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fxus61 klwx 180103 

Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
903 PM EDT Thu Oct 17 2019

high pressure will build across the mid-Atlantic through
Saturday afternoon. Rain is possible Saturday night into Sunday
as a low pressure passes southeast of the area. Showers are
again possible midway through next week due to a cold front.


Near term /until 6 am Friday morning/...
a strong surface low over the northeastern US will continue to
shift northeastward over eastern Canada overnight. As this low
moves further away from our region, the pressure gradient
continues to slowly weaken overnight. Skies continue to slowly
clear through the overnight periods as the westerly flow
weakens and drier air is transported into our area.
Temperatures this evening will be cooler with readings hovering
in the 40s east of the Blue Ridge and the 30s to low 40s west
of the Blue Ridge. A few places could see some patchy frost, but
think coverage should be low enough to preclude any advisories.
Best bet would be the more sheltered spots in the southern
Shenandoah Valley.


Short term /6 am Friday morning through Saturday night/...
high pressure will shift over our region from the Midwest on
Friday. No precipitation expected for Friday as winds weaken
and become more northwesterly. This will lead to advection of
cooler and drier air into our zones. Some lingering gusty winds
will be possible during the day over our land areas due to
weakening pressure gradient but I expect no gusts over 25 knots.
Given high pressure settling overhead with light winds and clear
skies, undercut guidance and issued freeze warning for inland
northern areas most likely to drop to 32 or below. Its possible
this area may need expansion, but frost advisories are likely in
areas beyond the current watch, so most locales outside the
cities and away from the tidal waters should be prepared to
protect tender vegetation.

High pressure will be in place over our region on Saturday
morning but will quickly shift out our region Saturday
afternoon. A potential tropical system forming in the Gulf is
forecast to shift northward through the southeast US and move NE toward
the southern parts our forecast area. Dry conditions expected
Saturday but a weak return flow is forecast to form ahead of the
coastal low. This will lead to weak advection of warm and moist
air into our region. The earliest that precipitation from the
tropical system could start to affect our region will be
Saturday evening in central Virginia. The exact track of this
system remains uncertain but the low is expected to move quickly
through our forecast area Saturday evening into Sunday. As most
guidance has precip reaching central VA, bumped pops upward with
some areas now into low likely range, but if trend continues,
some light rain may reach most of the County Warning Area.


Long term /Sunday through Thursday/...
potential tropical cyclone 16 is expected to move rapidly
northeastward during the next couple of days and pass south of
the area Sunday as an extratropical/Post-tropical cyclone. Some
light rain will be possible Sat night into Sunday morning on the
north and left side of the storm track. Not looking at a lot of
precip with this system as it will be fast mover and will be
far removed from the storm track. Mid-upper level ridge builds
during the early part of next week with another storm system
likely impacting the area during the middle portion of next


Aviation /01z Friday through Tuesday/...
through Saturday, the strong winds that have been occurring
will continue to weaken through this evening. Cloud cover
continues to gradually break. Winds will remain out of the west
overnight but will slowly become northwesterly Friday. Skies
are expected to be mostly clear Friday and Saturday but some
rain may move into the cho terminal by Saturday evening. VFR
conditions expected through Saturday afternoon.

MVFR cigs in rain possible Sat overnight into sun.


a strong pressure gradient will lead to strong gusty winds over
the waters today through Friday. Small craft advisories are in
place until 6pm on Friday. These small craft advisories may
need to be extended through Friday evening but winds will be
marginal near 18 knots. No small craft advisories expected at
this time for Saturday.

Small Craft Advisory conditions likely Sunday into Monday.


Lwx watches/warnings/advisories...
District of Columbia...none.
Maryland...freeze watch from late Friday night through Saturday morning
for mdz003-501-502.
Virginia...freeze watch from late Friday night through Saturday morning
for vaz026>031.
WV...freeze watch from late Friday night through Saturday morning
for wvz050>053-055-501>504.
Marine...Small Craft Advisory until 6 PM EDT Friday for anz530>543.


near term...jmg

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