Area Forecast Discussion
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000
FXUS61 KBOX 261153
AFDBOX

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

.SYNOPSIS...
A DEVELOPING COASTAL STORM WILL TRACK NEAR NANTUCKET THIS EVENING...
THEN QUICKLY MOVING OUT TO SEA OVERNIGHT. THIS STORM WILL BRING A
VARIETY OF WEATHER IMPACTS TO THE REGION TODAY AND TONIGHT WITH
HEAVY SNOW WELL INLAND...HEAVY RAIN AND STRONG WINDS ALONG THE
COAST. WEATHER CONDITIONS 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 /THROUGH TONIGHT/...

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

7 AM UPDATE...

LEADING EDGE OF WARM CONVEYOR BELT PRECIP /NOSE OF MID LEVEL JET/
COMING ONSHORE ACROSS THE SOUTH COAST. LOW LEVEL DRY AIR WITH DEW
PTS IN THE M20S TO L30S HAS RESULTED IN DEW PT DEPRESSIONS ON THE
ORDER OF 10-20 DEGS. THIS LOW LEVEL DRY AIR WILL INITIALLY ERODE
LEADING EDGE OF PRECIP. THUS DELAYED PRECIP ARRIVAL BY ONLY AN
HOUR OR TWO. OTHERWISE PREVIOUS FORECAST ON TRACK.

MESOANALYSIS INDICATES LOW PRES ALONG THE CAROLINA COAST WITH GOOD
PRES FALLS FROM NJ SOUTHWARD. THIS HAS RESULTED IN WINDS SHIFTING
TO THE NORTHEAST AT NANTUCKET AND FALMOUTH. EXPECT THIS TREND TO
CONTINUE THRU THE MORNING..NNW WINDS TRENDING TOWARD NE.

AS FOR 06Z MODEL GUIDANCE...GFS AND NAM HAVE NOT DEVIATED MUCH
FROM THEIR 00Z RUNS WITH SURFACE LOW PASSING NEAR NANTUCKET ALONG
WITH MID LEVEL LOW TRACKING OVER NORTHWEST MA AND SOUTHWEST NH.
THUS THREAT AREA FOR HEAVY SNOW CONTINUES ACROSS NORTHWEST MA AND
SOUTHWEST NH. EARLIER DISCUSSION BELOW.

--------------------------------------------------------------------

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.

&&

.SHORT TERM /THURSDAY/...

THANKSGIVING DAY...H5 LONG WAVE TROUGH WILL MOVE OFF THE COAST
DURING THIS TIMEFRAME WITH A CUTOFF LOW IN THIS FLOW. AMPLE LOW
AND MID LEVEL MOISTURE WITH THIS SYSTEM...SO WILL SEE LINGERING
CLOUDS AND THE CHANCE FOR RAIN AND/OR SNOW SHOWERS. GOOD SHOT OF
COLD AIR ADVECTION WORKING IN. DAYTIME HIGHS ONLY EXPECTED TO BE
IN THE MID 30S TO LOWER 40S. H85 TEMPS FALL BACK TO -5C TO -10C
THU NIGHT SO TEMPS WILL TUMBLE...BOTTOMING OUT IN THE UPPER TEENS
AND 20S FOR MOST LOCATIONS...THOUGH WILL HOLD IN THE 30 TO 35
DEGREE RANGE ACROSS CAPE COD AND THE ISLANDS. WET ROADWAYS AND
SIDEWALKS WILL FREEZE UP AS TEMPS FALL THU NIGHT...ESPECIALLY ON
UNTREATED SURFACES.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
OVERVIEW AND MODEL PREFERENCES...
MEDIUM RANGE MODELS WERE IN PRETTY GOOD AGREEMENT IN FLATTENING
OUT THE OVERALL UPPER LEVEL FLOW ACROSS NORTH AMERICA...WITH
SURFACE WEATHER SYSTEMS TENDING TO MOVE QUICKLY ESPECIALLY ACROSS
THE NORTHERN TIER STATES THROUGH A GOOD PORTION OF THIS TIMEFRAME.
HAVE NOTED TIMING DIFFERENCES WORKING IN ESPECIALLY ON THE 00Z OP
RUN OF THE ECMWF EARLY NEXT WEEK AS IT TRIES TO DIG AN H5 SHORT
WAVE/CLIPPER SYSTEM MOVING ACROSS THE GREAT LAKES WHILE THE GFS
KEEPS THIS SYSTEM WEAK AND FLAT. OVERALL...WITH THE GENERAL W-NW
WIND FLOW...A COUPLE OF FRONTS WILL PASS WITH LITTLE FANFARE
THOUGH WILL BRING SHOTS OF COLDER AIR.

MODELS AND ENSEMBLES HAVE MAINTAINED PRETTY GOOD CONTINUITY EARLY
IN THIS FORECAST PERIOD...THEN LOWERS AS TIMING ISSUES COME INTO
PLAY EARLY NEXT WEEK. USED A BLEND OF AVAILABLE GUIDANCE THROUGH
THIS WEEKEND THEN LEANED TOWARD THE MODEL ENSEMBLE MEANS FOR THIS
FORECAST.

DETAILS...

