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Area forecast discussion 
National Weather Service Taunton Massachusetts
349 am EDT Monday may 4 2015

Synopsis...
warmest day so far on tap today...but showers follow ahead of a
cold front for Tuesday. High pressure builds over the eastern USA
midweek with dry weather through Friday and warming temperatures
through the weekend. A cold front approaches during the weekend
and may bring scattered showers.

&&

Near term /until 6 PM this evening/...
the combination of a slight increase in the surface pressure gradient and
persistent cloud cover which only dissipated within the last few
hours has led to a milder night overnight with temperatures mainly in the
middle 40s and low 50s.

Plenty of sunshine today...which will yield very efficient mixing
possibly as high as about h75 per latest BUFKIT profiles. Temperatures at
850 mb are around +10c to +12c so using extrapolation...highs should
be able to approach the upper 70s to low 80s across much of the
region /the S coast will experience cooler temperatures under onshore
flow/. The slight west component to the overall wind fields allow for
some downsloping so some of the better performing areas such as
the CT and Merrimack River valleys may come close to the middle 80s.
This west component will also stave off the East Coast sea breezes we
have experienced the last few days.

With these warm temperatures and gradual increase in winds this
afternoon...am still somewhat concerned about fire weather
potential. See the section below for this information.

&&

Short term /6 PM this evening through 6 PM Tuesday/...
tonight...
high pressure will give way to an approaching cold front from the northwest.
This front will be slowing as it begins to parallel steering flow
aloft. Therefore...aside from increasing high-middle clouds across
the region especially after midnight it will likely take until 09z
or later for enough moisture flux and lift associated with the
front to yield -shra activity mainly across northwest Massachusetts. This band will
gradually shift to the S through the morning...so a damp commute
is expected for some. Looking at BUFKIT profiles...soundings are
relatively stable for the overnight and morning timeframe so will
run with just showers rather than including any thunderstorms and rain. The
increasing clouds and low level moisture support even milder mins
than Sun night...mainly in the 50s across the board.

Tuesday...
slowing and gradually dissipating cold front will be making it/S
way from north-S across the region. It/S timing is slow enough that it
will likely be just barely at the north border of Massachusetts by 12z and only
just off the S coast by 00z. Therefore...there will be a focus for
lift in the vicinity pretty much all day and precipitable waters will increase
to around 1.25 inches. Therefore...likely see plenty of -shra
activity across the region...although a slow improvement will
begin from north-S through the afternoon as strong ridging moves in
behind the exiting front.

There is some question of convective potential. Soundings are
conditionally unstable in a narrow corridor mainly through CT/Rhode Island
and southeast Massachusetts /in essence where better early morning heating is
expected/. This will likely yield cape values on the order of
300-500j/kg by the afternoon with middle level lapse rates around
6.5c/km. Therefore...still can/T rule out some isolated thunder
mainly across the S and mainly during the afternoon hours. Main
issue will be a brief heavy downpour thanks to the higher precipitable water
airmass.

&&

Long term /Tuesday night through Sunday/...
big picture... shortwave racing across eastern Canada passes north
and east of southern New England midweek. Upper ridge builds over
the eastern USA while upper trough digs over the western USA. Models
show a couple of shortwaves moving through the ridge next weekend
and pushing a cold front into or through our area. Overall a dry
warm pattern for southern New England through Friday. Models suggest
a couple of shortwaves moving over the ridge during next weekend but
at times feature probability of precipitation with mostly clear skies...so confidence in
precipitation is low at this time.

We used our usual blend of long range data. One departure was with
temperatures...for which the model data seemed 3-5f too cool for the
expected thermal profile aloft. We adjusted Wednesday through
Friday maximum temperatures a little warmer that guidance to be more
consistent with other data.

The dailies...

Tuesday night... cold front along the South Coast moves farther
offshore. High pressure builds over New England overnight. Any
lingering showers along the coast should move off. Expect clearing
skies and a light northeast wind.

Wednesday through Friday...surface high pressure builds over the
region. Moisture profiles are mainly dry although cross sections
show some high level moisture which may be thin cirrus. Cross
sections also show some low level moisture Thursday night and Friday
night which may be fog and/or stratus. Mixing profiles reach to 800
mb Wednesday and Thursday...and between 800 and 850 mb Friday. Temperatures
at the top of the mixed layer support 70s Wednesday...warming to 80
or lower 80s by Friday. Onshore flow will keep coastal areas in the
60s. Inland maximum temperatures were adjusted warmer during this period based
on expected temperatures aloft.

Saturday-Sunday...shortwaves move through the upper ridge. This
draws a cold front through New England. Moisture is limited Saturday
but could generate a shower in northern/western areas. Better chance
of showers Sunday as the front moves through southern New England.

&&

Aviation /07z Monday through Friday/...
forecaster confidence levels...

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

Today and tonight...high confidence.
VFR. Winds become SW. Gusts of 20-25 knots are possible late afternoon
and evening. Winds diminish overnight with skies increasing.

Tuesday...moderate confidence.
A cold front brings a risk of -shra from north-S through the day.
VFR likely dominates...but periodic MVFR due to lowered ceilings are
possible.

Kbos taf...high confidence in taf.

Kbdl taf...high confidence in taf.

Outlook...Tuesday night through Friday...moderate to high confidence.

Mainly VFR. Areas of fog may develop each night between midnight and
sunrise with local IFR cigs/vsbys.

&&

Marine...
forecaster confidence levels...

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

Short-term /through Tuesday/...

Through today...high confidence.
SW winds will increase this afternoon with a few gusts to around
20-25 knots near shore. Suspect conditions will remain mostly below
Small Craft Advisory thresholds however...given cool ocean waters.

Tonight into tomorrow...moderate confidence.
The SW flow will slowly give way to west flow as a cold front cross
the waters during the Tuesday evening hours. With the persistent SW
flow today...some suggestion wind driven seas could approach 5 feet
on the ocean waters...but do not have high enough confidence to
issue a Small Craft Advisory at this time. This will need to be
monitored. Conditions improve on Tuesday if they reach criteria at
all...but some showers and possibly even a thundershower

Outlook...Tuesday night through Friday...moderate to high confidence.

High pressure moves over the waters. Wind directions become
southwest by Friday...but speeds remain 15 knots or lower through
the period. Light flow will also mean light seas with heights below
5 feet through the period. No small craft headlines are expected.

&&

Fire weather...
will be issuing a red flag warning primarily for the terrain
influence in western Massachusetts. Special statements will be
issued elsewhere. Plenty of sunshine will allow temperatures to
rise into the upper 70s and low 80s across the region by this
afternoon. Efficient mixing will allow dewpoints to drop back into
the upper 30s and low 40s...which yield min relative humidity values around the
20 percent mark this afternoon. Winds will start relatively light
out of the SW...but then increase during the afternoon. Sustained
winds should generally remain between 10 and 15 miles per hour. Gusts will
peak mainly between 3pm and 7pm this afternoon/evening...and a
period with gusts to around 25 miles per hour is likely.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...red flag warning from 2 PM this afternoon to 8 PM EDT this
evening for maz002>004-008>012-026.
Rhode Island...none.
Marine...none.

&&

$$
Synopsis...wtb/doody
near term...doody
short term...doody
long term...wtb
aviation...wtb/doody
marine...wtb/doody
fire weather...staff

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