Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Taunton Massachusetts
711 PM EDT Monday Jul 6 2015

Synopsis...

Warm and muggy conditions are anticipated tomorrow and Wednesday
as a series of fronts brings scattered showers and thunderstorms.
The last frontal boundary will stall in proximity of the
S-shoreline of New England for the remainder of the week becoming
a focus for additional wet-weather. All of this looks to clear out
by the weekend allowing for dry and seasonable conditions. Will
potentially see wet weather return along with a warm and muggy
pattern into early next week.

&&

Near term /until 6 am Tuesday morning/...

7 PM update...

Mild-muggy conditions prevailing overnight. Will see increasing
moisture within the low-levels approach from the SW parent with
the lifting warm-front as a middle-level ridge of high pressure and
drier air erodes to the east. Acting as a blanket...lows this evening
should be mild with values around the middle- to upper-60s...warmer
more so in SW New England where lower clouds are expected into the
morning hours as there is a greater probability of increasing h975
moisture.

Some concern over patchy fog mainly for the S/se-coast where
dewpoints presently are in the middle- to upper-60s and S-winds
continue to slowly advect higher dewpoint air northward. Lesser
confidence across the interior considering forecast lows and
crossover thresholds as many locales mixed out well today with
dewpoints around the upper-50s...though dewpoints have rebounded
nicely. May need to keep an eye on this.

&&

Short term /6 am Tuesday morning through Tuesday night/...

Tomorrow into tomorrow night...

Warm front will lift northward tomorrow putting southern New England
into a the warm/moist airmass. A weak shortwave aloft will trigger a
few scattered showers will develop across the region after 11 am lasting
into the evening hours. Mu cape values could increase to 1500 j/kg
and with 20-30 knots shear could see some strong storms. Have a very
low confidence on if any would be come sever. Limiting factor is the
lapse rates and the cloud cover...which would limit the amount of
instability that could develop. Yet precipitable water values are over 1.5 inches
and with warm rain core processes...could see some heavy downpours
with perhaps urban/poor drainage flooding.

As 850 mb temperatures warm to 16c and with dewpoints reaching close to
70f...anticipate a warm/muggy day.

Convection will begin to wind down by the evening hours as heating
is lost and we are on the backside of the shortwave. Southwesterly
flow ahead of an approaching cold front will keep the region in
warm/moist flow. This will allow for fog to develop especially along the
South Coast. Overnight temperatures will will be mild with several places
only dropping into the low 70s.

&&

Long term /Wednesday through Monday/...

*/ highlights...

- scattered showers / thunderstorms for Wednesday
- continued periods of wet weather into the end of the week
- looking dry and seasonable for the weekend
- a possible return of a warm-wet-muggy pattern next week

*/ discussion...

Wednesday:

Skeptical on cold front timing. Feel it will slow as it sweeps S/east
with attendant middle-level energy away from faster middle- to upper-level
flow...running up against the offshore Bermuda high. Expectation
that the front will enter S New England around the 11a-2p timeframe
slowing up towards S/east New England around 2p-5p. Higher confidence
with sref-probs over deterministic solutions.

Thus considering a high Theta-E / instability environment along and
ahead of the cold front within a weak-shear environment with vector-
orientation not overtly perpendicular to the cold front. Do expect
scattered activity with plausible line-echo wave patterns especially
for southeast New England where there is a greater residency time for the
environment to destabilize and there is enough shear. Think forcing
is not in question along the front as low- to middle-level flow is also
perpendicular to the front. Also am not thinking anything severe.
Maybe strong. Lapse rates are fairly poor aloft based on a consensus
of forecast guidance. Mainly focused on greater areal coverage of
activity more so than the NAM/GFS deterministic suggest. And with
precipitable waters advertised in excess of 2-inches...the biggest threat is heavy
rain. Will lean with likely probability of precipitation especially for S/se-portions of S
New England.

