Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 191440
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1040 AM EDT SAT APR 19 2014

.SYNOPSIS...
HIGH PRESSURE IN CONTROL WILL RESULT IN A DRY WEEKEND...WITH MILD
AFTERNOON/S EXCEPT FOR CHILLY SEA BREEZES ON THE COAST ON SUNDAY.
THE DRY WEATHER CONTINUES INTO TUESDAY. LOW PRESSURE AND AN
ASSOCIATED COLD FRONT WILL LIKELY BRING A PERIOD OF WET WEATHER TO
THE REGION TUESDAY NIGHT INTO A GOOD PORTION OF WEDNESDAY. ANOTHER
HIGH BUILDS IN WITH DRY...PLEASANT CONDITIONS INTO LATE NEXT
WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
1030 AM UPDATE...
ONLY MINIMAL CHANGE TO THE FORECAST THIS MORNING. ADJUSTED NEAR
TERM CONDITIONS TO BRING THEM IN LINE WITH OBSERVED TRENDS. A COLD
FRONT HAS FINALLY MOVED OFF THE COAST. WIND GUSTS WILL BE
GRADUALLY INCREASING INTO EARLY AFTERNOON AS DEEPER BOUNDARY LAYER
MIXING DEVELOPS.

PREVIOUS DISCUSSION...

A COLD FRONT WILL CROSS SOUTHERN NEW ENGLAND THIS MORNING.  EVEN
THOUGH WE ACTUALLY WILL BE COLDER AT 850 MB THAN YESTERDAY...WINDS
WILL BE NORTHWEST AS OPPOSED TO EAST.  THAT MAKES ALL THE DIFFERENCE
THIS TIME OF YEAR...SO IT WILL BE MUCH MILDER TODAY THAN THE LAST
FEW DAYS.

SKIES WILL BE PARTLY TO MOSTLY SUNNY WITH JUST SOME FAIR WEATHER
DIURNAL CUMULUS CLOUDS EXPECTED.  A VERY WELL MIXED ATMOSPHERE
SHOULD RESULT IN AFTERNOON HIGHS MAINLY IN THE UPPER 50S TO THE
LOWER 60S.  NORTHWEST WIND GUSTS OF 20 TO 30 MPH ARE ALSO EXPECTED
TO DEVELOP BY AFTERNOON...BUT STILL MUCH MORE PLEASANT THAN THE LAST
TWO DAYS.

&&

.SHORT TERM /SUNDAY/...
TONIGHT...

STRONG HIGH PRESSURE WILL BUILD SOUTH FROM EASTERN CANADA. THIS WILL
RESULT IN MAINLY CLEAR SKIES/LIGHT WINDS AND IDEAL RADIATIONAL
COOLING CONDITIONS.  LOW TEMPS WILL BOTTOM OUT IN THE LOWER TO
MIDDLE 20S ACROSS PORTIONS OF SOUTHWEST NH/NORTHWEST MA...TO MAINLY
THE UPPER 20S TO MIDDLE 30S ELSEWHERE.  THESE READINGS ARE QUITE
COLD FOR THE LATTER HALF OF APRIL...BUT WILL BE SHY OF ANY RECORDS.

SUNDAY...

