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Area forecast discussion 
National Weather Service Taunton Massachusetts
355 am EDT Friday may 29 2015

Synopsis...
high pressure will bring dry conditions today. Another cold front
will slowly move across the region this weekend...bringing a greater
chance for showers and some scattered thunderstorms. This front may
linger near our area into the beginning of the next week...with high
pressure returning by midweek.

&&

Near term /until 6 PM this evening/...

4 am update...

Cold front continues to slowly push across the South Coast this
morning. It has pushed through Block Island...but is till hung up
across the canal towards Provincetown. This front eventually will
washout this morning. Ahead of the front...dewpoints continue to
pool along it allowing for low-level moisture to increase. With dry
air moving in aloft per clear skies...a low level inversion has set
up allowing for fog. Visibilities have dropped down to 1sm across portions
of southeast mass/cape/islands. In fact fmh is down to 1/4sm. As the
sun begins to rise...expect fog to dissipate once mixing will occur.

Today...

High pressure will move overhead yielding to dry weather for the
day. Some middle-level moisture will pool in from the north and with
steepening lapse rates from diurnal heating...will see diurnal
clouds develop. Otherwise weak winds aloft will allow for sea
breezes to evolve and move along the coastlines. Temperatures will still be
above average...with highs reaching into the low to middle 80s with 70s
along the coastlines.

&&

Short term /6 PM this evening through 6 PM Saturday/...

Tonight...

High pressure will begin to shift offshore as southwesterly flow
returns to the region. This will allow for another mild and muggy
night for southern New England. Warm air advection will be on the increase which
will increase cloud cover...especially for the south coastal regions.
Cannot rule out another round of marine fog/stratus. Otherwise temperatures
will remain in the upper 50s to low 60s with dewpoints also in the
middle to upper 50s.

Tomorrow...

Cold front will move across the Great Lakes region on Saturday allow
for showers and thunderstorms to develop. Best dynamics and forcing
will be well to the west of the region...however because we are in a
very warm and moist airmass cannot rule out a few pop-up showers and
thunderstorms out ahead of this front late Saturday
afternoon/evening. Otherwise bulk of the day will be dry with temperatures
warming into the low to middle 80s...cooler along the South Coast.

&&

Long term /Saturday night through Thursday/...
overview and model preferences...

Overall upper level ridging along eastern Seaboard appears to
break down Saturday...then trough out of central Canada begins to
shift east late this weekend into early next week. Associated cold
front will be slow to clear the region as it runs parallel to the
upper flow. Timing issues come in play from Monday Onward...
depending upon how far S the front finally settles while high
pressure builds out of southern Ontario and the Great Lakes eastward.

Leaned toward the available guidance early in this period then
transitioned over the gefs and ecens guidance which showed a bit
better continuity.

Details...

Saturday...high pressure off the eastern Seaboard pushes further
offshore during this timeframe...with good SW wind flow and
increasing humidity moving NE into the region. Models tending to
slow the progress of the approaching front out of western Quebec
as the upper ridge slowly breaks down and shifts east. Have mention
of chance probability of precipitation moving into western areas during Sat afternoon...
then should push slowly southeast Sat night.

Good instability with this front as k indices increase to the
Lower-Middle 30s. Have mentioned chance probability of precipitation...but mentioned only
slight chance of thunderstorms Sat night. Noting increasing precipitable waters
along and ahead of this front as well...up to 1.7 inches during
Sat night so could see some locally heavy downpours with any
activity. Will see high temperatures reach around 80 inland...but only in
the upper 60s to lower 70s along the immediate S coast. May see
SW winds gusting up to around 25-30 miles per hour across Rhode Island/southeast Massachusetts Sat
afternoon/night.

