DETERMINISTIC GUIDANCE IS VERY SPREAD OUT...THUS LEADING TOWARDS A LOW CONFIDENCE FORECAST ESP FOR NEXT WEEK. QUICK MOVING SHORTWAVE OVER THE GREAT LAKES WILL MOVE INTO THE REGION PUSHING A COLD FRONT THROUGH NEW ENGLAND BY SATURDAY. UPPER LEVEL LOW WILL CONTINUE TO INFLUENCE THE REGION AS LOW WILL ROTATE THROUGH THE MARITIMES. HOWEVER A CLOSED TROUGH/LOW OVER THE ROCKIES ON MONDAY WILL EVENTUALLY BE FORCED EASTWARD ACROSS THE EASTERN US BY WED IN A DEVELOPING REX BLOCK SETUP AS WARMING RIDGES BUILD STRONGLY OVER THE WRN US. DETAILS... FRIDAY... HIGH PRESSURE WILL MOVE OFFSHORE DURING THE DAY ON FRIDAY BUT CONTINUE TO ALLOW FOR DRY WEATHER AND SUNNY SKIES TO START THE DAY. WINDS WILL BE RELATIVELY LIGHT WITH MAX TEMPS IN THE LOW TO MID 60S DUE TO RETURN FLOW FROM THE SOUTH. CONDITIONS ALONG THE COASTLINES WILL BE COOLER AS SEABREEZES DEVELOP. FRIDAY NIGHT INTO SATURDAY... UPPER LEVEL LOW WILL APPROACH THE REGION OVER THE WEEKEND RESULTING IN A WET WEATHER. THE EC WANT TO DEVELOP A SURFACE LOW ALONG THE FRONT RESULTING IN MORE QPF VERSUS THE GFS WHICH JUST PUSHES THE FRONT THROUGH THE REGION. REGARDLESS IT APPEARS TO RAIN SOMETIME ACROSS THE REGION BEGINNING SATURDAY MORNING LASTING INTO THE OVERNIGHT HOURS. LOW CONFIDENCE ON EXACT LOCATION AND OVERALL TIMING. GUIDANCE DOES INDICATE SOME ELEVATED INSTABILITY MOVING THROUGH ON SATURDAY SO HAVE INSERTED ISO THUNDER FOR NOW. HOPEFULLY OVER THE NEXT FEW RUNS MODELS WILL BECOME MORE IN-LINE WITH ONE ANOTHER. OTHERWISE WITH SOUTHERLY FLOW AHEAD OF THE APPROACHING SYSTEM EXPECT TEMPS TO WARM UP INTO THE LOW TO MID 60S ON SATURDAY. AS THE SYSTEM PASSES...WINDS WILL SWITCH MORE TO THE NORTH OR NORTHWEST RESULTING IN HIGHS BACK DOWN INTO THE UPPER 50S TO LOW 60S BY SUNDAY. SUNDAY TEMPS MAY BE COOLER THEN FORECASTED AS NW FLOW ON THE BACKSIDE OF THE LOW COULD YIELD TO ANOTHER COLD CORE LOW SITUATION. THE EC IS MORE AGGRESSIVE SHOWING THIS WHERE AS THE GFS IS WARMER. MONDAY INTO TUESDAY NORTHWESTERLY FLOW WILL CONTINUE ON MONDAY AND TUESDAY. CONDITIONS LOOK TO BE BREEZY ON MONDAY WITH THE DEPARTING LOW MOVING OFFSHORE AND WEAK HIGH PRESSURE TRYING TO MOVE INTO THE REGION...INCREASING THE PRESSURE GRADIENT. TEMPERATURES WILL BE CLOSE TO AVERAGE. MID NEXT WEEK... NORTHERLY FLOW WILL CONTINUE WITH A POSSIBLE WARM FRONT ACROSS THE MID-ATLANTIC INTO THE SOUTHERN NEW ENGLAND BY LATE TUES/WED. HOWEVER WILL NEED TO WATCH WHERE EXACTLY THE LOW PRESSURE SETS UP. IF IT IS SOUTH OF THE REGION THEN WE COULD SEE BELOW AVERAGE TEMPS DUE TO THE EASTERLY FLOW AS WELL AS UNSETTLED WEATHER. && .AVIATION /06Z 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 VFR THROUGH THE PERIOD. MAIN CONCERN WILL BE GUSTY NW WINDS TODAY AS GUSTS TO 35-40 KT EXPECTED. WINDS WILL GRADUALLY DIMINISH TONIGHT WITH LIGHT WINDS FRIDAY. KBOS TERMINAL...HIGH CONFIDENCE IN TAF. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... FRIDAY NIGHT AND SATURDAY...MODERATE CONFIDENCE. MAINLY VFR. BRIEF PERIODS OF MVFR IN SCT -SHRA. LOW PROB OF SOME ISO THUNDER ON SATURDAY. SUNDAY AND MONDAY...MODERATE CONFIDENCE. VFR. SOME SHOWERY WEATHER POSSIBLE.
