Area Forecast Discussion
Issued by NWS Wakefield, VA-- Remove Highlighting --
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FXUS61 KAKQ 201120
Area Forecast Discussion
National Weather Service Wakefield VA
720 AM EDT WED JUL 20 2016
Weak cold front drops over the area this morning, stalling over
North Carolina today. The front dissipates tonight as high pressure
builds over the region. High pressure prevails through the weekend.
.NEAR TERM /THROUGH TONIGHT/...
Latest surface analysis depicts a cold front just to the north and
west of the local area with high pressure over the Great Lakes.
Earlier shower/thunderstorm activity has diminished, but a shortwave
dropping over the region may help enhance some showers over the
Northern Neck early this morning in an area of elevated instability.
Will maintain isolated to widely scattered showers from the Northern
Neck to the Maryland Eastern shore. Elsewhere, only isolated showers
linger over the southern Piedmont into south central Virginia.
Showers expected to dissipate by daybreak as the wave drops into
North Carolina. Guidance still hinting at patchy fog early this
morning, but has not been verifying thus far. Will keep mention
inland due to moist air mass.
Diffuse frontal boundary expected to drop into the southern forecast
area late this morning. Dry conditions expected to persist through
the morning hours. Any morning fog quickly burns off by 8am. A weak
convergence boundary is expected along the coast this afternoon with
onshore flow. The diffuse boundary across southeast
Virginia/northeast North Carolina and along the Eastern Shore will
provide a focus for isolated to scattered showers and thunderstorms
as weak waves drop over the region in northwesterly flow aloft. SPC
maintains a marginal risk for severe weather across northeast North
Carolina due to steep low level lapse rates and better boundary
layer moisture. High`s generally in the mid 80`s today under a
generally partly cloudy sky.
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
Anomalous upper trough over the nations mid section continues to
build eastward Thursday and Friday. Upper level trough remains over
the western Atlantic. High pressure slides off the coast Thursday
with onshore flow suppressing the heat for one more day. Similar
thicknesses and low level temps to today will result in highs back
in the mid to upper 80`s. Dry with a mostly sunny sky. Lows Thursday
night in the upper 60`s to low 70`s under a mostly clear sky. The
upper ridge expands eastward Friday, with 850mb temperatures of 22C
(+2 standard deviations) reaching the Piedmont. High`s forecast in
the low to mid 90`s, just slightly above normal. A southwest wind
around 10 mph will help mix dewpoints into the mid 60`s, resulting
in heat index values in the mid to upper 90`s. Pressure falls along
the lee side of the mountains will sharpen a thermal trough over the
Piedmont, but a lack of moisture and appreciable forcing results in
silent POP`s. However, will see more afternoon cumulus.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Long term period will feature mainly dry conditions and above normal
temps. For Friday night/Saturday, dry wx expected as surface high
pressure stays off the se coast and a broad upper-level ridge slides
east into the eastern Conus. Cannot rule out an aftn/eveng
shra/tstm, but chance for rain is less than 20%. Very similar
conditions for Sun with a weak thermal trough over the Mid Atlc and
weak zonal flow aloft. Expect hi temps in the mid/upr 90s both days,
and with dewpoints in the lo/mid 70s, aftn heat indices will reach
near 105F (heat advsry criteria).
Temps a bit lower for Mon/Tue...but still hot with highs in the 90s.
Mainly climatological PoPs (20-30%) in the aftn/eveng.
.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
Patchy fog/low clouds have generally not affected TAF sites early
this morning, with dry conditions and mostly sunny skies to
prevail for the remainder of the morning. Drier conditions with
less shower/tstm development is anticipated today, only a few
isolated showers/tstms possible from mid afternoon through early
this evening/primarily along and near the coast.
OUTLOOK...Dry weather and mainly VFR conditions are expected
from tonight through Sat. Only flight restrictions would be from
the chance for patchy fog from 06-12Z Thu morning.
No headlines necessary over the next several days as a weak
frontal boundary drops south of the waters this morning with high
pressure building in from the north later today. The high becomes
centered off the mid-Atlantic/SE coast Thu-Fri as another weak
front moves in from the NW Fri night and washes out across the
area on Sat. Winds will become NE around 10 KT later this morning,
and will shift to the E at 5-10 KT most areas this afternoon. Winds
then transition to the E/SE Thu then S/SW Fri. The pressure gradient
will increase a bit on Fri, so winds will avg around 15 KT fri
afternoon/evening ahead of the front. Waves over the Bay will avg 1-2
ft, with seas over coastal waters 2-3 ft (3-4 ft Fri afternoon/evening).