Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 070742
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
242 AM EST Thu Dec 7 2017

.SYNOPSIS...
A frontal boundary remains nearly stationary off the Mid
Atlantic coast through Saturday. A series of low pressure
systems will track northeast along this boundary through
Saturday. Cold high pressure builds into the area Saturday
night into Monday.

&&

.NEAR TERM /THROUGH TODAY/...
Frontal boundary remains (well) S and E (off the coast) today.
Initial weak s/w aloft in SW flow exits early this morning...w/
a general trend to RA (now mainly invof NE NC) settling a bit
farther SE. Otherwise...expecting widespread mid-high clouds to
stream NE over much of the FA today. PoPs (blo 20% - highest
invof NE NC) after 12Z/07. Near seasonable temps w/ winds VRB
blo 10 mph. Highs within a degree or two either side of 50F.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
Frontal boundary will remain offshore nearly parallel to the SSW
upr flow through early Saturday. A series of disturbances will
move through the region Thursday night through Saturday
morning. Thursday should be a mainly dry day, although have
maintained chc/slgt chc POPs for light rain across NE NC, near
the deepest moisture. Upper flow begins to back Thursday
night/Friday, allowing moisture to pull NWWD, and increase
precipitation chances back toward the I-95 corridor. Surface
temperatures through 00Z Saturday expected to be warm enough for
all liquid precipitation.

The 00Z Friday through 15Z Saturday is the time period where
potential snow could occur across the region. 12Z NAM/Canadian
are most aggressive with snow potential Friday night/saturday
morning, with GFS/ECMWF nearly identical through 00Z Sunday with
regard to precip trends and snowfall potential. GFS/ECMWF would
suggest limited precip west of the I-95 corridor, with the best
chance for snow across interior southeast Virginia northeastward
toward the MD Eastern Shore. Lots of factors limiting snow
potential, including a marginal temperature profile, and
relatively weak forcing. Thus, while some snow is likely,
precipitation rates are expected to be low enough to prevent
much accumulation. A small area of around an inch of snow has
been forecast south of a South Hill to Petersburg to Suffolk
area, mainly before 12Z Saturday. Lighter amounts extend
northeastward into the Lower MD Eastern Shore. Given warm
temperatures recently, and warm road temperatures, expect little
impact from the snow, which will likely melt within a few hours
of sunrise Saturday.

Precipitation, mainly in the form of rain or a rain/snow mix,
gradually moves offshore by early Saturday afternoon, with a
surge of colder air moving into the area Saturday
afternoon/evening.

Temperatures return to below normal levels Thursday through
Saturday. Lows Thursday night in the near 30 NW to the upper 30s
at the immediate coast in SE VA-NE NC. Highs Friday low to mid
40s. Lows Friday night from the upper 20s to low 30s away from
the Bay/Ocean the upper 30s near the coast. Highs Saturday
generally in the low to mid 40S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Long term period characterized by a broad (and amplifying)
Eastern U.S. trough. In general, 12Z/06 suite of models, and
their respective ensemble means, continue to be in good
agreement with the overall setup. However, temporal/spatial
differences remain and become greater later in the period. The
period begins with deep/cold upper level low pressure centered
over the NE CONUS Sat night/Sunday, with shortwave energy aloft
brushing NE zones of the CWA. Cold Saturday night with temperatures
most areas dropping well into the 20s. Partly cloudy except
mostly cloudy NE where will have a ~20 PoP for snow showers.

Flow becomes temporarily less amplified Sunday through Monday,
with a slow moderation in temperatures starting Sunday night,
under clear to partly cloudy skies. High temperatures Sunday
only around 40-45 F (highest SE), with low temps Sunday night
again mostly in the 20s (with some upper teens possible well
inland). Highs Monday in the upper 40s NW to lower 50s SE.

Next shortwave trough amplifies the flow Monday night through
Tuesday, with the attendant Arctic cold front moving through the
area late Tuesday/Tuesday night. This front is expected to be
accompanied at least scattered showers, with enough low level
warm air intrusion ahead of the system to keep the precipitation
mainly in liquid form initially. Lows Monday night in the lower
30s, with highs Tuesday mid/upper 40s to lower 50s (SE). By Tue
night into Wed, any lingering moisture will change to snow as
much colder air moves in from the NW. This is period where the
models diverge, the GFS developing sfc low pressure later and
farther south than the ECWMF. Latest WPC guidance and model
consensus will be followed for now, with a chance for snow into
the forecast late tue night/wed morning, but not as high as what
the 12Z GFS would suggest. Turning very cold Wed with highs
only in the 30s.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
Frontal boundary remains (well) S and E of the local area
through the 06Z/07 TAF forecast period. BKN-OVC VFR CIGS (mainly
aoa 10kft) continuing. Area of -RA now in far SE VA-NE NC
settles a bit SE through today into tonight. Winds mainly
VRB blo 10 kt. The frontal boundary remains off the coast
through Sat with a series of weak low pressure areas tracking
ENE along it but remaining offshore. BKN-OVC CIGS/occasional
pcpn expected at KORF/KECG, and possibly KPHF (by late)
tonight/Fri. Pcpn may trend NWWD Fri afternoon/night and reach
KRIC/KSBY. Pcpn...possibly as a mix of rain/snow...is expected
to move offshore by 18Z Sat. VFR conditions are expected for
the upcoming weekend after Saturday morning.

&&

.MARINE...
Cold front now SE of the area, and pressure gradient has
weakened with winds now mainly NNE at 10-15 kt or less. Only SCA
headline still in effect is for NC coastal waters for 5 ft seas.
Light onshore winds shift to the WSW and then WNW overnight at 10
to 15 knots and will continue through Thursday, before winds
turn northerly as low pressure develops off the southeast coast
Friday/Friday night. The consensus forecast still keeps low
pressure not intensifying until it is well offshore Fri night
through Sat, which means winds will generally remain below
Small Craft Advisory criteria Friday through Saturday. Did
however ramp the winds up a bit across the far southern VA and
NC coastal waters where low end SCA conditions will be possible
Sat. Strong cold front passes through sat night ans SCA
conditions look to prevail for all zones Sunday (potential for a
few brief gusts to Gale force Sun morning).

&&

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

&&

$$
SYNOPSIS...ALB/MPR
NEAR TERM...ALB
SHORT TERM...WRS
LONG TERM...LKB
AVIATION...ALB
MARINE...AJB/LKB



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