Area Forecast Discussion
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000
FXUS61 KBOX 071045
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
545 AM EST SUN FEB 7 2016

.SYNOPSIS...
HIGH PRESSURE WILL BRING DRY WEATHER WITH MILD TEMPERATURES TODAY.
ALTHOUGH WE WILL BE ON THE WESTERN FRINGE OF A STRONG OCEAN STORM
PASSING FAR TO THE SOUTHEAST OF THE REGION...OCEAN-EFFECT
ENHANCEMENT MAY BRING A PLOWABLE SNOWFALL TO MUCH OF THE EASTERN
HALF OF SOUTHERN NEW ENGLAND MONDAY AND MONDAY NIGHT. AN ADDITIONAL
COASTAL LOW WILL BRING SNOW TO THE REGION ON TUESDAY...WITH
LINGERING SNOW SHOWERS WEDNESDAY. AN ARCTIC COLD FRONT WILL CROSS
THE REGION THURSDAY...FOLLOWED BY DRY AIR AND COLDER THAN NORMAL
TEMPERATURES TO FINISH THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
515 AM UPDATE...
A MOSTLY SUNNY DAY IS IN STORE TODAY WITH HIGH PRESSURE AT THE
SURFACE. LIGHT SOUTHWEST WINDS WILL SHIFT TO A NORTHEASTERLY
DIRECTION LATE IN THE DAY. HIGHS WILL BE IN THE LOWER TO MID 40S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
TONIGHT...
1035 QUEBEC SURFACE HIGH ADVECTS SHALLOW ARCTIC AIR SOUTHWARD
INTO SOUTHERN NEW ENGLAND. MEANWHILE MID LEVEL SOUTHERN STREAM
TROUGH OVER THE GULF STATES INDUCES CYCLOGENESIS OFF THE EAST
COAST OF SC THIS EVENING AND THEN RAPIDLY INTENSIFIES INTO A SUB
980 MB LOW/GALE CENTER WELL EAST OF THE NC COAST TONIGHT.

TYPICALLY THIS TRACK IS TOO FAR OFFSHORE TO YIELD ACCUMULATING
SNOW TO SOUTHEAST MA. HOWEVER THIS CYCLONE HAS A VERY LARGE
CIRCULATION/WCB/FIREHOSE IN ADDITION TO 1035 MB SURFACE HIGH OVER
QUEBEC...AND AS INDICATED BELOW...WE ARE EXPECTING OCEAN-EFFECT
ENHANCEMENT. LIGHT SNOW SHOULD MOVE ONSHORE FROM THE SOUTH BEFORE
DAYBREAK MONDAY.

MONDAY...
HAVE EXPANDED THE WINTER STORM WATCH TO INCLUDE MUCH OF EASTERN MA
INCLUDING WORCESTER AND BOSTON METROPOLITAN AREAS...AND TO THE
NORTHEAST HALF OF RI. CONTINUED THE WINTER STORM WATCH FOR
SOUTHEASTERN MA...ALTHOUGH CONFIDENCE HAS INCREASED ALMOST TO THE
POINT OF WARNINGS THERE BUT WILL LET THE DAY SHIFT GIVE A FINAL
ASSESSMENT.

ALTHOUGH WE WILL BE ON THE WESTERN FRINGE OF A STRONG OCEAN STORM
PASSING FAR TO THE SOUTHEAST OF THE REGION...OCEAN-EFFECT
ENHANCEMENT IS EXPECTED TO BE THE KEY TO THE FORECAST. WITH WATER
TEMPERATURES RUNNING ABOUT +5C TO +6C...WE WOULD TYPICALLY BEGIN
TO SEE OCEAN EFFECT WITH A DIFFERENTIAL OF ABOUT 13 DEGREES C
BETWEEN THE OCEAN SURFACE AND 850 MB...OR ABOUT -7C. ALL MODELS
INDICATE THAT THIS WILL HAPPEN...AND THE GFS AND ECMWF HAVE -10C
AIR AT 850 MB EXTENDING ALONG THE EASTERN MA COAST MON AFTERNOON
INTO MON NIGHT. WITH STRONG NE WINDS...GUSTING TO 40+ MPH AT THE
COAST...THE SNOW SHOULD EXTEND WELL INLAND.

