Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 211938
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
338 PM EDT Mon May 21 2018

.SYNOPSIS...
A weak frontal boundary over northern North Carolina will lift
back north as a warm front late tonight into Tuesday. A more
pronounced cold front will cross the region on Wednesday,
followed by a period of dry weather Thursday and Friday under
the influence of high pressure.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 330 PM EDT Monday...

Plenty of thunderstorms across far southside VA and NE NC in
vicinity of the frontal boundary. Can continue to expect some
locally heavy rainfall from these storms as they slowly
drift/propagate to the SW. Just enough movement so rainfall
amounts not too extreme. However, up to 2-3 inches have locally
fallen, and flood advisories have already been issued for parts
of NE NC. General trend is for these storms to continue to
propagate to the SE, so although locally heavy rainfall is
still possible simply due to the high moisture content of the
atmosphere, the fact that the outflow continues to move south
would suggest that significant heavy rainfall is not expected as
the storms should continue to propagate with the outflow.
Otherwise, areas north of a Farmville to Emporia to Chesapeake
line will likely stay dry this evening with these areas being
north of the frontal boundary.

These storms are generally diurnally driven and expect them to
diminish significantly in coverage and intensity this evening.
Meanwhile, the front will begin to once again move back north as a
short wave over the MS valley moves east. This will allow for any
showers to spread back north and east tonight and have continued
with chance pops as far NE as the Northern Neck after midnight.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
As of 330 PM EDT Monday...

The front will continue to move northward on Tuesday. This will
likely allow for a dry period at least across the W in the morning.
However, a lee side trough develops during the afternoon. This,
combined with a weak upper wave moving through the W-NW flow aloft
will allow for a line of storms to develop across northern VA and
perhaps impact the far northern part of the forecast area late
Tuesday afternoon. The winds aloft are in the 35-40kt range
Tuesday afternoon, which may be just enough for some strong wind
gusts with any thunderstorm Tuesday afternoon. SPC has placed
northern VA into a marginal risk for severe thunderstorms, and
this just clips the northern neck and Caroline and Louisa
Counties.

This line of showers/storms will move through the forecast area
Tuesday evening and will likely diminish after sunset due to loss of
daytime heating. A more pronounced period of showers and storms
are expected late Tue night into Wednesday as the cold front
approaches the area and slowly moves through the area on
Thursday. Best chances for showers/storms will be Wed afternoon
due to height falls aloft and decreasing stability along the
frontal zone. There is a marginal risk for severe storms on
Wednesday across the entire area, but the best chance for any
severe weather will likely be across the far southern tier where
the best instability will occur.

The tropical moisture will finally be scoured out with this front,
and Thursday looks to be dry with much lower dew points as high
pressure builds across the region from the NW.

Highs each day will continue in the mid 80s, although Thursday will
be much less humid. Lows continue muggy in the upper 60s/low 70s
until Wed night which will see low-mid 60s. &&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 320 PM EDT Monday...

A strong surface ridge and northwest flow aloft with the upper
ridge axis to the west over the Mississippi Valley will provide
dry weather with moderate temperatures for the beginning of the
extended forecast. Expect highs in the low to mid 80s Friday and
the mid to upper 80s on Saturday. Overnight lows in the low to
mid 60s Thursday night and mid to upper 60s Friday night. But
the upper ridge will erode through the holiday weekend with a
gradual increase in moisture as it appears that another area of
low pressure will form in the northeastern Gulf of Mexico by
Sunday and push more tropical moisture northward into the
region. This could allow for more showers and tropical downpours
for Sunday and again on Monday. The big model difference in the
models is the handling of a backdoor cold front between the 12z
GFS and ECMWF with the GFS pushing the front south through the
area and the ECMWF keeping the boundary well north of the area.
In either case, the chance for showers and some possibly heavy
rainfall exist for the second half of the Holiday weekend. If
the GFS is right with the front Monday could be a damp cool
rainy day while the ECMWF would lead to more periodic showers
with some breaks. At this time of year, seems more likely the
for the front to hang north of the area. So have kept the
temperatures up more in the low to mid 80s for Sunday and
Monday.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
As of 755 AM EDT Monday...

A weak front is now pushing through central and SE VA with patchy
IFR/MVFR stratus and MVFR vsbys through about 15Z at KORF/KPHF.
The front becomes located from the VA Piedmont to NE NC by aftn.
Chance for showers by this aftn/evening are 30-40% for KECG,
~20% for KRIC/KPHF/KORF, and <10% for SBY. Tstms look rather
unlikely through 00Z given the onshore flow but there is a
slight chance at KECG and along/west of I-95 including KRIC. The
boundary returns N as a warm front across the local area late
tonight/early Tuesday with a potential for showers and isolated
tstms (PoP 20-50%) though did not include this in TAFS yet. Cigs
look to lower overnight and flight restrictions are in the TAFS
from 06-12Z.

Aftn/evening showers/tstms are possible Tuesday and Wednesday.
A moist airmass will remain over the region and a potential will
exist for patchy early morning fog and/or stratus. High
pressure looks to build in from the N by Thursday and Friday
bringing mainly VFR conditions during the end of the week.

&&

.MARINE...
As of 330 PM EDT Monday...

A Small Craft Advisory remains in effect for the Lower Chesapeake
Bay and the Lower James River. Observations continue to show a
persistent east wind of around 15 knots with gusts in excess of of
20 knots at times. Choppy conditions can also be expected in these
locations with waves of 2 to 4 feet. Winds and waves should begin to
diminish after sunset.

A weak boundary slowly lifts north of the waters overnight and into
Tuesday. Winds will turn to the SE and then S or SW as the boundary
lifts to the north. Winds Tuesday will range from 5 to 15 knots,
with seas of 2 to 3 feet and waves of 1 to 2 feet. A cold front
crosses the region on Wednesday and turns the winds to the W and NW
around 5 to 10 knots through Thursday morning. High pressure builds
into the area Thursday through Friday leading to generally tranquil
marine conditions.
&&

.HYDROLOGY...
As of 1115 AM EDT Monday...

Flood warnings continue for the James and Appomattox River
basins. Mattoax is now forecast reach moderate flooding by early
Wednesday morning. Warnings also continue for the Meherrin and
Nottoway rivers (at Stony Creek), as well as portions of the
Chowan Basin. Additional flood warnings continue for the
Chickahominy, South Anna and Mattaponi rivers, as well as the
Pocomoke River in MD. See FLWAKQ or FLSAKQ for more details.

&&

.CLIMATE...
As of 355 AM EDT Monday...

* RIC monthly rainfall total through 5/20 remains at 8.84"
  (already ranks as 5th wettest May on record). (precipitation
  records date back to 1880)

* SBY monthly rainfall total through 5/20 is now 8.52" (already
  ranks as 3rd wettest May on record). (precipitation records
  date back to 1906)

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ632-
     634-638.

&&

$$
SYNOPSIS...MRD
NEAR TERM...MRD
SHORT TERM...MRD
LONG TERM...ESS
AVIATION...LKB
MARINE...AJB
HYDROLOGY...
CLIMATE...



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