Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 231635
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
1135 AM EST Mon Jan 23 2017

.SYNOPSIS...
Low pressure will track from western North Carolina eastward
across the Mid Atlantic region during today, then lifts
northeast just off the northern Mid Atlantic and southern New
England coasts tonight through Tuesday. The low will then move
away from the New England coast Tuesday night into Wednesday, as
high pressure builds into the area. A cold front will cross the
region late Wednesday night into Thursday morning.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Latest GOES water vapor imagery centers anomalous upper level
low pressure over the Carolinas. At the surface, associated
~990mb low pressure is centered over western North Carolina with
a warm front extending eastward into southern Virginia. Ongoing
overrunning precipitation has spread northward into central and
northern Virginia, with lingering light precipitation across
southern Virginia. Latest RAP/NAM12 isentropic surfaces are
handling the area of precipitation well, with the brunt of the
showers expected to continue to lift northward through late
morning. Favorable mid level lapse rates, effective shear, and
modest instability will result in a few rumbles of thunder in
the strongest cells. Otherwise, anomalous precipitable water
values and moisture flux (thanks to strong onshore flow around
the northern periphery of the upper low) results in periods of
moderate to locally heavy rainfall. Rainfall amounts through mid
morning have generally been around one half inch, with
localized amounts up to three quarters of an inch. Thanks to
strong flow (showers are moving at 40-50 mph), no flooding
threat is expected.

The surface low pushes off the North Carolina coast mid to late
afternoon as the upper low centers over the Mid-Atlantic
region. Deepest moisture pushes northward along with the best
moisture flux. Best chances for precipitation will push
northward across the north to northeast forecast area by mid
afternoon. Due to the potent upper low lifting into the region,
expect scattered activity elsewhere, even with decreasing
moisture. Limited elevated instability and favorable mid level
lapse rates will keep a mention of thunder in the forecast.
Locally heavy rainfall remains the greatest threat.

Trended temperatures downward today, as temperatures will
likely warm very little compared to current temps. Highs range
from the upper 40`s northwest to mid 60`s southeast under a
cloudy sky. NC.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
This evening thru Tue morning, the sfc low will lift NNE just
off the Delmarva and NJ coasts as the upper low moves fm ern NC
NE to off the MD/DE coast. This will result in more showers
likely over ENE counties, with chc pops diminishing to slgt chc
pops over the WSW counties. Lows tngt will range fm the upper
30s to mid 40s.

Low pressure will finally move away off the New England coast
late Tue aftn into Tue night. Thus, have lingered likely to slgt
chc Pops for the Lower MD and VA ern shr, portions of the VA
nrn Neck down into Hampton Roads and coastal NE NC into early
Tue aftn. Lingered slgt chc/chc pops over ern Lower MD thru Tue
aftn. But, should see increasing sunshine over WSW counties
during Tue. Highs will range fm the upper 40s to the upper 50s.

H5 ridge and sfc high pressure over the SE states builds into
the area for Tue night into Wed aftn. Becoming clear or mostly
clear Tue night with lows ranging fm the mid 30s to lower 40s.
Partly to mostly sunny on Wed with highs ranging fm the upper
50s to mid 60s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A broad trough of low pressure will enter the region Wed night
into Thursday as a sfc cold front slides into the area. The front is
expected to cross the local area Thursday morning but just how much
moisture it has to work with is still up in the air. The GFS is more
bullish with pcpn compared to the ECMWF and would provide a better
opportunity for meaningful rain areawide. The ECMWF is drier with
any pcpn limited to far SE locations. Consensus is to lean closer to
the drier ECMWF solution and therefore will have no higher than 30%
PoPs Wed night/Thu morning. Lows Wed night in the 40s to near 50.
Highs Thursday in the 50s.

For Thursday night into next Saturday, the region will be dominated
by strong NW flow which will drop temperatures back down into
the 40s for highs and lows in the upper 20s to low 30s. The
forecast looks to remain dry.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Strong low pressure will lift ENE acrs the Mid Atlc region and
off the srn New England coast today thru Tue. Widespread IFR/LIFR
conditions will continue over the area into early Tue morning.
Off and on rain or showers will affect the region thru this time
period with some heavy at times. During this aftn, improvement
to VFR or MVFR can be expected ovr SE VA and NE NC, as drier
air temporarily filters in to that area. Strong NE or E winds
expected today, especially at SBY and ORF with gusts over 30
knots at SBY.

