Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 290151
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
951 PM EDT SAT MAY 28 2016

.SYNOPSIS...
High pressure will push farther off the Mid Atlantic coast tonight.
Tropical storm Bonnie will approach the South Carolina coast
overnight, and will linger and weaken along the coastal Carolinas
through the holiday weekend.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
The current surface analysis continues to show high pressure well
off the VA/NC coast, and ridging back into the Mid-Atlantic
region. TS Bonnie (a minimal 35kt storm) is about 100mi se of
Charleston, SC. Aloft, strong upper level ridge centered offshore
is still ridging back west into VA.

Another mild evening prevails across the local area, with the
upper ridge holding strong and leading to mostly clear conditions
over the CWA. Temperatures across the area this evening are
generally in the upper 60s to mid 70s. A large-scale zone of
subsidence continues to control the sensible weather locally, with
dry conditions expected to continue through 06z, and only a slight
chc PoP across the far srn counties from 06-09z.

Models show the upper ridge buckling e-ne late tonight/early Sun,
with TS Bonnie, approaching the SC coast. PW values AOA 2"
expected to push into ne NC after 09z, and expand N into srn VA
by 12z. The latest high-res guidance and the 28/18z NAM/GFS
suggest PoPs begin to increase across the Srn tier VA counties and
ne NC between 09-12z. Warm and becoming more humid tonight with
increasing moisture and clouds...lows range from the low-mid 60s
north/central zones to upper 60s/near 70 F south.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
Tropical Storm Bonnie forecast to slow down and linger along the
SC coast on Sunday, before lifting ne and lingering along the
Carolina coast through Mon. More uncertainty in track develops
thereafter. Refer to discussions issued by the National Hurricane
Center for the official track and forecast.

An unsettled period will dominate the short term, with a warm and
quite humid airmass in place. Expect a chance of showers in the
morning, expanding NNW and becoming more widespread by late
morning/aftn. Models still suggest greatest lift and instability
to be inland from the coast along an inverted trough by aftn and
will continue forecast with highest POPS/80% to be along/west of
i-95 by aftn. Accordingly expect to see numerous periods of rain,
falling moderate to heavy at times. Highs on Sun generally in the
upper 70s wrn 2/3 to to lwr 80s acrs the eastern 1/3.

The low is slow to weaken acrs the Carolinas and get slowly
transported NE Sun night/Mon as upper level trough from the W
tries to push through. The increasing support from the upper
levels may lead to the most widespread precip for the entire event
Sun night. Potentially very wet conds, with occasional moderate
to heavy showers are expected in the modified tropical airmass.
Will have likely to categorical POPS Sun night into Mon morning,
with likely POPS lingering into Monday aftn/evening along the
coast. Warm and humid with early morning lows 65-70 F Monday
morning and highs in the upper 70s/lower 80s on Memorial Day.

Disagreement amongst deterministic models by Tuesday, with the
12z/Operational GFS wanting to dry western portions of the area out
under developing weak sfc ridging, The ECMWF is slower to clear
out the sfc low altogether, ejecting it quicker to the NE.
Will continue to follow a WPC blended solution, weighted towards
the more consistent respective ensemble means. This translates to
a decreasing rain chance for Tuesday, but still mostly cloudy with
POPS to around 50% SE to 20-30% NW. Highs Tuesday in the low 80s
inland, upper 70s to low 80s along the coast.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
TD2 is progged to linger in the vicinity of the NC coast Wednesday
and Thursday. There was some agreement in the earlier model runs,
but the 28/12z ECWMF lifts the low center farther north off the VA
coast Wednesday and Thursday. Main impacts from that solution would
be better chance for showers/thunderstorms east of Interstate 95,
cooler temperatures, and north to northeast winds of 10 to 15 mph.
Have stuck with overall model consensus with keeping the low in the
vicinity of the NC coast, but have bumped POPS Weds and Thurs up
slightly east of Interstate 95. For Wednesday and Thursday, a warm
and humid air mass will be in place over the local area with
vorticity maxima associated with the mid level features of TD2
providing modest forcing for ascent. Expect generally scattered
showers and diurnal thunderstorms. Subsidence between TD2 and an
upstream cold front expected to limit showers/thunderstorms over the
Piedmont Weds, with better chances Thursday as a warm front lifts
northward over the central Appalachians. Highs in the low to mid
80`s and lows in the 60`s. Sky averages Partly Cloudy.

