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Area Forecast Discussion
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000
FXUS61 KBOX 260924
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
424 AM EST WED NOV 26 2014

.SYNOPSIS...
A DEVELOPING COASTAL STORM WILL TRACK NEAR OR OVER NANTUCKET THIS
EVENING...THEN QUICKLY MOVING OUT TO SEA OVERNIGHT. THIS STORM
WILL BRING A VARIOUS WEATHER IMPACTS TO THE REGION TODAY AND
TONIGHT WITH HEAVY SNOW WELL INLAND...HEAVY RAIN AND STRONG WINDS
ALONG THE COAST. WEATHER CONDITIONS WILL IMPROVE FOR THANKSGIVING
DAY. HIGH PRESSURE BUILDS OVER NEW ENGLAND FRIDAY AND SHIFTS
OFFSHORE OVER THE WEEKEND. A COLD FRONT SWINGS THROUGH NEW ENGLAND
LATE SUNDAY NIGHT OR MONDAY.

&&

.NEAR TERM /UNTIL 7 AM THIS MORNING/...

00Z MODEL GUIDANCE IN GOOD AGREEMENT ON TIMING OF PRECIP...COMING 
ONSHORE TO THE SOUTH COAST 6 AM TO 8 AM. THUS MOST OF THE MORNING 
COMMUTE WILL REMAIN DRY. COOLER AIR ADVECTING INTO THE REGION EARLY 
THIS MORNING ON LIGHT NNW FLOW. DEW PTS DOWN INTO THE MU20S ACROSS 
MUCH OF THE REGION.

&&

.SHORT TERM /7 AM THIS MORNING THROUGH 6 AM THURSDAY/...

TODAY AND TONIGHT...

*** WINTER STORM TRENDING CLOSER TO COAST RESULTING IN A RAIN/SNOW
 LINE FARTHER INLAND ***

IMPACTS...

* HEAVY SNOW WESTERN AND CENTRAL MA INTO SOUTHERN NH
* STRONG WINDS SOUTHEAST MA AND SOUTHERN RI
* HEAVY RAIN AND MINOR POOR DRAINAGE/URBAN FLOODING MUCH OF RI AND 
  SOUTHEAST MA

SYNOPTIC OVERVIEW AND MODEL PREFERENCES...

00Z MODEL GUIDANCE HAS TRENDED CLOSER TO THE COAST WITH THE SURFACE 
LOW PASSING OVER OR NEAR NANTUCKET. THIS SHIFT TO THE NORTHWEST MAY 
BE THE RESULT OF WIDESPREAD AND PERSISTENT UPSTREAM CONVECTION FROM 
OFFSHORE OF THE CAROLINAS EXTENDING SOUTHWEST ACROSS FL TO WEST OF 
CUBA. THIS CONVECTION MAY HAVE YIELDED A STRONGER DOWNSTREAM RIDGE 
OVER THE WESTERN ATLC RESULTING IN A STORM TRACK CLOSER TO THE COAST.

REGARDING MODEL SOLUTIONS ECMWF AND GFS ARE FARTHEST NORTHWEST AND 
WARMEST. NAM CONSIDERABLY COOLER. FOR EXAMPLE THE NAM BUFKIT AT ORH 
OFFERS AN ALL SNOW EVENT WITH 9-12 INCHES. MEANWHILE THE GFS BUFKIT 
HAS MID LEVEL WARM INTRUSION WITH SNOW MIXING WITH OR CHANGING TO 
SLEET THEN BACK TO SNOW...BUT RESULTING IN ONLY 5 OR 6 INCHES. MORE 
OF THE SAME AT BDL. PATTERN RECOGNITION SUGGEST AXIS OF HEAVIEST 
SNOW SHOULD BE ALONG AND JUST NORTHWEST OF H7 LOW TRACK...WHICH 
MODELS AGREE WILL BE ACROSS NORTHWEST MA INTO SOUTHWEST NH.

PTYPE AND SNOWFALL...