THERE IS INCREASING CONSENSUS IN MODEL QPF BUT STILL SOME BIG
DIFFERENCES. THE UKMET HAS BETWEEN 0.5 AND 1.2 INCHES OF LIQUID
EQUIVALENT ACROSS EASTERN MA WITH THE HIGHEST ON CAPE COD AND
NANTUCKET. THE GFS HAS INCREASED SINCE THE PREVIOUS RUN. THE 00Z
NAM IS IN LINE WITH THE GFS AND THE ECMWF. IN GENERAL...4 TO 6
INCHES IS A REAL POSSIBILITY IN THE I-95 CORRIDOR PERHAPS EVEN
BACK TO WORCESTER AND NORTHEAST TO THE MERRIMACK VALLEY AND CAPE
ANN. ONLY 2 OR 3 INCHES OUT IN HARTFORD/SPRINGFIELD AREAS AND THE
CT RIVER VALLEY. HOWEVER...THE JACKPOT COULD BE SOUTHERN PLYMOUTH
COUNTY AND PORTIONS OF CAPE COD WHERE 6 TO 10 INCHES ARE POSSIBLE.
THE FORECAST IS VERY TRICKY FOR NANTUCKET WHERE WET BULB COOLING
SHOULD MEAN ALMOST ALL SNOW. WE MAY NEED TO UP POTENTIAL SNOW
AMOUNTS CONSIDERABLY.

ONE CONCERN IS THE HIGHER RESOLUTION NAM AND THE LOWER RESOLUTION
CANADIAN MODEL WHICH BOTH FORECAST MUCH HIGHER AMOUNTS IN
SOUTHEAST MA.

WITH THE WINDS NEAR 40 MPH AT TIMES...IT IS POSSIBLE THAT NEAR
BLIZZARD CONDITIONS COULD OCCUR ALONG THE COAST...ESPECIALLY IN
PLYMOUTH...BARNSTABLE...DUKES...AND NANTUCKET COUNTIES.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
BIG PICTURE...

LONGWAVE SCALE SHOWS RIDGE OVER THE WESTERN USA AND TROUGH OVER THE
EASTERN USA THROUGH THE FORECAST PERIOD. AT SHORTER SCALES...MODELS
CONTINUE TO ADVERTISE THREE SHORTWAVES AFFECTING SOUTHERN NEW
ENGLAND DURING EARLY TO MID WEEK. THE FIRST PASSES WELL OFFSHORE ON
MONDAY AS NOTED IN THE SHORT TERM DISCUSSION. THE SECOND SHORTWAVE
DIGS OVER THE MIDWEST INTO THE MEAN TROUGH POSITION AND GENERATES
ANOTHER COASTAL LOW MONDAY NIGHT...THIS ONE ON THE MID ATLANTIC
COAST. THE THIRD SHORTWAVE DIVES SOUTH FROM THE ARCTIC INTO THE
EASTERN USA TROUGH...THEN SWEEPS ACROSS NEW ENGLAND THURSDAY. CLOSED
UPPER LOW FROM BAFFIN ISLAND THEN DIVES SOUTH OVER EASTERN CANADA
AND MAINTAINS THE EASTERN CYCLONIC FLOW AND LOW HEIGHTS INTO
SATURDAY.  THIS POINTS TO AN UNSETTLED PERIOD MUCH OF THE COMING
WEEK WITH NEAR SEASONABLE TEMPS EARLY WEEK AND BELOW NORMAL TEMPS
LATE WEEK.

MODEL MASS FIELDS ARE SIMILAR THROUGH TUESDAY AND INDICATE THE SAME
GENERAL PATTERN THROUGH SATURDAY. BUT THERE ARE ALSO DIFFERENCES IN
DETAILS IN TIMING OF THE SHORTWAVES...ESPECIALLY STARTING TUESDAY.
WE CONTINUE TO USE A BLEND OF MODEL DATA. CONFIDENCE IS LOW-MODERATE
TUESDAY-WEDNESDAY AND MODERATE FOR THE LATE WEEK.

