Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 240920
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
420 AM EST SAT JAN 24 2015

.SYNOPSIS...
A COASTAL STORM WILL IMPACT MUCH OF THE REGION TODAY AND THIS
EVENING WITH HEAVY SNOW AND A WINTRY MIX ACROSS PARTS OF THE
AREA. DRY AND SEASONABLE WEATHER EXPECTED ON SUNDAY. A WINTER
STORM "MAY" BE BACK ON THE TABLE FOR SOME OF THE REGION LATE
MONDAY INTO TUESDAY...BUT CONFIDENCE IS LOW. WHETHER OR NOT WE
HAVE A WINTER STORM...IT WILL BE VERY COLD MONDAY THROUGH
WEDNESDAY WITH MODERATING TEMPERATURES BY THE END OF THE WORK
WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

**COASTAL STORM BRINGS MIXED PRECIP...WINDS AND COASTAL FLOODING**

4AM UPDATE...

OVERRUNNING PRECIP IS ONGOING AHEAD OF DEVELOPING LOW PRESSURE
SYSTEM IN THE CAROLINAS. MOST OF THE EASTERN SEABOARD IS IMPACTED
RIGHT NOW WITH HEAVY SNOW. IN FACT PORTIONS OF NJ AND EASTERN PA
HAS SEEN OVER 5 INCHES AS OF 330 AM. SNOW IS ALREADY STARTING TO
FALL IN CT AND SOUTHERN RI AND EXPECT THE SNOW TO SPREAD RAPIDLY
NORTHWARD.

LATEST SREF GUIDANCE INDICATES THAT SNOW FALL RATES MAY BE AN INCH
AN HOUR AT THE ONSET AND THIS SEEMS TO BE VERIFYING DOWNSTREAM. HI-
RES GUIDANCE INCLUDING THE HRRR ARE PINPOINTING CT AND RI AS
LOCATIONS THAT COULD SEE THIS SNOW BURST. VISIBILITIES WILL ALSO BE
REDUCED VERY QUICKLY...DOWN TO HALF OF A MILE OR LESS IN SOME
LOCATIONS. EXPECT A QUICK THUMP OF SNOW ONCE PRECIP MOVES IN WHICH
COULD QUICKLY ADD UP TO 1-3 INCHES BEFORE ANY WINTRY MIX BEGINS.

MORE DETAILS ON THE EVOLUTION OF THIS STORM BELOW:

HIGHLIGHTS...

* FAST MOVING COASTAL STORM TODAY.
* NARROW BAND OF HEAVY WET SNOW POSSIBLE IN INTERIOR NORTHEAST MASS.
* CHANCE OF FREEZING RAIN/SLEET POTENTIAL ALONG AND SOUTH OF THE
  PIKE.
* STRONG WINDS FOR THE SOUTHEAST MA THIS EVENING.

HEADLINES...

NO MAJOR CHANGES TO HEADLINES AT THIS TIME AS SNOW AMOUNTS ARE
FAIRLY SIMILAR TO PREV FORECASTERS. HAVE A LOW CONFIDENCE THAT
ANYONE WILL SEE 10 INCHES DUE TO THE WET NATURE OF THE SNOW AND HOW
PROGRESSIVE THIS SYSTEM IS. DID ADD COASTAL ESSEX COUNTY TO THE
WARNING AS THERE COULD BE SOME DECENT ACCUMS ON THE BACKSIDE OF
THIS SYSTEM DUE TO DECENT FGEN AND OMEGA IN THE SNOW GROWTH REGION.
ALSO ADDED NEWPORT COUNTY IN RHODE ISLAND AND COASTAL PLYMOUTH TO
THE ADVISORY AS THEY COULD SEE A QUICK 1-2 INCHES OF SNOW AT THE
ONSET BUT WILL CHANGE TO SLEET/FREEZING RAIN MIX WHICH COULD MAKE
THINGS SLICK BEFORE TRANSITIONING TO RAIN.

OVERVIEW...