HIGH PRESSURE CENTERED OVER NORTHERN NEW ENGLAND WILL RESULT IN
MOSTLY SUNNY SKIES.  HOWEVER...IT WILL ALSO GENERATE A NORTHEAST TO
EASTERLY FLOW OF AIR OFF THE COLD OCEAN.  THIS SHOULD HOLD HIGHS
BETWEEN 45 AND 50 ALONG THE COAST.  INLAND LOCATIONS SEE HIGHS WELL
UP IN THE 50S TO POSSIBLY EVEN A FEW LOWER 60S IN THE LOWER CT RIVER
VALLEY.  WINDS WILL BE MUCH LIGHTER THAN TODAY...SO IT WILL BE A
PLEASANT AFTERNOON INLAND FROM THE COAST.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
OVERVIEW AND MODEL PREFERENCES...
19.00Z MODEL GUIDANCE SUITE SHOWING REASONABLY GOOD AGREEMENT IN
THE SYNOPTIC SCALE THROUGH THE LONG TERM. THIS IS EVEN WITHIN A
SPLIT FLOW REGIME WHICH IS EXPECTED TO TRANSITION FROM ZONAL TO
MORE AMPLIFIED BY LATE IN THE WEEK. THERE ARE SOME TYPICAL BIASES
APPARENT BY THE LATTER HALF OF THE WEEK REGARDING A POTENTIAL WAVE
OF LOW PRES FOR THIS COMING WEEKEND. WITH THE AGREEMENT THROUGH
MOST OF THE PERIOD A CONSENSUS BLEND OF OPERATIONAL AND ENSEMBLE
GUIDANCE WILL BE USED...BUT WITH MORE WEIGHT ON ENSEMBLE MEANS
WHICH AGREES WITH LATEST WPC LONG RANGE THINKING.

AS MENTIONED ABOVE...A ZONAL SPLIT FLOW WILL GIVE WAY TO MORE
AMPLIFIED FLOW AS SRN AND NRN STREAM WAVES PHASE TO CREATE A
LONGWAVE TROF IN VICINITY OF THE GREAT LAKES BY MID WEEK. THIS
WILL YIELD A DRY-WET TRANSITION FROM MON INTO TUE NIGHT-WED.
HOWEVER...THIS MORE AMPLIFIED PATTERN DOES FEATURE A STRONGER
RIDGE TO FOLLOW FOR THE LATTER HALF OF THE WEEK. HOWEVER...BECAUSE
OF THE DIFFICULTY GUIDANCE HAS WITH THESE MORE AMPLIFIED FLOW
PATTERNS TOWARD THE ENDS OF THEIR CYCLES...THERE IS A LOT OF
VARIANCE WITH YET ANOTHER LOW PRES WAVE FOR THE WEEKEND.
HOWEVER...THE PROPOSED BLEND SHOULD AT LEAST HIT THE MAIN POINTS.

DETAILS...

SUN NIGHT INTO MON...
HIGH PRES CENTER CONTINUES TO SLIDE INTO THE CANADIAN MARITIMES.
WITH BUILDING H5 RIDGE...THE SFC RIDGE INVERSION REMAINS IN
CONTROL INTO THE THE DAY TUE SUPPORTING A DRY FORECAST EVEN AS A
WARM FRONT SLIDES INTO NRN NEW ENGLAND. AFTER A COOL START MON
MORNING WITH H85 TEMPS AVERAGING +7C AND FULL MIXING UNDER PARTLY
CLOUDY SKIES...SFC TEMPS ARE EXPECTED TO REBOUND TO THE MID 60S.
S-SW WINDS MAINLY AROUND 10 MPH ON MON MAY ALLOW FOR A WEAK SEA
BREEZE EVEN ON THE E COAST...BUT THIS WOULD BE SHALLOW AND ONLY
WITHIN A FEW MILES OF THE SHORE. MON NIGHT INTO TUE WEAK WARM
ADVECTION SHOULD KEEP LOWS IN THE 40S...WITH MID-HIGH CLOUDS
BUILDING OVER DURING THE DAY TUE. THESE CLOUDS SHOULD STILL ALLOW
FULL MIXING TO H85 THOUGH...WHERE TEMPS ARE CLOSER TO +10C.
THEREFORE...WARMER TEMPS ON TUE...WITH SOME LOCATIONS BREAKING
INTO THE 70S IN SPITE OF THE INCREASING CLOUDS.

