Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 291807
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
207 PM EDT SUN MAY 29 2016

.SYNOPSIS...
Tropical Depression Bonnie will linger along the South Carolina
coast today, and will slowly track northeast along the Coastal
Carolinas through the middle of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Late morning analysis indicating TD Bonnie now located just inland
of Charleston SC (was downgraded from a tropical storm at 8 am). Please
continue to refer to discussions/forecasts issued by the National
Hurricane Center for the track on TD Bonnie. Upper level ridge
remains in place well off the mid Atlantic coast, and has been
slowing/limiting the coverage of precip acrs the NE 1/2 of the CWA
thus far this morning. However, with the warm/humid, modified
tropical airmass now rapidly overspreading the region in tandem
with increasing forcing, scattered to numerous showers have now
pushed north from ne NC and into southern VA. Models in good
agreement with an inverted sfc trough is developing and will
continue to strengthen acrs the I-95 corridor this aftn.

WV/IR imagery and radar trends support Likely to Categorical POPS
this aftn for most areas, though it will take a few more hrs
(until after 18-19Z acrs NE zones). Models suggest the highest
POPS/categorical will tend to shift inland from the coast after
18Z, with high-end chc POPS persisting along the SE coast. Not
much in the way of lightning activity so far, but will probably
see at least scattered TSTMS later in the aftn and through the
evening. Main issue today will be locally heavy rain, noting 12Z
sounding from MHX at 2.18 PWAT (1.68 at WAL per 12Z). Steering
flow today looks to be S to SSE and will need to monitor
showers/storms closely for training due to high precip rates and
potential localized flooding. Temps not expected to rise much if
at all from current readings in the upper 70s/lower 80s (and will
avg in the mid 70s in areas of heavier rain).

TD Bonnie or it`s remnant low is very slow to weaken acrs SC and
get slowly transported NE tonight as broad, Upper level troughing
pushes in from the SW. Bulk of widespread and heavy precip may
weaken for awhile in the evening or shift to far western portions
of the CWA, but expect to see it regenerate overnight into Mon
morning as increasing lift returns after midnight which will be
further enhanced by upper divergence provided by RRQ of upper jet.
Given the setup, there`s no avoiding the likelihood of a sharp QPF
gradient across the area, owing to moisture/best lift likely
becoming focused along the trough axis. A swath of 1-2" (locally
higher amounts) appears likely given the moist airmass (PW 2-2.25)
and aforementioned lift, maximized along the boundary.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
TD Bonnie (or her remnants) look to linger along the SC coast
into Monday aftn/evening along the coast. Continued warm and humid
with highs in the upper 70s/lower 80s on Memorial Day. With the
sfc boundary/trough axis sliding toward the coast by midday, areal
coverage of pcpn becomes a bit less widespread by afternoon,
especially out west in the piedmont. Thus, while pops remain
elevated they are a bit lower than today, ramping from sct
(30-40%) far west to likely (60-70%) along the coastal plain,
coincident with lingering boundary.

Models seem a bit better resolved with handling the meandering
remnants of Bonnie along the NC coast on Tuesday/Tuesday night.
Slower solution makes a bit more sense considering that there
really isn`t any synoptic feature present to kick it out to the
NE as GFS wanted to do in previous cycles. The WPC-blended
solution we`ve been following for a few cycles now does reflect
this preference, and will continue to depict higher chc pop along
the coast closer to the low, with a lower (more diurnally-driven)
pop well inland. Temps remain near to a bit above climo despite
mostly cloudy sky. Highs Tuesday in the low 80s inland, upper 70s
to low 80s along the coast. Remaining variably cloudy and mild
with lows in the 60s Tuesday night.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The remnants of Bonnie are progged to linger in the vicinity of
the NC coast through Wednesday and Thursday. Main impacts from
look to be lingering showers/thunderstorms along the coast/east
of Interstate 95, w/ cooler temperatures, and north to northeast
winds of 10 to 15 mph.

A warm and humid air mass will remain in place over the local
area with vorticity maxima associated with the mid level features
providing modest forcing for ascent. Expect generally scattered
showers and diurnally-driven thunderstorms. Subsidence between
Bonnie`s remnants and an upstream cold front expected to limit
showers/thunderstorms over the Piedmont Wed, 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 /18Z SUNDAY THROUGH FRIDAY/...
Moisture associated with T.D. Bonnie will continue to stream
northward resulting in periodic MVFR cigs and vsbys in showers
through the taf period. Some RW+ with brief gusts to 30 mph are
possible next few hours as well based on current radar trends.
Pcpn expected to become more widespread and stratiformed after 06z
which is expected to result in local IFR cigs and vsbys in rain
through 12z and possibly 18z. Thunder chances are rather low attm
(no lightning observed through this writing) so thunder was kept
out of the forecast for now. Best timing for any thunder would be
through 00z.

Outlook...low pressure to the north will push a cold front across
the region Mon aftn/evening. This boundary will push the tropical
moisture offshore by Tue morning. However the weakening/remnant
tropical low pressure system is expected to linger invof the
Carolina coast through the middle of the week and keep rain
chances in the forecast during this time...highest chances along
the coast.

&&

.MARINE...
Still no major impacts expected due to Tropical Depression Bonnie.

Sfc high pressure across the nrn Mid Atlantic Region slowly
erodes through the morning as Tropical Storm Bonnie tracks NNW
twd the SC coast. Precip chances will be increasing through
the day from south to north as wraparound rain bands from TS
Bonnie move into the area. Thunderstorms will be possible this
aftn/evening with periods of moderate to heavy rainfall and
quick reductions to visibilities. Southeast winds aob 15kt will
prevail today and tonight. Seas building to 3-4ft southern waters
this morning...then all waters by this evening through Tue
morning. Waves generally 1-2ft with up to 3ft possible in the
mouth of Ches Bay due to persistent onshore swell from the
Atlantic during this timeframe.

A low pressure system tracking ewd above the Great Lakes in Canada
is expected to drag a cold front through the region Mon
aftn/evening and collect the initial batch of tropical rainfall,
thus pushing it offshore by either late Mon night or Tue morning.
A brief period of n winds are possible Tue morning, but will turn
around to a ne-e direction by Tue aftn. However the weakening
tropical system low pressure is expected to linger invof the
Carolina coast through the middle of the week and keep rain
chances in the forecast during this time. In addition, low
stratus and periods of fog should linger over the waters Tue-Thu
due to ample moisture present, persistent onshore winds, and no
discernible weather features present to mix out the lower
atmosphere. Next cold front approaches the waters on Thu and will
help to kick the tropical system out to sea. This front is
expected to cross the waters on Fri. Seas 2-4ft/waves 1-2ft (up to
3ft mouth of Bay) Tue-Thu.

&&

.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 Today/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...LKB
SHORT TERM...LKB/MAM
LONG TERM...SAM
AVIATION...MPR
MARINE...BMD
CLIMATE...akq


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