Scientific Forecaster Discussion
fxus61 kakq 251035
Area forecast discussion
National Weather Service Wakefield Virginia
635 am EDT Thu may 25 2017
unsettled conditions will continue today as an upper level
trough approaches from the west. Conditions improve on Friday. Warmer
temperatures and chance for showers and thunderstorms will
return over the weekend. A cold front will approach from the
west on Memorial Day.
Near term /through tonight/...
a cold front is quickly crossing the forecast area this morning, taking
with it the remaining showers from overnight. These showers will
push east and exit eastern areas thru 12-13z. Mixing taking
place behind the front is causing breaks in the clouds across
the Piedmont this morning and expect at least partial sunshine
to spread east thru the morning. Should be a nice mid to late
morning period with dry conditions.
A potent upper low over the Ohio Valley this morning lifts NE
across the mountains through the day. A strong shortwave trough
will lift across the mid-Atlantic during the afternoon/early
evening. Pops ramp up quickly again by noon-2pm...to 55-70%
from the Piedmont to central Virginia to the Maryland ern shore, with 40-50%
far southeast. 500mb flow of 45-55 kt is expected along with modest
instability. Therefore...a few stronger to marginally severe
storms are possible. The main threat would be wind and hail as
low-level shear is minimal but a decent cold pool aloft will
exist. Additional quantitative precipitation forecast this aftn/evening should average up to
~0.25" with locally higher amounts possible. Highs today in the
mid 70s west of I-95 to the upr 70s to near 80 across eastern
portions of the forecast area.
Short term /Friday through Saturday/...
the upper low continues to lift NE across PA/NY/New England
late tonight into Fri. Drier conditions finally arrive as deep
layered west-northwest flow develops over the region. Some lingering mid-
level energy could result in scattered-broken cumulus mid/afternoon Fri.
Otherwise...drier and breezy with highs in the upr 70s to low 80s,
after morning lows in the mid 50s west to low 60s at the coast.
Weak ridge aloft nudges into the region from the west-southwest Fri night
into Sat. Differing potential/timing in arrival of weak short wave
tracking into the forecast area by Sat afternoon. Combination of daytime
heating and that short wave in west-northwest flow aloft may result in at least
scattered convective development. Otherwise...partly cloudy Fri
night-Sat morning...then becoming mostly cloudy Sat afternoon.
Lows from the upr 50s northwest to the low 60s southeast. Highs Sat from the
mid/upr 70s-around 80f on the Eastern Shore to the mid 80s
Long term /Saturday night through Wednesday/...
long term period starts off Sat night into sun with a warm front in
the vicinity and plenty of energy passing through the west-northwest flow
aloft. This will lead to a chance of shras/tstms everywhere, with
low temps in the 60s Sat night and high temps in the low/mid 80s
sun. Continued chance of rain into Mon with a weak cold front
passing through the area. Highs again in the low/mid 80s. Drier
weather into Tue and Wed behind the front, but still cannot rule out
the chance of a shra or tstm with continued cyclonic flow aloft.
High temps in the upr 70s to mid 80s both days.
Aviation /12z Thursday through Monday/...
showers ahead of a cold front will continue to lift NE and exit
eastern locales including ksby by 12-13z. Conditions will
improve to VFR once the front passes. Additional showers and
thunderstorms are expected to develop this afternoon as an
upper trough moves overhead. Reduced flight conditions are
Drier/VFR wx returns by Fri as weak high pressure builds over
the region. Unsettled conditions return for the weekend when
another frontal boundary affects the mid Atlantic states.
latest msas has the frontal boundary stalled just south of the
Albemarle Sound westward to a cold front crossing the mts. The
boundary is still progged to lift north as a warm front this morning
before the cold front crosses the waters this afternoon and evening.
Once again, a challenging forecast as the models continue to show
different solutions with respect to the frontal movements. Thus,
will basically keep the current forecast going with some minor
changes made to the grids and headlines.
Consensus suggests several bouts of Small Craft Advisory level winds over the next 24-
36 hours. Thus, elected to keep just one headline through Friday to
cover the winds but tweaked directions a bit based off the
frontal movements. SW winds 15-20 kts through this evening
become west at the same speeds late tonight and Friday as the
cold front moves offshore. Went ahead and added Small Craft Advisory to the
Currituck Sound. Data also supports 15-20 kts today across the
lower James River so added a Small Craft Advisory headline there. Current sea obs
in line with wna forecast in keeping 4-5 ft seas through Friday
across the coastal waters (highest out near 20 nm).
Weak high pres builds in for late Fri leading to improving marine
conditions. Sub-sca conditions expected Fri night into the weekend.
the continued onshore flow combined with high astro tides will
result in elevated water levels through Friday. The south-southeast winds
continue to pile up the water across the middle ches Bay so
based off the latest data, went ahead and extended the coastal
flood advisory for the Bay Side of the lower MD Eastern Shore
for the next high tide cycle. Also issued coastal flood statements
for the VA Northern Neck and Atlantic coastal waters from oxb-Cape
Charles for levels approaching minor flood levels. See cfwakq
for more details.
Maryland...coastal flood advisory until 4 PM EDT this afternoon for
Marine...Small Craft Advisory until 4 PM EDT Friday for anz630>634.
Small Craft Advisory until 6 PM EDT this evening for anz638.
Small Craft Advisory until 1 PM EDT Friday for anz650-652-654.
Small Craft Advisory until 7 am EDT Friday for anz656-658.