THE DAILIES...

MONDAY NIGHT... OFFSHORE LOW PRESSURE MOVES OFF SOUTH OF NOVA SCOTIA
MONDAY NIGHT. ALTHOUGH UPPER DYNAMICS ARE MARGINAL...LOW LEVEL LIFT
WILL DRAW UPON THE LINGERING NORTHEAST FLOW OFF THE GULF OF MAINE TO
BRING SNOW TO THE REGION...ESPECIALLY AREAS EAST OF THE CENTRAL
HILLS. THE BEST CHANCE WILL BE IN SOUTHEAST MASS/CAPE COD WHERE THE
EXPOSURE TO THE NORTHEAST FLOW IS STRONGEST. SNOW WILL TAPER OFF
OVERNIGHT AS THE OFFSHORE LOW GETS FARTHER AWAY.

TUESDAY-WEDNESDAY-THURSDAY... THE SECOND COASTAL LOW GEARS UP ALONG
THE MID ATLANTIC COAST EARLY TUESDAY AND MOVES NORTHEAST PASSING
JUST SOUTH OF THE 40N/70W BENCHMARK. THIS IS CLOSE ENOUGH...AND
MODELS AGREE...TO BRING ANOTHER SURGE OF PRECIP INTO SOUTHERN NEW
ENGLAND. THE STRONGEST LIFT TUESDAY MORNING IS FOCUSSED IN THE LOWER
LEVELS...AOB 850 MB...WITH DEEPER LIFT TUESDAY EVENING AND NIGHT.
THE MOST FAVORED AREAS FOR SNOW WILL BE ALONG THE SOUTH COAST...WITH
DECREASING POPS FARTHER NORTH AND NORTHWEST.

THE UPPER TROUGH AND COLD POOL WILL WORK INTO NEW ENGLAND WEDNESDAY
WITH SUFFICIENT UPPER MOISTURE FOR CLOUDS...AND ENOUGH COOLING TEMPS
ALOFT TO GENERATE SCATTERED SNOW SHOWERS.  ONE MORE SHORTWAVE MOVING
THROUGH THE TROUGH WILL MOVE THROUGH EITHER WEDNESDAY NIGHT OR
THURSDAY...MODELS SHOW SOME TIMING DIFFERENCES. THIS SHORTWAVE COMES
FROM NORTHERN CANADA...WILL SUPPORT AN ARCTIC COLD FRONT THAT WILL
BRING ONE MORE CHANCE OF SNOW SHOWERS.

FRIDAY-SATURDAY... COLDER AIR POURS IN BEHIND THE ARCTIC FRONT.
LINGERING LOW LEVEL MOISTURE MAY SUPPORT DAYTIME CLOUDS BUT THE
DEEPER COLUMN WILL BECOME DRY SUGGESTING AT LEAST SOME SUNSHINE. THE
TOP OF THE MIXED LAYER SHOULD BE BETWEEN 900 AND 925 MB FRIDAY...AND
875 MB SATURDAY. TEMPS AT THESE LEVELS WOULD SUPPORT MAX SFC TEMPS
IN THE 20S FRIDAY AND MID TEENS TO MID 20S SATURDAY. THIS COLD AIR
ALONG WITH 15-25 KNOT WEST-NORTHWEST WINDS WILL GENERATE OCEAN
EFFECT SNOW SHOWERS OFF THE COAST. THE FRIDAY WEST-TO-EAST FETCH
WILL NEED TO BE MONITORED FOR POTENTIAL SNOW BANDS SOUTH OF NEW
ENGLAND AFFECTING THE ISLANDS.  THE SATURDAY NORTHWEST FETCH SHOULD
MAINLY BE OFFSHORE.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH MONDAY/...

TODAY...HIGH CONFIDENCE VFR. LIGHT AND VARIABLE WINDS BECOMING NE
TOWARD SUNSET.

