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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 250820
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
420 AM EDT SUN SEP 25 2016

.SYNOPSIS...
A backdoor cold front settles across the Carolinas tonight. High
pressure tracks across Southeast Canada Sunday and Monday. A
second and stronger cold front will cross the region Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Latest wx analysis features sfc cool front oriented just south
of the local area, extending from E NC back into far western VA
and SKY. The front will continue to nudge south today as 1024+mb
Sfc high pressure builds south from QC across New England through
tonight. Already noting sct-bkn post-frontal stratus deck across
the local area. Bufkit data continues to indicate slow improving
trend this morning through midday across the Northern Neck and
Eastern Shore counties as drier air drops south across the area.
This should allow for low clouds to get mixed out through the
morning along the coast Farther inland, weak/shallow isentropic
lift and onshore flow will result in overcast conditions for much
of the day along and west of I95. Highs today mainly in the low to
mid 70s. After some short-lived clearing early tonight, clouds re-
develop by midnight and through the overnight as the cool air
wedge is reinforced by renewed isentropic lift, underneath upper
ridge axis nudging in from the west. Sky cover ranges from
overcast with areas of light rain or drizzle well inland across
the piedmont to partly cloudy along the VA coast over to the MD
Eastern Shore. Look for chilly early morning lows from around 50
MD Eastern Shore...to mid 50s to around 60 central and south (mid
to upper 60s along the SE coast.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
-- Changed Discussion --
High pressure moves offshore of the New England coast on Monday
as the next front approaches from the west Monday afternoon.
Flattening of upper ridge will slow the advance of the front, and
serve to break down the cool air wedge slowly from NW to SE
Monday afternoon as the sfc high slides offshore. However, clouds
should hold firm across the piedmont through much of the day,
resulting in another mostly cloudy to overcast day Monday,
variably cloudy along the coast. Highs in the mid to upr 70s.

A strong cold front still on track to cross into the region late
Monday night ahead of a potent northern stream trough. Moisture
increases along the front with PW`s climbing above 1.75 inches
along with marginal instability per Showalter values trending
around 0 after 00z/Tue. Pcpn enters the region from the NW with
highest pops Monday evening, spreading east as best forcing nudges
from sw to ne Tuesday morning. Lows Mon night in the mid 60s.

Models show possible weak s/w energy riding east along the
boundary Tuesday. This will likely enhance pcpn and allow it to
linger a bit longer especially along coastal sections. Likely pops
linger across the Se zones through Tue. Kept thunder chcs in as
well, again with modest instability lingering. Highs Tuesday in
the low to mid 70s. QPF generally between 1/2 to 3/4 inch.
-- End Changed Discussion --

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Medium range guidance continues to indicate anomalous heights over
Canada through the period, as well as over the western Atlantic. A
deep/anomalous upper low drops over the eastern Great Lakes region
Wednesday, under the upper ridge. Ensemble and deterministic
guidance continues to struggle with a more progressive versus
blocked flow over the eastern CONUS. The result is a relatively low
confidence forecast, but have trended more toward GFS/GEFS
solutions.

Tuesdays cold front progged to stall along the coast in deep layer
southwesterly flow across the Mid-Atlantic. POPs taper off inland
Tuesday night, with chance POPs remaining across the southeast
forecast area. A series of upper level disturbances will lift along
the frontal boundary Wednesday. The combination of waves lifting
along the front and strong upward vertical motion will bring solid
chance POPs back to the southeast local area and slight chance to
low end chance inland. The upper low locates in the vicinity of the
Mid Atlantic region Thursday. While the best moisture pushes
offshore, will keep mention of slight chance to chance POPs Thursday
and Thursday night to account for uncertainty and potential light
rain. Thereafter, the upper low likely begins to slowly lift
northeastward as the upper ridge over the western Atlantic begins to
break down. With the upper low lifting away from the region Friday
and Saturday, large scale subsidence over the region will result in
a drying trend. Will keep chance POPs northeast Friday and retain
silent POPs on Saturday.

Slightly below normal temperatures forecast through the period, with
highs generally in the low to mid 70`s. Lows range from the low to
mid 50`s inland to mid 60`s along the coast.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
MVFR to low end VFR conditions across area terminals in post-
frontal stratus deck this morning. Noting some localized IFR to
LIFR (CIG/VIS) around KSBY, which should clear between 12-14z as
drier air filters in and scours out low clouds. VFR conditions at
SBY/RIC after 12z, with CIGS trending to VFR by mid morning at
remainder of terminals. Will likely see low clouds linger west of
KRIC as cool air wedge sets up. Will likely see a return to sub-
VFR cigs and perhaps some patchy drizzle/sprinkles inland late
Sunday night into Monday morning. Sub-VFR cigs possible at
KRIC/KPHF ahead of the front Monday afternoon. The next chance
for widespread precipitation will arrive Monday night into
Tuesday ahead of a strong cold front.

&&

.MARINE...
Cold front has located south of the waters early this morning, as
high pressure builds in from the north. North to northeast winds of
10 to 15 knots observed over the waters, with occasional gusts of 20
knots over the southern coastal waters. Have dropped SCA headlines
for the lower Chesapeake Bay. Seas remain elevated thanks to distant
tropical cyclone Karl and onshore flow, ranging from 3 to 5 feet.
SCA headlines remain in effect for the coastal waters. Based on the
latest guidance, have extended headlines through 1 pm this
afternoon. Thereafter, seas subside to 3 to 4 feet. This mornings
cold front lifts back to the north Monday as a cold front approaches
from the northwest. Flow becomes south to southeast with marginal
SCA conditions possible late Monday into Monday night. The front
pushes across the region Tuesday, likely stalling along the coast
Tuesday night and Wednesday. A weak pressure gradient progged over
the region, but a cooler and drier air mass may result in at least
marginal SCA conditions late Tuesday night. An upper level low is
progged to drop into the region Wednesday and Thursday, resulting in
unsettled weather conditions through the end of the week. Flow
generally out of the north.

&&

.HYDROLOGY...
-- Changed Discussion --
The Cashie River at Windsor remains in minor flood stage. The
river is forecast to slowly fall below flood stage by late this
afternoon. See FLSAKQ for details.
-- End Changed Discussion --

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 1 PM EDT this afternoon for ANZ650-
     652-654-656-658.

&&

$$
SYNOPSIS...MAM
NEAR TERM...MAM
SHORT TERM...MPR/MAM
LONG TERM...SAM
AVIATION...MAM
MARINE...SAM
HYDROLOGY...