Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 250621 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 121 AM EST THU DEC 25 2014 .SYNOPSIS... STRONG LOW PRESSURE TRACKING ACROSS THE GREAT LAKES WILL BRING HEAVY RAINFALL AND GUSTY WINDS THROUGH CHRISTMAS. DRY WEATHER WITH ABOVE NORMAL TEMPERATURES WILL FOLLOW FROM CHRISTMAS AFTERNOON INTO SATURDAY. A COLD FRONT MAY BRING A FEW RAIN OR SNOW SHOWERS SUNDAY. ANOTHER STORM MAY AFFECT US LATE MONDAY INTO WEDNESDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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1 AM UPDATE... JUST A FEW SHOWERS MOVING ALONG THE S COAST AND COASTAL PLAIN EARLY THIS MORNING...OTHERWISE MAINLY DRY CONDITIONS. HOWEVER...HRRR SHOWS NEXT ROUND OF RAIN MOVING INTO THE REGION 09-12Z AS COLD FRONT ADVANCES EAST FROM CENTRAL NY. HIGH PWATS COMBINED WITH LOW LEVEL JET AND FRONTAL CONVERGENCE SUGGESTS LOCALLY HEAVY DOWNPOURS. SPC MESOANALYSIS SHOWS DECENT ELEVATED INSTABILITY ALONG THE S COAST WITH MUCAPES 500 J/KG SO CANT RULE OUT AN ISOLD TSTM ACROSS SE NEW ENG WITH A LOW PROB FOR A DEVELOPING FINE LINE ALONG THE FRONT...ALTHOUGH BEST INSTABILITY IS MODELED OFFSHORE AT TIME OF FROPA. SOME STRONGER WIND GUSTS TO ADVISORY CRITERIA HAVE OCCURRED IN SE MA WHERE TEMPS IN THE LOW TO MID 60S HAVE WEAKENED THE INVERSION. CONTINUED THREAT FOR GUSTS TO 35-40 KT IN SE MA AND RI UNTIL FROPA. AS OF 06Z...WARM FRONT HAS BEEN SLOW TO ADVANCE NWD ALONG THE NE MA COAST AS FRONT IS STILL S OF BOS...EXTENDING ACROSS CENTRAL MA INTO CENTRAL CT. LOW LEVEL COOL AIR HANGING TOUGH IN CT VALLEY. AS COLD FRONT APPROACHES...EXPECT WINDS TO BECOME SOUTHERLY WHICH WILL ALLOW TEMPS TO RISE RAPIDLY INTO THE 50S...BUT THIS MAY NOT HAPPEN UNTIL AFT 09Z IN CT VALLEY.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... CHRISTMAS DAY...HIGH CONFIDENCE. SHORT RANGE MODELS IN VERY GOOD AGREEMENT IN PUSHING FRONT OFFSHORE BY MID MORNING WITH LEFTOVER SHOWERS MOVING OFFSHORE AS DRY SLOT WORKS IN. WINDS SHIFT TO W-SW WITH DRIER AIR WORKING IN. LAPSE RATES STEEPEN ESPECIALLY FROM 900 HPA AND BELOW WHICH WILL ALLOW GOOD MIXING TO WORK IN. QUESTION IS HOW STRONG WILL THE GUSTS BE. AT THIS POINT...CONTINUED TO SEE WIND GUSTS JUST BELOW WIND ADVISORY CRITERIA...THOUGH COULD BE SOME MARGINAL GUSTS TO CRITERIA MAINLY ALONG THE S COAST...CAPE COD AND THE ISLANDS THU AFTERNOON. MIGHT ALSO SEE SOME HIGHER GUSTS ACROSS THE HIGHER INLAND TERRAIN OF THE WORCESTER HILLS AND MONADNOCKS AS WELL AS THE E SLOPES OF THE BERKSHIRES. KEPT ADVISORY THROUGH LATE MORNING ACROSS RI/SE MA...BUT MAY NEED TO EXTEND INTO THE AFTERNOON. WITH GENERAL OVERALL MID LEVEL STEERING CURRENTS FROM W-E...NOT MUCH COLD AIR TO TRANSPORT INTO THE REGION. TEMPS WILL HOLD IN THE 50S DURING THE MORNING BEFORE STARTING TO SLOWLY FALL BACK THU AFTERNOON WITH THE INCREASING WIND. CHRISTMAS NIGHT...HIGH CONFIDENCE. HIGH PRES RIDGE BEGINS TO BUILD E OUT OF THE APPALACHIANS. WINDS WILL SHIFT TO W-NW. WINDS WILL REMAIN GUSTY EARLY THU NIGHT...THEN WILL DIMINISH OVERNIGHT WITH DRY CONDITIONS. COLDER AIR REMAINS N OF THE REGION. WITH GENERALLY MOSTLY CLEAR SKIES IN PLACE...THOUGH SOME CLOUDS LINGER ACROSS NW MA...TEMPS WILL FALL BACK TO THE UPPER 20S ACROSS N CENTRAL AND W MA TO THE UPPER 30S ON THE OUTER CAPE AND NANTUCKET. THESE READINGS ARE AROUND 10 DEGREES ABOVE SEASONAL NORMALS FOR LATE DECEMBER. