Area Forecast Discussion
Issued by NWS Wakefield, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KAKQ 261445
AFDAKQ

Area Forecast Discussion
National Weather Service Wakefield VA
1045 AM EDT Wed Apr 26 2017

.SYNOPSIS...
Low pressure lifts along the Northeast coast today, resulting in
a warming trend through the remaining work week. A cold front
weakens west of the region Thursday night. High pressure
prevails through the weekend. The next cold front pushes across
the region early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Update...Added more drizzle into the forecast through this
afternoon; primarily for Northern Neck and MD/VA Eastern Shore
where stacked low will keep moisture rotating over these areas.
Clearing has occurred this morning over the Eastern Piedmont
with peaks of sun as far east as a Tappahannock-Wakefield-
Downtown Suffolk line. This will be short-lived as visible
satellite trends show clouds filling back in with daytime
heating and northwest flow aloft. Adjusted temperatures for
today as well by showing better warming to the west and highs
struggling to reach the mid 60s across portions of the Northern
Neck and MD/VA Eastern Shore.

Previous discussion...
Latest water vapor and surface analysis depicts vertically
stacked low pressure just offshore the Delmarva. Moisture and
energy wrapping around the backside of the system is producing
an area of light rain/drizzle from the Northern Neck to
southeast Virginia. Latest radar trends depict a decrease in
coverage, with latest RAP/HRRR guidance pushing the upper level
energy offshore shortly after daybreak. As the energy slides
offshore, expect light rain to dissipate/slide offshore. Stratus
and mixing has limited fog development this morning. Given the
upper level cyclonic flow and low cloud bases, patchy/areas of
drizzle expected to linger thru mid morning.

The surface low weakens and slowly drifts northeast today as an
upper level ridge builds in from the west. Cloud deck will be
slow to erode/lift thru mid morning, with the late April sun
expected to erode the deck inland mid to late morning. However,
warming temperatures aloft ahead of the building ridge and wrap
around moisture from the departing upper low will keep a partly
cloudy to mostly cloudy sky across the area. Cloudy across the
far northeast, nearest the upper low and associated energy.
While soundings indicate drying aloft for the Maryland Eastern
Shore, abundant low level moisture and some modest isentropic
lift will keep a chance of rain thru early afternoon. Mixing
will be limited today (south-southwest winds of 5-10 mph) due to
a strong subsidence inversion, but temperatures expected to warm
nicely into the mid to upper 70`s. Cooler near the coast.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
The stubborn upper low finally picks up speed and pushes
northeast away from the area tonight as the ridge axis aligns
along the Eastern Seaboard. Lingering moisture will keep some
clouds along the coast, but clearing expected inland. Lows
generally in the upper 50`s to low 60`s.

Ridge axis slides offshore ahead of an approaching cold front
Thursday. Increasing return flow and 850mb temps around +14 to
+16C (around +1 standard deviation) result in warm (and dry)
conditions with highs generally in the mid 80`s. Cooler along
the coast. Plenty of sunshine expected.

