Area forecast discussion
National Weather Service Wakefield Virginia
834 PM EDT Friday may 24 2013
Synopsis...
surface high pressure builds over the Ohio Valley tonight. High
pressure will continue to build into the middle Atlantic this
weekend...resulting in dry and cool conditions. A warming trend
will begin Memorial Day through next week.
&&
Near term /until 6 am Saturday morning/...
a much cooler and drier airmass has moved into the region this
evening. Temperatures at 8 PM EST are generally in the middle to upper 50s
and on track to fall into the low to middle 40s overnight under
mostly clear skies. One area of exception will be the Maryland/Virginia
Eastern Shore where a stratus deck will remain persistent
overnight...preventing temperatures from falling below the middle 40s for
interior locations and no lower than the upper 40s to lower 50s
along the immediate coast.
Northwest winds with gusts up to 25 miles per hour will subside through the evening
from west to east. Near the coast...winds will stay elevated and
gusty overnight as an upper level trough swings through the region
late tonight...which is then quickly followed by a 100-120 knots jet
streak. Northwest wind gusts of 30-35 miles per hour will be common along coastal
areas tonight into Saturday morning.
&&
Short term /6 am Saturday morning through Monday night/...
upper pattern during the short term will be characterized by a
trough in both the west and east with ridging over the ctrl
Continental U.S.. upper closed low will develop off the middle Atlantic coast
Sat...slowly lifting up the NE coast Sat-sun due to blocking over
the western Atlantic. Confluence aloft will usher in cool surface high
pressure over the weekend. The resultant deep layer northwesterly flow will
result in dry...but cool conditions through the Memorial Day
weekend. 850mb temperatures will fall as low as 2 Standard dev below normal
this weekend...with temperatures generally upper 60s/low 70s Sat and low
70s sun (-1 Standard dev). Temperatures will fall into the middle/upper 40s Sat
night and upper 40s/low 50s Sun night.
Meanwhile...stalled frontal boundary over the northern Gulf will begin
to lift northward late Sunday and Monday...locating over the deep south
Monday morning...extending nwwd into the plains. Upper ridge will
finally progress eastward Monday as the upper low over southeast Canada lifts. As
a result...a warming trend will commence Monday. As the ridge
progresses eastward...a warm/moist airmass will interact with the
boundary to produce showers and thunderstorms over the Midwest
into the Ohio Valley Monday afternoon. Activity then expected to
form into a mesoscale convective system. Mesoscale convective system will round the
ridge...but will die out before reaching the mid-Atlantic.
Boundary will continue to lift northward Monday night...with better
chance for showers and thunderstorms in the extended period.
&&
Long term /Tuesday through Friday/...
have again gone close to a European model (ecmwf)/hpc(wpc) blend for the midweek time
frame. Have allowed for some rain showers/isolated T later Tuesday as warm front
lifts north across the area, with best chances across areas north of
fvx/ric/wal line.
The front shunts north of the area for the middle to latter part of the
week. Meanwhile, middle-upper level ridging rebuilds across the eastern
half of the Continental U.S. As surface high slides off the middle-Atlantic coast.
Resultant Bermuda high/Summer-like setup will allow for increasing
temperatures (and humidity values) for the middle to latter part of next
week. Rainfall opportunities during this period will primarily be
diurnally driven, with little more than partly cloudy and
increasingly muggy conditions by night.
&&
Aviation /00z Saturday through Wednesday/...
potent middle/upper level trough pivots offshore this evening and
overnight. Middle-level stratus (4-5k ft) will remain stubborn across
the Virginia Northern Neck onto the Eastern Shore for the next several
hours...if not much of the overnight hours...before finally scouring
out. Otw...clear/VFR ceilings expected at remaining taf sites tonight.
Winds will continue to diminishing through 02z...ending up at or below 10 knots
overnight for most taf sites.
VFR/dry conditions on Sat...but all sites can expect gusty northwest
flow...to 20-25 knots (25-30 knots at ksby). Generally sky clear with lighter winds
Sat night-sun.
Generally dry/VFR through Monday with increasing moisture later Monday-
Tuesday as a warm front begins to affect the area. This would be next
chance for more significant ceiling/visibility restrictions.
&&
Marine...
Gale Warning currently in place over the Northern Bay zones and
far northern coastal zones. Wind gusts are very close to gale in
these areas at this time...and with strongest surge of cold air advection just not
arriving...expect predominate gusts to gale for a few hours between
00z/8p and 10z/6a. Have run headline through 15z/11a for now...with
the idea that overnight crew can keep an eye on observation and expire
early as needed.
Seas will run on the order of 5-8 feet on the coastal waters...waves
~2 feet on the sound...2-3 feet on the rivers...3-5 in the lower ches
Bay. Period of Small Craft Advisory flags will be re-issued as soon as gales are
expired as developing low pressure off New Jersey/southern new eng coast slowly
lifts to the NE into sun...resulting in only gradual improvement
(sca per wavewatch potentially to linger over the northern ocn waters into
late sat). Small Craft Advisory flags drop off over all but coastal areas Sat
night...extending into early Sunday over northern coastal zones.
Far more favorable boating conditions expected for the latter half
of the Holiday weekend as high pressure builds in from the northwest. Winds
and seas will gradually diminish through this period with west winds at or below 15
knots.
&&
Akq watches/warnings/advisories...
Maryland...none.
NC...none.
Virginia...none.
Marine...Small Craft Advisory until 6 PM EDT Saturday for anz633-
635>638.
Small Craft Advisory until midnight EDT Saturday night for
anz632-634-654-656-658.
Gale Warning until 11 am EDT Saturday for anz630-631-650-652.
&&
$$
Synopsis...Sam
near term...bmd
short term...Sam
long term...mam
aviation...lkb
marine...mam
