Area Forecast Discussion
Issued by NWS Wakefield, VA

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194
FXUS61 KAKQ 230836
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
436 AM EDT Wed May 23 2018

.SYNOPSIS...
A cold front will cross the region later today through tonight.
Dry weather is expected Thursday and Friday under the influence
of high pressure. Low pressure over the Gulf of Mexico will
gradually bring a return of moisture for the upcoming weekend,
especially by Sunday and Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM EDT Wednesday...

Latest analysis indicates sfc low pressure over the St Lawrence
Valley with a cold front extending SW into the OH Valley. Aloft,
flow is beginning to increase from the WNW as an upper low is
situated over Atlantic Canada with shortwave energy currently
pushing ESE from the Great Lakes around the base of this broad
upper trough. A few spotty showers linger over the region early
this morning, but coverage is now about 20% over SE VA and less
elsewhere. An area of tstms is ongoing upstream over WV with
the shortwave aloft, but IR satellite imagery shows warming
cloud tops and high res models suggest this activity diminishes
est of the Mtns as it approaches the AKQ CWA. Thus, expect
little if any shower activity over the local area this morning
under partly cloudy skies on avg.

The surface front will gradually push through the area this
aftn, and south of the region by the evening. As a result much
of the southern half of the local area will remain south of the
front through the mid/late afternoon. This should allow for
thunderstorms to once again develop along the front. Winds
aloft are only marginal for severe storms in the afternoon with
only about 20-30 kt of shear during the afternoon. Could not
rule out some line segments with gusty winds but organized
severe unlikely and overall it appears like less of a threat
compared to Tue. High res models (the last few runs of the HRRR
in particular) have also backed off quite a bit on the coverage
of aftn convection. With a WNW to NW flow aloft and shortwave
energy aloft, did not go quite as dry as some of this new
guidance, though did lower the PoPs somewhat, mainly on 20-30%
from about metro RIC northward and for most of the eastern
shore. Maintained a period of likely PoPs in NE NC where
greatest instability Will persist the longest. Hampton Roads
area may see the winds shift to the NNE by around 18Z or so and
this would tend to push the highest coverage of storms inland
and to the south near the VA/NC border. Will continue to
highlight the marginal risk per latest SPC outlook, though
believe the best chance for any strong storms will reside in NE
NC and south central/interior SE VA along the NC border. Highs
today will be mainly into the mid 80s, though temperatures look
to fall near the coast later in the aftn as flow turns to the
N/NE. Will maintain some chance PoPs over the south this
evening, otherwise becoming mostly clear overnight as drier air
filters in from the NNW. Lows tonight mainly 60-65 F, though
the far NW could drop into the upper 50s and SE zones along the
coast will avg in the mid/upper 60s.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 230 AM EDT Wednesday...

A needed respite from all of the recent heavy rain will prevail
as ~1025 mb sfc high pressure is progged to be centered over the
lower Great Lakes by 12Z/Thu, ridging SE into the local area by
Thu aftn. Dew pts dropping into the 50-55 F range for most of
the region will make for comfortable/pleasant conditions. Highs
Thu stay slightly above avg inland with lower-mid 80s, while
areas near the coast will be cooler due to onshore low level NE
flow (highs there in the upper 70s to around 80 F). Mostly clear
and relatively cool Thu night with lows mainly in the mid 50s to
around 60 F. This is close to avg but noteworthy as most of the
CWA except on the eastern shore and far northern portions have
not had a low below 60 F in over 10 days. Mostly sunny and warm
and continued dry with dew pts Fri in the 50s and highs ranging
from the mid 80s inland to the upper 70s/lower 80s near the
coast. Mostly clear and trending a bit warmer Fri night with
lows primarily in the 60s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 320 PM EDT Monday...

