Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 260907 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 407 AM EST THU FEB 26 2015 .SYNOPSIS...
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LOW PRESSURE PASSING OUT TO SEA MAY BRING AN INCH OR TWO OF SNOW TODAY TO THE FAR SOUTHEAST NEW ENGLAND COAST. DRY BUT UNSEASONABLY COLD WEATHER CONTINUES TONIGHT AND FRIDAY AS HIGH PRESSURE BUILDS IN FROM THE WEST. TEMPS SLOWLY MODERATE SAT AS HIGH PRES BUILDS INTO THE REGION...THEN A FRONTAL SYSTEM MAY BRING SOME SNOW LATE SUN INTO MON AND POSSIBLY FOLLOWED BY ADDITIONAL SNOW OR MIXED SNOW AND RAIN TUE NIGHT INTO WED.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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*** AN INCH OR TWO OF SNOW POSSIBLE TODAY FOR THE FAR SOUTHEAST NEW ENGLAND COAST *** LOW PRESSURE JUST OFF THE CAROLINA COAST EARLY THIS MORNING WILL PASS WELL SOUTHEAST OF THE BENCHMARK THIS AFTERNOON. WHILE THIS SYSTEM IS BRINGING HEAVY SNOW ACROSS SOUTHERN VIRGINIA EARLY THIS MORNING...IT WILL PASS TOO FAR SOUTH FOR THAT TO OCCUR HERE. NONETHELESS...A FEW DIFFERENT PROCESSES WILL COMBINED TO BRING US A LITTLE BIT OF SNOW TODAY...MAINLY FOR THE FAR SOUTHEAST NEW ENGLAND COAST. FIRST...ENOUGH WEAK BROAD SCALE FORCING FROM THE SHORTWAVE MAY RESULT IN A BRIEF PERIOD OF LIGHT SNOW SHOWERS/FLURRIES FOR MUCH OF THE REGION LATER THIS MORNING/EARLY AFTERNOON. BEST CHANCE FOR THIS IS SOUTH OF THE MA TURNPIKE. ANY ACCUMS SHOULD RANGE FROM JUST A DUSTING TO LESS THAN AN INCH. THE SECOND PROCESS IS COLD NORTHEAST WINDS THAT SHOULD RESULT IN SOME SCATTERED OCEAN EFFECT SNOW SHOWERS ACROSS FAR SOUTHEAST MA...ESPECIALLY PLYMOUTH COUNTY. TEMPS AT THE INVERSION LAYER ARE AROUND -12C...WHICH SHOULD BE ENOUGH OF A DIFFERENTIAL OVER THE OCEAN FOR THE FORMATION OF THESE SCATTERED SNOW SHOWERS. THE THIRD PROCESS IS A PERIOD OF SYNOPTIC SCALE LIFT THAT MAY CLIP THE CAPE/ISLANDS THIS AFTERNOON FROM THE ACTUAL LOW PRESSURE SYSTEM. THIS REMAINS UNCERTAIN AS ITS POSSIBLE THAT THIS STRONGER LIFT REMAINS JUST SOUTHEAST OF NANTUCKET. AS FOR ACCUMS...LOOKING AT A DUSTING TO LESS THAN 1 INCH FOR MOST OF THE REGION. HOWEVER...1 TO 2 INCHES OF SNOW SEEMS REASONABLE FROM PLYMOUTH COUNTY ONTO THE CAPE FROM BOTH OCEAN EFFECT SNOW SHOWERS AND PERHAPS A PERIOD OF SYNOPTIC SCALE FORCING. ACROSS NANTUCKET WILL GO FOR 1 TO 3 INCHES...WHERE THERE WILL BE THE HIGHEST RISK FOR GETTING GRAZED BY STRONGER FORCING. EVEN A LOW RISK FOR AROUND 4 INCHES OF SNOW ON THE ISLAND. WHILE WE WILL CONTINUE TO MONITOR...DO NOT HAVE ENOUGH CONFIDENCE TO ISSUE A WINTER WEATHER ADVISORY FOR