DIGGING SHORTWAVE IN THE SOUTHEAST HAS DEVELOPED A SURFACE LOW OFF
THE COAST OF THE CAROLINAS. THIS LOW WILL QUICKLY DEEPEN AND BOMB
OUT AS IT MOVES TOWARDS THE GULF OF MAINE TODAY. 00Z GUIDANCE HAS
COME INTO BETTER AGREEMENT THEN PREV RUNS HOWEVER THIS STILL SOME
UNCERTAINTY SINCE THERMAL PROFILES ARE ISOTHERMAL...ONE DEGREE CAN
ADD OR SUBTRACT SIGNIFICANTLY FROM SNOW AMOUNTS.

FOR THIS FORECAST TRENDED TOWARDS THE 00Z NAM/EC/RGEM WHICH ARE ALL
IN LINE WITH ONE ANOTHER. FEEL THE GFS QPF IS A LITTLE UNDERDONE.
THE 06Z NAM CAME IN RATHER WARM THEN REST OF GUIDANCE AND ITS 00Z
COUNTERPART. SO EVEN FORECAST GUIDANCE IS STILL FLIP-FLOPPING ON
THERMAL FIELDS WITHIN 3-6 HOURS OF THIS EVENT. THE 00Z TREND IS ALSO
FASTER SO HAVE SPEED THE SYSTEM UP WITHIN THE FORECAST BY AN HOUR OR
TWO. APPEARS THAT TONIGHT WE MAY JUST SEE A FEW FLAKES ON THE CAPE
AS THIS SYSTEM EXIT THE REGION QUICKLY. LASTLY...MODELS ARE ALSO
INDICATING A GOOD COLD CONVEYOR BELT SET-UP ON THE BACKSIDE SO
HAVE ADJUSTED SNOW TOTALS ACROSS EASTERN MASS WHICH COULD SEE
DESCENT SNOW AMOUNTS LATE THIS AFTERNOON/EVENING HOURS.

1) TIMING AND PRECIPITATION TYPE...

PRECIP HAS ALREADY ENTERED SOUTHERN NEW ENGLAND AND SHOULD OVER
SPREAD TO THE REST OF THE REGION BY 7AM. AS NOTED BY PREV
FORECASTERS...THIS SYSTEM IS VERY PROGRESSIVE DUE TO LACK OF
BLOCKING UPSTREAM. SINCE GUIDANCE CONTINUES TO SPEED THE
ONSET...EXPECT PRECIP TO COME TO AN END FROM WEST TO EAST BETWEEN 5-
9PM.

P-TYPE ISSUES ARE TRICKY WITH THIS SYSTEM AS A DIFFERENCE OF ONE
DEGREE CAN CAUSE CHANGES WITH P-TYPE. SNOW WILL START AREA WIDE
INCLUDING THE CAPE AND THE ISLANDS THANKS TO OVERRUNNING FROM THE
WAA. THERMAL PROFILES ARE STILL WAVY...SO BELIEVE THAT A MIX OF
SNOW/SLEET/FREEZING RAIN WILL WORK ITS WAY INTO NORTHERN CT...RHODE
ISLAND AND SOUTH OF THE MASS PIKE INTO BOS WHEN TEMPS BEGIN TO WARM
AT 850MB. EXPECT MOSTLY RAIN AFTER THE INITIAL ONSET OF SNOW ACROSS
THE CAPE AND ISLANDS. ALL SNOW WEST OF THE WORCESTER HILLS IN MASS.

TOTAL SNOWFALL FOR THIS EVENT...WILL GENERALLY BE 3-6 INCHES WITH
SOME 6 TO 9 INCH REPORTS ALONG THE WORCESTER HILLS AND INTO INTERIOR
NORTHEAST MASS.

2) RISK FOR NARROW BAND OF HEAVY WET SNOW...

THERE IS A RISK FOR A NARROW BAND OF HEAVY WET SNOW.  THE MOST
LIKELY AREA IS IN INTERIOR ESSEX COUNTY AND PORTIONS OF MIDDLESEX
COUNTY THAT IS ALONG THE I-495 BELT. IT WILL PROBABLY BE TOO WARM
FOR ANY SIGNIFICANT SNOW FOR THE FAR SOUTHEAST NEW ENGLAND COAST.
ALSO THERMAL FIELDS SOUTH OF THE PIKE ARE TO MARGINAL AND WITH MIX
MOVING IN...SNOWFALL AMOUNTS WILL BE LOWER. WHERE THIS HEAVY BAND
SETS-UP THE RISK FOR POWER OUTAGES AND DOWN TREE LIMBS WILL BE A
POSSIBILITY ESP IF SNOW TOTALS ARE 6+ INCHES.