GIVEN GOOD MODEL AGREEMENT ON TRACK OF H7 LOW FAIRLY CONFIDENT ON 
AXIS OF HEAVIEST SNOW ALONG AND NORTHWEST OF A LINE FROM BAF-CEF-FIT-
ASH-MHT. A SWATH OF 6-12 INCHES IS EXPECTED ACROSS THIS AREA. SNOW 
WILL LIKELY BE HEAVY AT TIMES ACROSS THIS REGION FROM 18Z-02Z-ISH AS 
STRONG MID LEVEL FGEN COMBINES WITH SYNOPTIC SCALE LIFT TO PRODUCE 
SNOWFALL RATES OF 1-2 INCHES PER HOUR. EVEN A LOW PROB OF 
THUNDERSNOW AS DRY SLOT APPROACHES. GIVEN THERMAL PROFILES ARE 
ISOTHERMAL HEAVY WET SNOW MAY RESULT IN A RISK OF DOWN 
BRANCHES/SMALL LIMBS...INCREASING THE RISK FOR POWER OUTAGES ACROSS 
NORTHWEST MA INTO SOUTHWEST NH. SNOW GROWTH DOES NOT LOOK IDEAL SO 
EXPECTING SLR TO RANGE FROM 8-1 TO 12-1.

FARTHER SOUTHEAST INTO NORTHERN CT-WORCESTER COUNTY OF MA AND INTO 
NORTHEAST MA...SNOW MAY MIX WITH SLEET FOR A TIME LATE THIS 
AFTERNOON AND EVENING BEFORE CHANGING BACK TO ALL SNOW LATER IN THE 
EVENING. THIS MIX OF SLEET WILL REDUCE SNOW TOTALS SOMEWHAT HOWEVER 
WILL ADD TO THE HAZARDOUS TRAVEL CONDITIONS. 

FARTHER SOUTH AND EAST INTO THE BOSTON TO PROVIDENCE CORRIDOR
EXPECTING A COLD RAIN TO MIX WITH SLEET AND SNOW LATER IN THE DAY 
AND EVENING...YIELDING A SLUSHY MINOR ACCUMULATION POSSIBLE. 
NEVERTHELESS THIS WILL YIELD SLIPPERY TRAVEL ESPECIALLY 21Z-03Z WHEN 
PRECIP INTENSITY IS AT ITS GREATEST. 

FINALLY FOR SOUTHERN RI AND SOUTHEAST MA...MAINLY A WIND SWEPT RAIN 
STORM WITH MINOR POOR DRAINAGE/URBAN FLOODING AS RAINFALL TOTALS OF 
UP TO 2 INCHES POSSIBLE.

OVERALL...NOT PLANNING ON CHANGING ANY HEADLINES DESPITE LOWERING 
SNOWFALL TOTALS. THE COMBINATION OF SNOW AND SLEET ON THIS BUSY 
TRAVEL DAY WITH PRECIP INTENSITY HEAVY AT TIMES IN THE AFTERNOON AND 
EVENING JUSTIFIES THE WARNINGS AND ADVISORIES DESPITE SNOW TOTALS 
POSSIBLY FALLING SHORT OF CRITERIA. THUS HEADLINES WILL BE MAINLY 
BASED ON IMPACTS. AS FOR SNOWFALL TOTALS...BASICALLY BLENDED THE 
WARMER 00Z MODEL SOLUTION WITH PREVIOUS SNOWFALL FORECAST WHICH 
RESULTED IN LOWER SNOW TOTALS AND AXIS OF HEAVIEST SNOWFALL FARTHER 
INLAND. HOWEVER IF 12Z GUIDANCE TRENDS CLOSER TO THE COAST DAY SHIFT 
WILL LIKELY HAVE TO LOWER AMOUNTS AND SHIFT AXIS OF HEAVIEST SNOW 
FARTHER INLAND.

ONSET...GOOD MODEL AGREEMENT ON PRECIP COMING ONSHORE TO THE SOUTH 
COAST 6 AM TO 8 AM AND THEN RAPIDLY OVERSPREADING THE REMAINDER OF  
CT/RI AND MA RAPIDLY SOUTHWEST TO NORTHEAST 8 AM TO NOON.

PRECIP INTENSITY...HEAVIEST 1 PM TO 8 PM FROM SOUTHWEST TO 
NORTHEAST. 

WINDS...

