Area Forecast Discussion
Issued by NWS Wakefield, VA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 221814
Area Forecast Discussion
National Weather Service Wakefield VA
214 PM EDT Sat Apr 22 2017
Several weak waves of low pressure will move across a nearly
stationary front in place across the area today. The front will
sink south toward Carolinas tonight through Sunday...as a slow
moving area of low pressure tracks along the southeast coast
Sunday and Monday. This system will bring periods of moderate
to heavy rainfall to the region Sunday through early next week.
.NEAR TERM /THROUGH TONIGHT/...
FYI...Preliminary results from the storm survey in the Colonial
Beach area shows mainly straight line wind damage. Official
statement to be issued later today once survey is completed.
Tweeked temps a bit more as readings are approaching 80 at ORF
with steadying readings in the mid 50s across the eastern shore.
Steady or slowly falling readings west of the bay and north of
the boundary this afternoon. Quite a differential heating boundary
for convection to fire up on, so went ahead and bumped up the
thunder chcs across southern most VA and NE NC zones after 18Z.
SPC now has a SLGHT risk across south central zones from AVC-AKQ-
RWI. Large hail and damaging winds main threat, minimal tornado
This is the kind of day that makes one go gray fast. Continue
to tweek temps per rises on south side of boundary while steady
or falling temps north of the front which is crntly located near
a fvx-ptb-phf line. Could easily see readings at ORF drop 10-15
degrees once bndry moves thru and the wind turns NNE. Radar
loop showing a "lull" in pcpn coverage but do expect that to
fill in over the next few hrs. Some fog developing in wedge
cooled airmass to the north but will leave fog out of grids for
now and re- evaluate for 4 PM update. After viewing some 12Z
data, latest thinking here is that any severe threat gets shunted
south into NC by 21Z as the front sags to near the VA/NC border.
More concern is the locally heavy downpours possible given the
combo of any TSTMS along and south of the bndry and the moisture
associated with the wave approaching from the SW. Again, stdy or
falling temps to btwn 55-60 north, highs in the 70s to nr 80
south but quickly falling after fropa.
Showers slowly settle south across NC this evening, with a brief
lull in showers once again overnight as we await upper trough
swinging east toward the region late tonight. This should add up
to scattered to numerous showers through the overnight with
plenty of low clouds and patchy fog developing. Lows in the 40s
out in the piedmont, low to mid 50s along the coastal plain.
.SHORT TERM /SUNDAY THROUGH MONDAY/...
A wet period ahead for the latter half of the weekend into at
least Monday night with rainfall amounts between 1-3 inches
through Monday, highest (2-3 inches) over the piedmont.
Broad upper level low currently over the Plains into the Mid-
Miss Valley will pivot SE into the deep south. The system then
takes on a neg tilt as it deepens Sunday, spawning a surface
low along the sern coast, which then is progged to get cut off
from the main flow and drift ivof the Gulf Stream wall into the
middle of next week.
Models show both spacial and timing differences with the
moisture fields but the jist of the forecast will be for waves
of Atlantic moisture to rotate inland resulting in periodic
showers (embedded tstrms especially over the sern coastal zones).
Locally hvy downpours psbl starting Sunday and Sunday night.
Meanwhile, high pressure to the NE results in a cool in-situ
wedge setting up over the piedmont, along with areas of fog.