3) STRONG WINDS ACROSS THE CAPE/ISLANDS...

LOW PRESSURE WILL UNDERGO BOMBOGENESIS AS IT TRACKS NEAR THE
BENCHMARK SATURDAY AFTERNOON.  THE SYSTEM DROPS 40 MB IN 24 HOURS AS
IT WILL BE A SUB 970 MB ONCE IT PULLS AWAY FROM THE BENCHMARK. WIND
POTENTIAL IS LIMITED DUE TO PROGRESSIVE NATURE OF THIS SYSTEM.
HOWEVER DUE TO THE STRONG PRESSURE FALLS BEHIND THIS SYSTEM WE COULD
SEE WIND ADV CRITERIA ALONG THE CAPE AND THE ISLANDS. EXPECT NORTH
TO NORTHWEST WIND GUSTS OF 40 TO 50 MPH ACROSS THE CAPE AND ISLANDS.
NO CHANGES TO WIND HEADLINES AT THIS TIME.

4) COASTAL FLOODING...

SEE COASTAL FLOODING SECTION BELOW.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...

TONIGHT...
AFTER THE BRIEF BURST OF SNOW/WIND EXPECT A BREEZY AND COLD NIGHT
BEHIND THE EXITING LOW PRES ESPECIALLY AFTER MIDNIGHT. DEPENDING
ON HOW QUICKLY THE WINDS ARE ABLE TO DRY AREA ROADWAYS AND
SIDEWALKS...MAY NEED TO WATCH FOR SOME LEFTOVER PATCHY BLACK ICE
AS TEMPS FALL BACK INTO THE UPPER TEENS AND 20S BY DAYBREAK SUN.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...

HIGHLIGHTS...

* DRY AND SEASONABLE SUNDAY
* WINTER STORM "MAY" BE BACK ON THE TABLE LATE MON/TUE - LOW
  CONFIDENCE
* VERY COLD MON-WED WITH MODERATING TEMPS THU/FRI

DETAILS...

SUNDAY...

RAPIDLY INTENSIFYING LOW PRESSURE WILL ALREADY HAVE LIFTED INTO THE
CANADIAN MARITIMES EARLY SUN AM.  IN ITS WAKE...DRY BUT BLUSTERY AND
SEASONABLY CHILLY WEATHER EXPECTED.  HIGHS MAINLY IN THE 30S...BUT
IT WILL FEEL A BIT COLDER WITH NORTHWEST WIND GUSTS BETWEEN 20 AND
30 MPH.

MONDAY AND TUESDAY...

VERY LOW CONFIDENCE FORECAST.  A FEW OF THE GFS ENSEMBLES AND
PARTICULARLY THE 00Z OPERATIONAL ECMWF ARE NOW STRONGER WITH THE
SHORTWAVE ENERGY DROPPING INTO THE SOUTHEAST STATES.  THIS ALLOWS
FOR A MORE AMPLIFIED UPPER LEVEL PATTERN...WHICH CAPTURES LOW
PRESSURE ALLOWING A TRACK CLOSER TO THE COAST.  FOR WHAT ITS
WORTH...THE 00Z ECMWF SHOWS A MAJOR WINTER STORM FOR EASTERN NEW
ENGLAND WITH HEAVY SNOW AND STRONG WINDS.  KEEP IN MIND THIS IS JUST
ONE OPERATIONAL MODEL RUN AND THE FIRST TO SHOW IT.  MUCH OF THE 00Z
GUIDANCE IS STILL WAY SOUTHEAST AND PRETTY MUCH A MISS FOR MOST OF
THE REGION.  WILL NEED TO SEE IF THIS WAS JUST A HICCUP OR IF THE
ECMWF AND A FEW OF THE GEFS ARE ONTO SOMETHING IN THE NEXT 24 HOURS.

REGARDLESS IF WE GET A WINTER STORM OR NOT...OCEAN EFFECT SNOW
SHOWERS WILL LIKELY AFFECT SOUTHEAST MA/CAPE ISLANDS WITH VERY COLD
NORTHEAST WINDS BLOWING OVER THE OCEAN.  IT WILL ALSO BE QUITE COLD
MON AND ESPECIALLY TUE...WHEN HIGHS MAY REMAIN IN THE TEENS FOR MUCH
OF THE REGION.