TUE NIGHT INTO WED...
SFC COLD FRONT WILL BE APPROACHING THEN CROSSING THE REGION INTO
THE EARLY HALF OF THE DAY ON WED. AM NOTING THE GUIDANCE DOES
SUPPORT A SECONDARY FRONTAL WAVE SLIDING ALONG THIS FRONT ALONG
WITH A MODEST 30-40 KT LLJ. THIS SUGGESTS IT MAY BE A LITTLE
SLOWER MOVING THAN SOME ENSEMBLE MEMBERS SUGGEST...AND THE
OPERATIONAL ECMWF IS A BIT SLOWER. THEREFORE...WILL SLOW THE
OVERALL RAIN THREAT...ALLOWING IT TO CONTINUE INTO MID DAY WED.
MODEST LIFT AND PWATS AROUND 1.0 SUGGESTS WIDESPREAD RAIN
EVENT...BUT NOT AS STRONG AS SOME EARLIER THIS SPRING. MOST QPF
AMOUNTS SHOULD LIE SOMEWHERE BETWEEN 0.25 AND 0.5 INCHES GIVEN ITS
SLIGHTLY FASTER MOVEMENT AND WEAKER LLJ ENERGY.

THU INTO FRI...
AMPLIFIED RIDGE GAINS CONTROL AS LONGWAVE TROF SLIDES OFFSHORE.
MAINLY DRY FORECAST EXPECTED. DESPITE THE INITIAL COLD ADVECTION
ON THU THE BUILDING RIDGE SHOULD HEIGHTS/MID LVL TEMPS RISING.
THEREFORE...LOOKING AT TEMPS NEAR TO SLIGHTLY ABOVE
AVERAGE...ESPECIALLY FOR HIGHS GIVEN DECENT LATE APRIL SUN.

NEXT WEEKEND...
ANOTHER TRANSITIONAL PERIOD AS LONGWAVE TROF APPROACHES FROM THE
W. THIS SUGGESTS UNSETTLED AND POTENTIALLY WET CONDITIONS FOR AT
LEAST SOME OF THE WEEKEND...BUT WITH A LOT OF VARIABILITY AND
MODEL DIFFICULTY RESOLVING AMPLIFIED FLOW BY DAY 7...CONFIDENCE IS
LOW IN EXACT TIMING OR HOW WET IT MAY BE. WHILE THERE IS SOME
AGREEMENT THAT THE ACTUAL ATTENDANT LOW WOULD BE AN INSIDE
RUNNER...HOW FAR NORTH THE CORRIDOR OF STRONGEST DYNAMICS GOES IS
DIFFICULT TO RESOLVE. LOOK FOR MORE UPDATES AS WE APPROACH.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

SHORT TERM...TODAY THROUGH SUNDAY...HIGH CONFIDENCE.

TODAY...
MAINLY VFR FROM NOW ON. W-SW WINDS WILL VEER TO THE NW THROUGH THE
MORNING...INCREASING IN SPEED. GUSTS 20-25 LIKELY THROUGH THE DAY.

TONIGHT AND SUNDAY...
VFR CONDITIONS. GUSTY NORTHWEST WINDS DIMINISH THIS EVENING.

KBOS TERMINAL...HIGH CONFIDENCE IN TAF.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF.

OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...

SUN NIGHT INTO TUE...HIGH CONFIDENCE.
MAINLY VFR. WINDS SHIFT FROM THE W ON MON TO THE S ON TUE.

TUE NIGHT INTO WED...MODERATE CONFIDENCE.
VFR GIVES WAY TO MIX OF MVFR/IFR IN PERIODS OF RAIN AND LOW CIGS.
CONDITIONS GRADUALLY IMPROVE DURING THE DAY ON WED...ALTHOUGH AS
THINGS IMPROVE THERE IS THE CHANCE FOR 25-30 KT W-NW WIND GUSTS ON
WED.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /TODAY THROUGH SUNDAY/...HIGH CONFIDENCE.

TODAY...

SCA SEAS WILL CONTINUE ACROSS THE EASTERN ATLANTIC WATERS TODAY AS A
RESULT OF EASTERLY SWELL FROM A DISTANT LOW PRESSURE SYSTEM.  IN
ADDITION...HAVE HOISTED SCA HEADLINES FOR NORTHWEST WIND GUSTS ALONG
THE NEAR SHORE WATERS OF THE EASTERN MA COAST THIS AFTERNOON.
ENOUGH MIXING OVER THE LAND SHOULD RESULT IN A FEW HOURS OF GUSTS UP
TO 25 KNOTS...INCLUDING BOSTON HARBOR.

