Area Forecast Discussion
Issued by NWS Wakefield, VA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 291213
Area Forecast Discussion
National Weather Service Wakefield VA
813 AM EDT Thu Sep 29 2016
An upper level low slowly drops south from the Great
Lakes overnight through Friday. Meanwhile, high pressure builds
well north of the region and steers a moisture rich airmass into
the region tonight Through Thursday night.
.NEAR TERM /THROUGH TONIGHT/...
Latest GOES water vapor imagery centers the anomalous upper low
over southern Indiana. Upstream of the upper low, a plume of
anomalous moisture is visible stretching from central North
Carolina into southern Pennsylvania. At the surface, low pressure
has developed over North Carolina with a weak frontal boundary
extending northward into the forecast area. Strong high pressure
remains centered over southeast Canada. Diffluent flow aloft in
combination with anomalous moisture flux has resulted in ongoing
showers over the region. Locally heavy rainfall still possible.
Will keep categorical POPs in the forecast away from southeast
Virginia and northeast North Carolina.
The upper low continues to dig southward through the Ohio Valleys
today into tonight. Meanwhile, upper ridging builds north of the
Great Lakes across southeast Canada. This will focus increasing
moisture flux and enhanced convergence north of the frontal
boundary draped across central Virginia. However, a high
precipitable water airmass (at or above 1.5 inches) remains over
the local area today, resulting in a continued heavy rainfall
threat across the northern half of the area into tonight.
Afternoon convection will enhance the rain rates. Rainfall amounts
could reach 2-3 inches across the far northern tier counties
bordered by 1-2 inches from Emporia to the Maryland Eastern Shore.
Flash flood watch remains in effect through tonight.
Highs today generally in the mid 70`s inland to low 80`s
southeast. Mild tonight, with lows 8-12 degrees above normal in
the mid to upper 60`s.
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
Unsettled conditions continue into Friday as the upper low
lingers w of the area, but overall moisture transport should
diminish, with the heavy rain threat diminishing. The upper low
begins to fill and lift n by Saturday resulting in gradually
The sky remains mostly cloudy to overcast through the period. High
temperatures range from the upper 70s to low 80s, with lows
generally in the 60s.
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Anomalous upper low will make its way through the eastern Great
Lakes Sat night/Sunday and into New England by Monday where it
becomes more of an open wave/trough. This feature then moves off the
Northeast coast early next week. Based on the latest model
guidance...have slowed the timing of pcpn exiting the FA with chc
pops (30-50%) lingering across eastern areas Sat night...diminishing
to slight chc pops across eastern areas by Sun eve. Will maintain
dry wx Monday, then a lot of uncertainty develops by Monday night
into the middle of next week. There`s the potential for the remnants
of the upper low/trough to linger offshore (providing moist
onshore/easterly flow locally) and also uncertainty with regards to
the eventual track of TS Matthew. Will carry low end pops for now
Tue-Wed. Highs through the period mainly in the 70s. Lows in the
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Areal coverage of showers and thunderstorms has diminished early
this morning, limited to north and east of KRIC. MVFR conditions
linger at KSBY, but has improved to VFR at the remaining TAF
sites. Unsettled weather conditions continue today as a frontal
boundary remains over the region. Locally heavy rainfall will be
the main threat, reducing visibilities to MVFR or lower at times
through the day. Less coverage expected across southeast Virginia
and northeast North Carolina. Winds generally onshore, gusting to
20 to 25 knots at times KSBY. Overcast conditions also persist
through the day.
Outlook: Unsettled weather persists into Friday with
continued chances for showers and thunderstorms due to the
frontal boundary remaining nearby. Improving weather conditions
are expected this weekend.
Latest analysis shows surface low pressure from the SC piedmont to VA,
with strong/anomalous surface high pressure (1035 mb+) centered over
eastern Canada. The pattern today and tonight will feature this strong
high building over eastern Canada, ridging into New England and the northern
mid-Atlc region. A persistent/strong E/NE flow will prevail over northern
portions of the marine area and have upgraded far northern coastal waters to
a Gale Warning for today/tonight based on pattern with the surface high
building to near 1040 mb). Elsewhere, have added several more zones to SCA
headlines as winds gradually taper off to the 10-15 KT in NC and for the
upper James. NC coastal waters still expected to have seas build to 5 ft
so only zones that will not have any headlines will be the upper James
and the sound.
Winds diminish from S to N tonight and for all areas on Fri as the surface
low lifts N and pressure gradient weakens. Coastal seas will diminish
but still remain elevated at 4-6 ft into Fri night and possibly Sat due to
residual swell. SSE flow expected Sat leading to sub-SCA conditions elsewhere
with 1-2 ft waves over the Bay.
-- Changed Discussion --The synoptic pattern with strong High pressure centered over
eastern Canada with a slow moving boundary/sfc low pressure inland
over the Carolinas/Mid-Atlantic will continue to bring persistent
ENE flow to the area today/Fri. Departures avg 1.0 to 1.5 feet for
the most part.
Have expanded Coastal Flood Advisories to now include all zones in
adjacent to the Bay and the James/York/Rappahannock River...with
ocean side of the eastern shore also included. Many areas in the
lower Bay to fall a little shy of criteria with the high tide this
morning, but should see departures rise a bit more by this
aftn/tonight/early Fri and have the advisory to cover the 2nd high
tide overnight/early Fri. Will likely need to extend these
advisories into Fri night and possibly Sat as offshore seas
remain elevated and water is expected to struggle to exit the bay
for several days. Chance for moderate- severe flooding is low,
best chance would be across ocean side of the Accomack VA and
Worcester MD by Fri.
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-- Changed Discussion --MD...Coastal Flood Advisory until 11 PM EDT this evening for MDZ024-
Flash Flood Watch through late tonight for MDZ021>024.
Coastal Flood Advisory from noon today to 8 AM EDT Friday for
VA...Flash Flood Watch through this evening for VAZ048-060>062-064-
Coastal Flood Advisory until 4 AM EDT Friday for VAZ075>078-
Coastal Flood Advisory until 1 AM EDT Friday for VAZ095>097-
Coastal Flood Advisory until 11 PM EDT this evening for VAZ099-
Flash Flood Watch through late tonight for VAZ075>078-083-085-
MARINE...Small Craft Advisory until 1 AM EDT Saturday for ANZ652-654.
Small Craft Advisory until 6 PM EDT Friday for ANZ656-658.
Gale Warning until 4 AM EDT Friday for ANZ650.
Small Craft Advisory until 7 PM EDT this evening for ANZ632-
Small Craft Advisory until 1 AM EDT Friday for ANZ634-635.
Small Craft Advisory until 7 AM EDT Friday for ANZ630-631.
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