Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 201159

Area Forecast Discussion
National Weather Service Wakefield VA
759 AM EDT Tue Mar 20 2018

Low pressure will redevelop from the southeast Virginia coast to
the North Carolina coast late this morning, and will intensify
while tracking northeast tonight and Wednesday. High pressure
gradually builds into the area late in the week.


Early morning analysis indicating double barreled sfc low
pressure from SC to SW VA, with a potent mid/upper level low
centered from the lower OH Valley to the mid/lower MS Valley.
Strong area of deep lift and overrunning moisture is pushing
through the local area early this morning and have PoPs of
80-100% through 15Z for the entire CWA. The rain is locally
heavy but genly not excessive and will avg from 0.75" to 1.50"
through this aftn. This is all rain (no concern for any
snow/sleet through the aftn). The sfc low deepens as it tracks
across the VA Capes later this morning. This will result in
windy conditions (NE wind) along the Atlantic coast of the VA/MD
Ern Shore where a wind advisory in in effect mainly for areas
from Chincoteague to Ocean City. The low then lingers off the
coast this aftn as weak high pressure tries to nudge in from the
north. This will result in the wind becoming more northerly
during the aftn. GFS/NAm depict main region of lift and moisture
through the DGZ pushing off to the NE from late morning into
early aftn. Low clouds and light rain or some drizzle will
remain but QPF amts this aftn will be minimal except over the
far NE where likely PoPs will persist. Most of the CWA will only
have highs in the 40s today (close to current values), but
highs in NE NC and far SE VA will be in the 50s to lower 60s.
Temperatures will likely fall off later in the aftn in these
locations as winds shift more to the N and increase.


The complex system will continue to impact the region
tonight into Wednesday. There is still some uncertainty on how
the system evolves tonight into Wednesday. However, the 20/00z
GFS/NAM/ECMWF continue to depict a deepening of the surface low
close enough to the coast with the potential for frontogenetic
banding over northern/NE portions of the CWA. Given enough model
spread and the potential for banding well inland, have expanded
the winter storm watch to to also include Accomack VA and the
northern Neck counties of VA. Will likely need a round of winter
wx advisories beginning late tonight or Wed morning, but given
the uncertainty in amounts and with just rain expected through
the evening commute, opted to allow dayshift to evaluate for
exactly where to draw these headlines.

The upper level system pulls in enough cold air to allow a
transition to snow late Tuesday night into Wednesday. Chc to
likely PoPs Tuesday evening ramp up to likely to categorical
everywhere after midnight through midday Wednesday as the
forcing from the upper level system taps into moisture.
Thicknesses suggest a mixed/rain and snow event across the
Piedmont Tuesday night changing to all snow, and rain/snow
Tuesday night changing to all snow around daybreak Wednesday for
central VA. A cold rain over the Delmarva will change to snow
Wednesday morning, and a cold rain for SE VA/NE NC could mix
with some snow Wednesday aftn. The current forecast is for 1-3"
of snow from the NW piedmont across central VA, with 2-5" for
the Nrn Neck and the VA Ern Shore, with the potential for 3-6"
over the MD Ern Shore. Elsewhere, expect an inch or less with
little to no accumulation for far SE VA/coastal NE NC. Lows
tonight range from 30-32F NW to the upper 30s SE, followed by
highs Wednesday in the mid 30s where snow falls to the upper
30s/low 40s where rain prevails. Highs in south central VA may
rise to around 40 F later in the aftn as the precip intensity

Drier air arrives Wednesday night into Thursday as the system pulls
to the northeast. Partly to occasionally mostly cloudy under the
upper trough. Lows Wednesday night range from the mid/upper 20s
NW to the low 30s SE, with highs Thursday in the mid to upper
40s, possible cooler over the MD Ern Shore depending on snowfall


Remained close to WPC grids for the late week into early next week.
Overall, cold high pressure building to the NW will provide a
continuation of (much) below temperatures for much of the forecast
period. After a cool, dry day on Friday, rain chances increase once
again ahead of next system, which develops across the central plains
on Fri/Friday night...then tracks east, undercutting the omega block
in place over the northern tier of states through the weekend.
Remaining partly to mostly cloudy through the weekend, with rain
chances to increase later Sat into Sat night before becoming more
widespread on Sunday.