Sunday...looks like best shot of moisture moves across the
region sun/Sun night. Carrying Cat probability of precipitation near/along the slowly
moving front...as well as some scattered thunderstorms. Precipitable waters increase
to 1.7 to 1.8 inches...so could also see some heavy downpours.
At this point...think the front will push near or S of the Mass
Pike around Sun night...but will tend to slow down across southern
areas overnight. This will lower the chance for thunderstorms as
more stable air moves into north Massachusetts Sun night...but still could see
spotty convection across north CT/RI/se Massachusetts. Have kept likely probability of precipitation
going through around 06z...then slowly lower across central and
northern areas after that. Precipitation looks to taper off across the
Route 2 area by around sunrise Monday...but timing is still in
question.

Monday...a lot of uncertainty continues as moving the front across
the region...with timing differences amongst the model suite.
Looks like the chance for precipitation lingers through Monday and even into
Monday night...with the best chance across north CT/RI/se Massachusetts. Winds do
start to shift around to north-NE across central and north Massachusetts so this will
cut back on thunderstorm activity as cooler air moves in. For
now...tend to taper off precipitation by Monday night across most
areas...but do linger it along the S coast through at least
midnight Monday night. It will be much cooler with highs only in the
60s...and may not even break 60 along the East Coast with onshore
winds.

Tuesday-Wednesday...precipitation should finally push off the S coast by
around midday Tuesday at the latest. NE winds pick up as high pressure
crosses northern New England during this timeframe. Have carried a
dry and seasonable forecast on Wednesday.

&&

Aviation /08z Friday through Tuesday/...
forecaster confidence levels...

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

Before 12z...high confidence. Cold front will sweep through
overnight. Ahead of front could see IFR/MVFR stratus and fog. Also
could see MVFR fog develop across CT valley sites.

Today and tonight...high confidence. Mainly VFR. Expect sea
breezes with winds shifting mainly to the east late in the day. Some
patchy MVFR ceilings could develop along South Coast tonight.

Saturday...moderate confidence. Mainly VFR through the day. MVFR
ceilings could develop within -shra/-tsra across CT valley region.

Kbos terminal...high confidence in taf. Sea breeze will develop
between 13-15z.

Kbdl terminal...high confidence in taf.

Outlook...Sunday through Tuesday...moderate confidence.

Sunday...numerous showers with scattered thunderstorms possible during
the day with local MVFR conditions. Light winds shift to north-NE
during the day...then become NE Sun night which may gust up to
around 20 knots along the S coast. Showers linger Sunday night.

Monday...scattered showers lingering with local MVFR conditions early
but will improve from north-S during the day except along the S coast
where showers will hang in through Sun night. May see brief MVFR
in any showers there Sun night. NE winds gusting to 20-25 across
Outer Cape cod and the islands.

Tuesday...mainly VFR conditions. May see isolated showers early Tuesday
along S coast but should move offshore. NE wind gusts to 25 knots
still possible across the Outer Cape and islands.

&&

Marine...
forecaster confidence levels...

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

Short term /tonight through Friday night/...

Today and tonight...high confidence. High pressure builds over the
waters. Mainly quiet boating weather expected although some
stratus/fog is possible mainly on the southern waters tonight.

Saturday...high confidence. High pressure will push east of the
waters as cold front approaches New England. SW winds may gust
near 25-30 kts. May need near shore Small Craft Advisory. Otherwise seas will be
close to 5ft as southerly swell increases.

Outlook...Sunday through Tuesday...moderate confidence.

Sunday...cold front slowly crosses the waters. May see brief
gusts to 25 knots as front passes during Sunday...then will stall
near or just S of the S coast Sun night. Winds shift to east-NE as
front passes. Areas of showers with scattered thunderstorms. Local visibility
restrictions.

Monday-Tuesday...expect mainly NE winds. Gusts to 25 knots across
the southern open waters as the front slowly moves offshore.
Seas build up to 6-8 feet on the southern outer waters to east of
Cape Cod...and up to 5 feet on the eastern outer waters. May see
lingering showers during Monday across the southern waters.

&&

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

&&

$$
Synopsis...dunten/evt
near term...dunten
short term...dunten
long term...evt
aviation...dunten/evt
marine...dunten/evt

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