Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 040134

Area Forecast Discussion
National Weather Service Wakefield VA
834 PM EST Sat Dec 3 2016

High pressure builds across the region tonight and Sunday. Low
pressure passes south of the region Sunday night into Monday.
A complex area of low pressure crosses the region Tuesday. A
strong cold front crosses the area Thursday.


Update...A steady stream of high clouds will move across the
region through the rest of tonight with zonal flow aloft. This is
keeping temperatures a few degrees warmer than previous
forecast...especially through the rest of tonight since no large
breaks are anticipated as sfc high pressure builds in from the
wnw. Clouds may thin across the Nrn Neck and MD/VA Eastern Shore
closer to morning, however any clearing should occur too late to
have any effect on the overall lows in these areas. Expect
overnight lows of 33-35F inland and 35-40F along the coast.

Previous discussion...
Sfc high slides east invof Mason-Dixon line tonight. Tsctns show
high level moisture overspreading the region ahead of the
developing low to the south.


High pressure slides east at a position along the Delmarva Sunday
aftn. While this high keeps it dry in the lower levels, the
mid/upr levels quickly moisten throughout the day. So while there
could be some dim sunshine early Sun morning across the east,
expect the day to turn out cloudy to mostly cloudy with any pcpn
remaining sw of the fa thru 00Z Mon. The clouds hold temps down
with highs in the upr 40s-lwr 50s.

First wave of energy from the low over the deep south ejects ENE
along a developing trof over the Carolinas Sunday night. Models
agree in quickly spreading moisture NE across the fa Sun evening.
Best lift/support progged over the SERN half of the fa where
greatest QPF will be (1/4 to 1/3rd inch). Will carry chc/likely
pops during the evening then ramp up to likely pops most areas
except categorical pops across SERN zones after midnight. In-situ
wedge leads to a chilly rain with lows in the upr 30s-lwr 40s.

The sfc low pushes off the coast near HAT Monday morning with weak
ridging building south across the area throughout the day. Despite
the high pressure building in, TSCTNS show enough leftover moisture
at various levels to keep cloudy to mostly cloudy skies. Chc pops in
the morning (except likely across extreme SE zones) lower to slght
chc across NC zones in the afternoon. Highs in the low-mid 50s.

Timing differences arise wrt the pcpn arrival Monday night with the
NAM the fastest, GFS the slowest with the 12Z ECMWF a compromise
between the two. Will lean toward the faster solution given pcpn
usually breaks out a bit faster given an overrunning scenario. Will
carry low chc pops Monday eve ramping up to chc to likely pops after
midnight. Lows in the mid 30s NW to upr 40s SE.

Tuesdays forecast is another typical Mid Atlantic system where
low pressure tracks NE along the mts with a secondary low tracking
NE along the coast. Copious amounts of both GOM/Atlantic moisture
will fall into a strong wedge across the piedmont. Expect a wide
temp range across the fa along with a much needed/widespread rainfall.
Challenge will be to define where the coastal low tracks as the NAM
has an inland track with both the GFS/ECMWF tracking the low right
along the coast. For now, will keep all pcpn stratiformed with
categorical pops. QPF averaging btwn 1/2 to 3/4 inches. Temps
tricky but will continue with a sharp thermal gradient. Highs from
mid-upr 40s across the wedged piedmont to near 60 across sern
coastal zones.


Long term period starts off wet with double-barrel low pressure
passing through the region and W/SW flow aloft. The best chance of
rain will be Tue eveng, with the rain possibly lasting into the
overnight hours and Wed morning depending on how fast the sfc low
pushes offshore. For now will maintain chance pops over far
eastern areas Wed, with high temps in the mid 50s. There will also
be a chance of rain Thu with a passing strong cold front, although
the chances and qpf are expected to be lower than with the system
earlier in the week. Hi temps Thu in the low/mid 50s. With a
slower cold fropa and some anafrontal pcpn, there is also a chance
of some snow showers over NE areas Thu night. Dry weather
thereafter for Fri and Sat as sfc high pressure builds in from the


High pressure slides out of the Ohio Valley and directly over
the Mid Atlantic Region tonight into Mon. VFR conditions will
persist with high cirrus increasing and thickening through the
day on Mon. The sfc high (and subsequent stacked ridging aloft)
slides offshore by Monday evening. This will allow steady rain
to overspread the area from sw-ne late in the evening and
overnight as shortwave energy streams into the area via the upper
ridge which is also flattening overnight. MVFR to IFR cigs/vis
(and maybe even LIFR conditions) should be anticipated. Meanwhile,
sfc low pressure develops along the Southeast Coast early Mon and
slowly exits off Cape Hatteras the rest of Mon.

High pressure briefly returns to the region Mon night...followed
by a more well-defined low pressure system Tue/Tue night, which is
expected to split into two lobes. One tracks across the TN Valley
and along the spine of the Appalachians during this timeframe. The
other tracks along the Southeast Coast Tue and the up along the Mid
Atlantic Coast Tue night before lingering well off the Delmarva
Coast. Widespread rain will be common across the area Tue...tapering
off from sw-ne after midnight Tue night. IFR conditions are more
likely with the passage of this system. With the low lingering off
the Delmarva and a progressive sw flow pattern aloft, periodic
showers/MVFR conditions will be possible Wed and Thu.


SCA headlines remain in place for the northern Bay and northern
coastal wtrs tonight with strong low pressure over SE Canada and
high pressure building in from the west leading to strong NW flow
over the local wtrs. Winds/waves/seas decrease into Sun morng as
the high builds into the Mid Atlc, leading to benign marine
conditions during the day. Next chance of SCA conditions will be
Mon night/Tue with double-barrel low pressure affecting the area
and E/NE flow increasing ahead of the low. Gale conditions then
possible at least over the coastal waters and Bay Thu night
through Fri night behind a strong cold front.


MARINE...Small Craft Advisory until 1 AM EST Sunday for ANZ630-631-650-


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