Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 051801
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
101 PM EST THU MAR 5 2015

.SYNOPSIS...
SNOW CONTINUES ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA
THIS AFTERNOON. HIGH PRESSURE WILL BUILD IN FOR FRIDAY THROUGH
THIS WEEKEND...BRINGING DRY CONDITIONS WITH COLDER THAN NORMAL
TEMPERATURES. A COUPLE OF WEAK COLD FRONTS MAY SLIP THROUGH WITH
WIDELY SCATTERED SNOW SHOWERS SATURDAY NIGHT AND MONDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
*** WINTER STORM WARNING NOW IN EFFECT FOR THE SOUTH COASTS OF
 MASSACHUSETTS AND RHODE ISLAND AS WELL AS THE ISLANDS ***

1 PM UPDATE...SNOW CONTINUES ACROSS RHODE ISLAND AND SOUTHEASTERN
MASSACHUSETTS. 12Z MODELS HAVE COME IN WITH AN ADDITIONAL TENTH TO
TWO TENTHS OF AN INCH OF QPF FOR THE AFTERNOON AND EVENING HOURS
ACROSS THE SOUTH COAST. THAT AND THE GROUND TRUTH REPORTS BEING
RECEIVED WITHIN THE OFFICE HAVE PROMPTED US TO UPGRADE THE WINTER
WEATHER ADVISORY ALONG THE SOUTH COAST TO A WINTER STORM WARNING.
IN ADDITION...WE HAVE ISSUED A WINTER WEATHER ADVISORY JUST NORTH
OF THE WARNING AREA. THIS INCLUDES WINDHAM CONNECTICUT...THE REST
OF RHODE ISLAND...AND NORTHERN BRISTOL AND PLYMOUTH COUNTIES IN
MASSACHUSETTS.

THE NORTHERN EDGE OF THE SNOW IS STILL A VERY TIGHT GRADIENT.
DEWPOINTS HAVE CRASHED INTO THE SINGLE DIGITS ACROSS MUCH OF
SOUTHERN NEW ENGLAND. THE NORTHERN EDGE OF THE SNOW BASED ON
OBSERVATIONS RUNS ROUGHLY FROM WILLIMANTIC CONNECTICUT...TO
SMITHFIELD RHODE ISLAND AND PLYMOUTH MASSACHUSETTS.

AFTER THE MILD DAY YESTERDAY...TODAY WILL FEEL MUCH COLDER. 850
MB TEMPERATURES WILL BE PLUNGING FROM NEAR 0C THIS MORNING TO
-15C BY EVENING. SURFACE TEMPERATURES WILL DROP INTO THE 20S AND
MAY HOLD STEADY FOR A WHILE DURING THE DAY BEFORE PLUNGING
TONIGHT.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
CLEARING SETS IN ACROSS ALL OF REGION TONIGHT AS SYSTEM HEADS
FARTHER OUT TO SEA AND VERY STRONG HIGH PRESSURE BUILDS INTO THE
OHIO VALLEY AND APPALACHIAN REGION. CLEAR SKIES AND NORTHERLY
WINDS WILL SPELL ANOTHER BITTERLY COLD NIGHT. WINTER IS NOT OVER
YET. OVERNIGHT LOW TEMPERATURES WILL RANGE FROM FROM ABOUT 2 BELOW
TO 5 ABOVE ACROSS THE INTERIOR...TO THE TEENS CLOSER TO COAST.

NAM SEEMS TO BE CAPTURING THE MAGNITUDE OF THE COLD AIR OVER THE
OCEAN WATERS THE BEST WITH 925 MB WINDS UP TO 25-30 KT AND SWANNAM
SHOWING SEAS BUILDING TO 4 TO 6 FT OVER THE EASTERN MA WATERS.
SURFACE WINDS COULD HAVE GUSTS TO 20-28 KT OVER THE WATERS.
HAVE ISSUED A FREEZING SPRAY ADVISORY FOR THE NORTHEAST MA
COASTAL WATERS FOR TONIGHT.

