Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/10/21
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
816 PM EDT Sat Oct 9 2021
.SYNOPSIS...
Developing low pressure off the Carolina coast brings
additional shower chances to the area tonight through Sunday
night. Drier conditions are expected to return early next week.
&&
.NEAR TERM /UNTIL 7 AM SUNDAY MORNING/...
As of 800 PM EDT Saturday...
Latest radar imagery shows the surface low located off the coast
of NC/SC with bands of rain rotating their way onto shore. After
a break from the showery conditions this afternoon, the next
band of rain is now moving onto the Eastern Shore and into NE
NC/SE VA. Hi-res models show a more pronounced area of rain
moving north into southeastern locations overnight as the
surface low slides closer to the NC coast. Locally heavy
rainfall will be possible in these areas - the heavier pockets
of rain produced totals up to 0.5-1" earlier today. Locations
further inland won`t see much more than spotty showers tonight
as the wedge remains in place. However, some areas of patchy fog
will be possible during the early to mid morning hours. Gusty
winds will persist along coastal areas overnight before winds
increase for most locations during the day on Sunday. Otherwise,
the current forecast looks to be on track, see the previous
discussion for additional details.
Important to note that a NOAA/USAF recon aircraft did fly
through the coastal low this afternoon. A broad area of gale-
force winds is occuring north of the center, but the team did
not find an organized center. As of the latest forecast, NHC is
maintaining a 40% chance of tropical (or sub-tropical)
development on Sunday, with conditions for development becoming
unfavorable by Monday. Whether it becomes a named system or not,
the local weather threats of rainfall, gusty winds, and coastal
flooding remain the same.
As of 330 PM EDT Saturday...
Another axis of enhanced llvl convergence has set up over the
outer banks and will continue to pivot W-NW over Hampton Roads
into early this evening, as sfc low nudges closer to the NC
coast. Likely to categorical PoP continues along the SE third of
the area (IXA- AKQ-MFV), with sct PoP for the Richmond
metro/central VA area, VA peninsulas/northern neck and MD
eastern shore. A slight chc PoP remains across the far NW for
tonight.
The trough aloft itself splits tonight. The northernmost portion
closest to the local area weakens as the approaching coastal
low deepens further just off the NC coast. Meanwhile, the
remainder of the trough splits off and closes offshore of the
SC/GA coast late tonight into Sunday morning. This will tend to
reinforce the CAD regime inland and also allow for continued
periods of rain along the coast this evening and through the
night, as weak shortwaves and moisture transport continue to
pinwheel up along the Mid- Atlantic coast in persistent E-NE
low-level flow. PoPs do start to ramp down across the piedmont
to the I-95 corridor late tonight, as mid-level ridging builds
sw to ne from the west-central Gulf coast. Likely to categorical
rain chances range hang on along the coast with low-level
moisture/IVT lifting toward the area.
Staying on the mild side of guidance for overnight lows with
persistent onshore flow. While measuring rain chances will be
minimal over inland areas after 00z tonight, llvls remain
saturated. So will go with OVC conditions with patchy fog
toward sun morning. Could also see some patchy dz from time to
time, but will keep the grids as simple as possible and hold
out such mention for now. Early morning lows in the low 60s NW
to mid to upper 60s SE.
&&
.SHORT TERM /7 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
As of 320 PM EDT Saturday...
Similar setup into Sunday, with upper trough in place along the
eastern seaboard and sfc low over the outer banks at sunrise
Sunday. Lingering showers along the coast for much of the day,
gradually tapering off Sunday morning inland...late Sunday into
Sunday night along the coast...as upper ridging slowly builds
to the west. Remaining mostly cloudy to overcast for much of the
day, with some clearing/thinning clouds out in the west in the
afternoon. Otherwise, mainly cloudy and cool with highs in the
70s. Any clearing gives way to returning SC/patchy fog Sunday
night, with early morning lows again in the 60s to near 70 SE.
CAD wedge looks to hang on one more day, bringing another partly
to mostly cloudy and cool day to the piedmont. Some additional
weak DPVA and llvl convergence could yield some additional stray
showers across the SE coastal plain Monday, so will maintain a
slight chc PoP there. Otherwise, one more mainly cloudy, cool
day with highs in the 70s.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 155 PM EDT Saturday...
Mid to late week period looks to be characterized by gradually
improving conditions, with CAD regime breaking and yielding to
increasing heights and resultant warming temps. Sfc high
pressure builds over the region from the west through midweek
before sliding off the NE coast Thu-Fri. Meanwhile, upper level
ridging builds into the region from the Gulf coast, promoting a
period of drier, more quiet wx.
Looking ahead, Low pressure moves into the Great Lakes next
weekend, with a trailing cold front approaching the local area
late next weekend. Showers/storms would be possible along the
cold front, but typical model timing issues apply at this time
range. Given the upper level ridge sliding in place this week,
would expect highs to run near to above average through the
medium range period. Highs in upper 70s to around 80F Tuesday,
lower to mid 80s Wed/Thu, lower to mid 80s Fri, and upper 70s W
to lower 80s E Sat. Early morning lows in the upper 50s NW to
the lower 60s inland, with low to mid 60s along the coast.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 800 PM EDT Saturday...
MVFR conditions persist across much of the area this evening
with CIGs of generally SCT-BKN020 OVC030-040. Winds remain ENE
AOB 10 kt, though coastal locations are seeing gusts to 15-25KT.