WEDNESDAY...

IF WE DO END UP WITH THAT WINTER STORM...IT WOULD HAVE COME TO AN
END BY EARLY WED.  STILL WILL BE VERY COLD ACROSS THE REGION WITH
SOME BELOW ZERO READINGS EXPECTED EARLY WED MORNING.

THURSDAY AND FRIDAY...

HIGH PRESSURE MOVES OFF THE COAST THURSDAY ALLOWING A RETURN FLOW OF
SOMEWHAT MILDER AIR.  SOME MODELS SHOWING LOW PRESSURE DEVELOPING
OFF THE COAST BY FRI...BUT VERY LOW CONFIDENCE AT THIS TIME.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH TONIGHT/...

TODAY...MODERATE CONFIDENCE.

ALTHOUGH HAVE SOMEWHAT HIGH CONFIDENCE...LOWER CONFIDENCE IN
EXACT TIMING OR WHERE THE RAIN/SNOW/MIX LINE ENDS UP. COASTAL LOW
WILL PASS SE OF THE REGION. ANY VFR CONDITIONS WILL DROP TO IFR
IN RAIN AND HEAVY WET SNOW. SNOW WILL ACCUMULATE ALONG THE RUNWAYS
AS SNOWFALL RATES WILL BE CLOSE TO AN INCH AN HOUR AND VSBYS WILL
DROP TO A QUICK 1/2SM AT THE ONSET. EXPECT MAINLY RAIN ON CAPE
COD AND ISLANDS BY MID-MORNING BEFORE CHANGE TO SNOW THIS EVENING
WHEN N/NW WINDS COULD GUST TO 45KT. A FEW SITES WILL SEE A WINTRY
MIX DURING THE MID-MORNING HOURS...ESP BDL-ORH-BOS LINE SOUTHWARD.

TOMORROW NIGHT...HIGH CONFIDENCE.
CONDITIONS IMPROVE WITH WINDS SHIFTING NW. COULD BE A BURST OF
SNOW AT CAPE COD TAF SITES BRIEFLY BEFORE ENDING WITH LOW VSBYS
AND QUICK ACCUMS DURING THE EVENING. AFTER ENDING EXPECT RAPID
IMPROVEMENT TO VFR BUT WITH WIND GUSTS 20-30KT OUT OF THE NW.

KBOS TAF...HIGH CONFIDENCE IN TAF TRENDS...LOWER CONFIDENCE IN
EXACT TIMING OF MIXING.

KBDL TAF...HIGH CONFIDENCE IN TAF TRENDS...LOWER CONFIDENCE IN
EXACT TIMING OF MIXING.

OUTLOOK /SUNDAY THROUGH WEDNESDAY/...

SUNDAY...HIGH CONFIDENCE. VFR. NW WIND GUSTS UP TO 25 KNOTS.

MONDAY AND TUESDAY...LOW CONFIDENCE.  MVFR-IFR CONDITIONS MAY
DEVELOP IF COASTAL LOW PRESSURE TRACKS CLOSE ENOUGH TO OUR REGION
LATE MON INTO TUE.  HIGHEST RISK SOUTHEAST NEW ENGLAND COAST.  STRONG
NORTHEAST WINDS ARE ALSO POSSIBLE ON THE COAST DEPENDING ON TRACK OF
THE STORM.

WEDNESDAY...LOW TO MODERATE CONFIDENCE.  WHAT EVER HAPPENS WITH THE
STORM LATE MON INTO TUE...EXPECT CONDITIONS TO IMPROVE TO VFR FROM
WEST TO EAST.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH TONIGHT/.


TODAY AND TONIGHT...HIGH CONFIDENCE.

STRENGTHEN COASTAL LOW WILL RAPIDLY MOVE INSIDE THE 70N/40W
BENCHMARK THIS EVENING. THIS LOW WILL `BOMB` OUT...MEANING THAT
INTENSE PRESSURE FALLS WILL BE ASSOCIATED WITH IT. THIS WILL ALLOW
FOR A PERIOD OF STRONG GALE FORCE WINDS OUT OF THE N-NE...THEN
SHIFTING TO THE NW BY LATE EVENING AS THE LOW MOVES OVER. EXPECT
HEAVY RAIN AND FOG...POSSIBLY EVEN A LITTLE BIT OF SNOW CLOSER TO
THE SHORE. THE GALES BEGIN DURING THE AFTERNOON. SEAS BUILD TO
ABOUT 15 FT ON THE OUTER SE WATERS.