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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 THURSDAY/...HIGH CONFIDENCE. LOW PRESSURE MOVES OFF THROUGH THE GULF OF MAINE. COOLER AIR DRAWN ACROSS NEW ENGLAND AND THE COASTAL WATERS TONIGHT AND THURSDAY...THIS WILL PROMOTE BRINGING STRONGER WIND GUSTS DOWN FROM ALOFT. WINDS AT THOSE HIGHER LEVELS WILL INCREASE TO 35 KNOTS DURING TONIGHT AND 35-40 KNOTS ON THURSDAY. THESE WINDS WILL ALSO DRIVE THE SEA HEIGHT TO 5-8 FEET TONIGHT AND THURSDAY. GALE WARNINGS ARE IN EFFECT FOR ALL NEW ENGLAND WATERS THROUGH THURSDAY EVENING. HIGH PRESSURE THEN BUILDS OVER THE WATERS LATE THURSDAY AND THURSDAY NIGHT. EXPECT DIMINISHING WINDS AND SEAS THURSDAY NIGHT...WITH HEADLINES STEPPING DOWN THROUGH SMALL CRAFTS BEFORE ENDING OVERNIGHT. THE OUTER WATERS WILL LIKELY MAINTAIN SMALL CRAFT HEADLINES THROUGH FRIDAY MORNING. OUTLOOK...FRIDAY THROUGH MONDAY... FRIDAY...MODERATE CONFIDENCE. SEAS ON THE OUTER WATERS MAY REMAIN ABOVE 5 FEET FOR A PORTION OF THE DAY. OTHERWISE...QUIET BOATING WEATHER. SATURDAY...LOW TO MODERATE CONFIDENCE. SW WINDS AND SEAS INCREASE AS A COLD FRONT APPROACHES THE WATERS. VISIBILITIES MAY BE REDUCED AT TIMES IN RAIN SHOWERS AND ISO THUNDER. SMALL CRAFT ADVISORIES MAY BE NECESSARY ON THE OUTER WATERS. SUNDAY INTO MONDAY...MODERATE CONFIDENCE. WINDS SHIFT TO NW AND INCREASE AS COLD FRONT CROSSES THE WATERS. WINDS WILL CONTINUE TO BLOW OUT OF THE NW ON MONDAY AND BE BREEZY AS WELL. SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED. && .FIRE WEATHER... WEATHER CONDITIONS THURSDAY ARE FAVORABLE FOR FIRE WEATHER HEADLINES...MIN RH 20-30 PCT WITH DRIEST VALUES IN THE CT VALLEY AND NORTHWEST WIND GUSTS TO 35 KNOTS/40 MPH MOST AREAS. BUT AFTER COORDINATION WITH STATE CONTACTS IT IS CLEAR THAT NON-WEATHER FACTORS ARE NOT FAVORABLE AT THIS TIME. SO WE HAVE OPTED FOR NO FIRE WEATHER HEADLINES. WE WILL CONTINUE TO MONITOR THIS MULTI- FACETED SITUATION AND UPDATE AS NEEDED. && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...GALE WARNING UNTIL 8 PM EDT THIS EVENING FOR ANZ230>237-250- 251-254>256.
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&& $$ SYNOPSIS...WTB/DUNTEN NEAR TERM...KJC SHORT TERM...WTB LONG TERM...DUNTEN AVIATION...KJC/DUNTEN MARINE...WTB/DUNTEN FIRE WEATHER...

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