Scientific Forecaster Discussion

Return to Local Conditions & Forecast
Area forecast discussion 
National Weather Service Taunton Massachusetts
1059 am EDT Wednesday Apr 16 2014

Synopsis...

High pressure will bring dry...but seasonably cool weather to the
region through Friday. Weak offshore low pressure may bring a
shower or two late Friday night into early Saturday then dry
through Monday. A cold front could trigger showers Monday night
and Tuesday.

&&

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

10 am update...

Cold front offshore. Clearing to the rear. Abundant sunshine and
the high April sun angle allowing for temperatures to warm above
freezing. Warming temperatures and colder air building in aloft
allowing for steep low-level lapse rates up to 850 mb. Subsequent
boundary layer mixing will result in breezy winds continuing into
midday with gusts up to 30 miles per hour...diminishing during the afternoon
with continued drying. With 850 mb temperatures around -8c...highs
around the middle- to upper- 40s anticipated.

&&

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

Tonight...

High pressure crests over the region. This should allow for skies to
remain mainly clear and winds to be fairly light. Therefore...good
setup for radiational cooling in an already seasonably cold
airmass. Expect with inversions most areas away from the immediate
coast to drop below freezing...with several areas in the low to
middle 20s.

Thursday...

High pressure remains in control thanks to inverted ridging with the
center of the high sliding into the Canadian Maritimes. This setup
allows winds to shift toward the east-NE through the day. Therefore...
despite a chance for temperatures to warm somewhat with 850 mb temperatures around
-1c east coastal locations will once again struggle to break out of
the low 40s given SST values themselves in the low to middle 40s. At
other interior locations temperatures should rebound to the middle to upper
40s with some areas finally breaking back into the 50s as well.
Skies should remain mainly mostly sunny...but some high clouds may
scrape S coastal locations as an ocean wave passes well S of the
area.

&&

Long term /Thursday night through Tuesday/...

Highlights...

* chilly Thursday night and unseasonably cool near the coast Friday
* mainly dry weather through Monday
* chance of showers Monday night and Tuesday

An active northern jet stream will exist through the period while
a separate southern stream upper low cuts off and meanders off the
southeast U.S. Coast. Strong surface high pressure to our
northeast will keep it cooler than normal through Friday...especially
near the coast. Then temperatures moderate to near seasonal
normals over the weekend and into next week. A cold front will
likely bring showers Monday night and Tuesday.

Daily details...

Thursday night...

Very strong high pressure centered over the Canadian Maritimes
and ridging across New England will provide mostly clear skies and
another cold night Thursday night...but not quite as chilly as Wednesday
night. Lows in the middle 20s to lower 30s except middle 30s islands.

Friday...

Strong high pressure will slowly slide eastward but there will be
a cool northeast to east flow over the region. Expect large
temperature differences from the coast to locations farther inland.
Across eastern Massachusetts the very chilly ocean waters with SSTs in the
lower 40s will advect this very cool and shallow maritime airmass
into the coastal plain. Therefore only expecting highs in the 40s
over eastern Massachusetts. The April sun will have more of an effect in the
interior...with middle 50s in the Connecticut valley.

Friday night and Saturday...

Models continue to struggle with northern and southern stream
waves. All models have weak surface low pressure southeast of the
40n/70w benchmark. The GFS and Canadian models suggest it is close
enough to bring a small chance of showers over mainly southeastern
areas late Friday night into early Sat. But the European model (ecmwf) is faster with
a northern stream trough which keeps US dry with the low far enough
offshore. Expect the rest of Saturday to be partly cloudy. The
GFS has the upper trough and associated cool pocket of air
overhead which could lead to a chance of showers through the day
but again other models are drier. Anyway...much ado about a small
chance of light showers.

Sunday and Monday...

Another high pressure settles over the region providing dry and
seasonably cool weather. Highs in the 50s Sunday. Lows Sunday
night mainly 35-40. Highs Monday a little warmer...in the upper 50s
and lower 60s Monday. Sunshine will fade behind increasing
cloudiness during the day Monday. There are some timing difference
on the approach of a cold front from the Ohio Valley. The general
consensus is that any chances of precipitation should be confined
to far western New England toward evening.

Monday night and Tuesday...

A cold front approaches the region Monday night and begins to wash
out over the area. Significant differences on placement of low
pressure along the front...with GFS favoring a middle Atlantic low
and the European model (ecmwf) winding up a storm system off the Carolinas. The net
effect for southern New England could simply be a band of light
rain showers with a decaying front. Still looking at high temperatures
in the lower 60s Tuesday despite partly to mostly cloudy skies.

&&

Aviation /15z Wednesday through Sunday/...

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

Short term /through Thursday/...high confidence.

14z update...

VFR. Northwest winds gusting 25-35 kts into midday diminishing into the
afternoon and evening hours. Winds shifting north overnight and
then northeast on Thursday.

Kbos terminal...high confidence.

Kbdl terminal...high confidence.

Outlook...Thursday night through Sunday...

Thursday through Friday...VFR.

Friday night into Saturday...VFR. Low probability of MVFR in
scattered showers especially southeast half.

Saturday night and Sunday...VFR.

&&

Marine...

Forecaster confidence levels...

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

Short term /through Thursday/...high confidence.

Winds will continue to diminish through the afternoon into the
evening hours...gusting over 25 kts with a few gusts near gale-
force over the next hour or two on the outer waters.

Gale warnings have been converted over to small craft advisories
accordingly. Small-crafts will drop off during midday hours for
the inner waters...but as to the outer waters present 8 to 10 foot
seas an average of 5 to 7 feet through Thursday.

Outlook...Thursday night through Sunday...

Thursday night through Friday...trend here will be decreasing southerly
swells with increasing east-northeast wind waves. Mainly dry with maritime
airmass over the waters courtesy of 1040+ mb high pressure across
Newfoundland. Overall seas still 5 to 7 feet over the outer waters.

Friday night and Sat...low pressure expected to pass southeast of the
benchmark of 40n 70w. Northeast winds shift to northwest and seas
begin to very slowly subside.

Sat night and Sunday...seas finally subside to Small Craft
Advisory criteria of 5 feet over the outer waters. Northwest winds
become northeast again as high pressure builds over New England...
but relatively light.

&&

Hydrology...

Several points along the CT river are flooding or will be in minor
flood soon. Warnings continue for the CT river at...

Thompsonville
Hartford
Middle Haddam
Montague
Northampton

Other points along the CT river will need to be watched as water
continues to runoff from rains overnight and yesterday as well as
drainage from rain and melting snow across northern New England. It
may take through the end of the week for some of the waters to
recede below flood stage at some of these points. Also...note
that it is possible some of these may also reach moderate flood at
some point later in the next couple of days as well before they
recede.

Outside of the CT river...the Pawcatuck at westerly continues to
rise as well and may need to be monitored for potential flooding
later in the overnight tonight. But given there is time to monitor
the response no warning is currently out.

&&

Box watches/warnings/advisories...

CT...none.
Massachusetts...none.
New Hampshire...none.
Rhode Island...none.
Marine...Small Craft Advisory until 4 PM EDT this afternoon for
anz231>234-251.
Small Craft Advisory until 2 PM EDT this afternoon for anz230-
236.
Small Craft Advisory until 2 am EDT Friday for anz235-237.
Small Craft Advisory until 8 am EDT Friday for anz250-256.
Gale Warning until 2 PM EDT this afternoon for anz254-255.

&&

$$

Synopsis...doody/gaf
near term...sipprell
short term...doody
long term...gaf
aviation...doody/gaf
marine...doody/sipprell/gaf
hydrology...doody/gaf