Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 191146
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
646 AM EST Sun Feb 19 2017

.SYNOPSIS...
Unseasonably mild temperatures today will be followed by a brief
cool down tonight into Tuesday, as a dry cold front crosses the
region. Milder weather returns the middle of next week. However,
another pair of fronts may be accompanied by some precipitation
sometime Tuesday night into Wednesday. At this point, Thursday
has potential to be the warmest day of the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

Only minor tweaks to bring the forecast back in line with
observed trends.

Previous discussion...

***Unseasonably mild temperatures today with highs well up into
 the 50s to around 60***

A cold front will cross the region today, but with a very dry
atmosphere no precipitation will occur. This is also a classic
setup for high temperatures to exceed guidance numbers by
several degrees. This a result of a very mild start in many
locations coupled with west northwest flow and cold air lagging
well behind the front. With that said, we think much of the
region will see highs in the middle to upper 50s to around 60
across portions of RI/SE MA.

Should see a fair amount of sunshine through early afternoon, but
model cross sections indicate some lower clouds will drop down
from the north by mid to late afternoon as low level moisture
increases.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Tonight...

Strong shortwave across eastern Canada dives southeast with
developing closed mid level low sliding south of the Canadian
Maritimes. This allows a dry but much colder northwest flow of
air into southern New England. Low temps will bottom out in the
upper 20s to the lower 30s by daybreak Monday.

Monday...

Partly sunny with a brief return to seasonably cool temps. 850T
between -8c and -10c should hold high temps mainly in the upper
30s to lower 40s. Bufkit soundings also indicate it will be a
bit breezy with northwest wind gusts of 20 to 25 mph expected.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Highlights...

* Seasonably cool Tuesday
* Light rain/pockets of freezing rain possible Tuesday night into
  Wednesday
* Thursday looks to be our warmest day
* More widespread rain possible Friday night into Saturday

Overview and model preferences...

General consensus is for amplified flow over the eastern half of
the USA to become more zonal toward mid week. Once this happens,
not expecting to see major temperature swings. In fact,
expecting trend of above normal temperatures to continue.

Still plenty of detail differences with timing of certain
features, which is not uncommon in nearly zonal flow scenarios.
While minor at first, these differences significantly grow with
time. Have low confidence in the details, after Friday.

Preferred a consensus approach to smooth over the less
predictable details, especially late this week.

Details...

Monday Night into Tuesday...Still quiet, with high pressure
overhead. Low risk for rain to arrive across western portions of
southern New England late in the day. Near normal temperatures.

Tuesday night into Wednesday...

Guidance converging on the idea of a brief period of rain, but
differ in their timing. GFS is fastest by about 6 hours. Most
likely window for precipitation looks to be Tuesday evening into
Wednesday morning. With this timing, cannot completely rule out
the possibility of some sleet or freezing rain. These details
will need to be resolved over the next day or so.

A weak front should move back north, allowing temperatures to
rise above freezing, ending the threat of mixed precipitation.

Thursday into Friday morning...

A clipper-like low pressure should move through the Great Lakes.
Persistent southwest winds should lead to above normal
temperatures once more. Not a lot of moisture to the southeast
of this system, so thinking dry weather should prevail across
much of our region.

It`s possible, if southwest winds become strong enough, for
Thursday to be the warmest day of this week. Will need to see
how much snow melts between now and then. The more snow which
melts, the more likely we could see a few locations approach 60
degrees.

Friday afternoon into Saturday...

Huge solution spread in the ensembles and deterministic
guidance. Have little confidence in the details, although there
is general agreement for a low pressure to move northeast near
the Great Lakes. Thus, expecting any precipitation would be
rain. Some signs this system could be energetic enough where
some thunderstorms would be a possibility.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

Today...Moderate to high confidence. Mainly VFR conditions. Some
MVFR CIGS may develop by late afternoon north of the MA Pike.

Tonight and Monday...Moderate to high confidence. VFR conditions
probably dominate, but some MVFR CIGS possible tonight into
Monday morning with the highest risk across the interior and
outer Cape. Northwest wind gusts of 20 to 25 knots expected
during the daylight hours Monday.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF.

Outlook /Monday Night through Thursday/...Moderate confidence.

Monday through Tuesday...

Monday Night through Tuesday morning...

Generally VFR. Winds diminish as a high pressure moves overhead.

Tuesday afternoon through Wednesday...

A weak cold front approaches our region, with southwest winds out
ahead of it. This front is likely not to make it completely through
southern New England. CIGs and Vsbys lower to  MVFR in showers, then
improve to VFR after the front passes a location.

Thursday...

Weak front returns north as a warm front, but not a lot of
moisture to work with. VFR conditions expected.

&&

.MARINE...
Forecaster Confidence Levels...

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

Short Term /through Monday/...High confidence.

Today...High confidence. Cold front crosses the region today,
but cold advection lags well behind front. Therefore, expect
winds and seas to generally remain below Small Craft Advisory
thresholds.

Tonight and Monday...High confidence. Cold advection develops
tonight into Monday behind the front and expect northwest wind
gusts of 25 knots over most waters. Have hoisted small craft
headlines for all open waters.

Outlook /Monday Night through Thursday/...

Monday Night and Tue...High confidence. Rough seas and winds
diminish.

Tuesday night into Wednesday...Moderate confidence. Relatively
tranquil boating conditions. Scattered rain may lead to reduced
visibility at times.

Thursday...Moderate confidence. Relatively tranquil boating
conditions continue.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 10 PM this evening to 7 PM EST
     Monday for ANZ231-232-254>256.
     Small Craft Advisory from midnight tonight to 7 PM EST Monday
     for ANZ233>235-237.
     Small Craft Advisory from 5 PM this afternoon to 7 PM EST
     Monday for ANZ250-251.

&&

$$
SYNOPSIS...Belk/Frank
NEAR TERM...Belk/Frank
SHORT TERM...Frank
LONG TERM...Belk
AVIATION...Belk/Frank
MARINE...Belk/Frank



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