Area forecast discussion
National Weather Service Wakefield Virginia
622 PM EDT sun may 19 2013
Synopsis...
a weak front will slowly push north of the area tonight as high
pressure becomes anchored well off the coast. Showers and thunderstorms
will become more widely scattered after Monday...with above average
temperatures prevailing through much of the upcoming week. A cold
front will pass through the Middle Atlantic States late Thursday into
early Friday...with cooler temperatures expected by next weekend.
&&
Near term /until 6 am Monday morning/...
added fog to coastal waters north of Parramore Island as well as the
adjacent portions of Worcester Maryland and Accomack Virginia through 9pm as
relatively light southeast flow off the chilly waters is leading to low
clouds and visibilities < 1 sm at oxb.
A rather diffuse upper level low continues from Kentucky to the
Carolinas. A deep trough was over the northern High Plains. A small
ridge was in between the two features. As the trough over the plains
states continues to press east...the upper low just to our west and
the aforementioned ridge will dissipate. A Bermuda high pressure
ridge extending from the Atlantic to the southeastern states will
begin to dominate the area weather toward middle week.
The front that has been over or just south of our area for the last
couple of days is still rather diffuse. There are indications that
it has moved into northern portions of the County Warning Area. The front is
expected to dissipate over northern portions of the Middle Atlantic
States on Monday.
A vorticity lobe as indicated by water vapor imagery was associated with
a band of thunderstorms moving into our southern Piedmont counties. This
area is expected to be the main focus for showers and thunderstorms into the
evening hours with likely probability of precipitation through 04z. Widely scattered showers
can be expected elsewhere and kept chance probability of precipitation throughout the
overnight.
Some patchy fog is expected to develop once again Monday morning...
especially in areas north of Interstate 64 and on the Maryland
Eastern Shore. Widespread dense fog is not anticipated as the fog
should mainly develop from lowering stratus.
Low temperatures Monday morning are forecast to range through the
60s across the area.
&&
Short term /6 am Monday morning through Wednesday/...
another round of showers and thunderstorms can be expected Monday
under the influence of the dissipating upper level trough. A bit
more instability is expected which will result in more widespread
thunderstorm activity than was experienced Sunday. Heavy rainfall
will be the main threat with activity moving rather slowly. Have
likely probability of precipitation across the southern Piedmont and south central Virginia
and into the North Carolina counties east to near the Chowan river.
High temperatures will be slightly warmer than Sunday with readings
generally around 80 inland and the low to middle 70s at the coast.
Conditions should begin to dry out Monday night and Tuesday as the
high pressure over the southeastern states begins to dominate.
Highest probability of precipitation (showers/thunderstorms) will be in southeast Virginia
and northeast North Carolina at 30 percent. Temperatures are
forecast to top out in the middle to upper 80s in most areas with upper 70s
to lower 80s near the coast and over the lower Eastern Shore.
Precipitation should end by late Tuesday evening.
For Wednesday...models are all over the place with probability of precipitation. With no
strong triggers for convection or indications of where convection
will focus...kept probability of precipitation at 30 percent throughout the County Warning Area. High
temperatures will be similar to what is forecast for Tuesday.
&&
Long term /Wednesday night through Sunday/...
long term period starts off Wednesday night with a chance for rain...mainly
west of I-95...ahead of an approaching middle-level trough and associated
cold front. S/SW flow will keep temperatures above normal...with lows in the
middle to upper 60s. This pattern continues into Thursday/Thursday night with still a
30-40% chance for shwrs/tstms. Deep-layer moisture is abundant however
forcing is a limiting factor due to a lack of warm air advection and most short wave
energy staying off to the north. Models have continued to speed up
the timing of the front...with the frontal passage now expected to be sometime
late Thursday/Thursday night. Highs Thursday in the low to middle 80s. Behind the front Friday
into the weekend...diminishing chances for rain and slightly lower temperatures
(but still around seasonal norms) with highs in the middle 70s to lower
80s and lows in the 50s.
&&
Aviation /00z Monday through Friday/...
a mix of VFR and MVFR conditions across the region this afternoon
with showers developing from ecg to orf and south of ric. Expect
mainly MVFR conditions at ric into this evening with a few showers
moving through after 19z. At orf conditions should remain VFR
until heavier showers reach the Airport around 19z reducing visibility
to MVFR and perhaps even temporarily IFR. Northeasterly flow at orf is due
to a weak Bay breeze and will become southerly this evening. Just to the
north phf has been slow to improve and will remain MVFR for the
afternoon and evening. Sby has continue to see IFR conditions but
this will temporarily improve to MVFR by this evening before
returning to IFR overnight.
Showers will dissipate with loss of heating overnight outside of a
few stray showers here and there. Despite most of the guidance
keeping conditions above IFR due to the low level moisture and
continues boundary across the region expect IFR ceilings and fog to
re-develop overnight at all taf sites. These IFR conditions will
linger into Monday morning improving slowly through middle morning.
More widespread showers are expected Monday afternoon and evening
with more coverage of heavy showers than compared to Sunday.
&&
Marine...
southeast flow prevails tonight as a warm front lifts north of the area. Hires
models show a quick shot of Small Craft Advisory winds over the Bay later this
aftn/eveng...but not confident enough or long lasting enough to issue a
Small Craft Advisory headline for this at this time. Winds stay genrly 10-15 knots overnight and
shift from southeast to S. Seas will approach 4-5 feet out 20 nm over coastal
waters...with best chance for 5+ feet over the northern two zones where
Small Craft Advisory headlines continue through the overnight hours. 12z wavewatch shows 5 feet
seas there lasting into Monday and Monday night...but with wavewatch
running high during southerly flow as of late...will end the Small Craft Advisory at
4 am tonight with the next shift either expiring the hazard or
extending it out in time. Otw...sub-sca southerly winds continue for
the next few days ahead of an approaching cold front which crosses
the area late Thursday/Thursday night.
&&
Hydrology...
river level forecasts have been lowered substantially due to lack
of significant rainfall in the headwaters.
&&
Akq watches/warnings/advisories...
Maryland...none.
NC...none.
Virginia...none.
Marine...Small Craft Advisory until 4 am EDT Monday for anz650-652.
&&
$$
Synopsis...lkb
near term...lkb/lsa
short term...lsa
long term...mas
aviation...jao
marine...mas
hydrology...
