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Area forecast discussion 
National Weather Service Taunton Massachusetts
1042 am EDT Tuesday may 5 2015

Synopsis...
a weak cold front may bring a few brief showers today...but dry
weather and mild temperatures will dominate. Little change is
expected through the weekend...with mild to warm afternoon/S and
mainly dry weather persist. A slow moving front may bring a few
showers late this weekend into early next week.

&&

Near term /until 6 PM this evening/...
1041 am update...

Weak cold front still crossing the region. This front extended
from just east of klwm...to near korh...to just south of kbdl.
05/12z chh sounding showed an impressive surface-based inversion.
Kbox 88d showing the majority of the showers moving over the
coastal waters east of Massachusetts mid-morning. Latest runs of the hrrr and
rap predicting more showers developing farther west late this
morning...then moving across portions of Rhode Island and southeast Massachusetts. This
is also starting to show in the radar data...so relied heavily on
a hrrr/rap combination to update rainfall chances through the rest
of today.

Temperatures will be tricky. Lots of cloud cover this morning.
Visible satellite data showing plenty of clearing though behind
the cold front...at least for now. Open-cellular stratocumulus
clouds starting to pop across southern Vermont and southern New Hampshire. Fully
expect this trend to continue across southern New England later
today...once this cold front moves completely offshore. Kept
temperatures well above normal...but not quite as high as
yesterday.

Previous discussion...

Plenty of middle level cloudiness will be around during the morning...
but still expect peeks of sun. As the afternoon wears on...expect
sunshine to become more prevalent as drier air works in behind the
cold front.

Given very mild start...high temperatures in most locales should climb well
up into the 70s. It/S not out of the question that a spot
location or two hits 80. However...across the immediate coast
weakening pressure gradient behind the cold front will allow
cooling sea breezes to develop. In these locations...mild late
morning temperatures will probably fall back into the upper 50s and lower
60s...including Boston. Just inland from the coast though it will
remain quite mild even behind the front.

&&

Short term /6 PM this evening through 6 PM Wednesday/...
tonight and Wednesday...
dry and pleasant weather expected for most of tonight as high
pressure builds in behind the cold front. Low temperatures will mainly be
in the 40s...to lower 50s.

A moisture starved shortwave will drop down in west to northwest
flow aloft Wednesday morning. Not sure if it will track far enough
northwest to result in a brief period of scattered showers across
any portion of our region. Best shot is northern CT...and perhaps
even into part of Rhode Island and southeast Massachusetts for a short time.
Regardless...even if a few showers occur they will be short-lived
and not amount to much. More in the way of sunshine should develop
from north to south through Wednesday afternoon. Highs should generally
reach well into the 70s in most locations...with the warmest
readings north of the Pike where the most sunshine is expected. Its
also possible that areas near the South Coast do not reach 70 on
Wednesday...if clouds hang on longer then expected.

&&

Long term /Wednesday night through Monday/...
highlights...

* Spring to Summer-like temperatures through early next week
* high pressure will keep mainly dry conditions into this weekend
* a slow moving front may bring scattered showers sun into Monday

Overview and model preferences...

00z gefs/12z ecens remain in good agreement with overall upper
level steering flow in keeping amplified pattern across the lower
48 through most of this forecast period. Noting long wave
troughing with a few cutoff short waves dive S into the base of
the trough into this weekend while long wave ridge slowly builds east
as it noses north through eastern Quebec to Labrador. Also noting
nearly stationary cutoff low off the southeast U.S. Coast with surface
low/possible subtropical system late in the week or this weekend.
While this system will not directly affect the region... it could
cause the ridge to hold in place and slow an approaching cold
front for late this weekend into next Monday.

00z model suite also in fairly good agreement into this weekend...
then the GFS looks to break down ridging faster than ggem/ECMWF...
mainly due to short wave trying to work out of central Canada
which flattens out the ridge. With overall blocking pattern in
place across North America and further east across the Atlantic...feel
this will be slow to break down so think the slower guidance is
the way to go for sun-Mon. However...with the wide model
solutions...have low confidence from Saturday into early next
week.

