Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
401 am EDT sun may 3 2015
high pressure builds over the area overnight...then becomes
nearly stationary off the Carolina coast through middle week. A
backdoor cold front approaches from the north late Wednesday.
Near term /through tonight/...
surface high pressure axis is located over the eastern Continental U.S. From western
New York/PA down to the Florida Panhandle. The axis slides over the middle
Atlantic region today... resulting in a continuation of dry/stable
conditions under mostly sunny skies. Temperatures rebound nicely
with highs generally in the upper 70s inland and in the low-middle
70s at the immediate coast (except Atlantic side of the Maryland lower
Eastern Shore where highs will struggle to reach the middle 60s due
to south winds). For tonight...high pressure axis straddles the
eastern US coastline and allow winds to become southwesterly but light. This
will be enough to promote weak warm air advection and overnight
lows in the low-middle 50s inland and middle-upper 50s closer to the
coast (or about 5 degrees above seasonal normals).
Short term /Monday through Tuesday night/...
high pressure slides off the coast on Monday but flattens out in
the process...keeping a more dominant area of high pressure across
the Carolinas Monday night into Tuesday. Meanwhile...a trough of
low pressure crosses New England Monday afternoon through Monday night.
This feature will drag a relatively flat frontal boundary across
the northern Virginia/Delaware-Maryland-Virginia areas Tuesday into Tuesday night. Lifting
mechanisms and moisture fields are not overly impressive with this
front...however a few light rain showers are possible Tuesday
evening (mainly across the Maryland lower eastern shore). If there is
enough daytime heating/instability present...a rumble or two of
thunder may also be possible. A warming trend will persist Monday
through Tuesday. Highs on Monday/Tuesday 80-85...mid- upper 70s immediate
coast. Lows Monday/Tuesday nights in the upper 50s to lower 60s.
Long term /Wednesday through Saturday/...
going with a blend of the 12z GFS/European model (ecmwf) for the extended period.
Surface hi pressure will be centered well off the middle Atlantic CST Wednesday morng...
maintaining dry weather. A backdoor front may possibly drop into northern
portions of the region later Wednesday through Thursday. For now...have
maintained a slight chance of a shower or thunderstorm over northern and western counties
during this time. Then...Thursday night through Sat...models continue to
Show Low pressure spinning somewhere off the southeast CST. Have a slight chance of
showers mainly over southern counties Thursday night through Friday night...then a slight
chance of showers over most of the area on Sat. Otherwise...mainly dry
weather will prevail with above normal temperatures during the extended period.
Lows mainly in the upper 50s to lower 60s...with highs in the middle 70s
to lower 80s.
Aviation /08z Sunday through Thursday/...
mainly clear skies across the region as of 06z...winds generally calm or
light S/SW. Added a tempo group at kecg for MVFR visibility in shallow
ground fog (due to higher relative humidity and calm conds there). Kept any
mention of fog out of the other sites with greater temperature/dew pt
spreads and some light winds.
A light west/SW flow to prevail today under mostly sunny skies...weak
synoptic pressure gradient typically conducive to winds shifting
onshore at the coast in the afternoon so have forecast winds turning NE
at korf (speeds less than 10 knots all areas). Light S/SW flow again
tonight with a modest increase in S/SW flow on Monday.
Outlook...dry weather is indicated through Tuesday. There will be
a low chance for showers and thunderstorms Wednesday afternoon through
as of early this morning have extended the sca's on the coastal
waters through 7 am for northern waters...and through 10am for
southern waters based on latest obs/trends...still 5-6 feet offshore (and
nearshore for NC waters).
Other than seas remaining somewhat elevated on the ocean into
tonight due to swell...an extended period of benign conditions
will prevail today into Wednesday...as high pressure settles over the
waters then becomes anchored along/just off the NC and southeast Virginia coast
Mon-Wed. Fairly minimal synoptic pressure gradient will be
conducive to daily seabreezes and some increase in southerly flow
up the Bay at night (though speeds expected to remain below Small Craft Advisory
thresholds). From Monday-Wednesday seas look to average 2-4 feet while waves in
the Bay generally 1-2 feet. Backdoor cold front possible later Wednesday into
Thursday combined with surface low off the Georgia/SC CST would potentially
increase wind speeds and shift directions to the east/NE although
model guidance has been slower at bringing that surface low northward
so any significant increase in winds/seas probably holds off until
Marine...Small Craft Advisory until 7 am EDT this morning for anz650-
Small Craft Advisory until 10 am EDT this morning for anz656-