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Area Forecast Discussion
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000
FXUS61 KBOX 130547
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
147 AM EDT FRI MAR 13 2015

.SYNOPSIS...
DRY BUT CHILLY WEATHER THROUGH FRIDAY NIGHT. LOW PRESSURE WILL
BRING A COLD SOAKING RAIN SATURDAY...PROBABLY STARTING AS A BRIEF
PERIOD OF FREEZING RAIN FOR SOME EARLY SATURDAY MORNING. LEFT OVER
RAIN SHOWERS WILL CHANGE TO SCATTERED SNOW SHOWERS LATE SATURDAY
NIGHT INTO SUNDAY. DRY WEATHER RETURNS MONDAY FOLLOWED BY A BRIEF
PERIOD OF MAINLY RAIN MONDAY NIGHT INTO EARLY TUESDAY. A SHOT OF
UNSEASONABLY COLD WEATHER WILL FOLLOW LATE TUESDAY INTO WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...

2 AM UPDATE...

NOT MUCH CHANGE FROM PREVIOUS FORECAST...LIGHT NORTHERLY WINDS
DRAINING COLD AIR FROM NORTHERN NEW ENGLAND INTO THE REGION WITH
DEW PTS IN THE SINGLE DIGITS. EARLIER DISCUSSION BELOW.

=================================================================

COLD NIGHT AHEAD WITH MODIFIED ARCTIC AIRMASS OVER THE REGION
WITH DEW PTS AOB ZERO...LOWEST VALUES OVER NORTHEAST MA. THIS IS
WHERE SOME OF THE COLDEST READINGS WILL BE OBSERVED TOMORROW
MORNING ESPECIALLY IN THE I495 CORRIDOR OF NORTHEAST MA WHERE
WINDS DECOUPLE. WHILE NOT RECORD BREAKING COLD TEMPS WILL AVERAGE
10 DEGS BELOW THAN NORMAL TONIGHT. PREVIOUS FORECAST MATCHES UP
WELL WITH LATEST SURFACE OBSERVATIONS AND SATELLITE IMAGERY...SO
NO MAJOR CHANGES WITH THIS FORECAST UPDATE. EARLIER DISCUSSION
BELOW.


&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
HIGH PRESSURE WILL MOVE EAST OF OUR REGION. THIS WILL ALLOW FOR A
RETURN SOUTHWEST FLOW AND MODEST WARM ADVECTION THROUGH THE DAY.
THE SUBSIDENCE ALOFT REMAINS IN CONTROL...SO DRY WEATHER WITH
PARTIAL CLOUDINESS IS EXPECTED. MAX TEMPERATURES WILL MODERATE
SOMEWHAT IN COMPARISON TO THURSDAY...BUT SUSPECT THAT MOST PLACES
REMAIN NEAR TO JUST BELOW NORMAL VALUES.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
HIGHLIGHTS...

* COLD RAIN SATURDAY BUT A PERIOD OF FREEZING RAIN LIKELY AT ONSET
* LIGHT ICING POTENTIAL SAT AM MAY BE HIGH IMPACT FOR MOTORISTS
* RAIN CHANGES TO SCT SNOW SHOWERS LATE SAT NIGHT/SUN WITH A LOW 
  RISK FOR A LIGHT ACCUMULATION
* A PERIOD OF MAINLY RAIN SHOWERS MON NIGHT INTO EARLY TUE
* SHOT OF UNSEASONABLY COLD AIR LATE TUE INTO WED

DETAILS...

FRIDAY NIGHT AND SATURDAY...

LOW PRESSURE WILL BE APPROACHING FROM THE SOUTHWEST AS HIGH PRESSURE 
SLOWLY MOVES OFF THE COAST.  FRI NIGHT SHOULD BE DRY...BUT EXPECT 
SOME PRECIPITATION TO DEVELOP SOMETIME TOWARD DAYBREAK INTO EARLY 
SAT MORNING.  MODEL SOUNDINGS SHOW A FAIRLY PRONOUNCED WARM LAYER 
FROM AROUND 950 MB TO 850 MB INTRUDING AHEAD OF THE MAIN 
PRECIPITATION SHIELD.  SNOW POTENTIAL IS VERY LIMITED ON THE FRONT 
END OF THIS SYSTEM...BUT THERE IS A LOW PROBABILITY OF A LITTLE BIT 
ACROSS EXTREME NORTHERN MA.  WE ARE MORE CONCERNED ABOUT A PERIOD OF 
LIGHT FREEZING RAIN.  MODELS ARE OFTEN TOO FAST IN ERODING BOUNDARY 
LAYER COLD WHEN SURFACE WINDS ARE RATHER LIGHT.  IN FACT...EVEN THE 
13 KM ECMWF/RGEM/NAM HAVE SURFACE TEMPS NEAR OR JUST BELOW FREEZING 
ACROSS A GOOD CHUNK OF THE REGION AT 12Z SATURDAY.  WHILE COLDEST 
AIR IS NORTH OF MA TURNPIKE...PRECIP ARRIVES EARLIER IN NORTHERN CT 
SO MUCH OF THE AREA IS AT RISK.  WHILE ANY ICING SHOULD BE QUITE 
LIGHT...GIVEN THAT PRECIP MAY BEGIN AS STRAIGHT FREEZING RAIN IS 
CONCERNING.  THESE VERY LIGHT ICING EVENTS OFTEN CATCH PEOPLE OFF 
GUARD AND RESULT IN NUMEROUS ACCIDENTS.  WE WILL LIKELY NEED 
FREEZING RAIN ADVISORIES FOR AT LEAST A PORTION OF THE REGION.