A SUNNY BUT COLD DAY IS FORECAST FOR FRIDAY AS HIGH PRESSURE
CENTERED OVER DELMARVA RIDGES NORTHEASTWARD ACROSS SOUTHERN NEW
ENGLAND. HIGHS ONLY IN THE 20S WITH LIGHT WINDS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
BIG PICTURE...

BROAD TROUGH OVER THE EASTERN USA DURING THE WEEKEND WITH BELOW
NORMAL CONTOUR HEIGHTS OVER NEW ENGLAND.  THIS FEATURE FLATTENS
DURING NEXT WEEK WITH CONTOUR HEIGHTS RETURNING TO NEAR NORMAL OR A
LITTLE ABOVE. THIS SUGGESTS COOLER THAN NORMAL WEATHER OVER THE
WEEKEND TRENDING CLOSER TO NORMAL DURING THE WEEK.

THE WEATHER-SUPPORTING FEATURES WILL BE GUIDED BY WEAK SHORTWAVES IN
THE FLOW. AS SUCH...CONFIDENCE IS LOW IN THE TIMING OF THESE
SHORTWAVES. TO MINIMIZE THIS...WE USED A BLEND OF MODEL DATA.

THE DAILIES...

FRIDAY NIGHT-SATURDAY...

HIGH PRESSURE MOVES OFFSHORE FRIDAY NIGHT SETTING UP A WEST-
SOUTHWEST FLOW ACROSS NEW ENGLAND. ANOTHER NORTHERN STREAM SHORTWAVE
DIVES SOUTH FROM NORTHERN CANADA TO THE GREAT LAKES SATURDAY AND NEW
ENGLAND SATURDAY NIGHT. LIMITED JET SUPPORT WITHIN THE NORTHERN
STREAM WHILE HIGH PRESSURE ACROSS THE SOUTH BLOCKS ANY INFLOW OF
MOISTURE INTO THE NORTHERN SYSTEM. EXPECT AN INCREASE IN SKY COVER
SATURDAY AND MAYBE SOME ISOLATED SNOW SHOWERS.

SUNDAY THROUGH WEDNESDAY...

SAME STORY EVERY COUPLE OF DAYS. ANOTHER NORTHERN SHORTWAVE AND
SURFACE COLD FRONT MAY BRING SCATTERED OR ISOLATED SNOW SHOWERS.
HIGH PRESSURE IN PLACE TO OUR SOUTH WILL AGAIN BLOCK INFLOW OF ANY
SIGNIFICANT PCPN. AN INVERTED TROUGH SOUTH OF THE HIGH AND ALONG THE
GULF OF MEXICO SUGGESTS THAT THE MOISTURE IS THERE TO BE
TAPPED...JUST THAT IT IS BEING PUSHED EAST OUT TO SEA TO OUR SOUTH.

SO THIS IS A GENERALLY DRY PERIOD WITH A MODERATING TREND ON
TEMPERATURES.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH FRIDAY NIGHT/...MODERATE CONFIDENCE TODAY.
HIGH CONFIDENCE TONIGHT THROUGH FRIDAY NIGHT.

IFR AND MVFR CONDITIONS IN LIGHT TO OCCASIONALLY MODERATE SNOW
ACROSS SOUTHERN PORTIONS OF THE REGION...MAINLY SOUTH OF A LINE
FROM IJD-SFZ-TAN-GHG. THESE CONDITIONS PERSIST MOST OF THE DAY.
VFR TO OCCASIONAL MVFR CIGS NORTH OF THAT LINE.

SKIES BEGIN TO CLEAR FROM NW TO SE LATE THIS AFTERNOON...REACHING
CAPE COD AND NANTUCKET LATE TONIGHT. CLEAR SKIES EXPECTED LATER
TONIGHT THROUGH FRIDAY NIGHT.

EXPECTED GENERAL SNOW ACCUMULATIONS TODAY...
BOS/BAF/BDL/BED/ORH...NO ACCUMULATION.
PVD...2-4 INCHES
FMH/HYA...6-8 INCHES
ACK...6-8 INCHES

KBOS TAF...HIGH CONFIDENCE.