This wind trend will continue through the night with eastern
locations such as ORF and ECG maintaining the gustiness. The
next band of showers is moving into coastal areas now and will
likely bring local IFR conditions to terminals as it moves
through. CIGs of OVC050 and VIS reductions to 2-4SM will be
possible into the morning hours as areas of rain move through.
Showers are expected to dissipate as they move further west, so
RIC will see less rain chances than the others. Some fog may be
possible inland mainly after 09Z. ENE winds will pick up AOB
12KT everywhere after 14Z, with higher gusts remaining over
coastal areas. Rain chances will become more spotty after mid-
day.
Outlook: Gradual improvement to conditions expected tomorrow
afternoon, but will be short-lived as they deteriorate back to
sub-VFR conditions Sunday night into Monday morning.
Thereafter, VFR conditions for much of the work week, as drier
high pressure builds into the area from the W-SW.
&&
.MARINE...
As of 300 PM EDT Saturday...
Low pressure south of Cape Hatteras continues to strengthen
this afternoon, and strong area of high pressure remains
centered in southeastern Canada. The tight pressure gradient
over the Mid- Atlantic between the high pressure to the north
and low pressure to the south is resulting in NE winds 15-20 kt
with gusts up go 25 kt this afternoon.
NE winds are expected to decrease to 10-15 kt with gusts around
20 kt this evening and into tonight, before 4 am Sunday. The
low pressure will move north and over the Outer Banks late
tonight and early Sunday morning. ENE winds will begin to
increase from south to north late tonight into Sunday morning.
Winds on Sunday will be ENE 20-25 kt with gusts around 30 kt,
ENE 15-20 kt for tidal rivers. Seas will be building overnight
and will likely be 6-9 ft tomorrow. Waves in the bay and low
James River are expected to be 3-4 ft, and 5-6 ft at the mouth
of the bay. Small Craft Advisories remain in effect for all our
coastal waters.
Low pressure could remain near our coast Monday and Tuesday.
ECMWF and GFS keep winds elevated early this week, N around 20
kt. This will lead to seas and waves also remaining elevated
next week (5-7 ft in the ocean and 3-4 ft in the bay). SCAs may
need to be extended beyond Monday evening.
&&
.TIDES/COASTAL FLOODING...
As of 500 PM EDT Saturday...
The combination of the King Tides and prolonged period of
northeast winds is has resulted in fairly widespread minor coastal
flooding over portions of the Bay and coastal areas in southern
VA and NE NC. Current tidal departures avg from 0.75 to 1 ft
along the Bayside of the eastern shore in MD to 1.25-1.50 ft
over VA zones along the western shore of the Bay and over all of
the lower Bay and York/James.
Given that the overall forecast has trended stronger with the
winds for the next 24 hrs, with high end SCA conditions likely
into at least the lower Bay and southern coastal waters, have
decided to upgrade all zones other than the MD Bay zones into a
Coastal Flood Advisory for the upcoming high tide overnight
(which will be marginal) but also through Sunday aftn/evening
(as this will be significantly higher). From Accomack VA S to Va
Beach and Currituck NC along the coast, have the Sunday high
tide covered via a Coastal flood Watch with the latest TWL
forecasts reaching a few tenths into moderate flood thresholds.
Have also done this for Hampton Roads, including up the James
River to Jamestown and into the York River as a majority of
these sites are currently forecast to reach moderate flood
threshold (or are within a tenth or two of doing so).
As the low pressure system continues moving N later Sun through
Mon, the water level forecast becomes more uncertain. Most of
the guidance suggests that the winds become more NNE or almost
due northerly which would tend to allow water levels to lower
somewhat; there will still likely be additional tidal flooding
through Mon however.
A high risk for rip currents is expected on Sunday. Nearshore
waves are forecast to get close to 8 ft so a High Surf Advisory
may also be needed.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...Coastal Flood Advisory from 6 AM to 2 PM EDT Sunday for MDZ024-
025.
NC...Coastal Flood Advisory until 4 AM EDT Sunday for NCZ102.
Coastal Flood Watch from 6 AM EDT Sunday through Sunday
afternoon for NCZ102.
VA...Coastal Flood Watch from Sunday morning through Sunday
afternoon for VAZ089-090-093-096-524.
Coastal Flood Advisory until 6 AM EDT Sunday for VAZ089-090-
093-096-524.
Coastal Flood Watch from Sunday morning through Sunday
afternoon for VAZ095-097-523-525.
Coastal Flood Advisory until 4 AM EDT Sunday for VAZ095-097-
098-100-523-525.
Coastal Flood Watch from 6 AM EDT Sunday through Sunday
afternoon for VAZ098-100.
Coastal Flood Advisory from 6 AM to 2 PM EDT Sunday for VAZ099.
Coastal Flood Advisory until 8 PM EDT Sunday for VAZ075-077-
078-084>086.
MARINE...Small Craft Advisory until 7 PM EDT Monday for ANZ650-652-654-
656-658.
Small Craft Advisory from 7 AM to 10 PM EDT Sunday for
ANZ635>637.
Small Craft Advisory until 7 AM EDT Monday for ANZ630>632-634.
Small Craft Advisory until 10 PM EDT Sunday for ANZ633-638.
&&
$$
SYNOPSIS...ERI/MAM
NEAR TERM...MAM/JKP
SHORT TERM...MAM/RMM
LONG TERM...MAM
AVIATION...MAM/JKP
MARINE...CP
TIDES/COASTAL FLOODING...AKQ