Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 251825
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
225 PM EDT Tue Apr 25 2017

.SYNOPSIS...
Low pressure tracks across the North Carolina coastal plain
today...then continues northeast along the Mid Atlantic coast
tonight and Wednesday. High pressure builds into the area
Thursday. A cold front stalls north of the region on Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Adjusted grids a bit this aftrn per crnt conditions. Dry slot
has quickly shut off pcpn in most areas but expect addntl shwrs
to develop as dytme heating combines with the upr level energy.
Kept thunder confined mainly along the coast and areas that has
seen sun. Temps range from the 60s NW...70-75 SE.

PVS DSCN:
Tropical moisture plume and associated showers now lifting
north northwest as the system continue to wrap around the
upr level low to the south. Of note is the dry slot noted by
sct-bkn mid level clouds across ne nc/sern va. Still have the
upr level systm to deal with this afternoon so will continue
with the cat to likely pops for the next few hrs slowly ramping
down toward evening. Thunder chcs continue across the south and
east as the system tracks ne, especially in areas that do get
some partial sunshine. Highs arnd 60 NW to mid 70s SE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
Upper/surface low pressure lifts along the Mid-Atlantic coast
this evening, and then north of the local waters late tonight.
Wrap around moisture keeps chance to likely POPs across the
northeast local area through late tonight. Given the recent
rainfall and saturated soils, have included patchy fog across
much of the region. However, cloud cover and light winds will
limit the overall coverage. Lows tonight generally in the mid to
upper 50`s.

Low pressure lifts along the Northeast coast Wednesday as an
upper level ridge builds over the region. Thermal soundings
indicate mid level moisture trapped beneath a strong subsidence
inversion aloft, which will help keep clouds around through the
day. However, given the late April sun, anticipate several
breaks in the clouds inland. Soundings also indicate very little
mixing, but given height rises and warming low level
temps/thicknesses, forecast highs are generally in the mid to
upper 70`s. Cooler along the coast. Mild Wednesday night under a
partly clear to mostly clear sky. Lows forecast in the upper
50`s to low 60`s.

Ridge axis slides offshore ahead of an approaching cold front
Thursday. Increasing return flow and 850mb temps around +14 to
+16C (around +1 standard deviation) result in warm (and dry)
conditions with highs generally in the 80`s. Cooler along the
coast. Plenty of sunshine expected.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Long term period will feature above normal temps with mainly dry wx.
For Thu night/Fri, deep SWly flow continues across the eastern
seaboard as an upper-level ridge then builds in through the weekend
allowing for warm temps and dry wx as most of the energy aloft will
stay N and W of the local area. At most a 20% chance of a late day
shra/tstm Fri and Sat. High temps Fri through Sun in the 80s,
pushing near 90 Sat and Sun. Low temps in the mid/upr 60s.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Low pressure continues to move northeast across the region this
afternoon before finally pushing offshore tonight. Widespread IFR
ceilings continue over mainly northern portions of the area,
including RIC and SBY, this afternoon. Closer to the center of low
pressure over southeast portions of the region, some temporary
clearing and mainly VFR ceilings are anticipated. Radar trends have
shown diminishing coverage in rain showers this afternoon, but model
guidance continues to hint at the redevelopment of showers across
eastern portions of the area.

Stratus and widespread IFR ceilings are expected to redevelop
overnight as moisture wraps around the backside of the low pressure.
Guidance has also been persistent with the development of patchy fog
tonight and into tomorrow morning. Included MVFR visibilities for
tonight, but it is possible IFR visibilities may develop in a few
locations. Conditions will improve during the day on Wednesday,
returning to VFR Wednesday afternoon.

Light easterly flow is expected to continue through this afternoon
and evening. Winds will shift to the W/NW as the low departs the
area tonight and Wednesday. Winds remain light on Wednesday,
generally 5-10 knots.

Outlook: Aviation conditions improve through the day on Wednesday
with VFR expected to return to the area. A shower or thunderstorm
will be possible during the day on Friday, but otherwise, VFR and
dry conditions should dominate the extended period.

&&

.MARINE...
Current analysis indicating sfc low pressure centered just S/SW of
Cape Hatteras, with E/NE flow ongoing across the local marine
area. Thus far, winds have been at SCA levels but have remained
below Gale criteria. Pressure falls have not been that
significant and therefore will be relying on mixing the stronger
winds aloft to the surface. High res models depict a short
period with Gale force gusts possible for the lower Bay and
southern coastal waters through mid morning, with higher winds
lingering across the northern coastal waters into early aftn.
Overall, this event looks marginal but will maintain continuity
and keep the Gale Warning in effect through 10 am S to 1 pm N.
SCA headlines remain in effect for the upper James/York/Rappahannock
Rivers where gusts up to 30 kt are expected. Seas up to 8-12
ft, with a high surf advisory remaining in effect for 8-9 ft
waves in the surf zone. No cold air surge in the wake of this
system later today and tonight, so aside from high seas
lingering for the coastal waters/mouth of Bay, expect rapidly
improving conditions later today and tonight. Seas should fall
off to below 5 ft later Wed/Wed night. Winds begin to shift to
the S Thu/Fri w/ sub-SCA conditions to prevail.

&&

.TIDES/COASTAL FLOODING...
Current tidal departures are averaging around 1.5 to 1.75 feet
in the lower Bay and southern coastal waters due to ongoing
onshore flow, while departures farther N are genly 1 ft or
less. Have raised coastal flood advisories for zones adjacent to
the lower Bay/James/York River, as well as the VA eastern
shore. This will be for the upcoming high tide later this
morning. More uncertainty exists farther N in the Bay up the
coast and have continued with another round of statements for
these areas for now. Surprisingly, despite continued onshore
flow, currents data from Cape Henry Channel shows that water has
been exiting the Bay at the same rate that it has been coming
in/ i.e. piling of water into the Bay has been fairly minimal
so far. ESTOFS and CBOFS data suggest this will change later
today through tonight with the potential for water to become
trapped in the Bay and for eventual minor flooding for the
mid/upper Bay by tonight. May need to raise a coastal flood
advisory later today for some of these locations, but did not do
this yet because of how the winds associated with this system
have genly underperformed so far.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...High Surf Advisory until 7 PM EDT this evening for MDZ025.
NC...High Surf Advisory until 4 PM EDT this afternoon for NCZ102.
VA...High Surf Advisory until 4 PM EDT this afternoon for VAZ098.
     High Surf Advisory until 7 PM EDT this evening for VAZ099-100.
MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ634.
     Small Craft Advisory until 4 PM EDT this afternoon for ANZ632.
     Small Craft Advisory until 7 AM EDT Thursday for ANZ650-652-
     654.
     Small Craft Advisory until 7 PM EDT Wednesday for ANZ656-658.

&&

$$
SYNOPSIS...ALB/MPR/SAM
NEAR TERM...MPR
SHORT TERM...SAM
LONG TERM...MAS
AVIATION...AJB
MARINE...LKB/MAS
TIDES/COASTAL FLOODING...



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