Leaned toward a blend of model guidance into this weekend...then
blended toward the ensembles for sun-Monday which was close to the
HPC guidance. This yielded good continuity to the previous
forecast.

Details...

Wednesday night...expect stalled front near the S coast to tend to
wash out as it shifts a bit further S as high pressure at the surface
and aloft slowly pushes across the region. Will see generally dry
conditions with light/variable winds.

Thursday-Friday...ridging builds east across New England into eastern
Canada during this timeframe. Expect light/variable winds early Thursday to
become S-SW. This will keep mild temperatures in place except along the S
coast where they will be tempered with the general onshore wind
flow. May also see brief sea breezes along the East Coast mainly on
Friday. Also...due to sea surface temperatures running in the middle-upper
40s and mild temperatures during the nighttime hours...may see overnight
patchy fog develop mainly along the coast while increasing dewpoints
may also mean brief patchy fog across the normally susceptible
inland locations each night.

Highs both days away from the S coast will be in the 70s...
possibly up to around 80 across portions of the CT valley both
days.

Saturday through Monday...as mentioned above...model solutions
Widen. Have mentioned only slight chance probability of precipitation mainly north of the Mass
Pike Sat afternoon/night. Increased probability of precipitation to only low chance for
sun/Monday for most areas...but will depend upon timing of the
approaching front. Expect mild temperatures to remain in place through
this weekend with highs in the 70s /except cooler along immediate
S coast/.

&&

Aviation /15z Tuesday through Saturday/...
forecaster confidence levels...

Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.

Short term /today through Wednesday/...

Today...high confidence. Expect VFR conditions...though ceilings will
lower to 4-5kft along front in vicinity of band of showers as it moves S
out of central Massachusetts through midday. May see brief local MVFR
conditions in any heavier showers.

Tonight and Wednesday...high confidence. Mainly VFR conditions. A
brief period of isolated to scattered showers may affect northern CT
and possibly a part of Rhode Island/southeast Massachusetts for a time Wednesday am. This may
result in very brief localized MVFR conditions if any occur.

Kbos taf...high confidence in taf. Sea breezes expected to develop
this afternoon as a result of a weakening pressure gradient behind a
cold front.

Kbdl taf...high confidence in taf.

Outlook...Wednesday night through Saturday...

High confidence through the period. VFR and dry conditions. Low
risk for patchy fog each night from around midnight through sunrise
with local MVFR-IFR cigs/vsbys.

&&

Marine...
forecaster confidence levels...

Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.

Short term /today through Wednesday/...

Today through Wednesday...high confidence. Marginal small craft
seas will continue to diminish across the outer coastal waters
into this afternoon. Winds/seas will remain below Small Craft
Advisory thresholds through Wednesday under a weak ridge of high
pressure.

Outlook...Wednesday night through Saturday...high confidence
through the period.

Wednesday night...light/vrbl winds become S-SW around or after
midnight at 15 knots or less. Seas 3 feet or less.

Thursday...W-SW winds up to 15 knots across the open waters during
the afternoon. Seas remain below 5 feet.

Thursday night through Saturday...SW winds 15 knots or less with seas
2-4 feet. Low chance of 5 feet seas on the eastern outer waters Sat
afternoon/night.

&&

Fire weather...
mainly dry weather with little appreciable rainfall will continue
through at least Saturday if not into Sunday/Monday. While winds
for the rest of the work week will probably not be strong enough
for fire weather headlines...we may have to be more concerned by
Saturday. There will be at least a bit more potential for some
marginal fire weather headline wind gusts.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...none.

&&

$$
Synopsis...Frank/evt
near term...Belk/Frank/evt
short term...Frank
long term...evt
aviation...Belk/Frank/evt
marine...Belk/Frank/evt
fire weather...staff

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