FRIDAY...SHORT WAVE CLEARS THE COAST DURING THE MORNING WITH ANY
CLOUDS TENDING TO DISSIPATE AND PUSH OFFSHORE. CORE OF COLDER AIR
WORKS IN ON GENERALLY LIGHT NW WINDS. HIGHS ONLY EXPECTED IN THE
30S...RUNNING AROUND 10 DEGREES BELOW SEASONAL NORMALS. HIGH PRES
APPROACHES FROM THE W FRI NIGHT. MAINLY CLEAR SKIES AND LIGHT
WINDS WILL CAUSE TEMPS TO DROP AGAIN TO THE TEENS TO MID
20S...EXCEPT LOWER 30S ON THE OUTER CAPE AND NANTUCKET.

SATURDAY-SUNDAY...HIGH PRES CRESTS ACROSS THE EASTERN SEABOARD
DURING SAT THEN SETTLES E OF THE REGION ON SUNDAY. RESIDUAL COLD
AIR IN PLACE ON SAT WITH HIGHS MAINLY IN THE 30S...THOUGH WILL
RISE TO THE MID 40S ALONG THE S COAST. A WEAK WARM FRONT MAY BRING
ISOLD SHOWERS TO THE REGION SAT NIGHT...THEN SW WINDS TAKE OVER
FOR SUNDAY. EXPECT HIGHS FROM 45-50 ACROSS THE INTERIOR...RANGING
TO THE MID 50S ALONG THE S COAST WITH GUSTY SW WINDS. SOME CLOUDS
AND A SLIGHT CHANCE FOR PRECIP WITH APPROACHING FRONT POSSIBLE SUN
NIGHT...THOUGH TIMING IN QUESTION.

MONDAY-TUESDAY...SOME QUESTION ON TIMING OF NEXT H5 SHORT WAVE
APPROACHING THE REGION...THOUGH WILL TEND TO BE A RATHER DRY
SYSTEM WITH NEARLY ZONAL UPPER FLOW IN PLACE. CONTINUED TO CARRY
SLIGHT CHANCE POPS MON...AND SOME QUESTION ON PTYPE DEPENDING UPON
TEMP PROFILE AS SYSTEM APPROACHES. FOR NOW...SHOULD SEE IMPROVING
CONDITIONS MON NIGHT/TUE THOUGH LOOKS LIKE ANOTHER SHOT OF COLD
AIR MOVES IN. LOW CONFIDENCE ON THIS PORTION OF THE FORECAST.

&&

.AVIATION /12Z 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.

7 AM UPDATE...

NO MAJOR CHANGES FROM 06Z TAFS. PRECIP SHIELD COMING ONSHORE ALONG
SOUTH COAST AS OF 12Z. PRECIP OVERSPREADS THE REMAINDER OF THE
REGION THRU 15Z/16Z...MAINLY IN THE FORM OF RAIN EXPECT NORTHWEST
MA AND SOUTHWEST NH SNOW OR A MIX OF RAIN AND SNOW. NNW WINDS
ALREADY BEGINNING TO TURN TO THE NORTHEAST. EARLIER DISCUSSION
BELOW.
-------------------------------------------------------------------
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 DURING THE DAY
THEN SHOULD IMPROVE THU NIGHT. DIMINISHING NORTHWEST WINDS.

FRIDAY...VFR. NW WINDS GUSTING 15-20 KNOTS.

SATURDAY-SUNDAY...MAINLY VFR...THOUGH CLOUDS INCREASE LATE SAT/SAT
NIGHT. LOW PROB FOR MVFR CIGS MOVING NORTH OFF THE OCEAN INTO CAPE
COD AND ISLANDS. SW WINDS INCREASE TO 30-40 KT AT 2-3KFT BY
SUNDAY...THOUGH WILL REMAIN LIGHTER AT GROUND LEVEL.

&&

.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...WILL SEE NW WIND GUSTS TO 25-30 KT EARLY...THEN SHOULD
DIMINISH DURING THE AFTERNOON. SEAS UP TO 6-11 FEET OVER OPEN
WATERS...HIGHEST WELL OFFSHORE...BUT WILL SUBSIDE TO 4-7 FT LATE IN
THE DAY AND CONTINUE TO LOWER THU NIGHT. SMALL CRAFT ADVISORY WILL
BE NEEDED ON MOST WATERS.

FRIDAY...NW WINDS GUSTING TO 20 KT. SEAS LINGER AT AROUND 5 FT ON
THE OUTER WATERS. SMALL CRAFT MAY NEED TO BE CONTINUES FOR A TIME.
WINDS AND SEAS SHOULD DIMINISH FRI NIGHT.

SATURDAY-SUNDAY...WINDS BACK TO SW DURING SAT...WITH GUSTS UP TO 20
KT. WILL SEE GUSTS UP TO 25 KT LATE SAT NIGHT AND SUN. SEAS BUILD TO
AROUND 5 FT DURING SUN. SMALL CRAFTS 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/EVT
NEAR TERM...NOCERA
SHORT TERM...EVT
LONG TERM...EVT
AVIATION...NOCERA/EVT
MARINE...NOCERA/EVT
TIDES/COASTAL FLOODING...



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