Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 160213 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1013 PM EDT WED APR 15 2015 .SYNOPSIS...
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HIGH PRESSURE WILL MOVE OVER NEW ENGLAND TONIGHT INTO THURSDAY... MOVING OFFSHORE THURSDAY EVENING. WEAK LOW PRESSURE WILL CROSS THE REGION LATE THURSDAY NIGHT INTO FRIDAY. A SECOND LOW AND ASSOCIATED COLD FRONT WILL CROSS SOUTHERN NEW ENGLAND SATURDAY. HIGH PRESSURE BRINGS DRY WEATHER ON SUNDAY. A MIDWEST SYSTEM FORMS OVER THE PLAINS SUNDAY AND SWINGS UP THROUGH THE GREAT LAKES MONDAY...AND MAY BRING RAIN TO SOUTHERN NEW ENGLAND FROM PATRIOTS DAY AFTERNOON INTO TUESDAY.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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10 PM UPDATE... NO MAJOR CHANGES TO THE FORECAST. WINDS BECOMING LIGHT AS HIGH PRESSURE SETTLES ACROSS THE REGION. UNDER MOSTLY CLEAR CONDITIONS WITH DEWPOINTS RANGING AROUND THE UPPER-TEENS TO LOW-20S...SHOULD SEE A FEW SPOTS FALL TO LOWS BELOW THE 30-DEGREE MARK. RADIATIONAL COOLING AT ITS BEST.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... THURSDAY... HIGH PRES WILL DOMINATE DURING THE DAY WITH CONTINUED DRY CONDITIONS. HOWEVER...EXPECT LIGHT/VRBL OR CALM WINDS TO START... THEN WILL BECOME S-SW UP TO AROUND 10 KT DURING THE AFTERNOON. WILL START TO SEE SOME HIGH CLOUDS FILTER INTO WESTERN AREAS LATE IN THE DAY. EXPECT HIGHS RANGE FROM THE LOWER-MID 50S ALONG THE IMMEDIATE COAST TO THE LOWER-MID 60S WELL INLAND. THURSDAY NIGHT... HIGH PRES PUSHES OFFSHORE THU EVENING...WITH SW WINDS AT 10-15 KT WITH SOME GUSTS TO 20 KT POSSIBLE ALONG THE OUTER CAPE. DECENT H5 SHORT WAVE WITH SURFACE REFLECTION MOVING STEADILY E TOWARD THE REGION IN BROAD W-SW FLOW ALOFT. CLOUDS WILL INCREASE DURING THE NIGHT...BUT LOOKS LIKE PRECIP HOLDS OFF ACROSS THE E SLOPES OF THE BERKSHIRES AND CT VALLEY UNTIL WELL AFTER MIDNIGHT...AND ONLY CHANCE POPS AT THAT. EXPECT LOWS TO FALL BACK TO THE LOWER TO MID 40S...BUT MIGHT SNEAK TO THE UPPER 30S ACROSS THE HIGHER TERRAIN OF N CENTRAL AND NW MA. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... BIG PICTURE...ACTIVE NORTHERN STREAM ACROSS CANADA AND THE NORTHEAST USA WITH TWO SHORTWAVES THAT WILL MOVE ACROSS NEW ENGLAND FRIDAY AND SATURDAY. CLOSED LOW OVER THE DESERT SOUTHWEST SLOWLY EJECTS INTO THE PLAINS OVER THE WEEKEND AND MERGES WITH A THIRD NORTHERN STREAM SHORTWAVE. THIS RECREATES THE CLOSED LOW BY TUESDAY...THIS TIME OVER THE GREAT LAKES...WITH A BROAD SOUTHWEST FLOW FEEDING INTO NEW ENGLAND. THE GFS SOLUTION IS TRENDING TOWARD THE ECMWF SOLUTION WHILE THE ECMWF SOLUTION IS A TAD FASTER THAN ITS ENSEMBLES. OUR SOLUTION WILL FAVOR THE SLOWER END OF THE ECMWF DATA. OUR NORMAL BLENDED DATA WILL BE AFFECTED BY THE FASTER GFS TIMING...SO WE WILL THROW ADDED WEIGHT