Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
446 PM EDT Sat Aug 27 2016
high pressure centered over New England will slowly build south
into the mid Atlantic region through Sunday. Meanwhile, low
pressure will linger off the southeast coast Monday into Tuesday.
Near term /through Sunday/...
latest analysis indicating a weak surface front/boundary now into
NC, with a broad area of high pressure centered over upstate New York.
Still a very warm afternoon across the local area (temperatures
avg 90-95 f inland), but dew points have dropped off into the 60s
except over the far south and southeast where they remain in the
lower 70s. Thus, heat indices are generally at or below 100 f
(which is about 5 degrees lower than yesterday at this time).
For tonight, scattered clouds currently over the SW zones should
dissipate and result in mainly clear conditions this evening.
However, light onshore flow coming off the ocean looks to
gradually bring low clouds into the area after midnight. NAM tends
to be too moist in the low levels with this scenario, but the GFS
bukit data also shows ample moisture from about 950-850 mb. Have
therefore bumped up sky cover to partly cloudy west of I-95 and to
mostly cloudy from roughly 08z through 13z Sunday morning farther
south and east. Some areas of fog will also be possible (mainly
farther inland where skies stay mostly clear for most of the
overnight). Lows tonight will range from 65-70 f over most areas
(locally 70-75 f in the southeast near the coast).
On Sunday, as low pressure well off the southeast coast is progged to
slowly push a little closer to the coast, models to a varying
degree show the potential for at least isolated to widely
scattered showers during the late morning and aftn hrs for far southeast
Virginia and NE NC zones (will keep the forecast dry elsewhere). Airmass
is progged to cool slightly from today, with highs around 90 f
over interior VA, to the mid to upper 80s elsewhere. Skies avg
partly to mostly sunny north and partly to mostly cloudy S/se.
Short term /Sunday night through Tuesday/...
not much change to the pattern Mon-Tue, another weak front pushes
through the NE Continental U.S. As a sfc trough lingers off the coastal
Carolinas. Highs continue to avg in the upper 80s to lower 90s
with lows in the upper 60s to lower 70s along with 20-30% chances
for mainly aftn/evening showers and tstms over se zones.
Long term /Tuesday night through Saturday/...
will continue to go with a blend of the 12z GFS and 12z European model (ecmwf) for
the extended period. Will have a slgt to sml chc (15-30%) for pcpn
Tue ngt into Thu evening FM the combination of possible tropical
moisture along the coast and a cold front pushing acrs the area
late Wed thru Thu. More comfortable airmass will filter into the
region for Thu ngt thru Sat, as high pressure blds in FM the north and
slides to just offshr by late Sat. Highs in the mid 80s to lower
90s Wed, in the mid to upper 80s Thu, and in the lower to mid 80s
Fri and Sat. Lows in the upper 60s to mid 70s Tue ngt and Wed ngt,
in the 60s to near 70 Thu ngt, and in the upper 50s to mid 60s Fri
Aviation /21z Saturday through Thursday/...
a weak cold front now situated in NC, with all showers/tstms SW of
our taf sites. NE winds average 5-10 knots (a little higher for
korf/kecg) and VFR conditions prevail. Some potential for low
clouds overnight/early Sun morning and have included broken IFR/MVFR
cigs at most taf sites from 08-13z/sun.
The front will dissipate by Sunday/Monday with high pressure
building over the area through midweek. Mainly dry weather is
expected through Wednesday. There will be a chance for isolated
shwrs/tstms Sunday/Monday afternoon and evening southeast
portions (orf/ecg) and isolated thunderstorms are possible
Tuesday and Wednesday.
sub-sca conditions will continue acrs the waters thru at least
the next few days. High pressure cntrd over the NE U.S. Late this
aftn, will shift off the coast for tngt thru sun. This will result
in NE or east winds 15 kt or less over the waters, with waves 1-3 ft
and seas 2-4 ft over the coastal waters. Winds will be arnd 10 or
less Mon thru Wed, as weak low pressure or a possible tropical low
will spin off the southeast or mid Atlc coast during this period. This
low will cause long period swells to propagate toward the coastal
waters, with seas remaining 3-4 ft.
has been a rather hot and dry month of August over much of the
area (quite a contrast to a Summer that began very wet). Based on
forecast temperatures for the rest of the month, Richmond and
Norfolk are both going to rank in the top 10 warmest (with a good
chance at being among the top 5 warmest). Richmond has only
received 0.53" of rain for the month (if this were to stand, it
would rank as the 3rd driest on record).