Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
156 PM EDT Wednesday Oct 1 2014
a weak cold front moves across the area today. High pressure will
build over the middle Atlantic region on Thursday...ahead of a strong
cold front which approaches from the west Friday. The cold front
crosses the region Friday night...ushering in much cooler and
drier weather for the upcoming weekend.
Near term /through tonight/...
most of the fog has burned off with plntly of St / SC left behind
across the Piedmont. Meanwhile...lght shower activity showing signs
of dsptg as they move east across the lower Maryland Eastern Shore. Assctd short wave
expeceted to move offshore next few hours as trailing cold front crosses
Kept low pop across northestern areas next few hours as systm moves off the
coast. Lingering trough across the Piedmont may spark off an afternoon
shower but it will be fighting the subsidence around departing short wave.
Becoming pt sunny most areas. Highs 75-80.
east-NE flow will bring increasing clouds tonight...and another
period of low stratus late tonight into early Thursday. Bufr soundings
are dry above h9 but are nearly saturated in low levels. Could see
some patchy drizzle late tonight mainly over the Piedmont, but west/
chances of accumulating precipitation quite low, will go with a dry forecast for
now. Went with warmer envelope of NAM guidance for minima tonight
with low clouds and onshore flow expected. Lows generally u50s to
Short term /Thursday through Friday/...
shortwave ridging continues to build east across the eastern
Seaboard downstream of upper level trough racing east across the
plains on Thursday. Meanwhile at the sfc, high pressure will ridge
south into the region from New England. Will hold onto a low chance
pop Thursday morning as low stratus/dz once again scours out.
Thereafter, expect vrb clouds and dry weather Thursday. Ggem and downscale NAM
do continue to hint at some very weak overrunning, but lift
appears too shallow to yield much more than some very light rain
rain showers/sprinkles, oriented mainly west of I-95. Once again, have
opted to go dry for now. High temperatures Thursday Manly from the middle 70s to
Aforementioned anomalously deep upper trough racing east across the
plains will dig east-southeast across through the Midwest/Tennessee Valley Thursday night and
Friday. East-southeast flow will result in incrsg moisture and overcast conditions
Thursday night and Friday and some isolated rain showers will be possible by Friday
morning. The most widespread precipitation associated west/ the approaching
strong cold front should remain just west of the forecast area Friday afternoon. Hi temperatures Friday
from the M/u70s on the eastern shr to l80s across interior portions of southeast
Long term /Friday night through Tuesday/...
a potent upper level trough will become cut off over the northern
Great Lakes region Friday night/early Saturday before lifting NE
into southeast Canada on Sunday. Strong jet energy rounding the base of the
trough/upper low will force a cold front quickly through the region
Friday night...then offshore Saturday morning. Widespread showers
are expected Friday night with the frontal passage and will carry high likely
probability of precipitation. Strong forcing but limited instability ahead of the front may
trigger an isolated thunderstorm or two Friday evening, so will include a
slight chance for thunderstorms. The front is expected to push off the coast
around 12z Sat...W/ shower chances to end quickly from west to
east Saturday morning. Will limit rain showers chances on Saturday
morning to the far eastern areas. High pressure returns Saturday
night and Sunday for dry weather. The aforementioned upper low lingers
across southern Canada early next week...with another spoke of
energy rotating around the base of the trough Monday night/Tuesday
for a slight chance of showers. Highs Saturday 70-75. Cooler
Sunday with highs 65-70. Highs Monday/Tuesday 70-75.
Aviation /18z Wednesday through Monday/...
weak frontal boundary has pushed south of the local area this
afternoon as high pressure begins to ridge in from the north. Scattered-
broken middle level clouds with decks generally 2-5k feet above ground level persist this
afternoon in light east-northeasterly flow. Surface winds generally at or below 10 knots.
Clouds will begin to dissipate with the loss of daytime
heating...resulting in more fog and stratus tonight. With high
pressure building in tonight...subsidence will combine with calm
to light onshore flow and dewpoints in the upper 50s to low 60s to
produce areas of fog. Stratus is possible overnight...but little
dispersion makes fog more likely at the onset. However...by early
Thursday morning...IFR stratus becomes more likely. A period of
onshore flow in NE NC...including kecg...this evening into tonight
may result in an earlier onset of IFR stratus before winds become
calm to light from the north...resulting in fog. While areas of
fog are anticipated...would not be surprised to not see widespread
IFR...similar to last night...at the taf sites. However...did
trend toward IFR all sites except for kric.
Otherwise...high pressure ridges over the area from the NE
Thursday...resulting in more dry conditions. Expect another round of
afternoon middle level clouds. Also anticipate more fog and stratus
again Thursday night. A cold front will cross the region Friday
night into Saturday morning. Precipitation along with low ceilings/visibilities expected.
opted to raise Small Craft Advisory headlines for the northern most coastal zone...north
of Chincoteague through 10 PM EDT for 4-5 feet seas. NE winds around
15 knots with gusts up to 20 knots have resulted in 5 feet seas at buoy
44009. The winds will diminish late this afternoon into this
evening as the gradient relaxes...but persistent north-NE winds just
north of the local waters will continue to push seas to 5 feet early
this evening. Expect seas to diminish by late this evening.
north-NE winds are generally light around 10 knots or less early this
morning as a weak cold front crosses the southern waters. An upper
level low pressure system will move east across PA and then NE along
the New England coast today...before pushing well off the coast on
Thursday. Winds today through Thursday will remain out of the north or NE
at or below 15kt. Seas will increase to 3-4 feet late tonight/early
Wednesday...highest over offshore waters. Swan guidance builds seas to
around 5ft near 20nm more aggressively than wavewatch. Due to weak
cold air advection and a surface pressure gradient that is not all that
impressive...have kept 5ft seas just beyond the 20nm mark for
tonight through Thursday night. Therefore no Small Craft Advisory flags have been issued
with this forecast package. Winds veer around to the S-SW Friday
into early Saturday ahead of a strong cold front...which crosses
into the area early Saturday. Winds then quickly swing around to the
northwest behind the front by Saturday afternoon. Winds and seas diminish Sunday
into Sunday evening. A period of Small Craft Advisory conditions may be possible late
Friday into Saturday.
Marine...Small Craft Advisory until 10 PM EDT this evening for anz650.