Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 120633

Area Forecast Discussion
National Weather Service Wakefield VA
233 AM EDT Sat Aug 12 2017

A weak frontal boundary remains near the local area today...resulting
in a high probability for showers and scattered thunderstorms.
A cold front crosses the region tonight...then stalls across the
Carolinas early next week as a series of low pressure systems
moves east along it.


Watching a strong thunderstorm head east toward Dorchester
County MD late this evening which is really the only area of
concern on the radar attm. Another slug of light to moderate
rain is moving across the SE Piedmont and will continue to
spread slowly east over the next couple of hours. Have adjusted
near term pops to account for these areas of pcpn. Elsewhere,
have minimal pops until after midnight.

Guidance suggests best likelihood of pcpn shifts east into E/SE
VA after midnight where the pops will be the highest. Isold thunder
possible as well and could be some pockets of heavier rain given
high PWs. Humid overnight with lows 70-75.

Low pressure lifts well north of the area Sat with the trailing cold
front weakening as it pushes across the mountains late in the day.
Strong height falls remain north of the region, but increasing winds
aloft and a strong influx of deep moisture associated with PW`s over
2 inches ahead of a lee/thermal trough will result in additional
scattered to numerous showers and thunderstorms. High end chc
to likely pops Sat morning with high end likely pops all areas
Sat afternoon. SPC has once again put most of VA and all of MD
in a marginal risk. The degree to Saturdays severe threat will
be whether any sun can occur during the late morning and early
aftn to destabilize the airmass. The main threat again is strong
wind gusts and heavy downpours. Given the anomalous moisture
feed and updated QPF forecast, have heavy rainfall mentioned in
the forecast for SE VA and NE NC on Saturday. Also hoisted a
flash flood watch for these areas from 6AM-8PM given recent
trends in the hi-res guidance showing heavier QPF amounts and
the heavy rain (2-4") that occurred earlier Friday over
interior NE NC. Highs Saturday 80-85.

The cold front crosses the fa Sat evening, then pushes offshore
late. Deepest moisture gets shunted offshore, but enough
lingering moisture to keep likely pops going across the east
early, tapering off to chc pops after midnight. Somewhat cooler
behind the front with lows ranging from the mid 60s NW to the
mid 70s sern coastal areas.


That frontal boundary will linger just S of the area or near
the SE VA/NE NC border Sun aftn thru Mon, maintaining slgt chc
to likely Pops fm N to S Sun aftn thru Sun night, then chc Pops
to likely Pops fm N to S Mon into Mon evening, as the boundary
lifts a little farther N with a wave of low pressure moving ENE
along it. Highs on Sun and Mon 80 to 85. Lows Sun night in the
mid 60s to lower 70s.


The period begins with more wet weather expected from Monday night
into early Wednesday as a frontal boundary remains stalled across
the Mid-Atlantic States and the Carolinas.  The biggest question has
been the location of the front which the GFS and ECMWF have had a
hard time reaching a consensus as run to run consistency has waffled
the front from over us to areas south of the forecast area.  The 12z
ECMWF run of the models has the front and associated surface wave
lifting over the Mid-Atlantic states while in the 12 GFS the front
remains south of the area and holds the bulk of the rain further
south over the Carolinas.  This is a flip from yesterdays runs.  So
for now, have generally played a scenario where the front stall near
the area and the wave of low pressure moves along the front and
should impact much of the area on Tuesday.  Have added likely pops
to SE VA and NE NC as this area appears to have the best chance of
rain on Tuesday/Tues night.

By Wednesday...the front will get drug south of the area as the wave
moves off the coast.  This will allow high pressure to build into
the area as the flow aloft turns nw as the upper trough swings
through the area.  This high will provide a couple dry days before
the next boundary crosses the area on Friday as the upper ridge over
the lower MS Valley and Southern Plains builds eastward.  There
could be some scattered convection along this warm front moves
through the area.

For temperatures...did go a little cooler on Tuesday with the idea
of clouds and rain, but without having a better handle on the
frontal position could easily see either much cooler temps, in the
70s, than shown or perhaps if the front lifts further north, it
could be more int he mid to upper 80s.  Once the front clears should
see drier conditions and initially having temps in the low to mid
80s with a warming trend into the second half of the work week with
readings back toward near normal values in the mid to upper 80s.


VRB conditions through the TAF fcst period w/ periodic SHRAs
and ISOLD-SCT tstms resulting in IFR/MVFR CIGs and occasional
VSBY restrictions. A cold front settles just S of the local area
tonight/early Sun. Generally VFR conditions RIC-SBY Sun while
periodic SHRAs/tstms and VRB CIGs/VSBYs likely at other sites.
Unsettled conditions with periodic convection expected
into/through early in the week as the boundary stalls across
the region with a series of disturbances pushing across the


No headlines in the short term tonight thru Sun. A warm front
will lift north acrs the waters tonight. SE winds 5 to 15 kt
this evening will become SSW later this evening into Sat
morning. Expect SSW winds mainly 10 to 15 kt Sat into Sat night
in advance of a frontal boundary. That frontal boundary will
then drop down acrs the waters late Sat night thru Sun morning,
with winds shifting to the WNW then NNE. That boundary will then
linger just S of the area or near the SE VA/NE NC border later
Sun into early next week. Expect NE thru SE winds 5 to 10 kt
thru the period. Waves 1 to 2 ft and seas 2 to 4 ft.


NC...Flash Flood Watch from 6 AM EDT this morning through this
     evening for NCZ012>017-030>032-102.
VA...Flash Flood Watch from 6 AM EDT this morning through this
     evening for VAZ092-093-095>098-523>525.


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