NANTUCKET. THE OTHER THING TO CONSIDER IS THAT WE ARE DEALING WITH THE INCREASING LATE FEBRUARY SUN ANGLE. WHILE THIS IS NOT A BIG PLAYER FOR MODERATE TO HEAVY SNOW...IF INTENSITY IS LIGHT THERE WILL BE A LOT OF MELTING ON ROADWAYS DESPITE TEMPS BELOW FREEZING. NONETHELESS...WILL GO AHEAD AND ISSUE A SPECIAL WEATHER STATEMENT FOR FAR SOUTHEAST MA ONTO THE CAPE/ISLANDS AS THERE IS CERTAINLY THIS RISK FOR SOME SLICK TRAVEL. HIGH TEMPS TODAY WILL ONLY BE IN THE 20S TO PERHAPS AROUND 30 ACROSS THE CAPE/NANTUCKET WITH LOTS OF CLOUDS ACROSS THE ENTIRE REGION.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
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TONIGHT AND FRIDAY... SPRAWLING HIGH PRESSURE ACROSS THE CENTRAL PLAINS BUILDS INTO SOUTHERN NEW ENGLAND TONIGHT AND FRIDAY. MAINLY DRY WEATHER EXPECTED...BUT A FEW LINGERING FLURRIES/LIGHT SNOW SHOWERS CAN/T BE RULED OUT ACROSS THE OUTER-CAPE TONIGHT. SHOULD SEE A LOT OF CLOUDS TONIGHT...BUT MAY SEE THEM SCATTER OUT LATE AS DRIER AIR WORKS IN FROM THE WEST. IT WILL BE QUITE COLD WITH LOWS MAINLY IN THE SINGLE DIGITS TO LOWER TEENS. SOME OF THE COLDEST OUTLYING LOCATIONS MAY DROP BELOW ZERO...BUT THAT WILL DEPEND ON HOW MANY BREAKS DEVELOP IN THE CLOUD COVER. A MIXTURE OF CLOUDS AND SUNSHINE EXPECTED ON FRIDAY...BUT ONLY EXPECT HIGHS IN THE 20S WITH LIMITED MIXING. WINDS WILL BE RATHER LIGHT AND WITH SOME SUNSHINE EXPECTED...IT WILL FEEL AT LEAST A LITTLE MORE COMFORTABLE THEN TODAY.
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&& .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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HIGHLIGHTS... * COLD AND MAINLY DRY FRIDAY THROUGH SUNDAY MORNING * CHANCE OF SNOW SUNDAY NIGHT INTO MONDAY * CHANCE OF SNOW POSSIBLY MIXING WITH RAIN TUESDAY NIGHT AND WEDNESDAY OVERVIEW AND MODEL PREFERENCES... WITH THE NAO/AO REMAINING POSITIVE FOR THE FORESEEABLE FUTURE...AS NOTED BY THE PREVIOUS FORECASTER...THE NEXT WEEK OR SO/S SENSIBLE WX IS LIKELY TO BE DEFINED BY WHAT HAPPENS IN THE SPLITTING FLOW REGIMES ACROSS THE WRN CONUS AND ERN PACIFIC. WITH SPLIT FLOW MERGING SOMEWHERE NEAR THE NE...IT WILL BE STRONGLY DEPENDENT ON WHETHER WAVES WITHIN THE SRN OR NRN STREAM REMAIN DOMINANT...SOMETHING GUIDANCE TYPICALLY DOESN/T HANDLE WELL UNTIL CLOSER TO THE EVENT. INITIALLY IN THE MID TERM...THE CONFLUENCE OF THESE STREAMS LOOKS TO BE TO OUR WEST...LEADING TO THE BUILDING OF NEARLY 1045+ HPA THROUGH THE WEEKEND. ALSO...IT SHEARS A NRN STREAM WAVE SUN NIGHT INTO MON...WEAKENING IT SOMEWHAT. THE SFC REFLECTION IS A COLD FRONT AND WHILE IT APPEARS THAT IT WILL HAVE WITH