Area Forecast Discussion
Issued by NWS Wakefield, VA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 281743
Area Forecast Discussion
National Weather Service Wakefield VA
143 PM EDT SAT MAY 28 2016
High pressure will push farther off the Mid Atlantic coast
through tonight. Low pressure northwest of the Bahamas will move
toward the South Carolina coast today and tonight, and will
linger along the coastal Carolinas through the holiday weekend.
.NEAR TERM /THROUGH TONIGHT/...
Late morning analysis reveals 1024+mb surface high pressure well
off the VA/NC Coast, ridging back toward the Mid- Atlantic/Carolina
piedmont. To our southeast, weak sfc low pressure (still TD #2 as
of 11am NHC position update) is located about 200 mi SSE of
Charleston SC. Aloft, strong upper level ridge centered offshore
is similarly ridging back west into VA.
The upper ridge looks to be slow to retreat/weaken over the region
out ahead of the advancing sub-tropical low. Models continue to
depict a large zone of subsidence over the local area through
this aftn. Current obs and satellite trends show driest low level
airmass/best subsidence located over southern VA where dew pts are
into the upper 50s, with higher dew pts into the mid 60s over NE
NC and also acrs northern zones. SCT/BKN Cu already developing in
ne NC, but do not anticipate this to develop into anything more
than perhaps an isolated shower by late aftn due to the subsidence
from the ridging aloft. Thus, will be keeping the vast majority
of the forecast area dry through the afternoon/early evening,
will maintain just a slight chc/20% pop across interior ne NC
counties due to diurnal instability and increasing moisture (PW
values increase to about 1.50" by late afternoon and early
evening). Highs in the mid to upper 80s inland/piedmont areas
(warmest highs approaching 90 F in the far NW), and in the upper
70s to lwr 80s along the coast.
Models remain in good agreement with showing upper ridge buckling
e-ne tonight, with TD#2, or quite possibly Tropical Storm Bonnie
by that point, approaching the se coast. PW values AOA 2" expected
to push across the area after midnight/Sunday morning. GFS
remains most aggressive with northward expansion of POP, with the
remainder of CAMs and probabilistic guidance in decent agreement
in trending pops upward from south to north late tonight into
Sunday morning. 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 /SUNDAY 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 the period. Refer to discussions issued by
the National Hurricane Center for the official track and forecast.
Have nudged pops upward Sunday, with unsettled conditions
continuing w/warm and quite humid airmass in place. Highest POPS
look to shift just inland from the coast by aftn, as h7 WAA/Omega
and upper jet dynamics (RRQ) favor likely pops, which could well
be focused along inverted sfc trough that will be oriented from
the piedmont into the Lower Eastern Shore of MD. Accordingly
expect to see numerous periods of rain, falling moderate to heavy
at times. Highs on Sun generally in the upper 70s to lwr 80s.
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. Potentially very wet conds persist, with
occasional moderate to heavy showers expected from time to time in
the modified tropical airmass. Will continue high chc to likely
POPS Sun night/Mon, with high end likely pop lingering into Monday
morning along the Northern Neck and Eastern Shore. Warm and humid
with early morning lows 65-70 F Monday morning and highs in the
upper 70s/lower 80s on Memorial Day.
A bit of disagreement amongst deterministic models by Tuesday,
with the 00z/Operational GFS wanting to dry us out under
developing weak sfc ridging, but curiously lingering the main
upper system along the coast. Meanwhile, the ECMWF is a bit
quicker to clear out the low altogether, ejecting it quicker to
the NE. Followed a WPC blended solution, weighted towards the more
consistent respective ensemble means. This translates to a
steadily decreasing rain chance for Tuesday. However, will still
carry a solid chance pop along the coastal plain, and a slight chc
inland. Highs Tuesday in the low to mid 80s inland, upper 70s to
low 80s along the coast.
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Unsettled weather conditions continue into the extended period as
the remnant tropical depression (per NHC latest forecast) lingers
over the Carolinas or near the Carolina coast Tuesday. Deepest
moisture gets pushed offshore Tuesday as upper level energy lifts
over the southeast local area. Will keep mention 30-50% POPS over
the southeast half of the local area with only slight chance
northeast half. The low weakens into Wednesday with an inverted
trough/coastal front locating along the Mid-Atlantic coast.
Lingering moisture along the coast will result in only chance POPs
northeast North Carolina and southeast Virginia. Dry conditions
expected Wednesday night with a partly cloudy sky. An upstream
trough approaches the region Thursday as upper level ridging remains
over the western Atlantic. An associated cold front is forecast to
reach the Ohio Valley early Thursday. Amplifying flow will lift the
frontal boundary northward with increasing chances for showers and
thunderstorms over the Piedmont and northeast North Carolina
Thursday. Meanwhile, the remnant low pressure is expected to weaken
off the Southeast/Mid-Atlantic coasts. Forecast confidence decreases
toward the end of the week and into the weekend as the cold front
approaches the region. The preference at this time is to stick with
the ECMWF, which pushes the front across the region Friday.
Unsettled conditions expected to persist into the weekend as the
front likely stalls along the coast.
Temperatures forecast generally around seasonable norms during the
period. Highs low to mid 80`s with lows in the 60`s.
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
VFR conditions should continue through this afternoon into this
evening as high pressure remains in control with a dry airmass
across the area. As Tropical Depression Two moves toward the South
Carolina Coast, tropical low level moisture will move northward
and surge off the Atlantic and into the region later tonight into
Sunday. This will allow for IFR cigs to spread across the area
late tonight. Higher low level dewpoints may allow for some ifr
vsbys overnight as well. On Sunday, rain will spread from south to
north during the day. In turn...cigs/vsbys will likely raise to
mvfr Sunday morning.
Outlook...Despite the depression forecast to dissipate to a
remnant low, the guidance suggests that the tropical moisture will
persist across the area for much of the week. As such...expect
plenty of shower activity through the week esepcially across far
south VA and NE NC. Expect many periods of VFR through the week,
however with the moist airmass in place, there will be periods of
MVFR or IFR conditions through much of the week, especially in the
overnight and early morning hours.
No major impacts related to Tropical Depression Two anticipated.
High pressure resides over the Mid Atlantic Region today and is
not expected to break down until later this evening. South winds
become more se by this aftn as Tropical Depression Two slowly
moves into the Southeast coast. Isolated showers and thunderstorms
could develop over srn Currituck Sound on seabreeze boundaries
this aftn/evening, but confidence is low. General trend is for
wraparound precip from the tropical system to move into the waters
from south to north late tonight through Sun...becoming more
persistently widespread over the waters Sun night through Tue
morning. Thunderstorms will be possible Sun-Mon evening. Although
the pressure gradient tightens over the waters as the tropical
low meanders over the Carolinas, se-s winds remain fairly steady
aob 15kt throughout the duration of this system. Seas generally
2-3ft today...building to 3-4ft srn waters Sun...then all waters
by Sun evening through Mon night. Waves 1-2ft today...building to
2-3ft srn Ches Bay during Sun only. Waves may stay elevated
around 3ft in the mouth of Ches Bay due to persistent onshore
swell through Mon.
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 remnants of the weakening tropical
system, thus pushing all rain offshore by either late Mon night
or Tue morning. Areas of fog may be possible over the waters Mon
night/Tue morning as high pressure starts to build back into the
region. A brief period of north winds are possible Tue morning,
but will turn around to an e-se direction by Tue aftn. Seas
subside to 2-3ft/waves 1-2ft on Tue. Low stratus and periods of
fog may 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. The next more
well-defined cold front is expected to cross the waters late in
the upcoming week.
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)