Area forecast discussion
National Weather Service Wilmington NC
854 PM EDT Friday may 24 2013
Synopsis...
high pressure will ridge down from the northwest bringing cool
and dry weather during the weekend. A gradual warm up begins on
Monday with seasonable temperatures expected for much of the
upcoming week. No significant rainfall is expected.
&&
Near term /until 6 am Saturday morning/...
as of 8 PM Friday...a broad area of Canadian high pressure will
continue to slowly build across the area. This is an unseasonably
chilly airmass. Temperatures at 850 mb will drop to around 5 degrees
celsius.
The sky will be clear through the night...but the boundary layer
will find it difficult to completely decouple overnight. Thus...
radiational cooling will be tempered by a mainly light north wind.
Dewpoints...indicative of the very dry air in place will drop into
the middle and upper 30s. Thus...there is plenty of opportunity for
temperatures to drop to near record lows and we are indeed forecasting
record lows for many locations. My only concern is that we may not
fully realize the chill of this airmass...at least tonight...given
the lack of a fully decoupled boundary layer and so lows may end up
a little higher than currently forecast. We are forecasting middle and
upper 40s for lows overnight.
The record low at ilm...50 and we are forecasting a low of 48.
The record low at flow...48 and we are forecasting a low of 47.
The record low at cre...47 and we are forecasting a low of 49.
&&
Short term /6 am Saturday morning through Sunday night/...
as of 3 PM Friday...surface high pressure ridging down from the
north and broad cyclonic flow within a longwave upper trough creates
cool and dry conditions for the weekend. While the weekend will be
pleasant with mostly sunny sky conditions other than some increased
middle level cloud cover beneath a weak shortwave late Sat
night...temperatures will struggle to 4-8 degrees below climatology for late may.
Stronger cold air advection Saturday will keep maximum temperatures only in the middle 70s even
with full sunshine. A weak surface trough associated with the
passing vorticity will turn winds briefly to the north Sat night...but a
more westerly component will develop Sunday which eases the cold air advection and
helps temperatures rise to near 80. Light winds in the cool/dry air mass
will permit decent radiational cooling Sat night...with mins falling
to 10+ degrees below normal...upper 40s in the cooler spots to
around 50 everywhere else. High pressure drifting offshore late in
the period creates some warmer southerly winds Sunday night...and
mins fall only into the low/middle 50s by Monday morning.
&&
Long term /Monday through Friday/...
as of 3 PM Friday...most of the country will remain fairly
active through the period with the notable exception of the
southeast...where middle level ridging will dominate especially late
in the extended forecast.
Wpc favors the European model (ecmwf) which shows an active middle level pattern across
the southwest with a meandering closed low and baroclinic zone
extending west to east well to our north. The only probability of precipitation for our area
are slight chance values late Monday across northern areas as a warm
front moves north and Tuesday before middle level ridging builds which
will all but put a lid on convection for Wednesday through Friday.
Temperature trends reflect the building ridge with at or just below
seasonal normals early trending to above climatology Tuesday and
Wednesday where they remain through the period.
&&
Aviation /00z Saturday through Wednesday/...
as of 00z...VFR will prevail at all terms through this taf period.
Expect clear skies tonight with north-northwest winds at or below 10 kts as high
pressure builds into the Carolinas. Dry air and subsidence
associated with this surface high should suppress any cloud cover on
Saturday. North/northwest winds around 10 kts during the day will become more
westerly after 18z...and the wind speeds will diminish as the
pressure gradient weakens over our County Warning Area.
Extended outlook...morning fog possible Monday through Wednesday.
Otherwise VFR.
&&
Marine...
near term /through tonight/...
as of 8 PM Friday...as high pressure builds slowly across the area
from the northwest...dry and cool air will continue to surge across the
waters on north winds. These winds will range from 15 to 20 knots
overnight. Seas will generally be 2 to 4 feet...but up to 5 feet across
the outermost northern waters where the fetch will be longest.
Short term /Saturday through Sunday night/...
as of 3 PM Friday...slightly pinched gradient ahead of an
advancing high pressure at the start of the period will create north/northwest
winds of 10-15 kts early Saturday before the high moves overhead
causing much weaker wind speeds. Winds become northwest less than 10 kts
Sat night into Sunday...before veering to the southeast at less than 10 kts
Sunday night when high pressure moves offshore. Combination of light
winds and a weak 2ft/8sec southeast swell will keep wave amplitudes low
through the period...1-3 feet...highest early Saturday.
Long term /Monday through Wednesday/...
as of 3 PM Friday...the marine community can expect a
summertime pattern through the period with south to occasionally
southwest winds. Wind speeds will hover around 10-15 knots for
most of the period with the higher end Tuesday as the gradient
increases courtesy of a wave moving by well to the north. Seas are
representative of a Summer pattern as well with 2-3 feet with
mostly shorter period wind waves.
&&
Ilm watches/warnings/advisories...
SC...none.
NC...none.
Marine...none.
&&
$$
Near term...rjd
short term...jdw
long term...shk
aviation...bjr