A STRONG LOW LEVEL NORTHEAST JET WILL MOVE ACROSS RI AND SOUTHEAST 
MA INCLUDING CAPE COD AND THE ISLANDS AROUND 00Z. MODELS PROJECTING 
50 TO 65 KT JET AT 925 MB. GFS IS THE MOST ROBUST. THIS COUPLED WITH 
STRONG PRES FALLS AND RELATIVELY WARM OCEAN WATERS PROVIDING A WELL 
MIXED BLYR WILL YIELD A MODERATE RISK OF 50 MPH WIND GUSTS FROM 
SOUTH COASTAL PLYMOUTH COUNTY/CAPE COD AND THE ISLANDS. GIVEN TRACK 
OF LOW IS FARTHER NW STRONG WIND FIELD NOW MOVES ACROSS COASTAL RI 
AND SOUTHEAST MA. THUS WILL EXPAND WIND ADVISORY TO THIS AREA. WINDS 
MAY DECREASE OVER THE ISLANDS FOR A TIME THIS EVENING AS LOW MAKES 
IT CLOSEST APPROACH...SOMEWHERE NEAR NANTUCKET. TIMING OF STRONGEST 
WINDS APPEAR 4 PM WED TIL 1 AM THU. 

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
BIG PICTURE... 
SOUTHERN STREAM TROUGH MOVES UP THE COAST ACROSS NEW ENGLAND
THURSDAY. NORTHERN STREAM SHORTWAVE THEN MOVES ACROSS THE REGION
FRIDAY. THE FLOW THEN TRANSITIONS TO ZONAL OVER THE WEEKEND.

THE LONG RANGE MODELS SHOW GOOD AGREEMENT ON 500 MB HEIGHTS THROUGH 
MONDAY AND THEN SMALL DIVERGENCE TUESDAY. THE GFS IS FASTER/FARTHER 
EAST WITH A CLIPPER SYSTEM CROSSING CANADA OVER THE WEEKEND. BUT THE 
MODELS COME MORE IN LINE WITH THE TRAILING COLD FRONT IN NEW ENGLAND 
SUNDAY NIGHT. THIS MAINTAINS AT LEAST MODERATE CONFIDENCE IN THE 
FORECAST THROUGH THE WEEKEND WITH DIMINISHING CONFIDENCE BY 
NEXT TUESDAY/DAY SEVEN.

THE DAILIES... 

THANKSGIVING DAY... SOUTHERN STREAM UPPER TROUGH TRAILS THE 
WEDNESDAY STORM...AND MOVES OVER SOUTHERN NEW ENGLAND DURING THE 
DAY. MODEL CROSS SECTIONS FROM THE GFS AND ECMWF SHOW A DEEP SUPPLY 
OF HIGH-RH AIR AND SOME WEAK LIFT AS THE TROUGH MOVES ACROSS THE 
REGION.  WE WILL EXPECT MOSTLY CLOUDS AS WELL AS A CHANCE OF PCPN. 
TEMPERATURE PROFILES SUGGEST SCATTERED SNOW SHOWERS INLAND AND 
SCATTERED RAIN SHOWERS IN RI/SOUTHEAST MASS. TEMPERATURE PROFILES 
SUPPORT MAX TEMPS IN THE 30S...EXCEPT LOWER 40S CAPE AND ISLANDS. 

WE STAYED CLOSE TO GUIDANCE THURSDAY NIGHT WITH MIN TEMPS IN THE
20S EXCEPT LOWER 30S CAPE AND ISLANDS. ANY WET SURFACES FROM THE
DAYTIME WILL REFREEZE IN MOST LOCATIONS RESULTING IN TRICKY POST-
MEAL TRAVEL ON ANY UNTREATED SURFACES.

FRIDAY... NORTHERN STREAM SHORTWAVE RACES ACROSS NEW ENGLAND IN THE 
MORNING WITH LINGERING AIRMASS MOISTURE BUT WEAK LIFT IF ANY. THIS 
COULD HOLD THE CLOUDS IN A LITTLE LONGER FRIDAY MORNING.  BUT IT 
MOVES OUT QUICKLY AND SURFACE HIGH PRESSURE BUILDS IN. SO THE TREND 
WILL BE FOR CLEARING SKIES.  MIXING DEPTH WITH THE SUNSHINE IS 
EXPECTED TO BE RATHER SHALLOW...AROUND 950 MB OR MAYBE A LITTLE 
HIGHER.  THIS WILL SUPPORT MAX TEMPS IN THE 30S AND WINDS GUSTING TO 
15-20 KNOTS.