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... * CLEARING...WINDY AND MILD CHRISTMAS DAY. * REMAINING DRY WITH ABOVE NORMAL TEMPERATURES FRI AND SAT. * POTENTIAL FOR SOME RAIN OR SNOW EARLY NEXT WEEK. FRIDAY AND SATURDAY...HIGH CONFIDENCE. HIGH PRESSURE BUILDS TO THE MID ATLANTIC COAST. DRY WEATHER WILL PREVAIL WITH LIGHTER WINDS. TEMPERATURES WILL REMAIN ABOVE AVERAGE WITH HIGHS IN 40S BOTH DAYS AND LOWS MAINLY IN 30S. SUNDAY THROUGH WEDNESDAY...LOW CONFIDENCE. MODELS DROP A WEAK COLD FRONT THROUGH SOUTHERN NEW ENGLAND SUNDAY. MOISTURE APPEARS TO BE LIMITED AND CONVERGENCE RATHER WEAK...SO ONLY EXPECTING WIDELY SCATTERED RAIN SHOWERS AS IT MOVES THROUGH. TEMPERATURE PROFILES MAY BE COLD ENOUGH FOR SOME WET SNOW TO MIX IN ACROSS HIGHER TERRAIN IN WESTERN MA. 24/12Z MODELS CONTINUE TO STRUGGLE WITH THE DETAILS OF THE SYNOPTIC PATTERN NEXT WEEK. THERE ARE SOME SIGNS THE SOLUTIONS ARE STARTING TO CONVERGE...WITH THE 12Z ECMWF COMING INTO LINE WITH THE 12Z GFS. THAT SAID...ENSEMBLES STILL SHOWING 100-140 DAM SPREAD IN THE 500 MB HEIGHTS...WHICH DOES NOT INSPIRE MUCH CONFIDENCE IN THE FORECAST DETAILS. LATEST DETERMINISTIC AND ENSEMBLE MEAN GUIDANCE ESTABLISH A FAIRLY ZONAL FLOW INTO SOUTHERN NEW ENGLAND MONDAY INTO WEDNESDAY. THIS WOULD STEER ANY STORMS EITHER TO OUR NORTH...OR TOO OUR SOUTH... DEPENDING ON WHERE IT ORIGINATED. LEANED TOWARD A CONSENSUS MODEL BLEND TO HELP IRON OUT THESE DIFFERENCES FOR NOW. THIS WOULD BRING A CHANCE FOR PRECIPITATION TO SOUTHERN NEW ENGLAND DURING THIS TIME PERIOD. THERMAL PROFILES SUGGEST THE POSSIBILITY FOR LIGHT SNOW ACROSS MUCH OF SOUTHERN NEW ENGLAND...WITH RAIN MORE LIKELY CLOSER TO THE SOUTH COAST. THIS IS SEVERAL DAYS AWAY...WITH LOW CONFIDENCE IN THE DETAILS. LOW LEVEL TEMPERATURES LOOK A BIT WARM FOR ANY SIGNIFICANT ACCUMULATIONS...ESPECIALLY FROM THE MASS PIKE TO THE SOUTH COAST. WE NEED TO SEE HOW LARGER SCALE FEATURES WILL BE RESOLVED OVER THE NEXT FEW DAYS. && .AVIATION /06Z 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 FRIDAY/... THROUGH 12Z...WIDESPREAD IFR/LIFR CONTINUES IMPROVING TOWARD 12Z IN THE CT VALLEY. AREAS OF DENSE FOG NORTH AND WEST OF THE WARM FRONT IN THE INTERIOR WILL IMPROVE AS THE FRONT LIFTS N. RENEWED AREA OF RAIN REDEVELOPS ACROSS SNE 08-12Z AS THE COLD FRONT APPROACHES. SW GUSTS TO 35-40 KT POSSIBLE ACROSS PORTIONS OF RI AND SE MA. TODAY...HIGH CONFIDENCE ON TRENDS. LOWER CONFIDENCE ON TIMING. IFR/MVFR CONDITIONS WILL IMPROVE TO VFR FROM WEST TO EAST 14-18Z AS THE RAIN MOVES OFFSHORE. GUSTY WEST WINDS DEVELOPING LATE MORNING THROUGH THE AFTERNOON WITH GUSTS TO 30-35 KT. LOW PROB FOR G40 KT OVER HIGHER ELEVATIONS IN NORTHERN AND WESTERN MA. TONIGHT...HIGH CONFIDENCE. VFR. W WINDS GUSTING TO 25-30 KT EARLY...HIGHEST ALONG COAST...THEN DIMINISHING AFTER MIDNIGHT. FRIDAY...HIGH CONFIDENCE. VFR. KBOS TERMINAL...HIGH CONFIDENCE IN TAF TRENDS. TIMING OF WARM FRONT MAY BE TOO FAST BY A FEW HOURS BUT WE DO EXPECT WIND SHIFT TO S BEFORE DAYBREAK. KBDL TERMINAL...HIGH CONFIDENCE IN TAF TRENDS. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... FRIDAY NIGHT AND SATURDAY...HIGH CONFIDENCE VFR. SUNDAY...MODERATE CONFIDENCE. MVFR POSSIBLE IN ISOLATED RAIN SHOWERS. MONDAY...MODERATE CONFIDENCE. MAINLY VFR. LOWER CONDITIONS SOUTH OF NEW ENGLAND. LOW PROBABILITY THESE LOWER CONDITIONS MOVE FARTHER NORTH INTO SOUTHERN NEW ENGLAND.