Upstream trough and associated cold front reach the Central
Appalachians Thursday night, either kicking the low off the coast or
weakening the system over the region. Best chance for dry conditions
appears to be Thursday night, before POPs ramp back up Friday as the
front reaches the local area. Trough progged to deepen over the Ohio
Valley Friday and Friday night, with the front slowing as it reaches
the coast. Will keep 30-40% POPs into the weekend as unsettled
conditions linger. Highs in the low to mid 80s Friday before cooling
into the upper 70s to around 80. Lows in the 60`s. Sky averages
partly cloudy to mostly cloudy.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
VFR conditions prevailed at the TAF sites early Saturday evening. A
high pressure ridge from the western Atlantic to the Mid Atlantic
States was losing its grip over the area. With a southeast flow in
place...this will allow moisture to surge into the area overnight
and Sunday. Showers are expected to develop over the area on Sunday.

The biggest challenge to the 00Z issuance was handling the low level
moisture that increases overnight. Looking at NAM BUFR soundings and
the synoptic situation...expect that fog will be the focus at RIC
and SBY while deeper moisture will bring stratus to the other three
locations. LAVMOS fits this plan the best and used it to construct
the TAFs. Have the lower conditions develop between 08 and 10Z with
one mile vsby at RIC and SBY...IFR stratus at ORF and PHF and MVFR
stratus at ECG.

Conditions improve to VFR or MVFR by late morning with showers
develoing at ECG at 15Z...ORF and PHF at 17Z and RIC at 21Z.
Held off mention of pcpn at SBY. Spotty pcpn could begin before
these times but expect these to be the times that more general
showers begin.

OUTLOOK...Tropical storm Bonnie is not expected to have a direct
impact on the area but a moist southeast flow will continue. Periods
of showers are forecast through Monday night with a chance for
showers continuing the rest of the week...especially near the coast.
Mainly MVFR conditions are indicated with brief IFR possible in
heavier pcpn.

&&

.MARINE...
Latest surface analysis centers TD2 roughly 150 miles southeast of
Charleston SC. High pressure remains over the western Atlantic,
extending over the local waters. Obs indicate south to southeast
winds of 10-15 kt over the waters. Waves 1-2 ft and seas 2 to 3 ft.
TD2 is expected to strengthen slightly over the Gulf Stream as it
lifts northwest toward the SC coast. Impacts for the local waters
remain limited to showers and thunderstorms Sunday and Monday.
Otherwise, flow will generally be out of the southeast at or below
15 kt. GFS/ECMWF lifts a wave of low pressure along a weak coastal
boundary off the Mid-Atlantic coast Monday with light (possibly
offshore) flow behind the wave. Seas may reach 5 ft in the northern
coastal zones late Monday into Monday evening. The main surface low
remains in the vicinity of the North Carolina coast, with the ECMWF
now lifting the center of the low off the Virginia coast by
Wednesday. Flow expected to be onshore at or below 15 kt, but if the
ECMWF verifies SCA conditions will be possible Wednesday and
Thursday. Gusts to 25 kt and high seas. Forecast reflects
persistence and general model consensus. A cold front is forecast to
reach the waters late in the week into next weekend. Sub-SCA
conditions expected.

For more information on TD2, please refer to NHC.

&&

.CLIMATE...
The monthly rainfall total to date for May at Richmond is 8.41".
May 2016 is currently the 6th wettest month of May on record at
Richmond. There is a good chance for additional rain Sun/Mon with
the potential to end as the wettest May on record.

Top 6 wettest months of May at Richmond

    1. 9.13"  1889
    2. 8.98"  1873
    3. 8.87"  1972
    4. 8.67"  1886
    5. 8.59"  2003
    6. 8.41"  2016 (to date)

&&

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

&&

$$
SYNOPSIS...LKB
NEAR TERM...AJZ/LKB
SHORT TERM...LKB/MAM
LONG TERM...SAM
AVIATION...LSA
MARINE...SAM
CLIMATE...AKQ


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