OUTLOOK /SUNDAY THROUGH WEDNESDAY/...

SUNDAY...HIGH CONFIDENCE.  NORTHWEST SMALL CRAFT WIND GUSTS OF 20 TO
30 KNOTS EXPECTED IN THE COLD AIR ADVECTION PATTERN.

MONDAY AND TUESDAY...LOW CONFIDENCE.  LOW PRESSURE TO OUR SOUTHEAST
WILL COMBINE WITH HIGH PRESSURE OVER EASTERN CANADA.  HOW CLOSE THIS
LOW TRACKS TO THE COAST REMAINS HIGHLY UNCERTAIN.
REGARDLESS...SHOULD HAVE STRONG SCA TO NORTHEAST GALE GUSTS LATE
MON/TUE WITH SEAS BUILDING TO 10+ FEET ACROSS OUR EASTERN WATERS. IF
COASTAL LOW TRACKS FURTHER WEST LIKE THE 00Z ECMWF...SEAS OF 20+
FEET AND STORM FORCE WIND GUSTS WOULD BE POSSIBLE.

WEDNESDAY...LOW CONFIDENCE.  WIND SPEEDS AND SEAS WILL LIKELY BE
DETERMINED BY TRACK OF THE COASTAL LOW LATE MON INTO TUE.  MAY HAVE
AT LEAST SOME LEFT OVER SMALL CRAFT ADVISORY WIND GUSTS FROM THE
NORTHWEST.

&&

.TIDES/COASTAL FLOODING...

**POCKETS OF MINOR COASTAL FLOODING LIKELY ALONG THE EASTERN MA
 COAST DURING THE MID AFTERNOON HIGH TIDE CYCLE**

GIVEN THE PROGRESSIVE NATURE OF THIS STORM AND LACK OF ONSHORE
WIND/HIGH SEAS...WE ARE NOT EXPECTING A SIGNIFICANT COASTAL FLOOD
EVENT. HOWEVER...EXPECT THAT WE WILL SEE SOME POCKETS OF MINOR
COASTAL FLOODING ALONG THE EASTERN MA COAST DURING THE MID AFTERNOON
HIGH TIDE CYCLE.  BOSTON HAS AN ASTRO TIDE OF 11.4 FEET AT 230 PM
THIS AFTERNOON. EXPECTING A 0.5 TO 1 FOOT STORM SURGE ALONG WITH
FAIRLY RAPID PRESSURE FALLS.  SO DESPITE THE LACK OF STRONG
WINDS/HIGH SEAS...EXPECT SOME POCKETS OF MINOR COASTAL FLOODING.

THERE IS A LOWER ASTRO HIGH TIDE OF 11.0 FEET IN BOSTON AT AROUND
230 AM SUNDAY MORNING.  HOWEVER...BY THIS TIME WINDS WILL BE
OFFSHORE SO WERE ONLY CONCERNED ABOUT THIS AFTERNOON/S HIGH TIDE.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
     CTZ002>004.
MA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ002-
     003-008-009-015>021.
     COASTAL FLOOD ADVISORY FROM 11 AM THIS MORNING TO 4 PM EST
     THIS AFTERNOON FOR MAZ007-015-016-019-022-024.
     WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
     MAZ004>007-010>014-026.
     WIND ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT EST TONIGHT
     FOR MAZ022-024.
RI...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
     RIZ002>007.
     WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR RIZ001.
MARINE...GALE WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST SUNDAY FOR
     ANZ231>235-237-250-251-254>256.
     SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST
     SUNDAY FOR ANZ230-236.

&&

$$
SYNOPSIS...FRANK/DUNTEN
NEAR TERM...DUNTEN
SHORT TERM...DUNTEN
LONG TERM...FRANK
AVIATION...FRANK/DUNTEN
MARINE...FRANK/DUNTEN
TIDES/COASTAL FLOODING...STAFF



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