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Area forecast discussion
National Weather Service Taunton Massachusetts
1037 am EDT sun Mar 26 2017

Synopsis...

A front will remain stalled to our south today, then push north as
a warm front late tonight into Monday. Another low pressure will
move across southern New England Tuesday, bringing some rain
showers. High pressure brings dry but cooler weather Wednesday
and Thursday. More precipitation possible late Friday into Saturday.

&&

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

*/ highlights...

* Special Weather Statement through noon for the possibility of
spotty sleet or freezing rain.

*/ Discussion...updated 1030 am.

Fair amount of cold air lingering across interior southern New
England beneath an overcast cloud deck. Certainly not warming as
fast as it is over east/southeast New England where mostly clear conditions
prevail and temperatures are quickly warming up into the low 40s
thanks to the late-March sun. We got our sunglasses on our here
in good ol' Taunton Massachusetts, it's so bright.

With the colder air around freezing in place as a line of wet
weather approaches from the SW associated with some mid level
frontogenesis and weak ascent per leading 500 mb-7 impulse upon
decent 850 mb-5 moisture, in other words the mid-level warm front
on the nose of very mild air moving North/East from the mid-Atlantic.
You can clearly see the differences in airmass from the 12z
soundings out of Upton New York and Chatham Massachusetts. Wow.
We are staged within the Battle Ground certainly.

Forecaster intuition, expect the northwest-southeast line of wet weather to
approach but erode in doing so, retreating to the northwest and thus
have timed pops accordingly so. Temperatures will gradually warm,
albeit slowly, with the daytime heating even with the overcast
cloud deck. It'll be slow, tough to time, more so with the
funneling north flow from high pressure over the north (ageostrophic
flow as noted by previous forecasters).

Precipitation mainly in the form of a cold, dreary rain, however
freezing rain is possible, more so over sleet, for those areas
still at or below freezing at the surface. Just look at the 12z
sounding out of Upton, that's quite a pronounced warm nose up
around 850 mb. A freezing rain sounding with shallow cold air.

The freezing rain threat diminishes into the afternoon and have
gone with special weather statements for now, but colder air
will work back in with continued north flow as we go into the evening
with the absence of daytime heating. Have gone ahead with the
Freezing Rain Advisory starting it off earlier in time.

&&

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

Tonight...

The stronger low level south winds shift farther east Sunday
evening and bring a greater potential for lift and precipitation
production through the night, especially after midnight.

Temperature profiles showing a strong warm nose aloft. North
ageostropic winds continue near the ground, which will set the
stage for freezing rain across the higher terrain of central and
western Massachusetts. Some freezing rain possible across northernmost
Connecticut. However, thinking coverage is too limited at this
time to warrant an advisory. This could change with later
forecasts.

Monday...

Warm front finally moves north into southern New England. This
will end the threat of any freezing rain across our region.
However, that will not end the possibility for rain as a low
pressure moves through our region. This rain could be moderate
to heavy at times. Temperatures should be near normal.

&&

Long term /Monday night through Saturday/...

Highlights...

* showery weather ahead of approaching cold front on Tuesday
* cooler but dry weather for mid-week
* active weather returns late in the week into the weekend

Pattern overview...

00z models and ensembles show fairly good agreement on the
maintenance of a longwave trough over the western states with
flat flow to moderate mean riding prevailing downstream over
the east. A separate northern stream progresses along either
side of the Canadian border. Within this consensus mean pattern
models and ensembles have been showing a lot of spread for some
of the embedded features. This is noticed as early as the day 3
forecast. Both the GFS and gefs are more amplified compared to
the rest of model suite. However still anticipate open wave
interacts with the northern stream bringing a shot of precip on
Tuesday. Upper level trough with surface high pressure for the
mid-week as another upper level closed low diffuses towards the
region late in the week.

Details...

Monday night into Tuesday...low confidence.

Weak ridging in the mid-levels will result in a break in the
precip Monday night into Tuesday morning. Focus then turns to
the next open wave and how it will interact with the northern
stream. The GFS is more amplified compared to the progressive ec
with the remaining guidance inbetween. Used a model blend for
this portion of the forecast.

First wave will move offshore and with weak ridging aloft,
anticipate a drying trend in the forecast. Timing issues for
the next shot of precip on Tuesday, but feel there is enough of
a chance to keep pops in the forecast ahead of approaching cold
front. Thermal ridge over southern New England may help increase
temps near or above seasonable. In fact, depending on mixing
and cloud cover, we could see temps warm into the 60s. Southerly
flow will help increase low level moisture and with approaching
front, could see iso thunder as guidance hints at elevated
convection.

