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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 242031
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
431 PM EDT Tue Apr 24 2018

.SYNOPSIS...
Low pressure tracks the local area today through tonight...then
will be slow to move away from the coast Wednesday. Weak high
pressure returns by Thursday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 400 PM EDT Tuesday...

The main rain band is along the I-64 corridor at the moment and
is lifting northward with some scattered showers continuing to
develop over the Carolinas. These showers will continue to move
northward ahead of the surface low and warm front that will be
moving into the region tonight. The surface low is currently
near CLT and will continue to slide NE tonight arriving in Srn
VA by Wed morning. At the same time the warm front will continue
to push north along the coast tonight and should lift across the
Delmarva by Wed morning as well. With the main band of pcpn
already moving north, will see the chances for rain gradually
diminish tonight with temperatures holding near steady or
perhaps even rising a few degrees by Wed morning in the vicinity
of the warm front. For overnight low did lean toward the warmer
guidance thinking clouds will keep temperatures from dropping
too much.

On Wednesday, the initial surface low and warm front will lift
north of the area, but the upper level low will settle over the
area. This will allow for some cooler air aloft to settle over
the area with more showers developing in the afternoon. Could
potentially see some thunder if there is enough heating ahead of
the upper lows arrival. Right now, it looks like it will stay a
little too cloudy, but it can`t be ruled out especially east of
I-95. Guidance is pretty spread on temps tomorrow with the MET
much cooler than the MAV. Have generally gone in between with
temps in the mid 60s to the lower 70s.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 400 PM EDT Tuesday...

The upper low will exit the region early Wed night taking any
chance of rain with it. Show a gradual decrease in pops from SW
to NE during the evening. Behind this system the newer model
runs are not as aggressive in pushing the drier air with the
next sfc high into the region. This is more like what the GFS
had been depicting in previous runs. As a result have kept the
clouds a little longer and also raised overnight lows by a few
degrees getting closer to guidance in the low to mid 50s.

With the front not pushing as far south on Wed night into
Thursday and stalling more along the NC/VA border expect to see
a little less sunshine especially across srn VA/Nrn NC. The next
surface wave is now progged to arrive sooner on Thursday night.
So expect to see clouds on the increase during the afternoon and
could even see some light pcpn in the Piedmont counties around
sunset. At this point held off on adding late afternoon pcpn but
will need to see how quick the overrunning develops. For highs
on Thursday did have readings back into the low to mid 70s with
the best warming in the eastern portion of the CWA.

With the next wave arriving sooner have sped up pops on Thursday
night and Friday morning. The best chance for rain looks to be
in the Piedmont counties so have increased pops to 50 for now
and they may need to be increased. Once the surface low lifts
through the area by Friday morning should see the chances for
rain diminish by later morning/early afternoon. For
temperatures, kept readings a little warmer Thurs night with the
sw flow and clouds. For highs on Friday did keep highs in the
low to mid 70s as the return of the sun in the afternoon should
allow for temperatures to warm especially ahead of the cold
front for Saturday.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 400 PM EDT Tuesday...

GFS/ECMWF differ early in this period with the GFS showing the last
in a series of s/w trofs rounding the base of the long wave trof
late Fri night with it moving off the sern coast Sat ahead of a weak
frontal passage. Meanwhile, the ECMWF is drier with little if any
support for pcpn even with the frontal passage Sat. A model blend
results in low chc shwrs across the sern zones late Fri night and
Sat keeping the rest of the local area dry for now. Lows Fri nite
upr 40s-mid 50s. Highs Sat upr 60s-mid 70s, cooler at the beaches.

After that, some delightful spring weather on tap early next week as
high pressure builds se from the Gt lakes region Sun to a position
over the local area Mon then off the Mid Atlantic coast Tue. Cool to
start then a warming trend.  Highs Sun generally in the 60s. Lows in
the 40s to near 50 se. Highs Mon upr 60s-lwr 70s. Lows upr 40s-lwr
50s. Highs Tue 75-80.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
As of 145 PM EDT Tuesday...

East to southeasterly flow continues across the region this
afternoon ahead of the the developing low over South Carolina.
The ceilings have been slowly lowering as the rain band has
moved northward, but along the coast the ceilings have remained
in mvfr range around 2k - 3k ft. Farther inland however the
ceilings have dropped lower to ifr range, but they have remained
just to the sw of RIC. Guidance still suggest that as the rain
moves northward and the easterly flow continues that ceilings
should drop to ifr levels across the region. So as the low
approaches the area this afternoon and evening will forecast
that the ceilings do drop to ifr levels for at least a period of
time.

The warm front lifts northward as the low tracks into the
area this evening. The warm front should slowly move north along
the coast and all taf sites except RIC should move into the warm
sector. This usually will bring ceilings up, but the guidance is
slow to do that waiting until Wed after 12z to show improvement.
So have gone against guidance a little bit to improve ceilings
after 6z in the south and slowly improve conditions heading
north by around 12z. But again confidence is not very high in
that part of the forecast.

By Wednesday, the upper level low will move over the area which
should allow the ceilings to rise to at least mvfr levels if not
vfr with some scattered showers in the area.

Outlook...Wed night - Sunday...
The upper low departs Wed night as high pressure noses into the
area. The system will impact the region on Thursday night with
some showers and mvfr conditions. A second cold front swings
across the the region on Saturday with vfr conditions returning
on Sunday as high pressure builds into the area.

&&

.MARINE...
As of 300 PM EDT Tuesday...

Broad low pressure is situated over Upstate SC this afternoon.
Meanwhile, high pressure is centered well off the New England coast.
The resultant pressure gradient between these two features is causing
east to southeast winds of 15-25 kt with gust up to 30 kt that will
last into this evening. Seas will continue to build to 6-10 ft by
this evening; waves reaching 3-5 ft, except up to 6 ft at the mouth
of the Bay. Winds/waves/seas diminish/subside overnight into
Wednesday morning as the pressure gradient relaxes. SCAs remain in
effect for all waters through late evening, with SCAs for the Rivers
coming down at 11 pm Tue, and for the Bay/Sound at 1 am Wed. SCAs
have been extended into Thursday morning for the southern coastal
waters and Thursday afternoon for the northern coastal waters due to
seas remaining elevated. A High Surf Advisory for OBX Currituck will
also remain in effect until 5 am Wednesday for nearshore waves of 8-
10 feet.

Broad low pressure lifts north through the region during Wednesday
with SSW winds 5-15kt becoming NW in the wake of the low Wed night
into Thurs morning. After a brief lull midweek the next low pressure
system then impacts the region Friday/Saturday.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...High Surf Advisory until 5 AM EDT Wednesday for NCZ102.
VA...None.
MARINE...Small Craft Advisory until 11 PM EDT this evening for
     ANZ635>638.
     Small Craft Advisory until noon EDT Wednesday for ANZ634.
     Small Craft Advisory until 1 AM EDT Wednesday for ANZ630>633.
     Small Craft Advisory until 6 PM EDT Thursday for ANZ650-652-
     654.
     Small Craft Advisory until 10 AM EDT Thursday for ANZ656-658.

&&

$$
SYNOPSIS...ALB/MAM
NEAR TERM...ESS
SHORT TERM...ESS
LONG TERM...MPR
AVIATION...ESS
MARINE...JDM