Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 291214
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
714 AM EST MON DEC 29 2014

.SYNOPSIS...
STRONG HIGH PRESSURE BUILDS SOUTH FROM WESTERN CANADA AND THEN
SPREADS ACROSS THE USA FOR MUCH OF THE WEEK. THIS WILL MEAN A DRY
AND COLD SPELL FOR NEW ENGLAND THROUGH THE END OF THE WEEK. A
STORM MAY IMPACT THE REGION SOMETIME LATER IN THE WEEKEND BUT
THERE IS MUCH UNCERTAINTY REGARDING POSSIBLE OUTCOMES.

&&

.NEAR TERM /THROUGH TONIGHT/...

7 AM UPDATE...

PRIOR FORECAST ON TRACK. JUST MADE SOME VERY MINOR ADJUSTMENTS TO
CLOUD COVER AND TEMPERATURES. FOR TEMPERATURES...HAVE ADJUSTED
DOWN JUST SLIGHTLY.

4 AM ISSUANCE...

NEAR ZONAL FLOW ACROSS GT LAKES AND NEW ENG WITH THE MAIN
FEATURE BEING A STRONG AND SPRAWLING HIGH PRES /1060 MB/ ACROSS
WESTERN CANADA. RIDGING FROM THIS HIGH PRES EXTENDS EAST ALL THE
WAY THROUGH THE GT LAKES AND INTO NEW ENG WITH DRY NW FLOW
PROVIDING PT-MOSTLY SUNNY SKIES AND COLDER TEMPS. THE COLUMN IS
MAINLY DRY BUT SOUNDINGS DO SHOW SOME LOW LEVEL MOISTURE TO
SUPPORT SCT-BKN CU ESPECIALLY IN THE INTERIOR...WHILE HIGH CLOUDS
MAY LINGER THIS MORNING ALONG THE S COAST. SOUNDINGS SHOW MIXING
UP CLOSE TO 850 MB TODAY WHERE TEMPS ARE -8 TO -11C. THIS SUPPORTS
MAX TEMPS RANGING FROM MID 30S HIGHER TERRAIN IN NORTHERN/WESTERN
MA TO LOWER 40S COASTAL PLAIN. MAY SEE SOME NW GUSTS TO 20 MPH IN
THE MORNING THEN DIMINISHING THROUGH THE AFTERNOON.

&&

.SHORT TERM /TUESDAY/...
THE LARGE HIGH PRES FROM WESTERN CANADA BUILDS SOUTH INTO THE
PLAINS DURING TUE WITH RIDGING EXTENDING TO THE EAST COAST.
CONTINUED DRY NW FLOW WILL BRING MOCLEAR SKIES TONIGHT AND TUE AS
LOW LEVEL MOISTURE DECREASES...BUT TURNING EVEN COLDER AS 850 MB
TEMPS DROP TO -13 TO -16C TUE. LOWS TONIGHT WILL BE IN THE TEENS
TO LOWER 20S...WITH HIGH TEMPS TUE RECOVERING TO LOW/MID
30S...EXCEPT UPPER 20S HIGHER TERRAIN. MODEST NW BREEZES EXPECTED
TUE.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
HIGHLIGHTS...

* DRY THROUGH AT LEAST FRIDAY NIGHT
* SEASONABLE TO A LITTLE BELOW NORMAL TEMPERATURES
* CHANCE OF RAIN OR SNOW DEVELOPING SOMETIME OVER THE WEEKEND

OVERVIEW...

