Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
448 am EDT Tuesday Jul 22 2014
high pressure will remain off the Canadian Maritimes through
today...as a frontal boundary remains nearly stationary from the
deep south to the coastal Carolinas. A cold front will approach from
the west on Wednesday...and push across the region Thursday into
Thursday night. High pressure will build over the area on Friday.
Near term /through tonight/...
forecast area will remain in an unsettled/murky patter surface-aloft through
tonight. Upper air low pressure will linger over the Gulf CST states while
weak hi pressure over the NE U.S. Slides east and off the middle Atlantic CST.
Deeper moist/scattered precipitation from the Carolinas and southeast states will try to
spread north-northeast into the County Warning Area later this morng into early tonight. Highest
chances (30-40%) will remain across the southern half of the region where
the best instability/dynamic forcing is forecast. East-northeast winds will turn
to the southeast or S during the day...and with at least partial sunshine
expected...maximum temperatures today will be mainly in the middle to upper 80s
inland...and 80 to 84 near the CST. Lows tonight in the upper 60s to
Short term /Wednesday through Thursday/...
by Wednesday...next trough aloft tracks through the Great Lakes and gradually
amplifies into the NE/middle Atlantic regions Wednesday into Wednesday night...pushing
the next surface cold front toward the forecast area. Low level flow becomes more south-southwest on
Wednesday...resulting in better opportunity for partly to mostly sunny
conditions and temperatures responding to near or slightly above seasonal
normals. Will maintain probability of precipitation at 20-30% on Wednesday...esply for Wednesday
aftn/eveng. Hi temperatures will be in the lower 90s inland...with 85 to
90 near the CST.
Adjusted probability of precipitation at bit for Wednesday night through Thursday...based on the latest
model fcst's (esply the GFS/ecmwf) movement of the next cold
front. Mainly have 30-40% probability of precipitation Wednesday night...with 50-60% probability of precipitation Thursday afternoon
into Thursday night. Lows Wednesday night in the lower to middle 70s...with highs on
Thursday ranging from the middle 80s to lower 90s. Some stronger storms could
be possible Thursday afternoon into Thursday night across southern/southeast Virginia and NE NC.
Long term /Thursday night through Monday/...
a cold front is forecast to move south of the local area Thursday
night into Friday morning...before stalling over North Carolina later
Friday. Because of the slow progress of the front will continue to
carry solid chance probability of precipitation all areas Thursday night (highest se). By
Friday...chance probability of precipitation will be limited to the southern half of the County Warning Area
nearest the front. Surface high pressure should begin to nudge into
northern parts of the area during the day...so have kept locations
north of Richmond dry. The front should sag far enough south by
Friday night to bring dry conditions all areas. However...will keep
slight chance probability of precipitation across NE NC...pending agreement of next couple of
model runs. Saturday is shaping up to be a dry day with high
pressure in control. By next Sunday/Monday...the front lifts back
north as a warm front and typical diurnal summertime convection will
again be possible. Highs through the period will mainly be in the
80s...except some low 90s inland by sun/Mon. Lows in the 60s to low
Aviation /09z Tuesday through Saturday/...
onshore flow continues to maintain low level moisture and thus
increased confidence in lowering ceilings between 07-12z. VFR
conds in place across area terminals should diminish over the next
2-3 hrs, west/ MVFR/ tempo IFR conds most or all of the sites. Precipitation
is not expected to be a factor through Tuesday morning, though did
include a vcsh at orf with some light returns just off southeast Virginia coast.
Conds quickly improve by middle to late morning with VFR occasional MVFR
prevailing most of the day. Convection is expected to be rather
isolated and mainly SW of terminals.
Outlook...little change expected for Wednesday except for a bit
of an increase in shower and thunderstorm activity in the afternoon.
Widespread showers and thunderstorms are forecast Thursday and
Thursday night as a cold front approaches and then moves through
the area. Friday and Saturday should be mostly dry/VFR, although a
few showers and thunderstorms will be possible Friday afternoon...especially
in the southeast.
Note: observations from sby are not readily available...technicians
are aware of the problem.
latest observation reflect a light easterly flow over the waters this
morning, ahead of a quasi-stationary frontal boundary extending SW
to NE along the southeast coast this morning. Meanwhile, surface high pressure
remains off the New England coast. Weak frontal boundary offshore
will slowly lift north and washout by midday, with winds becoming southeast
this afternoon at or below 10 knots. Winds veer around to the SW tonight, ahead
of next cold front approaching the waters from the west. Winds
gradually ramp up as gradient tightens ahead of the front. S-SW
winds increase to ~15 knots late Wednesday/Wednesday night, as model guidance once
again has become a bit quicker with the frontal passage. Latest
guidance indicates front will push across the waters from the northwest
Thursday/Thursday afternoon. Winds veer to the north-NE late Thu/Friday. Given a
rather weak cold air advection surge, Small Craft Advisory conditions are not expected at this time. Stayed
close to nwps depiction for significant wave heights, with seas 2-3
feet building to ~4ft Wednesday night/early Thursday before subsiding as
winds become north-NE Friday. Waves will remain 1 to 2 feet.
Maryland...moderate rip current risk through this evening for mdz025.
NC...moderate rip current risk through this evening for ncz102.
Virginia...moderate rip current risk through this evening for vaz098>100.