The upper ridge will be gradually weakening on Sat, but it will
still be mainly dry with just a 20-30% PoP for widely scattered
aftn/evening storms. Highs in the mid/upper 80s. The upper
ridge will then erode more significantly through the holiday
weekend with a gradual increase in moisture as it appears that
another area of low pressure will form in the northeastern Gulf
of Mexico by Sunday and push more tropical moisture northward
into the region. This could allow for more showers and tropical
downpours for Sunday and again on Monday. The big model
difference in the models is the handling of a backdoor cold
front between the 12z GFS and ECMWF with the GFS pushing the
front south through the area and the ECMWF keeping the boundary
well north of the area. In either case, the chance for showers
and some possibly heavy rainfall exist for the second half of
the Holiday weekend. If the GFS is right with the front Monday
could be a damp cool rainy day while the ECMWF would lead to
more periodic showers with some breaks. At this time of year,
seems more likely the for the front to hang north of the area.
So have kept the temperatures up more in the low to mid 80s for
Sunday and Monday.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
As of 215 AM EDT Wednesday...

Mainly VFR early this morning despite some lingering
isolated/scattered showers passing across central/southern VA.
Some patchy ground fog will be possible through 12Z, but do not
expect this to affect any terminals so VFR conditions will
generally be the rule. Later today, expect showers and tstms to
redevelop, mainly over southern VA and NE NC (though an isolated
storm will be possible at KRIC/KSBY through about 22Z). KECg has
the greatest chance and TAF there continues with a period of
prevailing SHRA in the mid/late aftn with VCSH at KORF/KPHF.
Some brief heavy downpours and gusty winds will be possible.
Otherwise, becoming mostly clear from N to S from 00-06Z with NE
winds.

Quiet conditions/no flight restrictions Thu/Fri with high
pressure in place and mostly sunny/clear skies. Increasing
moisture returns for the upcoming weekend with scattered
showers/tstms possible by Sat aftn/evening. The showers and
tstms overall will become more numerous on Sunday and beyond
with potential flight restrictions.

&&

.MARINE...
As of 355 AM EDT Wednesday...

Latest analysis reveals weak quasi-stationary boundary just
north of the waters over the upper eastern shore. Obs and buoy
reports indicate S-SW winds have nudged up slightly as
anticipated over the southern coastal waters, lower Chesapeake
Bay and the eastern VA rivers, in association w/tightening
pressure gradient between surface ridge oriented just to the
south and surface low and associated cool front to the west over
the OH/TN valleys. Front drops across the region later this
morning through the early evening, with the flow to veer around
to the W-NW post-frontal. Only a modest push of cooler/drier air
behind the front, and only a short-lived convective surge is
expected, likely best handled by SMW/MWS as needed. Once the
front clears the area, high pressure will settle over the waters
for Thursday into Friday night. This will provide light winds
and benign seas through Friday night.

On Saturday, the flow will return to the south as the high
pressure system slides off the SE US coast. Expect some increase
in winds to 10 - 15 KT for later in the day Saturday and
Saturday night. Upper ridge slowly breaks down Saturday night
through the remainder of the holiday weekend, with model
guidance intent on developing yet another low pressure area near
the Yucatan, tracking into the east-central Gulf coast by
Sunday morning. GFS remains the farthest east of the medium
range models, with the ECMWF/Canadian off to the west with the
sfc low. The GEFS is likely a good compromise for now. Either
way, expect S winds to increase slightly on Sunday and Sunday
night in response to this wave of low pressure, with wind wave
potentially nudging seas upward to 3-4 ft central and southern
waters.

&&

.HYDROLOGY...
As of 435 AM EDT Wednesday...

Flood warning continues for the Appomattox River basin. Mattoax
looks to have crested at 24.8 ft early this morning, just below
moderate flood threshold (25 ft). The river level will slowly
drop through tonight, dropping below flood stage Wednesday
evening. Additional flood warnings continue for portions of the
Chickahominy and Mattaponi rivers. See FLWAKQ or FLSAKQ for more
details.

&&

.CLIMATE...
As of 215 AM EDT Wednesday...

* RIC monthly rainfall total through 5/22 is 10.22" which now
  ranks as the wettest May on record. (breaking the old record
  of 9.79" in 2016). (Precipitation records date back to 1880).

* SBY monthly rainfall total through 5/22 is 8.63" which already
  ranks as 3rd wettest May on record (wettest is 10.38" in
  1948). (Precipitation records date back to 1906).

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.

&&

$$
SYNOPSIS...LKB
NEAR TERM...LKB
SHORT TERM...LKB
LONG TERM...BMS
AVIATION...LKB
MARINE...MAM
HYDROLOGY...
CLIMATE...



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