GIVEN HIGH MOVING AWAY FROM THE REGION...SHOULD SEE PTYPE CHANGE TO 
ALL RAIN SAT AFTERNOON.  RAINFALL AMOUNTS OF 0.50 TO 1.00 INCH SEEM 
REASONABLE AT THIS TIME.  IT WILL BE A COLD RAIN...SO NOT ENOUGH TO 
RELEASE A LOT OF WATER FROM THE SNOW PACK AND RIVER/STREAM FLOODING 
IS NOT A CONCERN.  HOWEVER...TYPICAL NUISANCE POOR DRAINAGE STREET 
FLOODING IS POSSIBLE.

SATURDAY NIGHT AND SUNDAY...

FORECAST CONFIDENCE REMAINS LOW.  FIRST WAVE OF LOW PRESSURE EXITS 
THE REGION.  HOWEVER...POTENT NORTHERN STREAM ENERGY DIVES SOUTH AND 
CLOSES OFF SOMEWHERE IN THE VICINITY OF SOUTHERN NEW ENGLAND.  WHERE 
EXACTLY THIS OCCURS WILL HAVE A HUGE IMPACT ON OUR WEATHER.  

1) MOST LIKELY SCENARIO: 

MOST OF THE 12Z GUIDANCE HAS THE UPPER LEVEL LOW CLOSING OFF ON TOP 
OF US OR TO OUR NORTH.  THIS WOULD RESULT IN JUST SCATTERED RAIN 
SHOWERS CHANGING TO SCATTERED SNOW SHOWERS.  PERHAPS A VERY SMALL 
SLUSHY ACCUMULATION WOULD OCCUR ON GRASSY SURFACES...BUT OF LITTLE 
IMPACT.

2) LOWER PROBABILITY SCENARIO:
 
GIVEN WE ARE STILL 3+ DAYS OUT WILL HAVE TO WATCH THAT THE UPPER 
LEVEL LOW DOES NOT CLOSE OFF A BIT FURTHER SOUTH THEN MODELS DEPICT. 
WHILE THIS IS MUCH LOWER PROBABILITY...UPPER LEVEL ENERGY IS FAIRLY 
ROBUST.  IF THAT WERE TO OCCUR RAIN WOULD CHANGE TO SEVERAL INCHES 
OF ACCUMULATING SNOW. AGAIN...A LOW PROBABILITY AT THIS POINT BUT 
SOMETHING WE CAN NOT COMPLETELY RULE OUT YET.

MONDAY THROUGH THURSDAY...

DRY DURING THE DAY MONDAY...BUT A FAST MOVING PIECE OF NORTHERN 
STREAM ENERGY WILL LIKELY BRING A ROUND OF PRECIPITATION MON NIGHT 
INTO EARLY TUE.  LOOKS LIKE MAINLY A PERIOD OF RAIN SHOWERS WITH 
WARM ADVECTION AHEAD OF THE SHORTWAVE.  THERE IS A LOW RISK THAT 
SOME AREAS COULD END AS A BIT OF SNOW...BUT A SECONDARY LOW WOULD 
HAVE TO DEVELOP CLOSE ENOUGH TO THE COAST.  OTHERWISE...A SHOT OF 
UNSEASONABLY COLD AIR MOVES IN TUE NIGHT INTO WED.  HIGHS WED 
PROBABLY STAY IN THE 30S.  TEMPS PROBABLY MODERATE SOME ON THU.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH SATURDAY/...HIGH CONFIDENCE INTO THIS EVENING
THEN LOWER CONFIDENCE ON EXACT TIMING THEREAFTER.

TODAY...VFR/LIGHT WINDS AND DRY WEATHER.