MEDIUM RANGE MODELS REMAIN IN GOOD AGREEMENT THROUGH THE WORK WEEK
BUT ARE DEPICTING WIDELY VARYING SOLUTIONS FOR NEXT WEEKEND IN
HANDLING THE TROF BEING EJECTED OUT OF THE SOUTHWEST USA. THE TIMING
OF THE EJECTION OF THAT TROF WILL BE CRITICAL. A FASTER TIMING WOULD
SEEM TO RESULT IN BETTER PHASING WITH THE NORTHERN STREAM AND A
POTENT SYSTEM HEADING TOWARD THE GREAT LAKES. THE 00Z GFS AND UKMET
OPERATIONAL RUNS AS WELL AS ENSEMBLE MEMBERS FROM PRIOR RUNS DEPICT
THIS TYPE OF SCENARIO. THE RESULT FOR SOUTHERN NEW ENGLAND WOULD BE
A PERIOD OF VERY MILD...WET AND WINDY SENSIBLE WEATHER. A SLOWER
EJECTION OF THE TROF WOULD APPEAR TO ALLOW THE NORTHERN STREAM TO
ESTABLISH GREATER DOMINANCE AND CAUSE THE SW TROF TO SHEAR TOWARD
THE EAST COAST WITH A SURFACE LOW PASSING SE OF NEW ENGLAND WITH
COLD AND POSSIBLY SNOWY OR DRY SENSIBLE WEATHER LATE IN THE
WEEKEND OR EARLY THE FOLLOWING WEEK. WITH SIGNALS OF A RETURN TO A
POSITIVE NAO BY THE END OF THE WEEK...IT SEEMS THAT THE EVENTUAL
SOLUTION SHOULD BE FAIRLY PROGRESSIVE WITH A DEEP COASTAL LOW
UNLIKELY.

BOTTOMLINE...CONFIDENCE IN NEARLY ALL ELEMENTS OF THE FORECAST FOR
THIS WEEKEND IS VERY LOW. THERE IS AN EXCEPTIONALLY WIDE RANGE OF
POSSIBILITIES FOR TEMPERATURE...WIND DIRECTION/SPEED...PTYPE...
QPF...AND TIMING OF ANY PRECIPITATION.

DAY TO DAY...

TUE NIGHT THROUGH WED...GENERALLY DRY AND COLDER THAN NORMAL
TEMPERATURES SUPPORTED BY BROAD TROF ALOFT CENTERED OVER HUDSON BAY
AND STRONG HIGH SPREADING S AND SE FROM THE CANADIAN AND USA HIGH
PLAINS. TUE NIGHT/WED AM LOOKS TO BE THE COLDEST NIGHT WITH 850 MB
TEMPERATURES OF -15C TO -17C...PROBABLY MOSTLY CLEAR SKIES AND LIGHT
WINDS. WILL LIKELY EXPERIENCE SURFACE TEMPERATURES IN TEENS ACROSS
MOST OF INTERIOR SOUTHERN NEW ENGLAND WITH POSSIBLY POCKETS OF 5 TO
10 ABOVE TEMPERATURES NW MA. LACK OF SNOWCOVER PREVENTS WHAT MIGHT
OTHERWISE BE COLDER TEMPERATURES. HIGH TEMPERATURES ON WED WILL
LIKELY TOP OUT IN THE MID 20S TO LOWER 30S MOST LOCATIONS.

WED NIGHT AND THU...THERE ARE A COUPLE OF ISSUES DURING THIS TIME
PERIOD. ONE IS THAT BELIEVE THERE IS A CHANCE OF SOME LIGHT OCEAN
EFFECT SNOW SHOWERS OVER NANTUCKET LATE WED NIGHT AND THU MORNING.
GIVEN SEA SURFACE TEMPERATURES STILL MID TO UPPER 40S OFF THE NEW
ENGLAND SOUTH COAST...ANTICIPATE STEEP ENOUGH LAPSE RATES TO
SUPPORT SCATTERED FLURRIES OR SNOW SHOWERS IN WSW FLOW THAT
DEVELOPS ACROSS SOUTH COASTAL AREAS LATE WED NIGHT AND THU. BUFKIT
SOUNDINGS SUPPORT LOW CHANCE POPS AT NANTUCKET...MAINLY IN THE 2
TO 10 AM TIME FRAME. SECOND ISSUE IS THE TIGHTENING SURFACE
PRESSURE GRADIENT THAT SHOULD RESULT IN BRISK WINDS WITH GUSTS 20
TO 25 MPH OVER LAND AND POSSIBLY MARGINALLY GALE FORCE OVER THE
OUTER COASTAL WATERS SOUTH AND SOUTHEAST OF NEW ENGLAND.

