Area forecast discussion
National Weather Service Wakefield Virginia
227 am EDT Thursday Jun 20 2013
Synopsis...
high pressure will build into the region from the north tonight
and Thursday. High pressure will slide offshore Friday as a wave
of low pressure lifts along the southeast coast through Saturday.
High pressure will return over the area Sunday.
&&
Near term /until 6 am this morning/...
dry conds overnight as surface hi pressure builds over the middle Atlantic and
middle-level energy pushes offshore. Will maintain prtly cloudy skies
with decent moisture confined below 700 mb. Otw...light onshore flow
and low temperatures in the upper 50s to lower 60s.
&&
Short term /6 am this morning through Saturday/...
cool surface high pressure will locate along the NE coast
Thursday...extending southwestward into the middle Atlantic region as the cold
front stalls along the southeast coast. An upper level shortwave will
traverse the deep south Wednesday night/Thursday morning. This will help
develop a wave of low pressure along the stalled boundary Thursday.
Meanwhile...onshore east/southeast flow will continue over the local area.
Dry air advecting into the region as well as subsidence aloft will
allow for dry conditions and generally mostly clear-partly cloudy
skies. Onshore flow will once again keep temperatures from reaching their
full potential. Have undercut guidance slightly Thursday...with
forecast temperatures reaching only into the low 80s (~-1 Standard dev). Temperatures
along the coast will once again only reach into the middle/upper 70s.
Biggest change in the short term is in response to the
aforementioned wave developing along the stalled boundary off the
southeast coast. Latest NAM/sref guidance lift the wave slowly northward Friday-
Sat. However...latest GFS/European model (ecmwf) guidance is more suppressed with the
wave...keeping the front to the south and the wave farther
offshore. NAM/sref bring moisture/clouds into NE NC/southeast Virginia Friday
into the weekend...with the GFS extending only as far northward as
extreme eastern NC. Have gone with a blend between the models...and have
introduced slight chance probability of precipitation Friday-Sat across extreme southeast Virginia/NE NC.
Confidence is not high at this time (evident of only slight chance pops)
as overall upper level energy is not being handled well by the
models. Overall lack of upper level support also makes it
difficult to predict. Temperatures Friday-Sat will rebound inland to near
seasonable norms (mid/upper 80s) as southerly winds return. Still cool
along the coast (thanks to southeasterly winds) with temperatures ranging from the
upper 70s along the immediate coast to low 80s about 50-60 miles
inland from the ocean.
&&
Long term /Saturday night through Wednesday/...
period begins with mainly quiet/dry conditions pattern is expected
sun/Mon...only caveat would be some weak surface troughing off the
coastal Carolinas into sun. Latest GFS/European model (ecmwf) remain in decent
agreement with ~590 dm ridge centered along/off the southeast coast
Sunday/Monday...with some slight height falls Tuesday/Wednesday as a more
significant middle/upper level trough develops from the upper Midwest
to eastern Canada (and the models begin to diverge a bit more during
this timeframe leading to lower than average confidence). Will carry a
slight chance for showers/thunderstorms sun over far southern Virginia/NE NC given
the weak troughing off to the southeast of the area...but in general expect
partly sunny skies and seasonable temperatures with highs in the
middle-upper 80s and lows mainly in the 60s. Expect a gradual warming
trend west/ temperatures averaging slightly above average into early next
week with highs in the upper 80s to lower 90s and lows in the upper
60s to lower 70s. Instability will slowly increase as upper heights
fall and a series of weak shortwaves push into the upper ridge
centered to our south. Will carry diurnal 20% chances for
afternoon/evening thunderstorms each day but with the only real trigger being a
Lee trough and weak shortwaves (no surface front) confidence is too low
to go any higher than 20% which is close to climatology for a 12-hour
period.
&&
Aviation /06z Thursday through Monday/...
drier air will continue to build in from the north-northeast tonight into
Thursday as high pressure builds in over the middle-Atlantic region.
Have noted some MVFR-IFR ceilings early this morning at ecg and ric, in
association with remnant moisture trapped below low level
inversion. Have accounted for 1kft ceilings towards dawn at ric/phf/ecg, but
have held off at orf/sby for now. Forecast soundings support rapid
lifting of any low clouds, with VFR conditions then expected to
prevail this afternoon/early Thursday night as the high slides off the coast.
Outlook: weak, stalled frontal boundary/coastal trough will
meander just to our south through the weekend. VFR conditions
should persist through much of the period, with minimal chances for
flight restrictions in association with primarily sct, diurnally
driven rain showers over southern terminals Sat-sun.
&&
Marine...
NE flow prevails across the entire region...with conditions just shy
of Small Craft Advisory criteria. Will continue to monitor but for now will have no
headlines in effect...seas average 3-4 feet and waves 1-2 feet in the Bay
(2-3 feet at the mouth of the bay). NAM remains a little stronger/more
of an outlier with respect to the development of a surface low off the
NC/SC coast tonight through early Friday. If this were to verify may
need headlines across southern waters for marginal Small Craft Advisory (seas to 5 ft).
Pattern will be slow to evolve into the weekend...winds gradually
shift to the east-southeast then the south-southeast by Sat night/sun (and subside to 10-15
knots or less).
&&
Akq watches/warnings/advisories...
Maryland...none.
NC...moderate rip current risk from 8 am EDT this morning through
this evening for ncz102.
Virginia...moderate rip current risk from 8 am EDT this morning through
this evening for vaz098.
Marine...none.
&&
$$
Synopsis...alb/Sam
near term...mas
short term...Sam
long term...lkb
aviation...mam
marine...lkb