OUTLOOK...The low moves away to the northeast during Tue with
showers gradually ending acrs ENE counties. High pressure
builds into the area for Tue evening into Wed. There will be a
chance for showers Wed night into Thu with dry conditions
expected for Thu aftn through Fri.

&&

.MARINE...
A complex low pressure system is centered over wrn NC early this
morning, with a warm front off the NC Outer Banks. Pressure falls of
-8mb/3hr have been observed over central NC as of 09z and this is
expected to shift toward the VA/MD coast between 12-18z as low
pressure becomes reorganized off the Mid-Atlantic coast. The
combination of modestly strong pressure falls and a tight gradient
will drive an E-NE wind of 20-25kt with gusts to around 30kt for the
Bay and ocean S of Parramore Is. for a 3-6hr period this morning
where SCA flags remain in effect. N of Parramore Is., the wind is
expected to increase to 25-35kt with gusts to around 40kt for a 3-
6hr period this morning through midday with gale flags continuing.
The rivers with the exception of the upper James should generally
experience an E wind of 15-20kt with gusts to around 25kt this
morning. The Sound may briefly have wind gusts to 20kt through 12z,
but not for a long enough period to justify an SCA. Seas build to 8-
14ft N to 4-7ft S.

The low stalls in vicinity of the NJ coast this aftn into tonight,
and will be slow to lift to the NE Tuesday. Meanwhile, high pressure
builds in from the NW. The wind become N-NW and increase to 15-25kt
(gusts to ~30kt possible early Tuesday with the strongest pressure
rises) for the Bay/ocean later tonight into Tuesday, with speeds
averaging ~15kt for the rivers/Sound, with 20kt possible. A lull of
less than 12 hrs is expected for the Bay so the SCA has been
extended through Tuesday aftn. For the srn ocean zones the SCA has
been extended through 06z Wednesday as seas will be slow to subside.
High pressure gradually builds into the region Tuesday night and
slides offshore Wednesday ahead of a cold front. This cold front
crosses the coast later Wednesday night into early Thursday. High
pressure builds in from the W Thursday night into Friday.

&&

.TIDES/COASTAL FLOODING...
A high surf advisory remains in effect for the Maryland beaches
and Accomack County today. Some minor beach erosion is
expected.

Low pressure pushes off the Delmarva coast late through midday
today resulting in a brief but modestly strong onshore wind.
This will push tidal anomalies to 1.5-3.0ft above normal today
into tonight/Tue morn. Coastal locations from Wachapreague to
Ocean City will reach minor flooding thresholds this afternoon,
with areas from Chincoteague to Ocean City coming close to
moderate flooding thresholds. Have added Accomack County to the
coastal flood advisory for this afternoon. Portions of the
middle and upper Bay will come within 0.5ft of minor flooding
thresholds during the high tides through tonight.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...High Surf Advisory until 1 AM EST Tuesday for MDZ025.
     Coastal Flood Advisory until 7 PM EST this evening for MDZ024-
     025.
     Wind Advisory until 1 PM EST this afternoon for MDZ021>025.
NC...None.
VA...Coastal Flood Advisory until 7 PM EST this evening for VAZ099.
     Wind Advisory until 1 PM EST this afternoon for VAZ099.
     High Surf Advisory until 7 PM EST this evening for VAZ099.
MARINE...Small Craft Advisory until 1 PM EST this afternoon for ANZ635-
     636.
     Small Craft Advisory until 4 PM EST Tuesday for ANZ630>632-634.
     Small Craft Advisory until 1 AM EST Wednesday for ANZ654-656-
     658.
     Gale Warning until 4 PM EST this afternoon for ANZ650-652.

&&

$$
SYNOPSIS...TMG
NEAR TERM...SAM
SHORT TERM...TMG
LONG TERM...JDM
AVIATION...TMG
MARINE...AJZ/JDM
TIDES/COASTAL FLOODING...AKQ


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