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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 NIGHT/...HIGH CONFIDENCE. TONIGHT...STRONG S-SE LOW LEVEL JET PASSES ACROSS THE WATERS THROUGH TONIGHT. LOW LEVEL INVERSION IN PLACE THROUGH 900 HPA SO WILL BE TOUGH TO MIX THE BULK DOWN. WILL SEE GUSTS UP TO 25-30 KT ON THE OUTER WATERS...INCREASING TO 35 KT S AND E OF NANTUCKET TOWARD DAYBREAK. HAVE ISSUED GALES FOR THE OUTER WATERS. MARGINAL CONDITIONS FOR GALES ON NARRAGANSETT BAY SO BACKED OFF THE STRONG SMALL CRAFT. VSBYS REDUCED IN PATCHY FOG AND RAIN. ISOLD TSTMS POSSIBLE OVERNIGHT. THURSDAY...COLD FRONT MOVES OFFSHORE BY MIDDAY. WINDS SHIFT TO W-SW AND INCREASE...GUSTS UP TO 40 KT ON THE OUTER WATERS. HAVE CONVERTED GALE WATCHES FOR SOUTHERN BAYS AND SOUNDS TO WARNINGS WITH GUSTS TO 35 KT. REMAINING WATERS HAVE SMALL CRAFTS. THURSDAY NIGHT...GALE FORCE W WINDS EARLY THU NIGHT WILL DIMINISH TO SMALL CRAFT CRITERIA OVERNIGHT. SMALL CRAFT WINDS ON BOSTON HARBOR/NARRAGANSETT BAY WILL DIMINISH OVERNIGHT. OUTLOOK...FRIDAY THROUGH MONDAY...MODERATE CONFIDENCE. WINDS GRADUALLY DIMINISH FRIDAY...WITH SEAS ALSO SLOWLY SUBSIDING INTO SATURDAY AS A HIGH PRESSURE BUILDS OVER THE MID ATLANTIC STATES. A WEAKENING COLD FRONT MAY BRING AN ISOLATED SHOWER OR TWO AS IT DROPS THROUGH NEW ENGLAND SUNDAY. WINDS AND SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS ACROSS ALL BUT THE OUTERMOST COASTAL WATERS FROM MIDDAY SATURDAY INTO MONDAY. MODERATE PROBABILITY OF 5 FOOT SEAS ACROSS THE OUTERMOST COASTAL WATERS...PARTICULARLY SOUTH AND EAST OF NANTUCKET. && .CLIMATE... RECORD HIGHS FOR TODAY / CHRISTMAS DAY BOS...61 IN 1996 / 65 IN 1889 PVD...60 IN 1990 / 63 IN 1964 BDL...59 IN 1996 / 64 IN 1964 ORH...57 IN 1996 / 60 IN 1964 && .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...FLOOD WATCH UNTIL NOON EST TODAY FOR CTZ002>004. MA...FLOOD WATCH UNTIL NOON EST TODAY FOR MAZ002>022-026. WIND ADVISORY UNTIL 7 AM EST THIS MORNING FOR MAZ013-016>021. WIND ADVISORY UNTIL 9 AM EST THIS MORNING FOR MAZ022>024. RI...FLOOD WATCH UNTIL NOON EST TODAY FOR RIZ001>007. WIND ADVISORY UNTIL 7 AM EST THIS MORNING FOR RIZ002-004-005- 007. MARINE...GALE WARNING FROM 10 AM THIS MORNING TO 9 PM EST THIS EVENING FOR ANZ232>234. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ230-236. SMALL CRAFT ADVISORY UNTIL 5 AM EST FRIDAY FOR ANZ231. GALE WARNING FROM 9 AM THIS MORNING TO 9 PM EST THIS EVENING FOR ANZ235-237. GALE WARNING FROM 9 AM THIS MORNING TO MIDNIGHT EST TONIGHT FOR ANZ250. SMALL CRAFT ADVISORY UNTIL 4 AM EST FRIDAY FOR ANZ251. GALE WARNING FROM 6 AM THIS MORNING TO MIDNIGHT EST TONIGHT FOR ANZ254>256.
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&& $$ SYNOPSIS...BELK/EVT NEAR TERM...KJC SHORT TERM...EVT LONG TERM...BELK AVIATION...BELK/KJC MARINE...BELK/EVT CLIMATE...

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