ON THE ECMWF VALUES OF THE BLEND TO SLOW THINGS DOWN. THE DAILIES... FRIDAY... WEAK SHORTWAVE MOVES THROUGH THE NORTHERN STREAM ACROSS NEW ENGLAND. MODEL DATA SHOWS NO SUPPORTING JET...JUST A WRINKLE IN THE FLOW. MOISTURE PROFILES SHOW HIGH-RH UP TO 700 MB WITH LIFT PRESENT BELOW 700 MB. SURFACE VALUES DO SHOW A THETA-E RIDGE CROSSING SOUTHERN NEW ENGLAND DURING THE DAY AND MOVING OFFSHORE IN THE EVENING. CONVECTIVE PARAMETERS ARE NOT IMPRESSIVE. THIS LEADS TO CONFIDENCE THAT THERE WILL BE SHOWERS BUT WITH SIGNIFICANT BREAKS OF DRY WEATHER IN BETWEEN. WILL INCREASE POPS FROM PREVIOUS FORECAST. TEMPERATURES ALOFT SUPPORT MAX SFC VALUES EITHER SIDE OF 60. FRIDAY NIGHT...SHORTWAVE MOVES OFF BUT SURFACE FLOW REMAINS WEST- SOUTHWEST. EXPECT PARTIAL CLEARING AND LIGHT WIND AND DEW POINTS IN THE 40S...THIS SHOULD SUPPORT LOWS IN THE 40S. SATURDAY... SECOND SHORTWAVE MOVES THROUGH THE NORTHERN STREAM ACROSS NEW ENGLAND...SWINGING A COLD FRONT ACROSS NEW ENGLAND. THIS SHORTWAVE IS SHARPER AND SUPPORTED BY A 100 KNOT JET. BUT IT CARRIES LESS OF A THETA-E RIDGE AND ALSO SHOWS POOR CONVECTIVE PARAMETERS. WILL CONTINUE WITH CHANCE POPS HIGHEST NORTH AND EAST. MIXING SHOULD REACH TO NEAR 850 MB BY AFTERNOON. FORECAST WINDS IN THE MIXED LAYER REACH 25 KNOTS WHICH POINTS TO NORTHWEST GUSTS NEAR THAT SPEED AFTER FRONTAL PASSAGE. TEMPERATURES AT 850 MB AT 7-8C SUPPORT MAX SFC TEMPS 67-72F. UPPER TROUGH AND COLD POOL MOVE ACROSS DURING THE AFTERNOON AND NIGHT. THIS MAY HOLD ONTO A FEW CLOUDS AT FIRST...BUT THE TREND OVERNIGHT SHOULD BE FOR DIMINISHING SKY COVER. SUNDAY... HIGH PRESSURE CENTERED OVER CANADA BUILDS SURFACE AND ALOFT OVER NEW ENGLAND. TEMPS ALOFT 0-2C SUGGEST MAX SFC TEMPS AROUND 60 OR THE LOWER 60S. PATRIOTS DAY AND TUESDAY... DEVELOPING MIDWEST SYSTEM WITH 50-KNOT SOUTH LOW LEVEL JET. BASED ON THE ECMWF...THIS JET IS AIMED ACROSS THE MID ATLANTIC STATES AND CENTRAL NEW YORK AT 12Z MONDAY AND IS JUST EDGING INTO WESTERN NEW ENGLAND AT 18Z MONDAY. THE JET CROSSES SOUTHERN NEW ENGLAND MONDAY EVENING AND NIGHT. SYSTEM REMAINS IN PLACE THROUGH TUESDAY...THEN MOVES OFF TO THE NORTHEAST TUESDAY NIGHT.WITH THE UPPER LOW SITTING OVER THE GREAT LAKES...EXPECT A BROAD SOUTHWEST FLOW ALOFT THAT WOULD OPEN UP THE ENTIRE EAST COAST TO GULF OF MEXICO MOISTURE. PRECIPITABLE WATER VALUES ARE FORECAST BETWEEN 1.0 INCH AND 1.5 INCHES WHICH IS ABOUT 2 STD DEVIATIONS ABOVE NORMAL FOR APRIL. THIS SUGGESTS INCREASING POTENTIAL FOR RAIN ON MONDAY...MOSTLY DURING THE AFTERNOON AND EVENING...WITH THE BEST CHANCE MONDAY NIGHT. POTENTIAL FOR A GOOD SOAKING. WEDNESDAY... UPPER LOW REMAINS IN PLACE TO OUR WEST WITH COLD POOL ALOFT EXTENDING OVER NEW ENGLAND...ESPECIALLY NORTHERN NEW ENGLAND. THIS SUGGESTS LINGERING CLOUDS...THICKEST NORTH...AND SCATTERED SHOWERS. && .AVIATION /02Z THURSDAY THROUGH MONDAY/...