TONIGHT...VFR AND DRY THROUGH ABOUT MIDNIGHT. THEN CEILINGS LOWERING
TO MVFR WITH INCREASING CHANCES OF SNOW OR MIXED RAIN/SNOW TOWARD
DAYBREAK MON ALONG THE SOUTH COAST. NE WINDS GUSTING UP TO 35 KT
CAPE COD AND ISLANDS TOWARD DAYBREAK.

MONDAY...IFR IN SNOW EASTERN MA AND RI. VISIBILITIES MAY BE
REDUCED TO NEAR ZERO ALONG THE IMMEDIATE COAST WHERE HEAVY OCEAN
EFFECT SNOW SQUALLS ARE LIKELY. MVFR IN LIGHTER SNOW IN WESTERN MA
AND NORTHERN CT. NORTHEAST WINDS GUSTING TO 40 KT ALONG THE MA
COAST...HIGHEST S OF BOSTON.

KBOS TERMINAL...HIGH CONFIDENCE THROUGH THIS EVENING THEN
MODERATE CONFIDENCE LATE TONIGHT REGARDING ARRIVAL TIME OF
LOWERING CEILINGS AND ARRIVAL OF SNOW. MODERATE CONFIDENCE FOR
MONDAY.

KBDL TERMINAL...HIGH CONFIDENCE THROUGH MIDNIGHT. MODERATE
CONFIDENCE ON THE TIMING OF THE ARRIVAL OF LOWER CEILINGS LATER
TONIGHT AND ARRIVAL OF SNOW MONDAY.

OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...

MONDAY NIGHT THROUGH WEDNESDAY...IFR/LIFR CIGS/VSBYS IN PERIODS OF
SNOW. NORTHEAST WINDS GUSTS TO 35 KNOTS ALONG THE COAST MONDAY NIGHT
AND 20-25 KNOTS TUESDAY. CONDITIONS IMPROVE TO MVFR IN SNOW SHOWERS
WEDNESDAY WITH WINDS SHIFTING WEST AND DIMINISHING.

THURSDAY...COLD FRONT MOVES THROUGH THE REGION BRINGING A WIND
SHIFT. WINDS PICK UP OUT OF THE NORTHWEST NEAR 30 KNOTS. BRIEF
MVFR/IFR IN SNOW SHOWERS WITH THE FRONT.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH MONDAY/...HIGH CONFIDENCE.

OVERNIGHT...W TO SW WINDS GUSTING TO 20-25 KT OVER THE EASTERN MA
WATERS...GRADUALLY DIMINISHING TOWARD DAYBREAK.

TODAY...TRANQUIL WIND AND SEAS ALONG WITH DRY WEATHER AND GOOD
VSBY.

TONIGHT...NE WINDS INCREASE TO GALE FORCE ACROSS THE RI AND
SOUTHERN MA WATERS...AND POSSIBLY THE NORTHERN MA WATERS TOWARD
DAYBREAK. GALE WARNINGS POSTED FOR ALL OF THE MA AND RI COASTAL
WATERS. VSBY LOWERING IN SNOW LATE ALONG THE SOUTH COAST. SEAS
WILL BUILD RAPIDLY WITH POWERFUL LOW PRES WELL OFF THE NORTH
CAROLINA COAST COMBINING WITH A 1035 MB SURFACE HIGH OVER QUEBEC.

MONDAY...GALE FORCE WINDS GUSTING TO 35-45 KTS OVER ALL COASTAL
WATERS ALONG WITH VISIBILITIES REDUCED TO BELOW 1 MILE IN SNOW.
LOCALLY NEAR ZERO VISIBILITY POSSIBLE IN HEAVIER SNOW SQUALLS. THE
ONLY EXCEPTION IS OVER NARRAGANSETT BAY WHERE SMALL CRAFT
ADVISORIES ARE POSTED FOR WIND GUSTS OF LESS THAN 30 KTS.
VERY ROUGH SEAS BUILDING UP TO 14-18 FEET OFF THE MA COAST.

OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...MODERATE CONFIDENCE...

