Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 190143
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
943 PM EDT Thu Apr 18 2019

.SYNOPSIS...
A warm front will be well north of the area tonight. A strong
cold front arrives late Friday. An upper level low will be slow
to lift northeast over the weekend.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 400 PM EDT Thursday...

Low pressure is moving across the MS/AL this evening and a high
pressure is located off the Mid-Atlantic coast. The tightening
pressure gradient is producing decent southerly winds. Overnight
winds will remain S 10-15 kt with gust near 20 kt, and up to 25
kt near the coast. Low clouds will move in after 06z tonight
and thicken overnight. A few showers will develop and move
north along and west of I95.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
As of 420 PM EDT Thursday...

Upper trough sharpens significantly W of the mountains Fri and
eventually closes off as it pushes into the TN valley by Fri
evening. The attendant sfc low pressure areas lift ENE into SE
OH and near the TN/NC border, with the trailing cold front
entering the mountains Fri evening. That front will be slow to
push E to the coast Fri night, due to deep layered S flow sfc-
aloft. Models continue to hone in on a narrow axis of deep
layered moisture. This influx of deep layer gulf moisture will
once again support PW values of 1.5-1.7" (or +2 to +3 Std Dev)
over the local area late Fri into Fri night, and cause a spike
in sfc dew points. Expect periods of showers/tstms with the
potential for some locally heavy rainfall late Fri aftn into
Fri night. QPF of 1-1.5" with the potential for locally higher
totals. No Flood Watches have been issued at this time, but will
need to possibly issue one for some areas, esply along and east
of I95. Also, SPC has a slight risk for NE portions of the FA
Fri/Fri night, and an enhanced risk over cntrl/srn/se portions
of the FA. Additionally, most of the FA is in a slight risk for
excessive rainfall. Highs on Fri will range thru the 70s, with
upper 60s right at the immediate coast.

Regarding the convective threat, there remains some question as
to how much instability can be generated given the forecasted
cloud coverage, but that may be overtaken to some degree by the
favorable dynamics the system will have. Strong forcing for
ascent will exist with wind fields aloft easily able to support
damaging winds in any bowing line segments. Additionally,
potential slight backing of near sfc/low level winds acrs
SE VA-NE NC will need to be watched very closely Fri
aftn/evening, esply if any clearing can be realized.

Aside from anticipated possible hydro issues, timing for any
strong/svr storms appear to be late aftn/evening (4p-8p) west
of I95, between 8p-midnight along and east of I95, and 12a-3a
along the immediate coast. Rainfall/convective wind potential
will continue to be highlighted in the HWO, and will continue to
mention for gusts even outside of convection, due to tightening
pressure gradient Fri morning into Fri aftn. Appears our area
may approach wind advisory criteria ahead of storms Fri
morning/aftn along the coast, and will need to monitor that in
future packages.

The cold front pushes offshore late Fri night/early Sat morning.
Going mainly dry the remainder of Sat into Sat night acrs the
region, as front/pcpn will be pushing out to sea and upper low
and associated moisture remains WNW of CWA. So, generally partly
sunny on Sat with highs ranging fm the mid 60s to lower 70s.

Upper low/associated moisture will then move into and acrs the
area late Sat night thru Sun. Partly cloudy to cloudy with a
slgt chc to sml chc of showers late Sat night and Sun. Lows Sat
night in the upper 40s to lower 50s. Highs on Sun in the 60s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 400 PM EDT Thursday...

Upper-level low will be over the area during the day on Sunday
and into early Monday morning. 20- 40 Pops were put in, with
the greatest chance in the northern parts of the area. There is
a chance of thunder as the cold pool core moves over the area,
but no thunder was added to the forecast at this time. As the
upper-level low moves off to the NE, a SW flow will begin ahead
of a front that will move south out of the Great Lakes. With
the upper-level flow out of the west early next week, the front
will stall and a chance of showers will be around for Tue-Thu.
However, models are in disagreements on were the boundary will
stall, therefore only 20-30 Pops were put in through Friday.