TONIGHT...

LOOKS LIKE WE MAY SEE A PERIOD OF NORTHERLY 25 KNOT WIND GUSTS OVER
THE EASTERN WATERS IN A SURGE OF COLD ADVECTION.  KEPT THE EASTERN
ATLANTIC WATERS IN SCA HEADLINES...BUT ITS POSSIBLE WE MAY NEED TO
EXTEND THEM INTO CAPE COD BAY AND NANTUCKET SOUND FOR A TIME.  ITS
MARGINAL AND SINCE ITS 2ND PERIOD DECIDED TO DEFER TO THE NEXT SHIFT.

SUNDAY...

WINDS SHOULD REMAIN BELOW SCA THRESHOLDS.  HOWEVER...MARGINAL SCA
SEAS THOUGH MAY LINGER INTO THE LATE MORNING/EARLY AFTERNOON ACROSS
PORTIONS OF THE EASTERN ATLANTIC WATERS BEFORE DIMINISHING.

OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...

SUN NIGHT INTO TUE...HIGH CONFIDENCE.
HIGH PRES REMAINS IN CONTROL ACROSS THE WATERS. THEREFORE...ASIDE
FROM WHAT MAY BE A FEW NEAR SHORE GUSTS APPROACHING 25 KT ON TUE
FROM THE S-SW...MAINLY QUIET BOATING WEATHER IS EXPECTED.

TUE NIGHT INTO WED...MODERATE CONFIDENCE.
COLD FRONT APPROACHES THEN CROSSES THE WATERS EARLY WED WITH
PERIODS OF RAIN. TUE NIGHT INTO WED...S WINDS SHOULD REMAIN BELOW
SCA THRESHOLDS BUT A BUILDING S SWELL ON THE SRN AND ERN OCEAN
WATERS MAY BREAK 5 FT...LEADING TO THE NEED FOR SMALL CRAFT
ADVISORIES. ON TUE...ONCE WINDS SHIFT TO THE W-NW WIND GUSTS 25-30
KT AND CONTINUED 5-7 FT SEAS WILL LEAD TO THE NEED FOR SMALL CRAFT
ADVISORIES ON ALL WATERS.

&&

.FIRE WEATHER...
TODAY...NORTHWEST WIND GUSTS OF 20 TO 30 MPH ARE EXPECTED TO
DEVELOP BY AFTERNOON. IN ADDITION...MINIMUM AFTERNOON RELATIVE
HUMIDITIES ARE EXPECTED TO DROP TO BETWEEN 20 AND 30 PERCENT.
AFTER COORDINATION WITH FIRE WEATHER CONTACTS...WILL NOT ISSUE ANY
FIRE WEATHER HEADLINES GIVEN CURRENT FUEL MOISTURES.

TOMORROW...
ALTHOUGH THE DRY WEATHER CONTINUES...WINDS WILL BE MUCH LIGHTER
AND HIGH TEMPS A BIT COOLER.

&&

.HYDROLOGY...
MINOR FLOODING CONTINUES ALONG PORTIONS OF THE MAINSTEM CT RIVER.
MOST POINTS HAVE CRESTED AND ARE NOW RECEDING...MIDDLE HADDAM WILL
CREST TONIGHT. SEE THE LATEST FLOOD STATEMENT FOR DETAILS.

FLOOD WARNINGS REMAIN POSTED ALONG CT RIVER AT...

HARTFORD AND MIDDLE HADDAM

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT SUNDAY FOR ANZ250-254.
     SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ251.
     SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ230.

&&

$$
SYNOPSIS...FRANK/DOODY
NEAR TERM...DOODY
SHORT TERM...FRANK
LONG TERM...DOODY
AVIATION...FRANK/DOODY
MARINE...FRANK/DOODY
FIRE WEATHER...STAFF
HYDROLOGY...STAFF



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