THU NIGHT THROUGH FRI NIGHT...ANTICIPATE DRY CONDITIONS THROUGH THIS
PERIOD WITH TEMPERATURES NEAR OR A LITTLE BELOW NORMAL.

SAT THROUGH SUN...THIS IS WHEN THE FORECAST GETS VERY CHALLENGING.
HAVE GONE WITH A MODEL CONSENSUS DUE TO THE EXTREME UNCERTAINTY. AS
NOTED ABOVE...THERE EXISTS A WIDE RANGE OF POSSIBLE OUTCOMES
DEPENDING UPON THE TIMING OF THE EJECTION OF THE TROF ENERGY FROM
THE SOUTHWEST USA. FOR NOW...HAVE LOW CHANCE POPS FOR MUCH OF THE
WEEKEND DUE TO UNCERTAINTY IN TIMING BUT DO NOT REALLY ANTICIPATE A
PROLONGED EVENT. HAVE LOWERED HIGH TEMPERATURES SOME FROM PRIOR
FORECASTS BUT HERE AGAIN THERE EXISTS AN EXTRAORDINARY WIDE RANGE OF
POSSIBILITIES DEPENDING UPON WHETHER WE EXPERIENCE A ROBUST SYSTEM
PASSING WELL WEST OF THE REGION OR A WEAK SYSTEM PASSING SOUTHEAST
OF OUR AREA.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...

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

TODAY THROUGH TUESDAY...CONTINUED HIGH CONFIDENCE. VFR. NORTHWEST
WINDS GUSTING 15-20 KTS TODAY.

KBOS TERMINAL...HIGH CONFIDENCE.

KBDL TERMINAL...HIGH CONFIDENCE.

OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY...

HIGH CONFIDENCE OF MAINLY VFR THROUGH THE PERIOD. THE ONLY EXCEPTION
IS A RISK OF MVFR CIGS AND VSBYS IN POSSIBLE OCEAN EFFECT SNOW
SHOWERS INVOF NANTUCKET LATE WED NIGHT INTO THU MORNING.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH TUESDAY/...HIGH CONFIDENCE.

7 AM UPDATE...WILL PROBABLY LET SCA EXPIRE AT 8 AM. SEAS STILL 5
FEET AT BUOY 44097 AT 1138Z BUT OVERALL TREND LOOKS TO BE
SUBSIDING SEAS.

4 AM ISSUANCE...

NW WINDS LIKELY TO REMAIN BELOW SCA THRESHOLDS THROUGH TUE WITH
GUSTS TO 20 KT...BUT A FEW HIGHER GUSTS POSSIBLE THIS MORNING.
SCA IN EFFECT UNTIL 8 AM FOR OUTER WATERS FOR SEAS UP TO 5
FT...OTHERWISE SEAS BELOW SCA THRESHOLDS.

OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY...

TUE NIGHT THROUGH WED NIGHT...EXPECT WINDS AND SEAS BELOW SMALL
CRAFT ADVISORY THRESHOLDS.

THU...W WIND WILL LIKELY INCREASE ABOVE SMALL CRAFT ADVISORY
THRESHOLDS ALL WATERS WITH A CHANCE OF GALE FORCE GUSTS OVER THE
OUTER COASTAL WATERS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST THIS MORNING FOR
     ANZ254>256.

&&

$$
SYNOPSIS...KJC/THOMPSON
NEAR TERM...KJC/THOMPSON
SHORT TERM...KJC
LONG TERM...THOMPSON
AVIATION...KJC/THOMPSON
MARINE...KJC/THOMPSON



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