HIGH PRESSURE MOVES OVERHEAD FRIDAY NIGHT.  THIS WILL ALLOW TEMPS TO 
INITIALLY FALL WITH MOSTLY CLEAR SKIES AND LIGHT WINDS. BUT MOISTURE 
FIELDS SUGGEST SOME MID AND HIGH CLOUDS OVERNIGHT...AND POSSIBLY LOW 
CLOUDS MOVING UP FROM THE OCEAN TOWARD CAPE COD AND THE ISLANDS. 
FORECAST TEMPS ARE CLOSE TO GUIDANCE WITH 14-23 EXCEPT 24-30
ALONG THE SOUTH COAST.

SATURDAY-SUNDAY...CONTINUED FAIR WEATHER OVER THE WEEKEND AS A
WARM FRONT SWEEPS NORTH ACROSS NEW ENGLAND AND HIGH PRESSURE
BUILDS OFFSHORE. THE COMBINATION SUGGESTS A WARMING TREND OVER THE
WEEKEND WITH A 12C INCREASED IN TEMPS ALOFT BETWEEN SATURDAY AND
SUNDAY. THE WARM FRONT WILL BRING VARIABLE SKY COVER...AS NOTED BY
RH FIELDS ALOFT IN THE MODELS. SOUTHWEST WINDS AT 925 MB INCREASE
TO 30 KNOTS SATURDAY AFTERNOON AND 30-40 KNOTS SATURDAY NIGHT AND
SUNDAY. EXPECT SOME GUSTINESS TO OUR SURFACE WINDS EACH DAY. BUT
LOW-LEVEL MIXING WILL BE LESS THAN IDEAL EACH DAY WITH BETTER
MIXING SATURDAY AND LESS SUNDAY.

MONDAY-TUESDAY...SHORTWAVE IN THE ZONAL FLOW WILL PUSH A COLD FRONT 
THROUGH NEW ENGLAND EITHER LATE SUNDAY NIGHT OR MONDAY. TIMING OF 
THE SHORTWAVE IN A ZONAL FLOW THIS FAR OUT IS IN QUESTION BUT THAT/S 
OUR BEST SHOT AT THIS TIME. LIMITED MOISTURE ALOFT TOGETHER WITH 
FAVORABLE JET DYNAMICS FROM A 125 KNOT JET...SO WE HAVE CHANCE POPS 
FOR RAIN/SNOW SHOWERS.  HIGH PRESSURE THEN BUILDS DRY WEATHER FOR 
THE REST OF MONDAY AND TUESDAY.

&&

.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT. 
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

.SHORT TERM /THROUGH TOMORROW NIGHT/...MODERATE CONFIDENCE.

THROUGH 12Z...MAINLY DRY WEATHER WITH A LOW RISK OF RAIN MOVING
ONSHORE INTO RI AND SOUTHEAST MA TOWARD 12Z. VFR WITH LIGHT NW
WINDS BECOMING NORTH.

AFTER 12Z...PRECIP OVERSPREADS THE REGION 12Z-16Z FROM SOUTH TO
NORTH. PRECIP MAINLY RAIN ACROSS MOST OF RI /EXCEPT NORTH-
NORTHWEST AREAS/ AND SOUTHEAST MA. HEAVY SNOW AND LIFR 18Z-00Z
ALONG AND NORTHWEST OF A LINE FROM BAF-CEF-FIT-ASH-MHT WITH
SNOWFALL RATES OF 1-2 INCHES PER HOUR POSSIBLE 18Z-00Z. SNOW MIXES
WITH SLEET SOUTHEAST OF THIS AREA FROM BDL-ORH-LWM. STRONG NE
WINDS UP TO 45 KT LIKELY AFTER 21Z OVER CAPE COD/ISLANDS AND
COASTAL PLYMOUTH COUNTY.

TONIGHT...HEAVY PRECIP LINGERS UNTIL 02Z/03Z ESPECIALLY EASTERN
AREAS INCLUDING MHT. PRECIP TAPERS OFF AFTER 03Z AND ESPECIALLY
AFTER 06Z FROM SOUTHWEST TO NORTHEAST. STRONG NNE WINDS TIL 06Z
THEN BACKING TO NNW.

KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS BUT LOWER CONFIDENCE IN
EXACT TIMING ESPECIALLY PTYPE. HEAVIEST PRECIP 20Z-03Z

KBDL TERMINAL...HIGH CONFIDENCE IN TRENDS BUT LOWER CONFIDENCE IN
EXACT TIMING ESPECIALLY PTYPE. HEAVIEST PRECIP 18Z-00Z.