Aforementioned cold front reaches the central Appalachians late
Thursday as an upper level trough lifts from the Ohio Valley
over the eastern Great Lakes region. Limited moisture return
expected ahead of the front as the best dynamics lift well north
of the Mid-Atlantic. The cold front progged to not make it over
the mountains Thursday night as southwest flow aloft prevails.
Pressure falls along the lee side of the Appalachians will push
a pre-frontal trough across the region Thursday night. Given
modest theta-e advection and warm temperatures, guidance does
indicated some marginal instability across the Piedmont Thursday
evening. However, temperatures aloft remain warm. Given the
limitations, have only slight chance to low end chance POPs
Thursday evening. Better moisture progged across the eastern
portion of the local area late Thursday night, so have 30-40%
POPs for scattered showers and possibly a thunderstorm. Deepest
moisture pushes offshore Friday morning, with only a slight
chance POP across the far southeast. Sky becomes mostly sunny to
partly sunny Friday afternoon. Another warm day in store, with
highs in the mid (possibly upper) 80`s. Cooler near the coast.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Temperatures are expected to remain well above normal through
the weekend as an upper level ridge remains anchored over the
Ern Conus. 850mb temperatures ~18C will support highs in the
upper 80s to around 90 Saturday (75-80F at the immediate coast)
after morning lows in the mid/upper 60s. A weak front will knock
high temperatures down a few degrees Sunday over the Ern Shore,
with low 80s expected and mid/upper 70s at the immediate coast.
Meanwhile, highs W of the Bay will once again be into the upper
80s. Aftn/evening chances for showers/tstms Saturday/Sunday
will be low and mainly aob 20%. A cold front approaches from the
W Monday. Forecast highs Monday are in the low/mid 80s after
morning lows in the mid/upper 60s. 25/12z GFS/ECMWF/CMC support
the best chc for showers/tstms very late Monday aftn into Monday
evening and shifting to the coast late Monday night.
Temperatures trend back toward normal Tuesday with highs in the
70s.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
Latest surface analysis centers low pressure just offshore the
Mid-Atlantic coast. The result is ongoing widespread IFR
conditions over the region. VFR conditions currently observed
across southeast Virginia into northeast North Carolina, but
expect deteriorating conditions as the low slowly lifts
northward. Area of light rain along the coast has reduced
visibilities to MVFR. Surface winds have become northwest at or
below 10 knots. IFR conditions prevail thru mid morning as the
low lifts slowly northward. Light rain wraps around the low,
mainly impacting the Northern Neck to Eastern Shore. Have kept
mention of patchy fog over the Piedmont and Eastern Shore, but
due to stratus and the upper low lifting over the region, expect
areas of drizzle to persist through early-mid morning. Expect
improving conditions mid to late morning inland as ceilings lift
to MVFR and rain/drizzle/fog lift/dissipate. IFR conditions will
be slow to improve KSBY as the low slowly lifts northward.
Elsewhere, VFR conditions return with a generally broken sky.
Surface winds generally out of the west at or below 10 knots.

Low pressure lifts along the Northeast coast Thursday as high
pressure/fair weather returns to the region. The next cold front
stalls north of the region Thursday night/Friday, with only a
chance of rain Thursday night. High pressure centers over the
western Atlantic this weekend.

&&

.MARINE...
Marine dense fog advisory is in effect thru 7am for the coastal
waters north of Parramore Island.

Latest sfc analysis shows a weak pressure gradient over the
region, with sfc low pressure centered just off the Delmarva
coast. Winds avg 10-15 kt (or less) over the entire marine area
and will be relatively light today, allowing flow to become
onshore by late aftn at 10 Kt or less. Seas remain elevated at
6-8 ft north and 4-6 ft south and given the light winds have
converted SCA headlines to Small Craft Advisory for hazardous
seas, these lasting through early this evening S and into Thu
morning N. Elsewhere, a relatively benign/decent boating day
expected with waves 1-2 ft or less. The gradient becomes a bit
stronger on Thu, with winds turning to the S and expected to avg
around 15 kt with some higher gusts. Some residual swell around
9-10 sec and the increasing winds look to keep seas
elevated/probably coming back up to 5 ft offshore and a SCA
headline may be needed for coastal waters. Marginal SCA
conditions possible for the Bay/Rivers Thu aftn/evening but
overall would expect this to be below criteria for headlines
given a very warm airmass (temps in 80s) over water temperatures
in the 60s or cooler leading to less than optimal mixing. Waves
will build to 2-3 ft in the Bay and 1-2 ft rivers. Similar
conditions expected Fri/Sat as the warm weather and a general
southerly flow persist. Some guidance depicting a backdoor cold
front could shift winds to the NE for awhile for northern
coastal waters by Sunday, but most places likely to stay south
of this boundary.

&&

.TIDES/COASTAL FLOODING...
Have cancelled all Coastal flood Advisories.

Current tidal departures now avg +0.75 to +1.25 ft (lowering
from earlier departures that were closer to +1.5 ft). High tide
just occurred at Cambridge and only peaked around 3.0 ft MLLW
(and has passed all other areas). While water levels will remain
elevated through the next 48 hrs with seas off the coast of 4+
feet and continued 9-10 sec swell, the upcoming high tide later
today is the lower of the two and all sites should stay at least
0.5 feet below minor criteria. The following high tide cycle
tonight/early thu morning could approach minor flooding and a
statement may be issued depending on trends today.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory for hazardous seas until 10 PM EDT this
     evening for ANZ654.
     Small Craft Advisory for hazardous seas until 7 PM EDT this
     evening for ANZ656-658.
     Dense Fog Advisory until noon EDT today for ANZ650-652.
     Small Craft Advisory for hazardous seas until 10 AM EDT
     Thursday for ANZ650-652.

&&

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


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.