TONIGHT...VFR WITH MVFR TOWARD SUNRISE. LIGHT RAIN LIKELY TOWARD
MORNING ESPECIALLY ACROSS CT/RI AND SOUTHEAST MA. INLAND /BAF-
BDL-ORH/ PRECIP LIKELY -FRZA.

SAT...IFR AND LIFR IN RAIN...HEAVY AT TIMES ACROSS EASTERN CT/RI
AND SOUTHEAST MA. -FZRA POSSIBLE UNTIL ABOUT 15Z ACROSS THE
INTERIOR.
 
KBOS TAF...HIGH FORECAST CONFIDENCE.

KBDL TAF...HIGH FORECAST CONFIDENCE EXCEPT LOWER CONFIDENCE ON
TIMING AND DURATION OF -FZRA LATE TONIGHT INTO EARLY SAT AM.

OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY...

SATURDAY NIGHT AND SUNDAY...MODERATE CONFIDENCE.  SOME MVFR 
CONDITIONS WILL REMAIN POSSIBLE IN SCATTERED RAIN CHANGING TO SNOW 
SHOWERS. 

MONDAY AND TUESDAY...MODERATE CONFIDENCE.  MAINLY VFR BUT A PERIOD 
OF MVFR-IFR CONDITIONS WILL PROBABLY OCCUR IN SOME RAIN SHOWERS 
MONDAY NIGHT INTO EARLY TUESDAY.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT-TERM /THROUGH FRIDAY/...HIGH CONFIDENCE.

GUSTY NORTHWEST WINDS WILL DIMINISH THIS EVENING INTO THE
OVERNIGHT HOURS AND SEAS WILL GRADUALLY LOWER.  HOWEVER...SMALL 
CRAFT SEAS FROM LEFT OVER SWELL WILL CONTINUE ACROSS THE EASTERN 
WATERS THROUGH DAYBREAK.

THESE SMALL CRAFT SEAS ACROSS THE EASTERN COASTAL WATERS WILL 
GRADUALLY DIMINISH THROUGH FRIDAY. SOME LIGHT FREEZING SPRAY IS 
POSSIBLE ACROSS THE EASTERN WATERS TONIGHT.

OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...

FRIDAY NIGHT AND SATURDAY...MODERATE TO HIGH CONFIDENCE.  WEAK LOW 
PRESSURE MOVES ACROSS THE WATERS.  PRESSURE GRADIENT SHOULD REMAIN 
WEAK ENOUGH TO KEEP WINDS BELOW SMALL CRAFT ADVISORY 
THRESHOLDS...BUT MAY SEE SMALL CRAFT SEAS DEVELOP ACROSS OUR 
SOUTHERN WATERS SAT AFTERNOON.  VSBYS WILL ALSO BE RESTRICTED AT 
TIMES IN RAIN AND PATCHY FOG.

SATURDAY NIGHT AND SUNDAY...MODERATE TO HIGH CONFIDENCE.  LOW 
PRESSURE INTENSIFYING EAST OF THE WATERS WILL COMBINED WITH HIGH 
PRESSURE OVER EASTERN CANADA.  THIS WILL GENERATE NORTHERLY SMALL 
CRAFT WIND GUSTS OF 20 TO 30 KNOTS AND LONG FETCH WILL LIKELY 
GENERATE 10 FOOT SEAS ACROSS OUR EASTERN WATERS. THERE IS EVEN 
THE RISK FOR BRIEF GALE FORCE WIND GUSTS ACROSS OUR EASTERN WATERS 
ON SUNDAY.

MONDAY...MODERATE TO HIGH CONFIDENCE.  NORTHERLY SMALL CRAFT WIND 
GUSTS SHOULD DIMINISH DURING THE MORNING.  HOWEVER...LEFT OVER 
EASTERLY SWELL WILL RESULT IN CONTINUED SMALL CRAFT SEAS INTO AT 
LEAST MONDAY EVENING ACROSS OUR EASTERN WATERS.  

TUESDAY AND TUESDAY NIGHT...MODERATE CONFIDENCE.  LOW PRESSURE 
INTENSIFIES ACROSS THE CANADIAN MARITIMES AND DRAGS A STRONG COLD 
FRONT ACROSS THE WATERS.  NORTHWEST GALE FORCE WIND GUSTS WILL BE 
POSSIBLE LATE TUE AND/OR TUE NIGHT.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EDT EARLY THIS MORNING FOR 
     ANZ231-232-251.
     SMALL CRAFT ADVISORY UNTIL 1 PM EDT THIS AFTERNOON FOR ANZ250-
     254-255.

&&

$$
SYNOPSIS...BELK/FRANK
NEAR TERM...BELK/FRANK/NOCERA
SHORT TERM...BELK
LONG TERM...FRANK
AVIATION...FRANK/NOCERA
MARINE...BELK/FRANK



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