Hydro wise, no flood headlines expected attm with numerous
breaks in between bouts of rain expected. Do expect some
healthy rises in local river by early next week, especially if
the heavy rainfall falls over the headwaters. QPF is mainly a
blend of the WPC preferred ECMWF/UKMET along with going forecast
continuity...resulting in 2-3" west of i-95 to 1-2" to the
east. Locally higher amounts are likely owing to developing
convection. Highs mainly in the 50s to near 60 Sunday...lower
to middle 50s inland...to mid 60s/nr 70 SE Monday.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Long term period will feature a trend towards drier and warmer
conditions. For Mon night/Tue, mid-level cutoff low and associated
sfc low continue to spin south of the area, allowing for moisture to
stream in off the Atlantic. Bumped up PoPs to likely for most of the
area Mon night and chance far NW, with models tending to push
cutoffs lows offshore too quickly. Slightly lwr PoPs for Tue, with
the best chance near the cst. Temps Tue slightly below
normal...highs in the upr 60s most spots. Warming trend then
commences for Wed as deep SWly flow develops across the eastern
seaboard, lasting through the end of the week with temps reaching
the 80s most areas Thu and Fri.
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --As of 18Z...A nearly stationary front is draped across southern
portions of the forecast area. This front should continue to slowly
drift south through the afternoon and evening hours. IFR ceilings,
currently impacting SBY/RIC/PHF, will continue to expand to the
south behind the boundary. Widespread IFR ceilings are expected
tonight and into tomorrow morning as the front moves south of the
region. Rain shower coverage is also expected to increase through
the afternoon and evening hours for much of the area with MVFR
visbilities possible in the heaviest showers. Winds turn to the NE
and will be gusty at times behind the front, occasionally gusting in
excess of 20 knots near coastal sites.
Outlook: Lower pressure will linger off the Carolina coast through
early next week. Unsettled conditions, widespread moderate to heavy
precipitation, and degraded aviation conditions are expected Sunday
through Tuesday. Drier conditions are expected on Wednesday and
-- End Changed Discussion --
Latest surface analysis depicts a cold front over the waters with a
weak area of low pressure over central Virginia. High pressure
resides off the Southeast coast. The wind north of the boundary has
become north to northeast, with a uptick in west to southwest winds
south of the boundary thanks to showers. Waves generally 1-2 feet
and seas 2-3 feet. Low pressure slides offshore mid morning as the
front pushes south of the waters early afternoon. A lack of good
cold air advection and gradient winds expected to keep north to
northeast winds at or below 15 knots, but a few gusts to around 20
knots are possible early afternoon in the lower Bay. Seas build to 3-
4 feet this afternoon as flow becomes northeast over the coastal
waters. High pressure builds in from the northwest tonight as low
pressure lifts along the Northeast coast. Winds increase to 10-20
knots tonight, with gusts of 20-25 knots expected in the bay, sound,
and coastal waters. Increasing northeast flow kicks seas up to 4-5
feet in the southern coastal waters tonight. Have raised SCA
headlines for the aforementioned waters. Seas build to 4-5 feet in
the northern waters Sunday morning. Gradient indicates SCA
conditions may subside Sunday afternoon in the upper Bay, but speeds
in the lower bay and lower James river increase to 15-25 knots.
Gusts in the southern coastal waters increase to 25 knots. Seas
build to 4-6 feet Sunday afternoon.
Onshore flow prevails thru Tuesday as low pressure develops over the
Southeast states then slowly slides offshore. As a result, an
extended period of SCA conditions is anticipated with speeds of 15-
25 knots and seas building upwards of 5-8 feet (or higher). Current
headlines run thru Sunday night (4th period). Improving marine
conditions thereafter as the surface low weakens and pushes off to
An extended period of onshore flow will result in increasing
tidal departures thru mid week. Tidal departures will reach +1
to 1.5 feet through Sunday night along the Atlantic coast and in
the lower Chesapeake Bay and James River. Northeast flow
increases Monday, with tidal departures of 1.5 to 2 feet. Minor
flooding is expected Monday night thru Tuesday during high tide.
Flow becomes offshore Wednesday.
-- Changed Discussion --MD...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ632-634-654-
Small Craft Advisory until 10 PM EDT Sunday for ANZ633.
Small Craft Advisory until 10 AM EDT Sunday for ANZ630-631.
Small Craft Advisory from 6 AM Sunday to 6 AM EDT Monday for
-- End Changed Discussion --