Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 222208

Area Forecast Discussion
National Weather Service Wakefield VA
508 PM EST Sun Jan 22 2017

A strong area of low pressure over the Tennessee Valley tonight will
slowly track east across the Carolinas Monday, then turn northeast
and move offshore Monday night. The low moves away from the New
England coast Tuesday. High pressure builds into the area for the
mid week period. A cold front crosses the area early Thursday.


Latest MSAS showing a sfc trof across swrn VA with strong low
pressure across the deep south (producing the widespread svr wx)
with a stacked low moving into western TN. Meanwhile, AKQ fa remains
wedged in a rather stable airmass along with areas of light rain
drizzle and fog. Expect a continuation of current conditions through
the evening hours as the main pcpn not expected to get into our
region until around 03Z.

Copious amounts of Atlantic moisture progged to move north and
overspread the Mid Atlantic region later tonight. Challenge is the
location of the warm front as the stacked low approaches from the
west. This will determine where the best chc for any thunder will
be. Given all the 12Z data to peruse, it appears that most of the
severe threat stays south of the Albemarle sound where the warm
front and best shear is progged by 12Z. Thus, will keep low chc
for thunder across the southern most zones late tonite, but
expect it to be mostly elevated. Added locally heavy rain across
the area after midnight to the grids given the progged lift.
Lows in the mid 40s to lwr 50s with steady or slowly rising
temps ivof Albemarle sound as the warm front approaches.

Wind advisory has been posted for the Maryland eastern shore and
Accomack county VA late tonight for wind ENE gusts over 40 mph.


Models still have different solutions of where the stacked low
tracks Monday. GFS tracks it across southern VA then lifts it NE
late in the day allowing the warm front to lift north into VA,
NAM/SREF/ECMWF keeps the track across NC then slowly turns NE toward
sern VA late keeping the warm front just south of the fa. This is
important because a large portion of the forecast will all depend on
the track of the low and location of the warm front.

A GFS solution would favor more dry slotting but run a higher risk
for tstms as part of the area would be warm sectored. What the
more southern track does is limit any dry slot from cutting off
the pcpn Monday as well as limiting thunder chcs. However, it
keeps the threat of heavy overrunning rainfall across the north
going longer then anticipated. Have gone with more of a southern
track keeping the morning wet with likely to categorical pops
across VA and high chc pops across NC. As the low pulls toward
the coast after 18Z, expect the pops to taper off across the
east but continue over the west. Will keep slght chc thunder in
mainly east of the I95 corridor given the strong dynamics. Highs
range from the low-mid 40s NW zones due to insitu-wedge to the
low-mid 60s along the se coast.

The low progged to move out into the VACAPES then just off the
Delmarva Monday night with lingering spokes of energy rotating
around the system. Enough moisture and support for shwrs to
continue. Chc to likely pops during the evening will taper off to
chc pops after midnight except likely pops continuing across the
lower Maryland eastern shore. Lows in the upr 30s NW zones to the
mid 40s SE.

Low pressure moves slowly NNE off the New England coast Tuesday.
The last spoke of energy to rotate around it continues the chc for
sct morning showers along the Delmarva. Otw, H5 ridge over the SERN
states builds into the area for the mid week period. W to SW flow
dries out the column resulting in pt to mostly sunny skies Tuesday
and Wednesday with temps remaining above normal. Highs Tuesday in
the 50s. Lows mid 30s to lwr 40s. Highs Wednesday in the upr 50s
to mid 60s.


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.


As of 17Z...Generally LIFR conditions across all of the region this
afternoon. Persistent low stratus deck and lowered visibilities are
expected to continue through much of the forecast period. Not
expecting much improvement in conditions this afternoon and tonight.
A warm front approaches the area from the south late tonight
bringing the next chance for widespread precipitation, rain may be
heavy at times. While much of the greatest instability will remain
south of the area, a few rumbles of thunder may be possible. The
potential for any damaging wind gusts appears limited at this time.
The warm front will lift north of the region Monday morning,
bringing the potential for a brief improvement in conditions late in
the forecast period. Winds will continue to be out ot of the E and
NE this afternoon at around 5-10kt, and are generally expected to
increase to 10-15kt (locally 15-25kt at SBY) late tonight into early
Monday morning. Winds become more southerly Monday morning as the
front lifts across the area.

Outlook: The upper level system will lift across the area Monday
afternoon bringing another chance of showers. Drier air gradually
returns Monday night and into Tuesday as high pressure builds in
from the NW. Low pressure tracks through the Great Lakes Wednesday,
and pulls a cold front through the area later Wednesday night into
Thursday. This will bring a chance of rain, before drier air arrives
from the NW later on Thursday.


Low visibility will remain a concern across the marine area into
tonight (near zero at times).

Weak low pressure currently off the mid-Atlantic coast is providing
for NE-N winds between 5-15 kt, except 15-20 knots off the lower MD
coast. This increase in NE winds off MD has allowed seas to build to
5 ft already. Instead of issuing a ramp-up SCA, just opted to go
ahead and begin the Gale Warning this afternoon.

Another wave of low pressure will track across the area late
tonight through midday Monday. A strong pressure gradient and modest
pressure falls develop late tonight through midday Monday and will
be strongest N of Cape Charles, and especially for the ocean N of
Parramore Island. Gale warning north of Parramore Island is for E-NE
winds of 25-35kt with gusts to around 40kt, with the SCA to the S
extending through Tuesday as seas remain aob 5ft. Seas build to 8-
13ft N to 5-7ft S Monday morning in response to the period of
strongest wind. SCA flags remain in effect for the Bay/Lower
James/York/Rappahannock. The wind will be strongest
in the Bay N of New Point Comfort, and low-end gale gusts are
possible N of Windmill Point. The low stalls in vicinity of the
NJ coast Monday night into Tuesday as high pressure builds
in from the NW. The wind should by NW 10-15kt/15-20kt ocean.
High pressure gradually builds into the region Tuesday night and
slides offshore Wednesday ahead of a cold front. This cold
front crosses the coast late Wednesday night into Thursday morning.


A high surf advisory has been issued for the Maryland beaches
for Monday. Some minor beach erosion is expected.

Low pressure pushes off the Delmarva coast late tonight through
midday Monday resulting in a brief but modestly strong onshore
wind. This has the potential to push tidal anomalies to
1.5-2.5ft above normal Monday into Monday night/Tue morn. Some
locations including the Atlantic coast from Chincoteague to
Ocean City and portions of the middle and upper Bay may come
within 0.5ft of minor flooding thresholds during high tide. The
most likely location to exceed minor flooding thresholds is
Ocean City Monday afternoon. Water levels will come close to the
4.0 ft minor flooding threshold at Ocean City early Monday
morning and thus have issued a Coastal Flood Statement to
address this possibility.


MD...High Surf Advisory from 4 AM to 6 PM EST Monday for MDZ025.
     Wind Advisory from 4 AM to 1 PM EST Monday for MDZ021>025.
VA...Wind Advisory from 4 AM to 1 PM EST Monday for VAZ099.
MARINE...Dense Fog Advisory until 4 AM EST Monday for ANZ630>638-650-
     Small Craft Advisory from 4 AM to 10 AM EST Monday for ANZ635-
     Small Craft Advisory from 1 AM to 1 PM EST Monday for ANZ630-
     Small Craft Advisory from 1 AM to 10 AM EST Monday for ANZ632.
     Small Craft Advisory from 1 AM to 7 AM EST Monday for ANZ638.
     Small Craft Advisory from 1 AM Monday to 6 PM EST Tuesday for
     Gale Warning until 1 PM EST Monday for ANZ650-652.


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