MONDAY NIGHT...MODERATE-HIGH CONFIDENCE.  DIMINISHING NORTHEAST
WINDS. GALES LINGERING NORTH AND EAST OF PROVINCETOWN EARLY IN THE
NIGHT. ROUGH SEAS EARLY WITH HEIGHTS AROUND 15 FEET EASTOF
MASSACHUSETTS...DIMINISHING TO 8-12 FEET BY MORNING. AS GALES COME
DOWN...A SMALL CRAFT ADVISORY WILL BE NEEDED.

TUESDAY-WEDNESDAY... DIMINISHING NORTH WINDS TUESDAY WILL BECOME
NORTHWEST WEDNESDAY...WITH SPEEDS 20-25 KNOTS TUESDAY AND BELOW 20
KNOTS WEDNESDAY. SEAS WILL REMAIN ROUGH WITH 7-10 FOOT HEIGHTS
TUESDAY AND 5-10 FOOT HEIGHTS WEDNESDAY.  SMALL CRAFT ADVISORY WILL
BE NEEDED.

THURSDAY... AN ARCTIC COLD FRONT SWEEPS ACROSS THE WATERS WITH
COLDER AIR MOVING IN. WINDS WILL SHIFT NORTHWEST WITH GUSTS UP TO 30
KNOTS. THESE WINDS WILL DRIVE 5-8 FOOT SEAS ESPECIALLY ON THE OUTER
WATERS. SMALL CRAFT ADVISORY WILL BE NEEDED. THE COLD FRONT MAY
BRING A FEW SNOW SHOWERS WITH BRIEFLY POOR VSBYS. THE ARCTIC COLD
AIR BEHIND THE FRONT WILL START TO GENERATE OCEAN EFFECT SNOW
SHOWERS WITH LOCAL POOR VSBYS LATER IN THE DAY ESPECIALLY EAST OF
MASSACHUSETTS.

&&

.TIDES/COASTAL FLOODING...
ASTRO TIDES LATE MON MORNING ARE HIGH WITH 11.2 FT AT BOSTON.
STRONG NE WINDS UP TO 40 KT WILL YIELD A STORM SURGE OF 1.5 FT TO
2.0 FT AT THE TIME OF HIGH TIDE. THIS COMBINED WITH STRONG WAVE
ACTION OF 14-18 FT JUST OFFSHORE WILL YIELD A RISK OF MODERATE
COASTAL FLOODING.

ETSS WAS A BIT HIGHER THAN ESTOFS AND SEEMS REASONABLE. WIND
FIELD IS SOMEWHAT LOWER NORTH OF PLYMOUTH COUNTY. THUS THREAT OF
COASTAL FLOODING IS LOWER FROM BOSTON NORTHWARD. THEREFORE HAVE
CONFINED THE COASTAL FLOOD WATCH SOUTH OF BOSTON THRU PLYMOUTH TO
CAPE COD AND NANTUCKET.

OTHER CONCERN IS BEACH EROSION GIVEN THE HIGH WATER LEVELS...STRONG
WAVE ACTION OVER MULTIPLE TIDE CYCLES. AGAIN APPEARS HIGHEST RISK
WILL BE SOUTH OF BOSTON. HOWEVER WILL HAVE TO MONITOR LATER MODEL
RUNS FOR POSSIBLE EXPANSION OF THE WATCH NORTHWARD.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...COASTAL FLOOD WATCH FROM MONDAY MORNING THROUGH MONDAY
     AFTERNOON FOR MAZ019-022-024.
     WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY MORNING
     FOR MAZ005>007-012>024.
RI...WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY MORNING
     FOR RIZ001-002-004-005-007.
MARINE...GALE WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST MONDAY FOR
     ANZ231>235-237-254>256.
     GALE WARNING FROM 4 AM TO 6 PM EST MONDAY FOR ANZ230.
     SMALL CRAFT ADVISORY FROM 5 AM TO 7 PM EST MONDAY FOR ANZ236.
     GALE WARNING FROM 4 AM TO 10 PM EST MONDAY FOR ANZ250-251.

&&

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


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