Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1031 PM EDT Friday Sep 19 2014
high pressure over New England will slowly exit the region on Saturday.
Low pressure develops off the South Carolina coast on Saturday and
lifts up the Atlantic Seaboard on Sunday. A quick moving cold
front sweeps through the region on Sunday night with high pressure
returning for most of next week with cooler and drier conditions.
Near term /through Saturday/...
surface hi pressure remains centered over extreme eastern new eng. Low level flow remains
from the east-northeast...and broken cloudiness trapped below inversion (mnly inland).
Minor adjustments to entire forecast package for overnight hours. Most low
temperatures l/m50s inland to l60s right at the CST.
On Saturday...the surface high to the NE retreats and a developing low
along the SC coast will organize. This will help to increase the
easterly flow and low level moisture. So have increased clouds and
kept a chance for some light showers along the coast. In
land...the surface ridge should keep the clouds at Bay for areas west
of a line from xsa/akq/fkn/asj. The cloud will be thicker across
eastern NC as the upper level cirrus will also be thickening during
the day. For temperatures...have warmed values inland with the
sunshine expected...along the coast however...did trim the highs
back a little under the guidance due to high clouds and onshore flow.
Short term /Saturday night through Monday/...
the models are in good agreement in the Middle Range period. The
close low aloft that is associated with the coastal low is
forecast to open up and begin to shear out as a stronger trough
digs through the Ohio Valley and Great Lake states. This will keep
the low from bringing more moisture and precipitation inland...with the
bulk of the precipitation remaining on the eastern side of the
storm off shore. So have kept slight chance to chance probability of precipitation along
the coast Sat night into early Sunday before removing the chance
of rain after noon Sunday. Temperatures will recover some during
the afternoon into the low to middle 80s.
Weak high pressure provides another dry and warm day away from
the coast on Sunday in advance of the cold front. With 850 temperatures
climbing to around 17c should see temperatures in the middle to upper
80s away from the coast.
The cold front front will approach from the northwest Sunday
evening. The models show a very narrow band of moisture with the
front and the strongest dynamics sweep across PA. With the best
forcing to the north and the limited moisture...have kept probability of precipitation in
the slight chance range except in the northern Delaware-Maryland-Virginia and along the
southeast coast where moisture may be a little more abundant. Once the
front clears the area by middle morning Monday...high pressure builds
into the area and much drier air arrives and temperatures should
remain in the middle 70s to around 80 degrees.
Long term /Monday night through Friday/...
the long term period looks to be mainly dry and uneventful with
below normal temperatures. Surface high Parks over the northeastern
states middle to late week. This means a continuation of NE to east winds
which may have some marine implications. Upper level ridging
develops over the eastern Continental U.S. Late in the week.
A surface trough may develop off the Carolina coast late in the
week. Models indicate low to middle level moisture increases with some
of it spreading into our area. Slight chance showers are in the forecast eastern
Virginia/NE NC late Thursday into Friday.
Temperatures average below normal Monday night through Friday with
highs in the 70s and lows in the 50s.
Aviation /03z Saturday through Wednesday/...
strong high pressure over New England with NE-east winds over the
County Warning Area. VFR conds generally prevail over the region but with middle and
low clouds due to plenty of moisture off the Atlantic. Winds are
mostly 10 knots or less but some gusty conds persist close to the
coast. A few very light showers over the region due to a weak surface
trough or upslope in the Piedmont. No sig weather expected through the
period. Clouds will gradually thin out this afternoon/evening from ric
east...while more cloudiness and possible MVFR conds expected west of
Outlook...mainly VFR and dry weather are expected to continue into
sun. An area of low pressure moving up the East Coast may bring
increasing clouds and chance of rain for NE NC and southeast Virginia late sun
northeasterly to Ely flow this afternoon is resulting from high pressure
over New England. Gradient has tightened a little this afternoon
allowing for gusts of 12-19kt especially at the mouth of the Bay and
over the coastal waters. Seas have been slow to build today with
3 to 4 feet seas off Duck NC and off Ocean City. Seas off southeast
Virginia remain around 3 feet. Seas south of Duck have been building to 5
to 6 feet and seas are still expected to build to marginal Small Craft Advisory later
tonight into Sat morning. Small Craft Advisory headlines go into effect for all the
coastal waters at 1 am.
High pressure pushes off the New England coast Sat as low
pressure develops along a stalled boundary off the NC coast. The
low will slowly lift along the boundary Saturday and Sunday
passing well off the Virginia coast late Sunday. This will result in a
northeasterly to northerly flow over the coastal waters and Bay for most of the
weekend. Small Craft Advisory conditions for wind speeds are not anticipated at this time
based on the gradient wind forecast. However...seas will likely
remain elevated (4-5 ft) through Sat...before subsiding on Sunday
ahead of a cold front with winds turning offshore. Small Craft Advisory have been
extended into Sat night and may need to extended into Sunday for
Surface low lifts NE off the coast late Sunday with a cold front
forecast to cross the region Monday morning. Seas may briefly
build to 5 feet again Sunday night into early Monday. Northwest winds 10-15 knots on
Monday will gradually become north-NE on Tuesday. High pressure will
lock in across New England and extend into the middle Atlantic for a
good portion of next week. This will result in a prolonged period
of northeasterly flow across the region.
latest drought information showing an area of abnormally dry cndtns across
portions of Virginia. This includes areas north of I 64 & rt 360 (including
the ric metropolitan area) in akq forecast area. Other than scattered convection with the
front sun evening...extended models do not show much in the way of relief
for the next week.
Maryland...moderate rip current risk from 8 am EDT Saturday through
Saturday evening for mdz025.
NC...beach hazards statement from 8 am EDT Saturday through
Saturday evening for ncz102.
Virginia...Beach hazards statement from 8 am EDT Saturday through
Saturday evening for vaz098.
Moderate rip current risk from 8 am EDT Saturday through
Saturday evening for vaz099-100.
Marine...Small Craft Advisory until 2 am EDT Sunday for anz652-654-656-
Small Craft Advisory until 2 am EDT Sunday for anz650.