Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
500 am EDT Sat Nov 1 2014
a strong low pressure system will develop off the North Carolina
coast today...pushing northeast of the area tonight into Sunday.
High pressure returns over the region late Sunday through Tuesday.
Near term /until 6 PM this evening/...
latest surface analysis reveals ~1001 mb low pressure off the middle Atlantic
CST with a weaker second area of low pressure developing off the SC/NC
CST. Aloft...a very potent upper-level trough continues to dig across
the southeast states. There are currently two areas of note in terms of
precipitation...one just off the Delaware-Maryland-Virginia CST and another approaching the
Virginia Piedmont. Both areas are struggling to make it into the County Warning Area as
subsidence remains with somewhat dry low levels as well. Therefore
kept probability of precipitation mainly in the chance range this morng...increasing through
the day as lift and moisture increase. With the best forcing
associated with the upper trough remaining S of the area today...not
expecting much in the way of heavy rain...with overall quantitative precipitation forecast amounts
being minimal and generally less than 0.25in. The highest amounts
(0.25-0.50in) should be across the lower Eastern Shore where the
duration of rain should be longest.
With surface cyclogenesis off the Outer Banks this
afternoon/evening...a period of strong north wind (25-35 miles per hour with
gusts to ~45 mph) is expected along coastal zones as the low
deepens off the coast and strong cold air advection commences. Areas of minor
tidal flooding are expected along the Atlantic beaches and lower ches
Bay (see coastal flooding section below). A Wind Advisory may be
needed over at least some of the coastal zones tonight for a 6-10
hour period. This will remain highlighted in the severe weather potential statement.
Short term /6 PM this evening through Monday/...
rain will taper off tonight with subsidence in the wake of the
departing wave. The sky clears out quickly into Sunday morning
(although a band of SC could develop off the Bay Sunday due to the
cooler drier air advecting over sst's ~62-64f). The surface high of
Canadian origin sinks from the Ohio Valley into the southeast
beginning Sunday. This will usher in the coolest air of the season
to date. Highs Sunday should range from around 50 N/NE...to the
middle 50s S. The first widespread freeze of the season should occur
late Sun night/early Monday morning as lows drop to 29-32 over the
interior coastal plain and Piedmont. Enough surface pressure gradient
will likely linger closer to the coast...which will keep lows in
the middle/upper 30s.
The high shifts offshore Monday...with south-southwest flow resuming across the
region. Highs should rebound into the upper 50s/lower 60s under a
mostly sunny sky.
Long term /Monday night through Friday/...
medium range period characterized by general moderation of
temperatures to begin the period as high pressure slides off the
southeast coast Tuesday/early Wednesday with resultant
south-southwest flow allowing maxima to rebound into the 60s to
lower 70s Tuesday and Wednesday, with early morning lows moderating
back into the 40s to near 50 Wednesday and Thursday morning.
Aloft, upper pattern will be characterized by upper ridging, which
will gradually break down and slip offshore late Wed/Thu. Northern
stream disturbance traversing the Canadian prairies into the upper
Great Lakes during the midweek period, with the associated weak
surface front dropping into the area by late Wednesday ngt/Thursday. Once
again, the best forcing/dynamics look to remain confined to the
north/northeast. Therefore, suspect the frontal passage will once again have
little moisture with which to work. Will keep pop no higher than 20%
for Wed/Thu...with only a slight drop off in temperature Post
frontal late in the into the 60s, with early morning lows near climatology
values Friday and Sat mornings.
Aviation /09z Saturday through Wednesday/...
low pressure off the middle Atlantic CST early this morng...will
strengthen offshr while lifting NE today into sun morng. North-northeast
flow/winds will increase across the area...esply later this morng
into this eveng. This will result in lowering clouds to MVFR ceilings
and isolated IFR ceilings along with -ra. The low will pull away to off
the New England CST and toward the Canadian Maritimes late tonight into
Sun afternoon. VFR conditions should return to all taf sites sun
morng...but gusty northwest winds will linger through the day on sun. Hi
pressure builds into and over the region Sun afternoon into Tuesday.
low pressure was off just off the middle Atlantic CST early this morng...and
will intensify today into tonight...as upper air low pressure energy dives east-southeast
off the coastal Carolinas then lifts NE. Have adjusted Small Craft Advisory/Gale Warning
headlines while also extending them through most of sun. For gale
warnings...will have gusts to around 40 knots or gusts up to 45 knots...esply
for tonight into sun morng. Waves/seas will build quickly this afternoon
into tonight...as north winds rapidly increase due to strengthening low
pressure off the CST. Northwest winds will gradually diminish sun eveng into
Monday morng...as the low moves into the Canadian Maritimes and hi
pressure builds in from the west.
low pressure is expected to rapidly strengthen off the coast late
Saturday afternoon into early Sunday morning. Strong north-northwest winds are
likely to result in tidal departures on the order of 1-2 feet above
normal Saturday night along the Atlantic coast and Lower Bay.
Minor tidal flooding is expected for these locations as the surge
appears to coincide with the high tide cycle Saturday night/early
Marine...Small Craft Advisory from 1 PM EDT this afternoon to 10 PM EST
Sunday for anz635>637.
Small Craft Advisory until 4 PM EDT this afternoon for anz634-
Gale Warning from 4 PM EDT this afternoon to noon EST Sunday
Gale Warning from 4 PM EDT this afternoon to 10 PM EST Sunday