Area forecast discussion
National Weather Service Wilmington NC
1049 PM EDT Sat may 25 2013
Synopsis...
dry and cool Canadian air will prevail across the region through
the Memorial Day weekend. A warming trend will begin on
Monday...continuing through the upcoming week...with minimal
rainfall chances. Daytime temperatures may rise above normal
Wednesday through Friday.
&&
Near term /until 6 am Sunday morning/...
as of 1030 PM Saturday...via latest satellite imagery...skies east
of the mountains continue with thin upper level cloudiness...with
some patches of opaque cirrus. Latest models indicate a couple
shear vorts within northwest flow to push across the area late tonight
through Sunday. These vorts may have enough moisture to produce
opaque altocu but really do not see that happening until around or
after daybreak sun. The scouring downslope trajectory of the flow
upstairs will be working against any moisture after crossing the
Appalachians. Basically will stick with a mostly clear forecast for
the overnight. Tonights mins look on cue...with upper 40s
inland...50 to 55 at the coast. A decent surface based inversion has
developed after sunset with decoupling of the winds soon
to follow. As a result...decent radiational cooling should occur
the remainder of tonight...allowing tonights mins to range from
the upper 40s inland...to 50 to 55 at the coast.
&&
Short term /6 am Sunday morning through Monday night/...
as of 300 PM Saturday...dry and seasonable weather for the
extended Holiday weekend with seasonable temperatures and partly/mostly
sunny sky conditions.
Broad cyclonic flow at 500mb will gradually give way to a more zonal
pattern during Monday. While this keeps the middle level winds W/NW...a
cool but drying direction...subtle height rises will aid in
temperature recovery by Monday. At the surface...high pressure will
drift overhead during Sunday before taking up a position offshore
into Monday with SW return flow flooding into the area. Temperatures Sunday
will rise to around or just below 80 degrees...then bump a few
degrees warmer for Memorial Day when most locations away from the
beaches will rise into the low 80s. Sunday night will again be
cool...middle 50s across the area...but the warm return flow Monday
night will keep mins from falling out of the lower 60s.
While precipitation chances will be quite low cannot entirely rule out an
isolated shower during Monday. Increased surface temperatures create some
enhanced instability which will trigger convective clouds...and
maybe a shower. However...northwest flow above 800mb is a drying flow...and
700mb thermal ridge remains displaced slightly west of surface high
leading to a weak inversion in the 800-700mb layer. This will
preclude widespread convection...but a few showers are
possible...especially along the sea breeze boundary where surface
convergence may be enough to send parcels through this convective
lid.
&&
Long term /Tuesday through Saturday/...
as of 300 PM Saturday...medium range guidance remains consistent
in building an anomalous ridge over the East Coast with troughing
out west. Anomaly is not the most impressive with heights near two
Standard deviations above normal. The same model suite is showing
the warmer 850mb temperatures confined to areas north of US in the
Middle Atlantic States. This seems reasonable looking at model
guidance and wpc numbers which only show modest warming throughout
the period. The County Warning Area remains void of any forecast maximum temperatures
at or above 90 degrees. Slight chance probability of precipitation remain in the forecast
Tuesday then dry conditions through the remainder of the period.
&&
Aviation /03z Sunday through Thursday/...
as of 00z...VFR expected through this taf period...with scattered
middle-level clouds along with periods of scattered to broken cirrus.
Because of the dry airmass do not expect fog to be an issue
overnight.
With high pressure over kflo/klbt terminals have indicated
light/variable winds through the taf period. Light/variable
winds at the coastal terminals overnight will become northwest-NE after the
inversion breaks 13-14z. Winds will then become southeast to south
as the sea breeze kicks in by afternoon. Few-scattered cumulus can be
expected with the sea breeze.
Extended outlook...early morning fog will restrict visibilities to MVFR/IFR
Monday through Thursday at kflo/klbt. Otherwise VFR.
&&
Marine...
near term /through tonight/...
as of 1030 PM Saturday...models indicate a bubble type surface high to
break off from the main ridging that extends from the Great Lakes.
This will add some confusion to forecasting a wind direction for
the overnight and subsequent periods. With the surface pg relaxed
speeds will only be around 10 knots or less. Significant seas will
run 2 to 3 feet...and be dominated by a 2 to 3 feet easterly swell at
8 to 9 second periods. The Shoals and longer shelf waters will
keep seas around 2 feet south of Little River Inlet to South
Santee River.
Short term /Sunday through Monday night/... as of 300 PM
Saturday...high pressure will drift across the waters
Sunday...settling in a position just NE of the local waters on
Monday. This will continue a relatively light pressure
gradient...and although winds will be 10 kts or less through the
period...they will gradually go from variable...to a predominant
southerly direction late Monday. With the weak gradient and light
winds...seas will be primarily swell-driven...with a 2ft/9sec southeast
swell producing 1-3 feet waves both days.
Long term /Tuesday through Thursday/...
as of 300 PM Saturday... typical Summer pattern will allow
favorable conditions for the marine community. Middle level ridging
will build over the Middle Atlantic States with the surface ridge
axis basically over the coastal waters. South to southeast winds
of 10-15 knots will prevail. Wavewatch bulletins continue to be
void of any appreciable swell component and significant seas can
be expected to hold in a 2-4 foot range.
&&
Ilm watches/warnings/advisories...
SC...none.
NC...none.
Marine...none.
&&
$$
Synopsis...jdw
near term...dch
short term...jdw
long term...shk
aviation...mrr
marine...