IT ENOUGH MOISTURE FOR WIDESPREAD SNOWFALLS...THE WEAKENING NATURE SUGGESTS THAT AMOUNTS ARE LIKELY TO BE AT OR BELOW ADVISORY LEVEL. TUE INTO WED...WILL LEAN AWAY FROM A 12Z ECMWF BLEND USING GFS/GEFS AND ECENS AS EVEN THE ENSEMBLES ARE NOT AS FAR SUPPRESSED WITH THE STORMTRACK AS THE DETERMINISTIC RUN. THIS IS A POTENTIALLY WETTER SOLUTION. HOWEVER...GIVEN THE FACT THAT IT WILL DEPEND ON WHETHER THE STREAMS PHASE OR ONE DOMINATES...WILL HAVE TO WAIT AND SEE BEFORE THERMAL PROFILES ARE DEFINED. DETAILS... FRI NIGHT INTO SUN... INITIALLY COLD HIGH PRES WILL BE MOVING ACROSS THE REGION...CRESTING EARLY SUN MORNING. THIS SUGGESTS TEMPS GENERALLY BELOW NORMAL FRI NIGHT INTO SAT NIGHT WITH SOME MODERATION DURING THE DAY SUN. DEEP SNOWPACK AND WEAK PRES GRADIENT SUGGEST GOOD RADIATIONAL COOLING. EXPECT MINS DIPPING INTO THE NEGATIVE DOUBLE DIGITS IN THE COLD NW...TO NEAR 0 FOR INTERIOR EA MA/RI AND CT. HIGHS ON SAT MAINLY IN THE TEENS AND LOW 20S...TO THE 20S AND NEAR FREEZING BY SUN AFTERNOON. SUN NIGHT INTO MON... COLD FRONT MOVES ACROSS THE REGION WITH ENOUGH ISENTROPIC LIFT IN ADVANCE AND F-GEN NEAR TO THE FRONT ITSELF TO YIELD LIGHT- MODERATE PRECIP ACROSS THE AREA. AT THIS POINT IT APPEARS THAT THERMAL PROFILES WOULD SUPPORT ALL SNOW. QPF VALUES RANGE FROM ABOUT 0.2 TO 0.5 INCHES TOTAL...SO GIVEN THERE IS AT LEAST MODEST LIFT IN THE SNOW GROWTH REGION ALOFT...SUSPECT SOME AREAS WILL APPROACH WINTER WX ADVISORY CRITERIA. SNOWS COME TO AN END TUE AFTERNOON. MON NIGHT INTO TUE... BRIEF RIDGE OF HIGH PRES FOLLOWS BUT IS SHORT LIVED DUE TO PROGRESSIVE PATTERN ALOFT. TEMPS REMAIN BELOW ZERO...BUT NOT AS COLD AS PREVIOUS DAYS. TUE NIGHT INTO WED... AS MENTIONED ABOVE...THIS IS A TRICKY FORECAST REGARDING A STREAM PHASING SCENARIO AND STRONGER LOW PRES WITH CONNECTION TO THE SUBTROPICS. GUIDANCE SUGGESTING THAT PWATS COULD BE 2-3 STD DEVIATIONS ABOVE NORMAL. HOWEVER...TRACK REMAINS UNCERTAIN. GFS CONTINUES TO SHOW INSIDE RUNNER WITH ENERGY TRANSFER TO OFFSHORE LOW...WHILE THE 00Z ECMWF HAS COME FURTHER N...BUT IS COLDER /ALTHOUGH STILL WARMER THAN THE 12Z/ AS MENTIONED IN THE MODEL DISCUSSION...WILL CONTINUE TO LEAN AWAY FROM ECMWF AT 12Z...BUT WILL ADD IN SOME OF THE 00Z ECMWF TO THE BLEND FOR THERMALS. WILL NEED TO KEEP AN EYE ON THIS EVENT HAS THE POTENTIAL TO BE A MIXED P-TYPE EVENT WITH MODERATE-HIGH IMPACT GIVEN THE AVAILABLE MOISTURE AND STRONGER POTENTIAL DYNAMICS. THU... UNCERTAIN BECAUSE OF DIFFICULTY IN NAILING DOWN THE FINAL STREAM DOMINANCE. CHANCE FOR FURTHER STORMS IF THE NRN STREAM DOMINATES...MORE SUPPRESSED PATTERN IF THE SRN STREAM DOMINATES.
