Area Forecast Discussion
Issued by NWS Wakefield, VA

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185
FXUS61 KAKQ 162101
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
401 PM EST Sat Dec 16 2017

.SYNOPSIS...
High pressure builds across the Southeast coast tonight, and
moves off the Carolina coast Sunday and Monday. The local area
remains in between weak low pressure to the south and strong low
pressure over Canada Tuesday. A cold front crosses the region
Tuesday night into Wednesday.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A region of zonal flow prevails across the central and ern
Conus this aftn upstream of a trough over the southwest Conus
and nrn Mexico. At the surface, high pressure is centered across
AL/GA/SC. Sunny this aftn with a few high clouds over the MD
Ern Shore. Temperatures are on the cool-side of seasonal
averages and primarily in the mid/upper 40s (low 40s over the MD
Ern Shore) with a light SW breeze. A mid/upper ridge will build
across the Ohio Valley tonight as a shortwave trough lifts to
the NE over the srn Plains. Surface high pressure will shift to
the Carolina coast with the local area remaining clear and dry
tonight with a calm to very light wind. Decent radiational
cooling is expected tonight with temperatures quickly dropping
into the 30s early this evening. Overnight lows are expected to
be in the mid/upper 20s with low 30s for coastal SE VA/NE NC.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
High pressure slides offshore Sunday as a weak trough pushes
across the Great Lakes. Some upper level srn stream moisture
(basically the remains of the aforementioned srn Plains trough)
will arrive ahead of this wave, which will result in increasing
mid/high clouds Sunday aftn and evening. Highs Sunday range from
around 50F N to the mid 50s S. Decreasing clouds Sunday night
with lows ranging from the mid/upper 30s N to the low 40s SE.
High pressure remains offshore Monday as the flow aloft remains
zonal. Mostly sunny early Monday and then becoming partly sunny
as a dampening srn stream wave pushes into the Tennessee Valley
by the aftn. Mild Monday with highs generally 55-60F.

The 16/12z model consensus keeps this system suppressed well S
of the local area Monday night and it quickly moves offshore
Tuesday as a nrn stream wave dives across the Great Lakes.
Meanwhile, surface high pressure is forecast to be centered off
the Southeast coast. Partly cloudy Monday night and Tuesday with
the airmass continuing to warm. Forecast lows Monday night
range from the upper 30s N to mid 40s SE. Quite warm Tuesday
with highs in the 60s, and even potentially close to 70F if
enough sun prevails.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The extended period will begin Tuesday night/Wednesday with
progressive split zonal flow continuing to prevail over the
central and ern Conus. A nrn stream wave passes across New
England Tuesday night, which will push a cold front through the
Mid- Atlantic. Meanwhile, a srn stream wave will track across
the Tennessee Valley Wednesday and off the Carolina coast
Wednesday night. 16/12z ECMWF/GFS/CMC demonstrate decent
agreement with this system. However, the best forcing is progged
to be S of the local area, so PoPs for rain are only 20-30%
across far srn VA and 30-40% for NE NC. Cooler behind the front
Wednesday with highs generally 50-55F (upper 40s far NE), after
morning lows in the upper 30s N to mid 40s SE. Drier air pushes
in from the NW late Wednesday night into Thursday with lows
Wednesday night ranging from the low 30s N to upper 30s S,
followed by highs Thursday in the upper 40s N to low 50s S. The
large scale trend by Friday/Saturday is for a trough over the
Great Lakes and a ridge off the Southeast coast. However, model
agreement is lacking on the details, specifically with respect
to the location of the cold front between these two features.
PoPs are trended toward or slightly above climo for the very end
of the forecast period, with temperatures generally remaining
above normal.

&&

.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
High pressure is centered over AL/GA/SC as of 18z and this is
resulting in a 5-10kt WSW wind under a primarily sunny sky aside
from a few patches of high clouds. High pressure becomes
centered over the Carolina coast tonight with a mostly clear sky
and a calm to very light wind. High pressure slides offshore
Sunday and Sunday night as a weak trough approaches from the
WSW. This will bring a period of bkn-ovc mid/high clouds Sunday
aftn into Sunday evening. High pressure remains near the
Southeast coast Monday through Tuesday with VFR conditions
prevailing along with occasional mid/high clouds. Low pressure
passes S of the region Wednesday with high pressure building N
of the region Thursday.

&&

.MARINE...
No headlines in the short term tonight thru Mon. High pressure
will be over the SE states tonight, then moves off the coast for
Sun into Mon. Expect winds mainly SW or W thru Mon with speeds
15 kt or less. A cold front will cross the waters Tue night into
early Wed morning, with winds shifting to the NW at least 10-15
kt. High pressure will be to the north and low pressure will
track south of the area and off the coast Wed aftn thru Thu.
North then NE winds 5-15 kt.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.

&&

$$
SYNOPSIS...AJZ/LKB
NEAR TERM...AJZ
SHORT TERM...AJZ/LKB
LONG TERM...AJZ
AVIATION...AJZ
MARINE...TMG



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