KBDL TAF...HIGH CONFIDENCE.

OUTLOOK...SATURDAY THROUGH MONDAY...MODERATE CONFIDENCE.

VFR. BRIEF MVFR CIGS/VSBYS POSSIBLE SATURDAY IN WIDELY SCATTERED
SNOW SHOWERS.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH FRIDAY/...MODERATE CONFIDENCE.

SMALL CRAFT ADVISORIES HAVE BEEN EXTENDED INTO MID-MORNING ON
FRIDAY FOR THE OUTER WATERS. A SMALL CRAFT ADVISORY IS IN EFFECT
FOR MASS BAY AND IPSWICH BAY AND FOR BLOCK ISLAND/RI SOUNDS
THROUGH TONIGHT. SEAS WILL BUILD TO 5 TO 6 FEET OVER THE OUTER
WATERS AND EVEN INTO A PORTION OF CAPE COD BAY AS WELL AS BLOCK
ISLAND/RHODE ISLAND SOUNDS.

A FREEZING SPRAY ADVISORY HAS BEEN POSTED FOR THE WATERS EAST OF
CAPE ANN AND EAST OF BOSTON FOR TONIGHT. TEMPERATURES IN THE TEENS
MAY COMBINE WITH NORTHERLY WIND GUSTS TO 20 TO 28 KT TO CREATE
MODERATE FREEZING SPRAY WHICH COULD BE A DANGER TO MARINERS.

A COLD FRONT WAS MOVING OFF OF CAPE COD AS OF 3 AM AND IT WILL BE
EXITING THE COASTAL WATERS EARLY THIS MORNING...THEN STALL AS LOW
PRESSURE TRAVELS ALONG THE FRONT. RAIN WILL CHANGE TO SLEET AND SNOW
TOWARD DAYBREAK. SNOW WILL CONTINUE ACROSS THE SOUTHERN COASTAL
WATERS THROUGH MUCH OF THE DAY BEFORE HEADING OFFSHORE TONIGHT.

STRONG HIGH PRESSURE BUILDS INTO THE REGION FROM THE WEST AND THIS
MAY CAUSE A PERIOD OF 25 KT NW TO N WIND GUSTS TONIGHT...MAINLY ON
THE EASTERN OUTER WATERS.

FRIDAY...NORTH WINDS BEGIN TO SHIFT TO THE SOUTHWEST. WINDS BELOW
25 KNOTS. SEAS LESS THAN 5 FEET.

OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...MODERATE CONFIDENCE.

FRIDAY NIGHT AND SATURDAY...INCREASING SOUTHWEST WIND WITH
FREQUENT GUSTS TO 25 KNOTS POSSIBLE BY SAT AFTERNOON AND EVENING.
SEAS BUILD TO 3-5 FEET ON THE OUTER WATERS. A SMALL CRAFT ADVISORY
MAY BE NEEDED.

SUNDAY-MONDAY...WINDS BELOW 25 KNOTS.  SEAS GENERALLY BELOW 5
FEET...ALTHOUGH OCCASIONAL 5 FOOT SEAS POSSIBLE ON THE OUTER WATERS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR CTZ004.
MA...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
     MAZ020>024.
     WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
     MAZ017>019.
RI...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
     RIZ003>008.
     WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR RIZ001-
     002.
MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM EST
     FRIDAY FOR ANZ231-251.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
     SMALL CRAFT ADVISORY UNTIL 10 AM EST FRIDAY FOR ANZ250-254>256.
     FREEZING SPRAY ADVISORY FROM 8 PM THIS EVENING TO 5 AM EST
     FRIDAY FOR ANZ250-251.

&&

$$
SYNOPSIS...WTB/GAF
NEAR TERM...RLG
SHORT TERM...GAF
LONG TERM...WTB
AVIATION...WTB/RLG
MARINE...WTB/GAF


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