Scientific Forecaster Discussion
fxus61 kakq 191233
Area forecast discussion
National Weather Service Wakefield Virginia
733 am EST sun Nov 19 2017
a strong cold front moves across the area this morning then
pushes off the coast by midday. High pressure builds into the
area this afternoon through Monday, before sliding offshore
Monday night through midweek. The next cold front crosses the
area on Wednesday.
Near term /through tonight/...
7am update...front pushing toward the coast at 12z, and should
be offsshore by mid morning. Shower wording has been removed for
all but southeast coastal zones.
Previous valid discussion...
hi-res models jiving very well with obs thus far, and a period
of rather gusty winds (30-40 mph) still anticipated over the
next few hours, with winds maxing out immediately behind the
frontal passage across the entire area, as some of the cold air
surge gets mixed down by strong subsidence behind the front.
Winds decrease slightly later this morning, but remain breezy
through the day, owing to still-tight pressure gradient and
mixing up to 875 mb. Northwest winds gusting to 25 to 35 mph (strongest
far north and Maryland eastern shore) through the afternoon before
they drop off.
Temperatures at 08z remain in the low to mid 60s (upper 50s far
west) across the local area. Temperatures do fall off quickly
behind the front over the Piedmont, reaching the upper 40s/low
50s by sunrise.
Cold front and sct showers along the coast just after sunrise
will push offshore by mid-morning. Subsequent subsidence will
allow for quick scouring out of the vertical column, with mostly
sunny conditions most zones by late morning. Blustery with
gusty west-northwest winds and only a slow rise in temps despite the
plentiful sunshine. Highs in the mid 50s- lwr 60s.
Sfc high settles over the sern states tonight through Monday,
sliding offshore Monday night into Tuesday. Look for early
morning lows in the mid/upper 20s Piedmont to mid 30s far southeast
zones under a mainly clear sky.
Short term /Monday through Wednesday/...
rather benign weather pattern to start the Holiday week.
Aforementioned high pressure sliding offshore of the southeast
coast will maintain dry weather across the mid-Atlantic and
southeast. Model thicknesses recover nicely and should allow for
a pair of pleasant late fall days. Highs Mon in the upr 40s to
low 50s Eastern Shore. Low to mid 50s west of the Bay. Partly to
mostly clear Mon night. Not quite as cool as flow turns around
to the west-SW, with some increasing mid to high clouds late. Early
morning lows in the 30s to near 40 se. Warmer in return flow on
Tuesday. Could see a few showers in association with a weak low
pressure sliding along the coastal Carolinas, but have kept the
daylight hours dry and held to slight/low end chance Tuesday
night for now. Highs Tue in the upr 50s to lwr 60s. Lows in the
40s to low 50s southeast zones.
Long term /Wednesday night through Saturday/...
model differences make for a challenging mid week and Holiday
fcst. The next cold front progged to cross the area tues nite.
Challenge comes from just how much moisture gets entrained ahead
of the front from a trof off the Carolina coast and weak low
progged to move NE along it? GFS much more aggressive with the
moisture than the European model (ecmwf). For now, elected to keep measurable
rainfall east of i95 Tue nite and Wed with slight chc pops
across the east thurs. Lows Tue nite in the 40s to near 50 se.
Highs Wed 55-60. Lows Wed nite in the 30s to lwr 40s se. Cool
thurs with highs mid 40s-lwr 50s.
Dry and cool Fri and Sat as high pressure builds into the area.
Highs Fri 50-55. Lows mid 30s-lwr 40s. Highs Sat 55-60.
Aviation /13z Sunday through Thursday/...
VFR conditions across area terminals to begin the taf period,
with VFR conditions to prevail through this evening and beyond.
West-northwest winds will remain gusty out of the west/northwest with gusts as high
as 30 to 35 knots.
Outlook: high pressure builds over the region Sunday evening
through Monday, then tracks off the southeast coast on Tuesday.
VFR conditions are expected during this time frame.
forecast well on track with cold front crossing central Virginia as of
300 am and then passing through the waters for a few hours
around sunrise. Solid Small Craft Advisory conditions (ssw 15-25kt with gusts up
to 30kt) Bay/sound/rivers with low-end gale force gusts over the
coastal waters. Seas 5-9ft north of Virginia beach; 3-5ft south. Waves
4-5ft. Strong cold air advection, a very tight pressure
gradient, and rapid pressure rises (5-9mb) behind the front will
all contribute to a quick wind shift to northwest 20-30kt with gusts of
25-40kt through today. Windy conditions will be common
everywhere (including land areas) and generally uniform with
slightly stronger winds occurring over the warmer waters. Winds
should remain generally unchanged through late tonight with northwest
winds averaging 15-25kt/gusts 30kt (30-35kt north of Parramore
island), however seas will gradually subside overnight due to
the offshore wind component. Seas 3-5ft all coastal waters
tonight. Waves 4ft this evening...subsiding to 3-4ft after
midnight. Marine flags remain unchanged and will expire at
previously set times.
High pressure builds over the southeast states into the srn mid
Atlantic region Mon/Mon night...sliding offshore on Tuesday.
Adverse boating conditions Monday morning will subside during
the day with more benign/quiet sub-Small Craft Advisory conditions anticipated
through Tuesday night. Seas 2-4ft north/2-3ft south during this
time. Waves generally 1-2ft. Models in fair agreement with
developing a low off the southeast coast...passing east of Cape
Hatteras Wednesday afternoon. Next chance for Small Craft Advisory conditions
should be Wednesday. With high pressure passing north of the
area, this may be the beginning of an active weather pattern
over the waters going into next weekend.
The Fan on the temperature sensor at the Richmond ASOS (kric)
has likely failed, causing erroneous temperature readings. The
contract observer is augmenting the official metar observations
(hourly metar and specis). However, the 5-min high resolution
data is automated directly from the sensor and is subject to
reporting this erroneous data. As such, do not rely on the 5 min
temperature data from kric until our techs can repair the
sensor, likely on Monday.
Marine...Small Craft Advisory until 7 am EST Monday for anz633-635>638.
Gale Warning until 3 PM EST this afternoon for anz634-656-658.
Small Craft Advisory until 10 am EST Monday for anz630>632.
Gale Warning until 4 am EST Monday for anz650-652-654.