Area Forecast Discussion
Issued by NWS Wakefield, VA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 301600
Area Forecast Discussion
National Weather Service Wakefield VA
1200 PM EDT SAT JUL 30 2016
A weak frontal boundary will linger over the Mid-Atlantic region
this weekend. Meanwhile, a trough of low pressure will become
centered across the eastern states this weekend through early next
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --Minor changes made for the afternoon and early evening to account
for Radar/Sat trends. HRRR/NCAR WRF ensembles handling current
convection well, and have leaned in its direction for the
afternoon. Shower activity which fired along piedmont trough
continues across metro Richmond. This activity is in association
with main shortwave sliding off to our north. Expect showers/storms
to become focused farther south across South Central and SE VA/NC
Coastal plain counties for the afternoon, in association with yet
another weak perturbation sliding across the E TN Valley at
PW values per GEFS/SREF reach +2 st dev through the afternoon, so
any showers/tstms will continue to have the potential to produce
moderate to heavy rain, although the forcing is not such to
support sustained high rain rates. NAM/GFS generally depict
1200-2000 J/kg of 0-1km MLCAPE this afternoon along with 25-30kt
of 0-6km bulk shear on the srn flank of stronger westerlies to the
n of the local area. As a result, a few loosely organized tstms
are possible, which could produce localized strong wind gusts (wet
microbursts). However, mid-level lapse rates less than 6C/km will
be a limiting factor. Temperatures early this morning range from
the low to mid 70s. Temperatures should rise quickly into the 80s
this morning under a partly to mostly sunny sky, before cu rapidly
develop late morning into the afternoon. Highs will generally be
in the mid/upper 80s with near 90 se.
Lingering sct showers/tstms gradually lift ne this evening toward
the Ern Shore, then slide offshore overnight. Otherwise, partly to
mostly cloudy and humid with lows in the 70s.
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.SHORT TERM /SUNDAY THROUGH MONDAY/...
The Midwest trough will slide into the region Sunday
into Monday and take up residence over the eastern Conus. Mainly
diurnally driven showers/tstms are possible Sunday with PoPs in the
30-50% range. With the trough in place will also see temps remain
close to normal. Highs Sunday range from the mid/upr 80s north to
the low 90s south.
The upper trough sharpens even further across the East Coast Sunday
night into Monday as a more substantial shortwave trough tracks
across the area helping to push cold front through the region by
midday Monday. Pcpn chances Monday will be highest over se VA/ne NC,
so chc pops (30%) will continue there, with slight chc (20%)
elsewhere. Highs again generally range from the upr 80s to low 90s
after morning lows in the 70s.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A cold front stalls off the Mid Atlantic coast into the
Carolinas Mon night through mid week...gradually washing
out as sfc high pressure builds into the NE CONUS from the
Great Lakes Region during the second half of the week. This
will keep a chance for thunderstorms in the forecast through
Tue night...with only a slight chance for storms across
far s-sw counties Wed/Thu closer to the remnant boundary.
With sfc high pressure building into New England early in
the week and then settling over the NE CONUS during the
second half of the week...expect temperatures to be more
seasonal with highs generally in the mid-upper 80s and
cooler dewpoints in the upper 60s to lower 70s...effectively
squashing heat indices and limiting them to the lower 90
degree range. Onshore winds also develop by Tue aftn and are
expected to persist through the rest of the week...thus
enhancing any drying and cooling effects to temps, dewpoints,
and overall precip chances.
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
Other than isolated IFR/MVFR fog early this morning, expect mainly
VFR conditions today into Sun morning. However, the combination of
a warm front, deeper low level moisture, Shortwave energy, and
vertical motion moving acrs the area this aftn into tngt, will
bring a decent chc for showers and tstms at the taf sites. Did not
mention any pcpn in tafs at this time due to POPs being 50% or
less. Lesser chcs late tngt thru Sun morning, as that energy moves
off the coast. There will be chcs again Sun aftn into Sun ngt, as
a trough of low pressure lingers over the area. Periods of
MVFR/IFR conditions will be possible in any tstms.
No headlines in the short term today thru Sun ngt. Winds were NE-
SE arnd 5 kt or less early this morning ovr the waters, and will
become SE 5 to 10 kt during today, as a warm front approaches and
moves into the region. Winds will then become S then SW later tngt
into Sun morning, as the warm front pushes off the coast. A cold
front will then drop acrs the waters and off the coast Mon into
Tue morning. High pressure returns to the waters on Wed. Seas
will average 2-3 ft thru the period with 1-2 ft waves in the Bay.