Area Forecast Discussion
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000 FXUS61 KBOX 151956 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 356 PM EDT WED APR 15 2015 .SYNOPSIS...
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HIGH PRESSURE TODAY PROVIDES DRY WEATHER AND WARMER THAN NORMAL TEMPERATURES. DRY BUT SEASONABLY COOL WEATHER FOLLOWS THURSDAY. HIGH PRESSURE MOVES OFFSHORE FRIDAY WHILE LOW PRESSURE RACES ACROSS EASTERN CANADA. A SECOND LOW...TRAILING THE FIRST ONE...WILL SWING A COLD FRONT ACROSS SOUTHERN NEW ENGLAND ON 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/... 2 PM UPDATE... THE FEW BANDS OF CIRRUS CLOUDS THAT WERE FLIRTING ALONG THE S COAST HAVE PUSHED OFFSHORE...THOUGH STILL SEE A COUPLE OF SPOTS WITH SOME HIGH CLOUDS HANGING NEAR THE ISLANDS AT 18Z. WITH LARGE HIGH PRES PUSHING E OUT OF QUEBEC AND THE GREAT LAKES...EXPECT THESE CLOUDS TO REMAIN S OF THE REGION THROUGH THE REMAINDER OF THE DAY. HAVE NOTED A FEW DIURNAL CUMULUS CLOUDS HAVE DEVELOPED ACROSS E MA INTO RI AROUND MIDDAY...BUT SHOULD SEE THOSE DISSIPATE BY 21Z-22Z. N-NE WINDS ACROSS EASTERN AREAS AND N-NW WINDS ACROSS THE CENTRAL AND WEST HAVE PICKED UP...WITH BRIEF GUSTS OVER 25 KT IN THE CT VALLEY AROUND MIDDAY /NOTED 32 KT GUST AT KBDL AT 17Z/ BUT LOOK TO BE DIMINISHING ACROSS W MA/N CENTRAL CT AT 18Z. A SEA BREEZE HAS ACTUALLY KICKED AT KBOS AT 18Z. CURRENT FORECAST LOOKS ON TRACK...BUT HAVE UPDATED NEAR TERM TO BRING CONDITIONS CURRENT. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... TONIGHT... WINDS RELAX AS HIGH PRESSURE BUILDS INTO THE REGION. EXPECTING LIGHT AND VARIABLE WINDS UNDER MOSTLY CLEAR CONDITIONS. SHOULD SEE DECENT RADIATIONAL COOLING AND THUS HAVE GONE WITH A CONSENSUS BLEND OF MOS GUIDANCE...DROPPING IT A COUPLE OF DEGREES ESPECIALLY IN SUSCEPTIBLE LOW-LYING AREAS PRONE TO RADIATIONAL COOLING. FROST AND FREEZE HEADLINES ARE NOT NECESSARY AT THIS TIME AS THE GROWING SEASON DOES NOT BEGIN TILL APRIL 21ST FOR LOW- LYING COASTAL AREAS. THURSDAY... HIGH PRESSURE PUSHES E ALLOWING FOR RETURN S-FLOW. MOSTLY CLEAR FORECAST WITH LOW DEWPOINTS AS TEMPERATURES WARM TO THE 60-DEGREE MARK. CONTINUED BOUNDARY-LAYER MIXING ALBEIT LIMITED TO H9 BY A DRY-AIR INVERSION. INFLUENCE OF HIGH PRESSURE SHOULD KEEP WINDS BELOW THE 25 MPH THRESHOLD...CAN NOT RULE OUT GUSTS UP TO 20 MPH WITH THE MIX-DOWN OF FASTER MOMENTUM AND DRIER AIR. WILL NEED TO RE-EVALUATE WITH THE NEXT FORECAST PERIOD WITH RESPECT TO THE FIRE WEATHER ENVIRONMENT. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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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.
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&& .AVIATION /20Z WEDNESDAY 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/...HIGH CONFIDENCE. THROUGH 00Z...VFR. N-NW WINDS GUSTING TO 25 KT THROUGH 19Z-20Z THEN DIMINISHING. E-NE WINDS FROM KBOS SOUTH TO CAPE COD AND THE ISLANDS IN PLACE...EXCEPT BRIEF SEA BREEZE AT KBOS THAT WILL BECOME E-NE BY AROUND 21Z. TONIGHT...VFR SKC. WINDS BECOME LIGHT/VRBL OR CALM AS HIGH PRES BUILDS OVER. THURSDAY...VFR. SKC THROUGH MIDDAY...THEN HIGH CLOUDS START TO MOVE INTO WESTERN AREAS DURING THE AFTERNOON. LIGHT E-SE WINDS VEER TO S AND INCREASE TO AROUND 10 KT DURING THE AFTERNOON. KBOS TAF...HIGH CONFIDENCE IN TAF. BRIEF SEA BREEZE SHOULD BECOME E-NE BY AROUND 21Z. 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 NORTHWST 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/...HIGH CONFIDENCE. THIS AFTERNOON...EXPECT N-NE WINDS GUSTING UP TO 25 KT. SEAS REMAIN BELOW 5 FT...BUT MAY POSSIBLY SEE BRIEF SWELLS UP TO 5 FT ACROSS THE FAR SOUTHERN OUTER WATERS. TONIGHT AND THURSDAY...LIGHT AND VARIABLE WINDS OVERNIGHT AS HIGH PRES MOVES ACROSS THE WATERS...THEN SHIFTS E ON THURSDAY ALLOWS FOR RETURN S FLOW THAT BECOMES BRISK WITH GUSTS UP TO 20 KTS TOWARDS THE END OF THE DAY. 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... 2 PM UPDATE... NOTED ERROR ON DEWPT AT MARTHAS VINEYARD DUE TO PROBLEMS WITH THE DEWPT SENSOR AT THE AIRPORT. BACKUP DEWPT SENSOR REPRESENTATIVE OF REGION...REPORTING 27 DEGREES AT 18Z. DEWPTS HAVE ACTUALLY RISEN ACROSS SE MA AS WINDS HAVE SHIFTED TO E-NE THROUGH MIDDAY. ELSEWHERE...DEWPTS REMAIN IN THE TEENS TO LOWER 20S WITH RH VALUES REMAINING IN THE 15-20 PERCENT. GUSTY N-NW WINDS BRIEFLY KICKED ON ACROSS THE CT VALLEY INTO N CENTRAL MA...BUT APPEAR TO BE DIMINISHING AFTER 17Z. RED FLAG CONTINUES FOR MOST OF MASSACHUSETTS THROUGH THE AFTERNOON...NOTING SOME BRUSH FIRE REPORTS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR MAZ002>023- 026. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...WTB/SIPPRELL NEAR TERM...EVT SHORT TERM...SIPPRELL LONG TERM...WTB AVIATION...WTB/SIPPRELL/EVT MARINE...WTB/SIPPRELL/EVT FIRE WEATHER...

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