Thanksgiving travel weather information

Updated weather discussion 11:01 am EST Wednesday Nov 27 2013

National Weather Service Taunton Massachusetts

1101 am EST Wednesday Nov 27 2013

Synopsis…
intensifying low pressure over New England will continue to move
northeast away from the region this afternoon. This will result
in diminishing winds and rain becoming more showery with rainfall
rates less intense. As the storm departs blustery west to northwest
winds and light snow showers will follow tonight. Drier and
continued blustery conditions continue into Thanksgiving. Very
cold but mainly dry weather continues Fri/Sat…before temperatures
moderate early next week along with the threat of some
precipitation.

Near term /until 6 PM this evening/…

11 am update…

Intensifying low pressure over northeast Massachusetts/southeast New Hampshire at 1030 am
and continuing to race northeast with maximum pressure fall center over
ME. Last bout of strong winds will be confined to Rhode Island and southeast
Massachusetts as heavy showers and embedded convection bring stronger winds
aloft to the surface.

Winds will continue to diminish from west to east today as low
level jet moves offshore and is replaced by a weakening pressure
gradient as surface low elongates over the area. However later
this afternoon and especially this evening southern New England
will get into strong pressure rises as cold air advection and
associated subsidence commences across the forecast area. May have
to extend Wind Advisory into tonight and possibly early
Thanksgiving day.

As for rainfall…heavy showers will be confined to Rhode Island and
southeast Massachusetts as low level jet moves across this area and then
offshore by 18z/1pm. Showers of lesser intensity will continue
much of this afternoon as middle-upper trough swings across the area.
Will hold onto Flood Watch given lots of standing water/additional
rainfall expected and small rivers/streams and creeks near
bankfull.

Very mild especially across Rhode Island and eastern Massachusetts with temperatures in the
low to middle 60s. May approach record high at Providence which is
66/1946. Although colder air lurking just off to the west across
eastern New York with temperatures currently in the 30s.

Short term /6 PM this evening through 6 am Thursday/…
Wednesday night…

Though winds drop off immediately in proximity to the cold frontal
passage…colder and drier air quickly rushes in to the rear.
Steepening low-level lapse rates allowing for effective momentum
Transfer of winds aloft to the surface coupled with a continually
intensifying low pressure center as it lifts north and east out of
New England will result in increasing west-northwesterly winds…
potentially reaching Wind Advisory criteria by morning.

Additional middle-level disturbances through the broader troughing
regime invoke low-level deformation as noted by q-vector convergence
between h925-700. Residual moisture within the cold pool behind the
front will likely undergo some forcing…especially orographically
along western slopes of higher terrain to yield snow showers and
light snow accumulations less than an inch.

Main regions of concern are across northern and western
Massachusetts…and southern New Hampshire. Slick spots along
roadways are possible with any snow accumulation. Expect subsidence
and drier air to prevail after midnight resulting in the conclusion
of disturbed weather for New England.

&&

Long term /Thursday through Tuesday/…
highlights…

* Thanksgiving dry but unseasonably cold and windy
* mainly dry Friday/Sat but very cold
* temperatures moderate sun-Tuesday with the threat of some precipitation

Details…

Thanksgiving day…while skies will be partly to mostly sunny…
strong cold advection will occur as 850 mb temperatures drop to between
-12 and -14c. This will result in unseasonably cold weather for
late November. Highs should only reach the upper 20s across the
interior high terrain…to the lower to middle 30s elsewhere.
Excellent mixing should support west to northwest wind gusts of 35
to 45 miles per hour. A few locations may reach Wind Advisory criteria during
the morning hours…so later shifts will have to consider
additional wind headlines. Regardless…wind chill values will be
in the teens…to lower 20s which will be a rude awakening after
the very mild weather this afternoon.

Thanksgiving night…large Canadian high pressure will begin to
build in from the west. This will allow winds to diminish and
result in a good night of radiational cooling. It will be quite
cold with overnight lows well down into the teens to the lower 20s.

Friday…a mixture of clouds and sunshine are on tap but with well
below normal temperatures. Large Canadian high pressure will result in
850 mb temperatures between -14c and -16c! This should only allow
afternoon highs to recover to the middle and upper 20s across the
interior high terrain…with 30 to 35 in the lower elevations. It
won’t feel quite as cold as Thanksgiving day though…as winds
will be much lighter. Nonetheless…certainly another impressive
shot of very cold air for the end of November.

Friday night and Saturday…an anomalous 1045 mb high pressure
system will position itself across northern New England. This
will result in the continuation of very cold but mainly dry
weather. The exception may be a brief period of light ocean effect
snow showers/flurries late Friday night/Sat across the far southeast
New England coast. Surface winds turn north northeast with 850 mb
temperatures till around -14c…so that may be enough to generate some
very light snow showers/flurries in that region. Otherwise…will
maintain a dry forecast elsewhere. Lows Friday night should mainly
be in the teens. Highs on Sat ranging from the upper 20s to the
middle 30s.

Sunday through Tuesday…moderating temperatures will occur as large high
pressure moves off the coast. Low confidence on precipitaton
potential and timing. We may have a round or two of scattered
light precipitation in the warm air advection pattern. Would
expect it to be mild enough in the boundary layer for mainly light
rain showers along the coastal plain…but some mixed precipitation
would be possible across the interior. Also…a few models are
indicating the potential for a period of more significant
precipitation with a possible coastal low pressure. Low confidence
if this occurs given its 5 to 6 days in the future…but something
will have to keep an eye on.

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