Temperatures will be cool on Sunday with the upper-level low over
the area. Highs will be in the 60s and lows in the 40s inland
to mid 50s along the coast and eastern shore. 80s will return
by Tuesday with a SW wind. Temps will remain mild for the
remainder of the week as a front stalls across the area, with
highs ranging from the 60s to near 70.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
As of 830 PM EDT Thursday...

VFR conditions will last through 06z Friday before moisture
begins to advect into the area as a low pressure systems
approaches. BKN CIGs between 020 and 030 ft will move in between
06z and 09z from S to N. Scattered showers and an isolated
thunderstorm will move across the western part of the area,
mainly affecting KRIC, during the mid morning. Vis may be
reduced to IFR during a heavier shower/Tstorm. Low CIGs may
become more SCT during the day on Friday ahead of the main line
of thunderstorms, therefore most site should return to VFR
during the early afternoon. KSBY and KRIC may return to MVFR
before the end of the 00 TAF period.

Winds this evening have already increased out of the S between
10 and 15 kt with gust near 20 kt. Winds will decrease slight
overnight before increasing during the day. Winds on Friday will
be S around 20 kt with gust exceeding 30 kt, especially at
KORF/KPHF/KSBY.

Flight restriction will likely return as the line of the heavy
thunderstorms moved through the area after 00z Sat. After, the
upper-level trough will move over the mid-Atlantic and bring
showers and possible more flight restrictions.

&&

.MARINE...
As of 400 PM EDT Thursday...

Will start the SCA headlines with this package (except the rivers)
as SCA level winds will likely develop within the next 12 hrs.
However, models are showing that the Ches Bay winds may actually
slacken a bit for a few hrs after midnight for a few hrs before
increasing again towards sunrise.

Tightening pres gradient Fri results in slowly increasing south
winds throughout the day, but remain below gale force. Will cap
gusts at 30 kts on Fri for now. Tricky forecast Fri nite with both
synoptic and convective gusts expected. Models show a quick increase
in synoptic winds Fri eve (tapping some of the low lvl jet). This
ahead of a fairly strong line of convective progged to move across
the waters through the night. Wind probs show fairly high confidence
for 35+ kts of wind across the srn cstl waters and Currituck Sound,
thus a gale warning will replace the current gale watch where gusts
up to 40 kts possible. Props a bit lower farther north and west, so
have elected to hoist a gale watch for both the nrn coastal waters
and the Ches bay Fri night for gusts to 35 kts. Data also indicates
this to no more than a 4-6 hr prd of gales with winds diminishing
behind the line of convection.

Slowly improving conditions are expected over the weekend as an
upper level low is slow to exit to the NE.

&&

.TIDES/COASTAL FLOODING...
As of 400 PM EDT Thursday...

Latest guid not as bullish with the threast for mdt flooding than
previous data suggested, so no coastal flood watches at this time.
However, Bishops Head is forecasted to just reach minor flooding
with tonights high tide cycle and go above minor flooding with
Friday nights high tide. Thus, will issue a coastal flood statement
for BH tonite as rising tidal departures to 1 to 1.5 FT above MLLW.
Otw, several other stages will likely reach or exceed action stages
due to the strong srly winds.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory from 8 AM to 8 PM EDT Friday for ANZ633-
     635>638.
     Gale Watch from Friday evening through late Friday night for
     ANZ630>632-634.
     Small Craft Advisory until 8 PM EDT Friday for ANZ630>632-634-
     650-652-654-656-658.
     Gale Warning from 8 PM Friday to 4 AM EDT Saturday for ANZ633.
     Gale Warning from 8 PM Friday to 5 AM EDT Saturday for ANZ654-
     656-658.
     Gale Watch from Friday evening through late Friday night for
     ANZ650-652.

&&

$$
SYNOPSIS...TMG
NEAR TERM...TMG/CP
SHORT TERM...ALB/TMG
LONG TERM...CP
AVIATION...TMG/CP
MARINE...MPR
TIDES/COASTAL FLOODING...


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