Cold front will sweep through during the overnight hours
ushering in dry air and northwest flow Tuesday night.

Wednesday into Friday...high confidence.

Trough overhead as upper level low deepens as it moves towards
the Canadian Maritimes. This puts the region in northwest flow
through the period resulting in dry but breezy conditions.
There might be a few showers across the northeast on Wednesday
in cyclonic flow. Despite cold advection, the environment should
be well mixed, so Max temperatures will be close to normal.

Northwest flow continues on Thursday with an area of high
pressure building in New England. Anticipate increasing
sunshine and lighter winds. Dry and seasonable conditions should
persist through Friday with high pressure in control.

Friday night into the weekend...low confidence.

Split flow remains over the region with the next southern stream
wave interacting with the northern stream. Large model spread for
the Friday night into the weekend time frame leading to a low
confidence forecast. The GFS suppresses the system well to our
south, with a dry northern stream flow dominating. However, the
European model (ecmwf) and CMC continues to indicate the low opening into a
progressive trough and tracking across the region. Overall this
portion of the forecast will depend on the strength and timing of
the upper level wave and thus surface reflections. Because of the
large spread in the guidance will continue with low confidence
forecast.

&&

Aviation /14z Sunday through Thursday/...

Forecaster confidence levels...

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

Short term /through Monday/...moderate confidence.

14z update...

Today...
mostly VFR. Believe MVFR-IFR mix will come in late across west Massachusetts
and west CT, 0z Monday. Continued north slowly turning east along the
coast. Spotty freezing rain possible across north CT / west and central Massachusetts thru
roughly 16z.

Tonight...
MVFR lowering to IFR-LIFR. North winds still turning east except within
the CT River Valley where they remain light north. Rain / freezing rain coverage
increasing across the terminals. Freezing rain more likely for interior
areas (e central Massachusetts across to west MA, northwest RI, north ct) with the highest
risk across the high terrain of the Berkshires and Worcester Hills.
Mainly trace accumulations but as high as a tenth of an inch. Main
impacts after midnight into Monday morning, freezing rain threat eroding
to the north as well towards Monday morning.

Monday...
freezing rain risk persists during the morning hours across north/west Massachusetts especially
the high terrain. Otherwise rain with MVFR-LIFR cigs with light east winds
initially turning southeast and increasing.

Kbos taf...not expecting any freezing rain impacts at the terminal with east onshore
flow. Lowering MVFR down to LIFR after midnight Monday into Monday
morning.

Kbdl taf...low risk freezing rain through noon as temperatures have already
warmed above freezing as of 14z. Greater threat around midnight
Monday with the possibility of spotty impacts. Not expecting any
ice accretion, at most a trace.

Outlook /Monday night through Thursday/...

Monday night...moderate confidence. Improving conditions to VFR.

Tuesday...high confidence. MVFR conditions within any passing rain
showers with improving cigs to VFR. Low risk for thunder.

Wednesday into Thursday...high confidence. Gusty north/west winds
Wednesday with VFR conditions into Thursday.

&&

Marine...

Forecaster confidence levels...

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

Short term /through Monday/...

1030 am update...no major changes to the forecast.

Today...high confidence.
East winds less than 20 knots. Seas less than 5 feet.

Tonight...high confidence.
Approaching low pressure from the west will spread rain across
the waters from west to east. Winds will remain below 20 knots
and seas below 5 feet through the period.

Monday...moderate confidence.
Warm front with weak low pressure along it may kick up
southeast to south winds to near 25 kt gusts and seas could
build to 5-6 ft over the outer waters. Small craft advisories
are likely for some of the outer waters.

Outlook /Monday night through Thursday/...

Tuesday...moderate confidence.
Frontal system will pass over the waters increasing them to
above 5 feet. Small Craft Advisory may be needed.

Wednesday into Thursday...high confidence.
Gusty northwest winds near gales on Wednesday will help increase seas.
Small Craft Advisory will be needed at the very least. High pressure nosing in
on Thursday will slowly relax seas.

&&

Box watches/warnings/advisories...

CT...none.
Massachusetts...Freezing Rain Advisory from 8 PM this evening to 8 am EDT
Monday for maz002>004-008-009-012-026.
Rhode Island...none.
Marine...Small Craft Advisory from 5 PM this afternoon to 8 am EDT
Monday for anz256.

&&

$$

Synopsis...Belk/dunten
near term...Belk/dunten/sipprell

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