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Area forecast discussion 
National Weather Service Wakefield Virginia
157 am EDT Tuesday Oct 21 2014

Synopsis...
low pressure moves into the region tonight and Tuesday...locating
off the northeast coast for much of the middle to late week period.

&&

Near term /until 6 am this morning/...
surface high pressure was centered well off the coast this evening
allowing for a relaxing pressure gradient along the coast and inland with
southerly winds 10 knots or less. Meanwhile...an upper level trough digs
into the Great Lakes/northeast tonight...with a surface cold front
reaching The Spine of the Appalachians around 12z Tuesday.

Shortwave energy rounding the base of the trough has been
providing weak lift supporting a thin band of isolated showers on
radar over the western County Warning Area...however due to the dry air in place
in the lower levels most of the radar are resulting in virga. Bufr
soundings show overall dry airmass in place tonight (pw's at or below
0... it will be hard to get much of precipitation to reach the
ground. The hrrr ties to develop a thin band of showers east of
I-95 around 06z...but this appears to be overdone. That said
cannot rule out a few brief sprinkles overnight. Overall dry
conditions are expected through tonight with some increasing cloud
cover. The cloud cover and light SW flow could keep some areas
from reaching forecast lows keeping conditions milder. Lows
generally in the upper west to middle 50s at the coast.

&&

Short term /6 am this morning through Thursday/...
flow amplifies during the short term as a blocking pattern develops
over eastern Canada. Additional energy dives south over the Great
Lakes/Ohio Valley Tuesday thanks to a ~100 knots jet streak diving southward
from Canada. As a result...upper low prognosticated to develop over the
middle-Atlantic into the NE states late Tuesday. The upper low will
progress slowly eastward Tuesday night into Wednesday...locating off the
Delaware-Maryland-Virginia coast late Wednesday. With the upper low pivoting across the
local area Tuesday/Tuesday night...will see a better chance for showers
develop especially north/NE where best upward motion is
anticipated. Have chance (pops 25-40%) along and NE of a line from
lku-ofp-mfv on Tuesday...then best chance (30-50%) mainly along the
Virginia coast and onto the Eastern Shore Tuesday night. Elsewhere...will
carry no higher then 20% probability of precipitation. Highs Tuesday in the upper 60s northwest to
middle 70s southeast. Lows Tuesday night in the middle 40s to middle 50s. Mostly
cloudy north to partly cloudy south during thie time.

Deep upper trough/closed low slowly moves east and offshore Wednesday.
Forecast soundings fairly dry aloft over inland sections as the
trough/surface reflection swing offshore. Will therefore keep chance probability of precipitation
limited to areas along and NE of the I-64 corridor Wednesday...with
emphasis on the Northern Neck and Eastern Shore (30-50% pops).
Could end up being dry over far SW zones. Cooler Wednesday with highs
only 60-65.

The closed low moves farther NE Wednesday night into Thursday...locating off
the New England coast by 00z Friday. Any leftover shower chances
by then will be limited to the Eastern Shore (20%). Decreasing
clouds are also expected across interior Virginia. Lows Wednesday night in the
low 40s to low 50s. Cool again Thursday with highs 60-65.

&&

Long term /Thursday night through Monday/...
low pressure lifts to the NE Thursday night through Saturday as
upper ridging expands eastward from the central US. A weak trough
clips the northern middle-Atlantic Saturday night and quickly moves off the
coast Sunday. Middle/upper level ridging builds over the eastern US early
next week. Overall...dry conditions should prevail through the
medium range period. High temperatures should average in the middle 60s
to around 70 Friday and Saturday...and trend upward into the upper
60s to low 70s Sunday...and potentially 70-75 by Monday. Lows should
range from the low/middle 40s northwest...to the low/middle 50s for southeast coastal
locations.

&&

Aviation /06z Tuesday through Saturday/...
expect mainly VFR conditions today into this eveng over the taf
sites...with periods of middle level cloudiness...as a weak cold front
moves across the area. Later tonight through Thursday...low pressure will intensify
off the New Jersey and New England csts. There will be a chance for
showers and MVFR ceilings...esply over northern and eastern portions late tonight
into Wednesday night. MVFR ceilings may linger into early Thursday at sby. The low
pressure system will move farther away to the NE and hi pressure builds in
from the north-northwest Thursday night into sun.

&&

Marine...
10 PM update...winds and seas have increased well offshore (off
the Maryland coast) according to buoy 09. Seas are just about 5 feet (4.9
feet last two hours). Winds and seas are much less toward the coast.
Included a strip of 5 feet seas (through 06z) in the zones north of
Parramore Island but holding off on Small Craft Advisory for now.

Hi res models are overdoing the winds over the Bay. As air
temperatures cool...mixing will increase and winds may increase
but expect them to stay below Small Craft Advisory criteria.

Previous discussion...
surface high pressure slides offshore tonight...allowing the wind
to remain S/SW. Expect sub-Small Craft Advisory conditions to prevail with wind
speeds averaging up to 15-20 knots across northern coastal waters...and
generally 10-15 knots elsewhere. The next cold front will slowly cross
the coast late Tuesday afternoon/evening...followed by eventual Small Craft Advisory
conditions later Wednesday into Wednesday evening as surface low pressure
then deepens off the coast. This system is expected to stall
offshore Thursday through the end of the week bringing a prolonged
period of Small Craft Advisory conditions. With flow being offshore from the
northwest...seas would tend to stay capped at 5-6 feet and tidal flooding
is not expected. North/northwest flow is expected to continue into next
weekend with speeds diminishing to 10-15kt and seas subsiding.

&&

Akq watches/warnings/advisories...
Maryland...none.
NC...none.
Virginia...none.
Marine...none.

&&

$$
Synopsis...jdm
near term...jdm/jao
short term...jdm/Sam
long term...ajz
aviation...tmg
marine...ajz/lsa

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