Rest of the week:

Continuing with sref-probs believe the frontal boundary will stall
somewhere in proximity to the S-coast of New England becoming the
focus for additional wet-weather as middle-level impulses travel
through the quasi-zonal flow aloft that is parallel to the front.
Likely to see the front wobble with later forecasts. Though overall
do think instability holds mainly S with once again the main threat
being heavy rain. Nevertheless can not rule out a rumble of thunder.
A consensus of guidance has the flow being overall progressive
despite training of disturbances. Waves look to be spaced out enough
to yield a low confidence concerning any flooding. Just looking like
a wet pattern with perhaps warm-muggy conditions depending on the
orientation and proximity of the stalled frontal boundary.

Weekend:

Both deterministic / ensemble guidance in good agreement of the
trough pattern lifting east. Within the west-periphery along with rising
heights expect a surface reflection of high pressure. Deep-layer
northerly winds should usher drier and more seasonable conditions
southward...so looks like a break from the warm-muggy pattern.

Early next week:

Appears the trough pattern returns based on ensemble means. A likely
return to warm-muggy conditions and an active weather pattern.

&&

Aviation /00z Tuesday through Saturday/...

Forecaster confidence levels...

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

Short term /through Tuesday night/...

Tonight...moderate confidence.

VFR. Monitoring terminals short wave for possible MVFR-IFR ceilings and visibility
combination. Possible fog development with higher confidence over
the immediate S/se-shoreline. Light southerly winds.

Tuesday...high confidence.

MVFR-IFR ceilings and any fog lift to high-end MVFR / low-end VFR.
-Shra/-tsra developing over west/SW-terminals by afternoon. Sea-
breezes during the morning will erode with increasing S-winds
gusting up to 25 kts possible along the S-coast.

Tuesday night...moderate confidence.

Conditions possibly dropping back to MVFR-IFR along with the
potential for patchy fog.

Kbos terminal...high confidence in taf. Sea-breeze during the
morning will erode by afternoon Tuesday per increasing S-winds.

Kbdl terminal...high confidence in taf. Patchy fog is possible
tonight. Low risk of a -tsra tomorrow afternoon.

Outlook /Wednesday through Saturday/...

Wednesday...moderate confidence. Mainly VFR. Scattered rain showers/thunderstorms and rain especially S
/se-New England. Tempo MVFR-IFR with any weather. Cold front pushes
offshore late. SW-winds shift northerly.

Thursday and Friday...low confidence. Low-end VFR / MVFR. Front
stalls in proximity to S-shore of New England. Focus of additional
-ra / rain. Variable winds.

Saturday...moderate confidence. VFR. N/NW-winds.

&&

Marine...

Forecaster confidence levels...

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

Short-term /through Tuesday night/...high confidence.

7 PM update...

Quiet boating weather tonight. Patchy fog possible over S-waters.
Otherwise seas will begin to build Tuesday as a warm front moves
over the waters. Could see some low end Small Craft Advisory during the afternoon
with southerly wind gusts near 25 kts and seas 4-5ft.

Although marginal...felt it was best due to all of the recreational
boaters across the waters this week. After sunset...S-winds will
die down but could see a chop along the waters overnight. Patchy
dense fog could also redevelop over the waters.

Outlook /Wednesday through Saturday/...

Wednesday...moderate confidence.

Scattered showers and thunderstorms for the waters into the
afternoon hours and continuing into the evening. Breezy SW-winds
ahead of the front becoming variable as the front stalls in
proximity to the S-coast. Waves holding below 5-feet. Patchy dense
fog possible at times.

Thursday and Friday...low confidence.

Front stalls west to east across the S-waters. Periods of wet weather.
Variable winds throughout keeping waves below 5-feet. Patchy dense
fog possible at times.

Saturday...moderate confidence.

High pressure building into the waters. North/NW-winds perhaps blustery
at times. Will hold waves below 5-feet.

&&

Box watches/warnings/advisories...

CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...Small Craft Advisory from 2 PM to 9 PM EDT Tuesday for
anz230>237-251.

&&

$$

Synopsis...dunten/sipprell
near term...dunten/sipprell
short term...dunten
long term...sipprell
aviation...dunten/sipprell
marine...dunten/sipprell

National Weather Service Glossary of Abbreviations