National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 121200
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
700 AM EST Wed Dec 12 2018

.SYNOPSIS...
High pressure will prevail over the Mid-Atlantic through
Thursday. Low pressure approaches from the southwest Thursday
night into Friday, and tracks across the region Friday afternoon
through early Saturday. An upper level trough will remain over
the area through Sunday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 400 AM EST Wednesday...

Current GOES wv data shows an upper trough pushing off the New
England and Mid-Atlantic coasts, ahead of a ridge over Ohio
Valley. A nrn stream trough is digging across the Midwest, with
a srn stream trough lagging back over the nrn Baja Peninsula and
Desert SW. At the surface, 1027mb high pressure is centered
over the nrn Gulf coast, with low pressure E of Cape Cod. There
was some light mixing earlier in WSW flow, but most locations
away from the coast are now decoupling, and temperatures are
dropping into the low 20s where snow cover is present under a
clear sky. Closer to the coast, temperatures are holding in the
low/mid 30s.

High pressure gradually slides off the Southeast coast today.
Sunny this morning with some high clouds arriving this aftn.
High temperatures today range from the low/mid 40s inland, to
the mid/upper 40s toward the coast, with a light W or NW wind
this morning becoming SE in the aftn.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
As of 400 AM EST Wednesday...

A weak trough (the one over the Midwest early this
morning) clips the nrn Mid-Atlantic Thursday, with high pressure
building across New England in the wake of this system. Temperatures
will be slow to moderate Thursday, although dewpoints rising into
the low/mid 30s should hasten snow melt. Remaining dry tonight to
Thursday with lows in the upper 20s/low 30s Thursday morning,
followed by highs in the mid 40s inland, to the low/mid 50s in SE
VA/NE NC.

The aforementioned srn stream trough will reach ern TX/LA by late
Thursday night, with a moist frontal band emerging from the Gulf
into the Deep South ahead of the low. Continued dry Thursday night
with lows in the low 30s inland to the upper 30s/low 40s at the
coast.

The upper level system traverses the Deep South Friday into Friday
night, as the moist frontal band pushes toward the Mid-Atlantic
Friday aftn into Friday night. 12/00z models remain in good
agreement with a warm and wet pattern prevailing Friday aftn into
Friday night. Storm total QPF of 0.75-1.5" is expected, with up to
2.0" possible through 12z Saturday. This combined saturated ground
from snowmelt will bring potential flooding. A Flood Watch will
certainly be worth consideration with later forecast packages if
current setup remains in place in modeled data, and will continue to
make a mention in HWO, given POPs in the 70-90% range. MMEFS still
depicts minor river flooding with moderate flooding possible.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 355 PM EST Tuesday...

Saturday`s low pressure system departs offshore by Sunday morning
with residual showers possible across far southern VA and northeast
NC as the upper level low swings across the region. Still some
disagreement between the models on this feature, decided to go
closer to the ECM/Fv3. ECM is still consistent with showing low
pressure redevelop off the NC coast Sunday night into Monday.
This would allow for rain showers to linger across the east into
Monday morning. The operational GFS is more progressive with
the upper level low, thus has dry weather by Sunday afternoon.
Introduced chance PoPs across the south and southeast Sunday
afternoon into Monday morning to take into account both model
solutions. Dry weather Monday and Tuesday as high pressure
builds back across the region. Temperatures moderate by this
weekend with southerly flow ahead of the next low pressure
system, currently have highs in the lower 50s NW to the low/mid
60s across the SE for Saturday. Sunday will feature highs in the
low to mid 50s across the region. Temperatures trend cooler
early next week as cool high pressure builds across the area.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
As of 700 AM EST Wednesday...

High pressure is centered over the Deep South early this
morning, and it will gradually slide across the Southeast coast
today and move offshore tonight. Localized bkn-ovc cigs at SBY
of 5-6kft should persist through about 14z. Otherwise, expect
mainly high clouds today. A light WSW wind early will become
NW, and then become SSE (locally ENE at ORF) as high pressure
slides off the coast later this aftn.

High pressure continues to prevail Thursday into Thursday night.
Low pressure approaches from the SW Friday and moves across the
area Friday night into Saturday bringing rain and degraded
flight conditions. An upper level trough lingers over the area
into Sunday.

&&

.MARINE...
As of 630 AM EST Wednesday...

Update: Went ahead and cancelled the SCAs south of Cape Charles
as buoy obs continue to show diminishing seas.

Previous Discussion:

Latest sfc analysis indicates low pressure well offshore of the
Mid-Atlantic/Northeast coast, with weak sfc troughing over wrn
VA. Winds are out of the NW/NNW at 10-15 kt over the bay/15-20
kt over the ocean. Since buoy 44009 is reporting ~4 ft seas ~20
nm offshore of the MD/DE border (w/ only 3.3 ft seas at the
Wallops buoy), opted to cancel all SCAs north of Cape Charles. A
weak shortwave trough aloft will be passing just to our NE from
now through around mid-morning. This will bring weak cold
advection to the region (mainly north), but wind gusts will
likely stay just below SCA thresholds over the bay and ocean
zones. Cannot rule out a few gusts to SCA thresholds in elevated
areas (mainly N of Parramore Island), but these will be
infrequent/short-lived.

Tranquil marine conditions are in store from this afternoon
through Thursday night as high pressure will dominate our local
weather. Longer term model guidance shows low pressure (sfc-
aloft) approaching the area on Friday. The latest 00z/12
GFS/ECMWF/GEM are in relative agreement that sfc low pressure
develops near or just south of the region late Fri- Sat as an
upper low slowly moves eastward across the deep South. This
first area of sfc low pressure likely moves offshore by late in
the day on Sat. The upper low may approach the region late this
weekend as a secondary area of low pressure deepens offshore.
However, the timing/placement of the upper low vary
substantially among the latest GFS/ECMWF/GEM. Will continue to
show increasing winds/seas beginning Friday with the potential
for SCA conditions (most likely across offshore zones) through
Sunday.

&&

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

&&

$$
SYNOPSIS...AJZ
NEAR TERM...AJZ
SHORT TERM...AJZ/MAM
LONG TERM...AJB
AVIATION...AJZ
MARINE...ERI