For temperatures, Highs Fri/Sat around 50F inland...m40s at the
coast. Lows Fri night in the l30s inland...u30s-around 40F at the
coast. Highs Sun in the 40s to around 50 F, and Mon 40s N to
mid 50s S.


Rain will persist through midday may be heavy at times through 15z.
Ceilings will be mostly IFR to occasional LIFR near the coast.
Winds will be mostly NE to E at 10-15 kt inland, but gusting to
25-30 kt near the coast. Winds shift more to the N after 18Z and
may see cigs improve a bit to MVFR levels inland with rain
becoming light/spotty except at KSBY. Rain, gusty winds, and
IFR conditions will generally prevail again later tonight as
next round of widespread rain moves back tonight.

Outlook: More IFR/LIFR flight restrictions will prevail on Wed.
Rain will be changing to snow from 12-18Z at area terminals.
There could be some accumulations of an inch or two, possibly
more at KSBY. Gusty winds buffet the coast Wed as well.
Drier/VFR Thu-Fri.


Current observations show E/SE winds of 15 to 25 knots over the
waters as low pressure slides south of the area. Seas range from 3
to 4 feet and waves range from 2 to 4 feet. Small Craft Advisories
are now in effect for all of the waters. A Gale Warning remains in
effect for the coastal waters north of Cape Charles.

Pressure gradient will continue to tighten over the region this
morning between approaching surface low pressure from the west and
surface high centered over Ontario. Low pressure is expected to move
offshore near the VA/NC border later this morning and redevelop off
the coast. Model guidance continues to show the highest wind
potential mainly north of Cape Charles, thus left the headlines
unchanged. Wind gusts could briefly approach as high as 40 to 45
knots from Chincoteague north Tuesday afternoon as the low deepens.
Wind gusts could also approach 35 knots over the northern Bay later
this morning, especially at the elevated stations.

Another surface low develops off the coast Tuesday night into
Wednesday allowing for another round of Gale force conditions over
the northern waters and SCA conditions over the remainder of the
waters. Seas also build quickly Tuesday into Wednesday with seas
reaching 8 to 12 feet on the coastal waters.

Low pressure moves well off the coast by late Wednesday/Thursday
morning allowing for conditions to slowly relax. Northwest flow
continues into Friday when high pressure finally settles back over
the area. Seas will likely remain elevated at or above 5 feet for
coastal waters through at least Thursday. Another low pressure
system may impact the waters by Sunday.


Tidal departures build this evening through Wednesday and there
will be the potential for at least minor coastal flooding for
locations adjacent to the lower Bay and the Atlantic coast. Went
ahead and issued a Coastal Flood Watch for coastal portions of
Worchester County where guidance continues to indicate the
potential for Moderate flooding Wednesday. Expect for tide
departures to run from 2 to 3 feet above normal tide around
times of high tide.


MD...Wind Advisory until 8 PM EDT this evening for MDZ024-025.
     Coastal Flood Watch from this evening through late Wednesday
     night for MDZ024-025.
     Winter Storm Watch from Wednesday morning through Wednesday
     evening for MDZ021>025.
VA...Wind Advisory until 8 PM EDT this evening for VAZ099.
     Winter Storm Watch from Wednesday morning through Wednesday
     evening for VAZ099.
     Winter Storm Watch from Wednesday morning through Wednesday
     evening for VAZ075>078.
MARINE...Gale Warning until 2 PM EDT Wednesday for ANZ650-652-654.
     Small Craft Advisory until 8 PM EDT Wednesday for ANZ630>638-


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