Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 231930 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 330 PM EDT WED APR 23 2014 .SYNOPSIS...
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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.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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UPPER LOW AND COLD POOL ARE SLOWLY MOVING EAST OF MASSACHUSETTS. EXPECT LINGERING SHOWERS TO DIMINISH. THE PRESSURE GRADIENT IS ALSO INCREASING WITH PRESSURE CHANGES OF 3-4MB/6 HOURS EXPECTED THIS EVENING. WE/VE SEEN STRONGER...BUT THIS SHOULD BE ENOUGH TO KEEP THE SUSTAINED WIND MOVING THROUGH THIS EVENING. TONIGHT... CLOUD-LEVEL MOISTURE DIMINISHES OVERNIGHT BUT WITH VALUES AROUND 70 PCT LINGERING BELOW 850 MB. EXTRAPOLATION OF THE BACK CLOUD EDGE OVER ONTARIO WOULD BRING IT TO THE CT VALLEY AROUND 1230- 1 AM. WE WILL CONTINUE TO FEATURE A CLEARING TREND AFTER MIDNIGHT. 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. WE USED A RANGE OF UPPER 20S AND 30S.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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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.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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HIGHLIGHTS... * UNSETTLED BUT SEASONABLE WEATHER LATE FRIDAY INTO SATURDAY * UNCERTAINTY HIGHER THAN NORMAL FOR EARLY NEXT WEEK 23/00Z MODELS ARE IN DECENT AGREEMENT THROUGH THE LONG TERM THOUGH THE GFS LEANS MORE TOWARDS A BLOCKED PATTERN EARLY NEXT WEEK THAN THE ECMWF. HIGH PRESSURE AND A MID LEVEL RIDGE BUILD OVER SOUTHERN NEW ENGLAND THROUGH FRIDAY. THEN LOW PRESSURE MOVING NORTH OF THE REGION WILL PULL A COLD FRONT THROUGH SOUTHERN NEW ENGLAND LATE FRIDAY INTO SATURDAY. THERE ARE SOME DIFFERENCES IN THE EXACT TRACK OF THE LOW AND THE SPEED OF THE COLD FRONT THROUGH SOUTHERN NEW ENGLAND BUT THERE IS LITTLE DIFFERENCE IN THE SENSIBLE WEATHER. BEYOND THIS...A BLOCKING PATTERN DEVELOPS ON BOTH THE ECMWF AND THE GFS...THOUGH THE GFS IS STRONGER WITH THIS BLOCK. STRONG MID LEVEL TROUGH EITHER OVER SOUTHERN NEW ENGLAND OR JUST EAST OVER THE MARITIMES RESULTS IN AN UNSETTLED NORTHWESTERLY FLOW OVER SOUTHERN NEW ENGLAND. THE ECMWF IS A BIT MORE PROGRESSIVE WITH THIS TROUGH ALLOWING MID LEVEL RIDGING TO REACH SOUTHERN NEW ENGLAND BY TUESDAY. CONFIDENCE IS LOWER THAN NORMAL FOR EARLY NEXT WEEK BECAUSE OF THIS. FRIDAY...HIGH PRESSURE BUILDS OVER SOUTHERN NEW ENGLAND WITH ACCOMPANYING QUIET WEATHER. TEMPERATURES WILL BE SEASONABLE. FRIDAY NIGHT AND SATURDAY...LOW PRESSURE MOVES EASTWARD NORTH OF SOUTHERN NEW ENGLAND. THE ECMWF IS A FARTHER NORTH SOLUTION WITH THE LOW MOVING THROUGH QUEBEC WHILE THE GFS MOVES THE LOW THROUGH NORTHERN NEW ENGLAND. REGARDLESS...THIS WILL RESULT IN A COLD FRONT MOVING ACROSS SOUTHERN NEW ENGLAND SATURDAY. SCATTERED SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM OR TWO WILL PRECEDE THE COLD FRONT. SUNDAY INTO EARLY NEXT WEEK...AS STATED ABOVE A MORE BLOCKED PATTERN LOOKS TO DEVELOP WITH MID LEVEL TROUGHING OVER THE NE BRINGING UNSETTLED WEATHER TO THE REGION. DRY WEATHER IS CURRENTLY FORECAST FOR SUNDAY WITH RAIN CHANCES INCREASING THROUGH MID WEEK.
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&& .AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
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LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THURSDAY/... VFR WITH GUSTY NORTHWEST WINDS TONIGHT AND THURSDAY. WINDS ALOFT WILL BE TAPPED FOR THE STRONG GUSTS. THOSE WINDS WILL INCREASE TO AROUND 30 KNOTS TONIGHT AND AT LEAST 35 KNOTS ON THURSDAY. THERE IS SOME POTENTIAL FOR 40 KNOT GUSTS. THE BACK EDGE OF THE CLOUD COVER SHOULD REACH THE CT VALLEY BY 1 AM...AND THE COASTAL PLAIN BY DAWN. ONCE SKIES CLEAR...EXPECT THEM TO REMAIN CLEAR OR MOSTLY CLEAR THROUGH THURSDAY AND THURSDAY NIGHT. KBOS TERMINAL...VFR. MODERATE CONFIDENCE TONIGHT AND HIGH CONFIDENCE THURSDAY. KBDL TERMINAL...VFR. HIGH CONFIDENCE IN TAF. OUTLOOK...FRIDAY THROUGH SUNDAY... FRIDAY...HIGH CONFIDENCE. VFR. FRIDAY NIGHT AND SATURDAY...MODERATE CONFIDENCE. MAINLY VFR. BRIEF PERIODS OF MVFR/IFR CONDITIONS IN RAIN SHOWERS/FOG. SUNDAY...MODERATE CONFIDENCE. VFR.
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&& .MARINE...
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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 SUNDAY... 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. SMALL CRAFT ADVISORIES MAY BE NECESSARY ON THE OUTER WATERS. SUNDAY...MODERATE CONFIDENCE. WINDS SHIFT TO NW AND INCREASE AS COLD FRONT CROSSES THE WATERS. SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED.
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&& .FIRE WEATHER...
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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.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...GALE WARNING UNTIL 8 PM EDT THURSDAY FOR ANZ230>237-250-251- 254>256.
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&& $$ SYNOPSIS...WTB/RLG NEAR TERM...WTB SHORT TERM...WTB LONG TERM...RLG AVIATION...WTB/RLG MARINE...WTB/RLG FIRE WEATHER...

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