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afdlwx

Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
930 am EST Thu Nov 23 2017

Synopsis...
high pressure will build over the area through Friday. Another
cold front will approach overnight Friday into Saturday before
passing through Saturday night. High pressure returns for Sunday
and Monday before moving offshore Tuesday.

&&

Near term /through tonight/...
temperatures are starting to rebound under sunny skies following
a night of cold advection and light winds leading to chilly
temperatures. Shenandoah Airport dropped to 16; New Market and
Petersburg both fell to 17. Everywhere fell to or below
freezing except downtown Baltimore and coastal Saint Mary's
County.

9 am temperatures ranged from 24 at Shenandoah and Petersburg to
39 at Pax river. Winds have diminished and the pesky low clouds
in the Hagerstown-Frederick corridor are finally breaking. High
clouds remain east of a Fredericksburg to Annapolis line but are
edging eastward.

High pressure will remain over the area all day today, leading
to light and variable winds and highs in the 40s. The sunny
sky will be peppered with some mid-level clouds this afternoon,
especially closer to the Mason-Dixon line, as a weak upper level
disturbance comes through the dry high pressure airmass
overhead.

What few clouds there are will dissipate in the evening, leaving
generally clear skies. However, dewpoints should come up a few
degrees, so despite calm winds and decoupling, lows probably end
up a few degrees warmer than this morning. Will lean on the
cool side of guidance given what happened this morning.

&&

Short term /Friday through Saturday night/...
Friday and Friday night will have seasonable fair weather under
the continued influence of high pressure, with very light
winds.

Saturday will start out with partly sunny skies, but quickly
become overcast as cold front moves through the region,
bringing chance of rain showers, with diminishing chances the
further east as deep westerly winds will promote downsloping
and associated drying. Most likely scenario brings scattered
showers Shenandoah Valley and points west, with sprinkles at
higher elevations along the Blue Ridge, and mid-deck along and
east of Interstate 95. Cold air advection with strong winds
behind the front for Saturday night, with snow showers
developing in favored upslope regions.

&&

Long term /Sunday through Wednesday/...
high pressure will build overhead Sunday through
Monday...bringing dry and seasonably chilly conditions. The high
will move offshore Tuesday and a southwest flow around the
departing high will usher in milder conditions...and it will
remain dry.

A cold front will approach the area Tuesday night and it may
pass through Wednesday or Thursday. Confidence in how far south
the front makes it is low at this time due to divergence in the
long range guidance. Leaned toward the superblend for
temperature forecasts during this time...which keeps temps near
or above climo. This makes sense this far out since there will
be an anomalous subtropical ridge over the southeastern
Continental U.S....and this would favor the front being slower and weaker.

&&

Aviation /14z Thursday through Monday/...
VFR for all terminals through 36 hours. Gusty winds develop
Saturday night behind cold front.

VFR conditions are expected Sunday through Tuesday as high
pressure controls the weather pattern.

&&

Marine...
winds have decreased on the Bay and the Small Craft Advisory was cancelled early.
Light winds should continue through Saturday. Small craft is
expected to return Saturday night and continue through Sunday.

High pressure will build overhead Sunday through Monday. A Small
Craft Advisory may be needed for portions of the waters Sunday
ahead of the building high.

&&

Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...none.
Virginia...none.
WV...none.
Marine...none.

&&

$$
Synopsis...bjl

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