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&& .AVIATION /09Z 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 /TODAY THROUGH FRIDAY/... TODAY...MODERATE CONFIDENCE. SURFACE WINDS TURNING NORTH NORTHEAST IN MOST AREAS WHICH WILL ALLOW MVFR CIGS TO DEVELOP LATER THIS MORNING AND AFTERNOON...ESPECIALLY ALONG THE SOUTHEAST NEW ENGLAND COAST. WHILE A FEW SNOW SHOWERS ARE POSSIBLE FOR A SHORT TIME ANYWHERE...THE MAIN FOCUS FOR SNOW WILL BE ACROSS FAR SOUTHEAST MA INCLUDING CAPE/ISLANDS LATER THIS MORNING AND AFTERNOON WHERE A PERIOD OF IFR CONDITIONS ARE POSSIBLE. NORTHEAST WIND GUSTS TO 25 KNOTS EXPECTED ALONG THE SOUTHEAST NEW ENGLAND COAST. TONIGHT AND FRIDAY...MODERATE TO HIGH CONFIDENCE. MAINLY VFR CONDITIONS EXPECTED BUT SOME OCEAN EFFECT MVFR CIGS WILL PROBABLY AFFECT THE CAPE AND NANTUCKET FOR A TIME TONIGHT INTO FRI MORNING. KBOS TAF...MODERATE CONFIDENCE IN TAF. BRIEF PERIOD OF LIGHT SNOW SHOWERS/FLURRIES POSSIBLE LATER THIS MORNING INTO THIS AFTERNOON. ANY ACCUMS WOULD LIKELY BE A DUSTING TO LESS THAN AN INCH. KBDL TAF...MODERATE CONFIDENCE IN TAF. BRIEF PERIOD OF LIGHT SNOW SHOWERS/FLURRIES POSSIBLE LATER THIS MORNING INTO EARLY THIS AFTERNOON. ANY ACCUMS WOULD LIKELY BE NO MORE THEN A DUSTING TO LESS THAN AN INCH. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... FRIDAY NIGHT INTO SUNDAY...HIGH CONFIDENCE. MAINLY VFR. SUN NIGHT INTO MON...MODERATE CONFIDENCE. PERIODS OF IFR/MVFR IN SNOW ACROSS THE REGION. WINDS SHIFT FROM SLY TO WLY...WITH GUSTS 20-25 KT AT TIMES DURING THE DAY MON.
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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 /TODAY THROUGH FRIDAY/...HIGH CONFIDENCE. TODAY THROUGH FRIDAY...HIGH CONFIDENCE. LOW PRESSURE PASSING WELL SOUTHEAST OF THE BENCHMARK WILL ALLOW FOR NORTHEAST WIND GUSTS OF 20 TO 30 KNOTS TO DEVELOP LATER THIS MORNING AND CONTINUE INTO EARLY THIS EVENING. A PERIOD OF SNOW...MAINLY ACROSS THE SOUTHEAST WATERS MAY RESULT IN VISIBILITIES 1 MILE OR LESS FOR A TIME LATER THIS MORNING INTO THIS AFTERNOON. WINDS SHOULD DIMINISH BY LATER THIS EVENING AND REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS INTO FRIDAY AS HIGH PRESSURE BUILDS IN FROM THE WEST. HOWEVER...SMALL CRAFT SEAS WILL CONTINUE ACROSS THE OUTER-WATERS THROUGH FRIDAY AFTERNOON. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... FRI NIGHT THROUGH SUN...HIGH CONFIDENCE. A PERIOD OF MAINLY QUIET BOATING WEATHER IS EXPECTED AS HIGH PRES BUILDS OVER THE WATERS. A RISK FOR LIGHT FREEZING SPRAY IS POSSIBLE DURING THE OVERNIGHT HOURS. SUN NIGHT INTO MON...MODERATE CONFIDENCE. LOW PRES WILL BRING A PERIOD OF SNOW MIXING WITH RAIN ESPECIALLY ON THE SRN WATERS. WINDS BEGIN OUT OF THE S THEN SHIFT TO THE W...INCREASING WITH GUSTS APPROACHING GALE FORCE POSSIBLE BY LATER SUN. SEAS INCREASE AS WELL. WILL LIKELY NEED AT LEAST SMALL CRAFT ADVISORIES IF NOT GALES.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. MA...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS EVENING FOR ANZ231>235-237-251. SMALL CRAFT ADVISORY UNTIL 7 PM EST FRIDAY FOR ANZ250-254>256.
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&& $$ SYNOPSIS...FRANK/DOODY NEAR TERM...FRANK SHORT TERM...FRANK LONG TERM...DOODY AVIATION...FRANK/DOODY MARINE...FRANK/DOODY

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