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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 NIGHT/...HIGH CONFIDENCE. INTO THURSDAY... VFR. LIGHT / VRB WINDS OVERNIGHT INTO EARLY THURSDAY. WINDS TURNING S THROUGH THE DAY WITH INCREASING HIGH-CLOUD LATE. WINDS TO REMAIN LIGHT AROUND 10 KT BY AFTERNOON. THURSDAY NIGHT... MAINLY VFR. MAY SEE MVFR VSBYS MOVE INTO W MA/N CENTRAL CT AFTER 06Z IN SCT SHOWERS. LOW PROB OF MVFR CIGS ACROSS NW MA TOWARD SUNRISE. KBOS TAF...HIGH CONFIDENCE IN TAF. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...FRIDAY THROUGH MONDAY...MODERATE CONFIDENCE. FRIDAY-SATURDAY...MODERATE CONFIDENCE. MAINLY VFR BUT WITH PERIODS OF MVFR IN SCATTERED RAIN SHOWERS. WEST-SOUTHWEST WIND SATURDAY MORNING BECOMES NORTHWEST SATURDAY AFTERNOON WITH GUSTS TO 25 KNOTS. SUNDAY...HIGH CONFIDENCE...VFR. DIMINISHING WIND. MONDAY...MODERATE CONFIDENCE...VFR IN THE MORNING. MVFR/IFR DEVELOPING BY NIGHT.
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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 NIGHT/...HIGH CONFIDENCE. 10 PM UPDATE...NO MAJOR CHANGES. TONIGHT...WINDS BECOMING LIGHT AND VARIABLE AS HIGH PRES APPROACHES. SEAS REMAIN BELOW 5 FT. THURSDAY...EXPECT LIGHT/VRBL WINDS EARLY TO SHIFT TO S-SW AT AROUND 10 KT OR SO DURING THE AFTERNOON AS THE HIGH PUSHES E OF THE WATERS. THURSDAY NIGHT...SW WINDS INCREASE...GUSTING UP TO 20 KT. SEAS MAY APPROACH 5 FT LATE ON THE EASTERN OUTER WATERS BUT SHOULD REMAIN BELOW SMALL CRAFT CRITERIA. OUTLOOK...FRIDAY THROUGH MONDAY...MODERATE CONFIDENCE. FRIDAY...A FEW SHOWERS SOUTHWEST WIND GUSTING TO 20 KNOTS. SEAS AROUND 5 FEET ON THE OUTER WATERS MAY REQUIRE A SMALL CRAFT ADVISORY. SATURDAY...LOW PRESSURE MOVING ACROSS EASTERN CANADA WILL SWING A COLD FRONT ACROSS THE WATERS IN THE AFTERNOON...WHICH MAY BRING A FEW SHOWERS. WEST-SOUTHWEST WINDS WILL TURN NORTHWEST AS THE FRONT PASSES. DURING THE DAY THE NEARSHORE WINDS MAY GUST NEAR 25 KNOTS BUT FARTHER TO SEA THE WINDS SHOULD REMAIN 15-20 KNOTS. SATURDAY NIGHT THE NEARSHORE WINDS WILL DIMINISH BUT THE OFFSHORE WINDS WILL INCREASE TO 20-25 KNOTS. EXPECT SEAS TO REMAIN BELOW 5 FEET. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR THE NORTHWEST WINDS. SUNDAY...DIMINISHING WIND AND SEAS AS HIGH PRESSURE BUILDS OVER EASTERN CANADA. DRY WEATHER. MONDAY...INCREASING EAST TO SOUTHEAST WINDS AS A LARGE WEATHER SYSTEM MOVES TO THE EASTERN USA COAST BRINING RAIN. WINDS MAY REACH 25 TO 30 KNOTS LATE IN THE DAY AND AT NIGHT. SEAS WILL BUILD TO 5 TO 10 FEET MONDAY AFTERNOON AND NIGHT. A SMALL CRAFT ADVISORY MAY BE NEEDED.
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&& .FIRE WEATHER... TONIGHT...WINDS ARE DIMINISHING AS TEMPERATURES COOL. THE FIRE WEATHER HEADLINE HAS BEEN ALLOWED TO EXPIRE. THURSDAY...HIGH PRESSURE WILL CONTINUE THE DRY CONDITIONS ACROSS THE REGION. HOWEVER...WINDS WILL BE LIGHT AND VARIABLE EARLY THEN SHIFTING AROUND TO S-SW AT AROUND 10 MPH. WHILE TEMP/DEWPT SPREADS WILL BE WIDE /DEWPTS REMAINING IN THE 20S EXCEPT LOWER 30S ALONG THE S COAST/...THE LACK OF WIND WILL BE A LIMITING FACTOR FOR ELEVATED FIRE CONDITIONS. NOT EXPECTING FIRE WEATHER HEADLINES AT THIS TIME. SCATTERED SHOWERS ARE FORECAST FOR LATE THU NIGHT AND FRIDAY AS A WEAK FRONT CROSSES THE REGION. RAINFALL AMOUNTS WILL BE ON THE ORDER OF 0.1 TO 0.2 INCHES...NOT A WHOLE LOT BUT WILL HELP SOMEWHAT WITH THE VERY DRY CONDITIONS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...WTB/EVT NEAR TERM...WTB/SIPPRELL/EVT SHORT TERM...EVT LONG TERM...WTB AVIATION...WTB/EVT MARINE...WTB/EVT FIRE WEATHER...WFO BOX STAFF

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