Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 181345

Area Forecast Discussion
National Weather Service Wakefield VA
945 AM EDT Sat Aug 18 2018

High pressure will remain well off the Southeast U.S. coast
through today. A cold front will approach from the northwest
today into tonight, then drops across the area late tonight into
Monday morning. The front will stall over North Carolina late
Monday into Tuesday.


As of 355 AM EDT Saturday...

Early morning forecast in good shape. Made some tweaks to POPs
through 18Z, as latest RAP/HRRR suggest development in our CWA
will largely be delayed until around 18Z. Still looking for an
active 18Z-04Z time period this afternoon/evening, with the
primary threats being locally heavy rainfall, and potentially
strong wind gusts. SPC has upgraded our southern third to a
Marginal risk, which seems reasonable, although morning
soundings are not as unstable as they were yesterday. This should
help limit severe potential.

Previous Discussion...Early this morning, isolated showers were
moving NE thru nrn VA and MD, with just clear to partly cloudy
and humid conditions over the AKQ CWA. Temps were ranging thru
the 70s into the lower 80s.

A pre-frontal trough will approach mid-morning/early this aftn
from the west, leading to shower/tstm development over the
Piedmont. Pops will increase to 40-60% for the aftn hrs into the
evening hrs. This activity will cross the area and move off the
coast from this aftn into early Sun morning. High temps today
should still reach into the upper 80s to lower 90s, even with
sky cover increasing from partly to mostly cloudy.


As of 355 AM EDT Saturday...

The actual cold front will drop across the area Sun into Mon
morning, then will sink into NC by late Mon. Sctd showers and
tstms will re-develop, esply for Sun aftn/evening. Amount of
cloudiness across the area will limit max temps. In addition, if
flow turns from the NE soon enough across the Lower MD Eastern
Shore, temps could remain in the upper 70s there. Otherwise,
expect max temps to mainly be in the mid to upper 80s most

Sun night and Mon, the highest PoPs will shift into the srn
half of the region closer to the frontal boundary. Lows Sun
night in the upper 60s to mid 70s. Partly to mostly cloudy on
Mon with highs ranging fm the upper 70s to mid 80s, under NE or
E flow.


As of 330 PM EDT Friday...

An upper level trough will be centered over the Upper Midwest
Tuesday morning, with a broad upper ridge well offshore of the Mid-
Atlantic. This will put us in moist SW flow aloft. At the surface,
low pressure will be centered over Illinois/Michigan/Wisconsin by 12z
Tuesday. As the area of low pressure moves eastward on Tuesday, deep
moisture will surge into the region ahead of a trailing cold front
(GFS forecast PW values are between 2-2.5" by Tuesday afternoon).
Thus, am expecting scattered shower/t-storm development throughout
the region during the day on Tuesday, with coverage peaking during
the afternoon/evening hours. Have maintained chance PoPs throughout
the CWA on Tuesday. The latest 17/12z GFS and ECMWF are slightly
quicker with the FROPA than yesterday`s runs (CMC still a bit
slower). Therefore, it looks like the best chance for shower/t-storm
development Wed afternoon-evening will be along and ahead of the
front over SE VA/NE NC. Have PoPs between 20-50% (lowest NW/highest
SE) on Wednesday. Both the GFS and ECMWF push the front south of the
CWA by Thursday morning, but the CMC stalls it over NE NC. Went with
a GFS/ECMWF solution for late next week, with mainly dry (and
slightly cooler) weather on Thursday and Friday as sfc high pressure
remains just north of the region. Cannot rule out a stray shower or
two across the region (most likely south of I-64), but kept PoPs at
or below 30% on Thu/Fri.

Afternoon high temperatures will be in the mid to upper 80s on
Tuesday and Wednesday, with overnight lows ranging from around 70
degrees inland to the low-mid 70s in coastal areas. Slightly cooler
(with lower dew points) behind the cold front on Thursday and
Friday, with highs in the low-mid 80s.


As of 210 AM EDT Saturday...

A cold front will approach from the NW today into tonight, then
drops across the area late tonight into Mon morning. Expect
SCT-BKN CU between 3-5k feet to develop early this aftn. At
least sctd showers/tstms will move across the CWA fm mid aftn
into late this evening. For now, have introduced VCSH at all
the terminals. Brief IFR/LIFR visibilities are possible in any
tstm due to +RA. Winds are expected to remain out of the SW at
5-15 kt. Pcpn chances will decrease fm WNW to ESE late this
evening into early Sun morning.

Outlook...The front will remain over the region on Sun, with
the chance of showers/tstms continuing. The front drops south
of the region Mon, with a chance of showers/tstms mainly across
srn VA and NE NC. Unsettled conditions potentially continue
into Tue.


As of 230 AM EDT Saturday...

No headlines as SW winds continue aob 20 kts around the offshore
high pres. Models push a cold front across the waters Sun shifting
the winds to the E-NE. Despite the wind shift, speeds remain blo SCA
levels as no real surge seen in the data. Waves 1-2 ft with seas
avgg 2-3 ft, near 4 ft out near 20 nm at times. Sub-SCA conditions
continue into next week as winds become SW once again.




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