Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1136 am EDT Sat Aug 30 2014
a frontal boundary will dissipate over the area today. High
pressure builds over the southeastern states through early next
week...resulting in an increase of heat and humidity through the
middle of the upcoming week.
Near term /through tonight/...
midday weather analysis features a weakening frontal boundary
extending from southeast Virginia/NE NC border back into far western Virginia. The
low stratus from earlier this morning has begun to lift/scatter
out over the last few hours, and expect this trend to continue
over the next few hours.
Despite an increasingly moist/humid airmass, support for
convection is rather weak today, as forcing remains well back
into the mountains and farther west into the Ohio Valley. Have
removed pop for the afternoon for the western half of the area,
but held onto a slight chance pop for a few isolated pulse type
convection over southeastern sections...mainly southeast of a
Williamsburg to Jackson.
Overall, a warm and moderately humid afternoon, with afternoon high
temperatures in the middle 80s north (along with Eastern Shore and
coastal locations)...with upper 80s to near 90 south.
Short term /Sunday through Monday/...
for sun and Monday...upr-level ridge flattens out but with surface hi
pressure remaining offshore with a persistent southerly flow over the middle
Atlantic...temperatures will be about five to eight degrees above normal.
Expect highs Sunday and Monday ranging from near 90 to the lower 90s
except middle to upper 80s on the lower Eastern Shore and along the
coast. Lows will be in the upper 60s to middle 70s.
Due to the upper level ridging over the southeast states...the
main support for showers and thunderstorms will remain to the
north. This is despite precipitable water getting into the two
inch range over parts of the County Warning Area. For Sunday afternoon...have 30
percent probability of precipitation over portions of the Piedmont counties north to near
Caroline County and on the lower Maryland Eastern Shore with lower
chances to the south. There are some indications...mainly from the
GFS...of some precipitation overnight Sunday night/early Monday morning and
have slight to low chance across northern portions. Chances for precipitation
are 30 percent most locations Monday afternoon with 40 to 50 percent probability of precipitation
over the Maryland Eastern Shore.
Long term /Monday night through Friday/...
Summer-like pattern will persist through the medium range period
as middle/upper level ridging centered along/off the southeast US coast...
gradually shifts to the west-southwest and becomes anchored from the Gulf
Coast to Tennessee Valley. Temperatures will begin about 5-10 f above average
Tuesday before falling a few degrees Wednesday-Friday (although readings will
remain a little above average through the end of the week).
After a fairly high chance for scattered thunderstorms Monday evening (~40%)...Tuesday
should be mainly dry in between the departing wave and a cold
front that is slow to approach from the northwest. Mostly sunny with
highs generally in the lower to middle 90s. Will carry a 20-30% chance for
Tuesday evening as the cold front moves closer to the local area and
heights aloft drop as the ridge breaks down. Did not go any higher
however...as front looks to be weakening at this time and best
lift/forcing remain north/west of the local area. Will carry 20-30%
mainly over far southern Virginia/NE NC Wednesday as the boundary is slow to
push through. Highs mainly upper 80s-lower 90s Wednesday.
By Wednesday night-Fri...a general consensus of the GFS/ECMWF/wpc forecast
does place the surface cold front south of the area with high pressure
centered from the Great Lakes to the NE Continental U.S.. this should allow
slightly cooler/drier air to move into the region...but the front
does not looks very strong so highs will still average 85-90 f Thursday/Friday
(coolest along the coast and eastern shore). Generally dry /partly-mostly
sunny but will keep diurnal afternoon/early evening 20% probability of precipitation across the
Aviation /15z Saturday through Wednesday/...
surface high pressure centered off the NE coast continues to ridge southwestward
over the local area. The result is onshore flow and abundant low
level moisture. Ceilings generally broken-overcast with decks 4-6k feet above ground level...with
a few locales over the Piedmont dropping to MVFR. Expect VFR
conditions to prevail through the early morning...but scattered-broken MVFR ceilings
possible between 10-12z at kric/kphf/kecg. No IFR anticipated.
For today...surface high pressure pushes off the NE coast as flow veers
to the S-southeast at or below 10 knots. Modest middle-level moisture indicated in bufr
soundings will resulting in a scattered-locally broken 4-6k feet above ground level deck
this afternoon with only high clouds by late today-this evening.
Only a slight chance of showers exists across southern Virginia...including
Outlook...mainly dry weather with continued VFR conditions expected
through much of the upcoming Holiday weekend. Slight to low
chance probability of precipitation for afternoon/evening thunderstorms Sunday evening increase to 30
to 40 percent Monday ahead of the next frontal passage. Otherwise,
some potential for fog or low clouds will exist each day within a
few hours of sunrise.
onshore flow averaging 10 knots persists over the waters as high
pressure remains centered off the NE coast. Waves average 1-2 feet with
seas 2-3 feet. High pressure pushes off the NE coast today as flow
veers to the S-southeast over the water. Gradient strengthens tonight as
low pressure lifts over the Great Lakes region. This will push winds
into the 10-15 knots range...remaining sub-sca. With relatively warm
waters...could see some diurnal effects with S-southeast flow channeling up
the Bay tonight and again Sun night with winds increasing to around
15 knots (and gusts close to 20 kt). However...headlines not
anticipated. Seas remain generally 2-3 feet...but persistent S-southeast flow
could push seas to 4 feet late tonight and Sunday before building to
3-4 feet all coastal zones late Sunday into Monday. Waves generally
1-2 feet...but may build to 2-3 feet tonight and again Sun night.
Sub-Small Craft Advisory conditions continue into early next week as high pressure
remains offshore. Seas average 2-4 feet and waves 1-2 feet. Next cold front
prognosticated to reach the waters Tuesday night-weds.
Maryland...moderate rip current risk until 8 PM EDT this evening for
NC...moderate rip current risk until 8 PM EDT this evening for
Virginia...moderate rip current risk until 8 PM EDT this evening for