Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1116 am EDT Sat may 23 2015
high pressure will build over the region today...before sliding
offshore late tonight and remaining just off the coast through
Near term /through tonight/...
surface high prs moves across the forecast area this afternoon. A pleasant day with
north-NE winds grdlly become E-se. Mostly sunny skies as scattered-broken cirrus
spills east of mts. Highs in the l-m70s along with comfy humidity.
Upper level ridging will build east across the southeast/Lower
Middle- Atlantic coast as surface high pushes offshore late tonight.
Resultant low level flow veers to the south-southeast overnight. This will
allow for a modest increase in dewpoints overnight, but with
mostly clear sky and light winds, expect a cool night. Look for
early morning lows in the u40s to low 50s inland to middle 50s southeast
Short term /Sunday through Tuesday/...
latter half of the Holiday weekend into early next week to be
characterized by gradual warming trend on southerly flow with the surface
high oriented offshore and an upper-level ridge amplifying across
the eastern Seaboard. Subsidence beneath the upper ridge in place will
once again serve to keep probability of precipitation at a minimum...and thus have kept
the forecast dry despite a gradual increase in dewpoints through
the period. Look for hi temperatures sun in the upper 70s to lower 80s to
warm into the middle to upper 80s Monday...and the upper 80s to low 90s on
Tuesday. Early morning lows will be in the 60s, but will
similarly warm slightly each morning.
Long term /Tuesday night through Friday/...
medium range continues to appear to be dominated with a strong upper
level ridge centered over the southeast/Middle Atlantic States through the
period. Latest European model (ecmwf)/GFS remain in fairly good agreement...with
the GFS still a bit more aggressive at breaking down/weakening
the ridge by middle to late week (though not to the extent it had
been over the past few days). Models also differ somewhat with
respect to 850 mb temperatures...the European model (ecmwf) remaining warmer by
about 2-3 c than the GFS. Overall...this pattern will lead to warm
/Summer-like/ weather through the entire period...with very minimal
chances for rain...limited to isolated/widely scattered mainly
late afternoon or evening thunderstorms developing to our north and west
drifting into the region. Will have just 20% pop over just the far
northwest portions of the County Warning Area on Wednesday...and generally a 20% pop in the late
afternoon/evening over much of the area Thursday/Friday (up to 30% far nw).
Increasing humidity and high temperatures warming back to the upper 80s
to lower 90s through the period...favoring European model (ecmwf) for highs (gfs
highs only in middle 80s well inland appears too cool in this
pattern). Conditions will generally be about 5 degrees cooler at the
coast. Lows average in the middle 60s to lower 70s through the period.
Aviation /15z Saturday through Wednesday/...
weak cold front is beginning to sag southward into the middle Atlantic
region as of 23/0500z and will continue to push south-southeastward during the
overnight hours...crossing all terminals. Any gustiness associated
with the frontal passage will be limited to korf...where north
winds off ches Bay will occur closer to daybreak (or between
23/0900-1100z). Otherwise...high pressure builds over the region
by this afternoon and remains in vicinity of the coast through Saturday night
before moving offshore Sunday and remaining anchored off the coast
through Wednesday. VFR conditions should prevail during this time
update...Small Craft Advisory flags dropped for all of ches Bay.
A weak cold front has pushed offshore and will stall as high
pressure drops south and slides off the coast this afternoon.
Winds on the Bay this morning are around 10 to 15 knots and waves
around 2 feet. This will continue through early afternoon as winds
gruadually become east.
The surface pressure gradient slackens quickly behind the weak
frontal passage this afternoon...therefore expect winds to
decrease by late morning/early afternoon as the high builds
overhead. Winds shift to the S-southeast Sat night into sun as the high
shifts off the coast. Winds should then follow a diurnal
pattern...increasing a bit mainly in the late afternoon/evening/early
am hours late sun through middle week as an upper ridge develops with
surface high pressure well off the coast. Overall conditions will
generally remain sub- Small Craft Advisory although southerly winds may gust to near 20kt
in the Bay during the aforementioned diurnal surges.