OUTLOOK...THURSDAY THROUGH SUNDAY...MODERATE CONFIDENCE

THURSDAY...MVFR WITH SCATTERED RAIN/SNOW SHOWERS. DIMINISHING 
NORTHWEST WINDS.

FRIDAY...VFR WITH NORTHWEST WINDS GUSTING 15-20 KNOTS.

SATURDAY-SUNDAY...INCREASING SKY COVER BUT MAINLY VFR. LOW POTENTIAL 
FOR MVFR CIGS MOVING NORTH OFF THE OCEAN INTO CAPE COD AND ISLANDS. 
INCREASING WINDS AT 2000 FEET...REACHING SOUTHWEST 35-40 
KNOTS...WITH LIGHTER SOUTHWEST WINDS AT SURFACE.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT. 
MODERATE...30 TO 60 PERCENT. 
HIGH...GREATER THAN 60 PERCENT.

.SHORT TERM /THROUGH TONIGHT/...MODERATE CONFIDENCE.

TODAY AND TONIGHT...GALE CENTER TRACKS OVER OR NEAR NANTUCKET EARLY 
THIS EVENING. THIS WILL RESULT IN A PERIOD OF NE GALES WITH A LOW 
RISK OF A FEW STORM FORCE GUSTS NEAR SHORE EARLY THIS EVENING. WINDS 
LIKELY EASE AROUND MIDNIGHT OVER CAPE AND ISLANDS AS LOW CENTER 
TRACKS ACROSS THIS AREA. SEAS BUILD RAPIDLY TODAY AND THIS EVENING. 
POOR VSBY IN HEAVY RAIN. WINDS BECOME NNW LATER TONIGHT AS THE GALE 
CENTER RACES NE TOWARD NOVA SCOTIA.

OUTLOOK...THURSDAY THROUGH SUNDAY...MODERATE CONFIDENCE.

THURSDAY... NORTHWEST WINDS GUSTING TO 25 KNOTS IN THE MORNING BUT 
DIMINISHING. SEAS START THE DAY 5 TO 11 FEET ON THE EXPOSED WATERS 
AND SUBSIDE TO 5 TO 6 FEET BY THE END OF THE DAY. SMALL CRAFT 
ADVISORY WILL BE NEEDED ON MOST WATERS.

FRIDAY... LINGERING 5 FOOT SEAS ON THE OUTER WATERS. NORTHWEST WINDS 
WILL GUST 20 TO 25 KNOTS. A SMALL CRAFT ADVISORY MAY BE NEEDED ON 
SOME OF THE WATERS.

SATURDAY-SUNDAY... SOUTHWEST WINDS GUSTING TO 25 KNOTS AND SEAS 
BUILDING TO 5 TO 6 FEET ON THE EXPOSED WATERS.  A SMALL CRAFT 
ADVISORY MAY BE NEEDED.

&&

.TIDES/COASTAL FLOODING...
HIGH TIDE OF CONCERN IS SHORTLY AFTER MIDNIGHT THURSDAY. STRONGEST 
WINDS AND PRESSURE FALLS OCCUR DURING LOW TIDE THIS EVENING WITH 
WINDS AND SURGE EASING TOWARD HIGH TIDE.  THUS IMPACTS WILL BE 
LIMITED WITH VERY MINOR EROSION AND TIDAL FLOODING.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR CTZ002>004.
MA...WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR MAZ002>006-
     008>012-026.
     WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 3 AM EST THURSDAY 
     FOR MAZ019>024.
     WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR MAZ007-
     013>016.
NH...WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR NHZ011-012-
     015.
RI...WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 3 AM EST THURSDAY 
     FOR RIZ005>008.
     WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR RIZ001>003.
MARINE...GALE WARNING FROM 3 PM THIS AFTERNOON TO 5 AM EST THURSDAY FOR 
     ANZ230>237.
     GALE WARNING FROM 3 PM THIS AFTERNOON TO 7 AM EST THURSDAY FOR 
     ANZ250-251-254>256.

&&

$$
SYNOPSIS...NOCERA
NEAR TERM...NOCERA
SHORT TERM...NOCERA
LONG TERM...WTB
AVIATION...WTB/NOCERA
MARINE...WTB/NOCERA
TIDES/COASTAL FLOODING...NOCERA



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