Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 251641
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
1241 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 /18Z TUESDAY THROUGH SUNDAY/...
Widespread IFR conditions observed over the region this morning
as low pressure lifts over eastern North Carolina. Ongoing
showers over the region this morning lifts north of the region
by late morning/early afternoon as the upper level low lifts
along the Southeast coast. IFR visibilities are expected under
the heaviest showers. Areal coverage of the precipitation
decreases across the region mid to late morning, but still
expect light rain/drizzle and IFR conditions to persist.
Additional scattered to numerous showers expected across the
region this afternoon as the upper low lifts over the region. A
thunderstorm is possible across the southeast.

Easterly winds gust to 25 to 35 knots this morning, diminishing
at or below 10-15 knots this afternoon as the surface low lifts
over the region.

Outlook: Precipitation lifts northeast of the region overnight,
but IFR conditions expected to persist through late tonight.
Conditions begin to slowly improve late tonight into Wednesday
as the system moves farther north. Dry weather is in store for
Thursday and Friday as high pressure builds over the southeast
states.

&&

.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...Coastal Flood Advisory until 2 PM EDT this afternoon for
     VAZ089-093-523>525.
     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...SAM/JEF
MARINE...LKB/MAS
TIDES/COASTAL FLOODING...



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