-- Discussion containing changed information from previous version are highlighted. --
751
FXUS61 KAKQ 170811
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
411 AM EDT Tue Sep 17 2024

.SYNOPSIS...
Low pressure will slowly lift west to northwest along the
border of South Carolina and North Carolina today. The system
will gradually weaken today through Wednesday. Widespread rain
is expected across the local area today, with the pattern
remaining unsettled Wednesday and Thursday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 315 AM EDT Tuesday...

Key Messages:

- Rain chances increase this morning into this afternoon from south
to north, rain may be locally heavy at times and lead to instances
of flash flooding.

- A Flood Watch remains in effect for much of the area along and
east of I-95 (excluding the Maryland and Virginia Eastern Shore)
today.

This morning, low pressure that was previously associated with PTC8
continues to drift WNW along/near the North Carolina and South
Carolina border. Meanwhile, high pressure that has been with us for
the past few days continues to linger just off the New England
coast. Rain shower activity this morning has been generally
scattered and light to this point. Expect the activity to pick up
over the next couple of hours, with colder cloud tops associated
with more widespread rain, beginning to approach our NE NC counties.
CAMs also remain in decent agreement that this activity will
continue to lift north into our area through the morning hours. Also
wanted to make note that we still have a marginal severe weather
risk from SPC across our NE NC counties this morning. As similar to
what was discussed earlier, 0-1km SRH values are as high as
200m^2/s^2 across southern portions of the area, but instability is
lacking across our area with less than 500 J/kg of MLCAPE. In
addition, activity to our south has been relatively tame thus far.
Still, cannot rule out a very low tornado threat across NE NC this
morning if we can get some better instability to work north into the
area.

Shower and thunderstorm activity (best thunder chances across the
southern half of the forecast area) picks up later this morning
through this afternoon as the low continues to lift off to the NW.
Models continue to show a strong and long enough fetch of 850 mb
winds will align itself from the coast continuing to fetch in an
abundance of moisture (PWATs increase to 2.00"+ for much of the
area) across the region this afternoon. This fetch of wind would
allow for training showers to continue throughout the day producing
heavy amounts of rain. WPC has much of the area highlighted in a Day
1 slight risk ERO for today for scattered instances of flash
flooding, especially in urban or poor drainage areas. A Flood Watch
remains in effect for much of the area along/east of I-95 (excluding
the Maryland and Virginia Eastern Shore), where the 00z HREF shows
10-30% chances of >3" of rain in 3 hours. Total QPF over the next 24
hours is generally expected to be in the 1-2" range with lesser
amounts NE and SW. Localized amounts in excess of 4" are possible
under any heavier banding, with recent CAMs highlighting this
potential over SE VA and NE NC in particular. Best rain chances
begin to shift north later this afternoon into this evening, with
southern portions of the area beginning to dry out tonight.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
As of 345 AM EDT Tuesday...

Key Messages:

- Continued unsettled conditions Wednesday into Thursday with an
upper low lingering near the region.

- A backdoor cold front drops southeast across the local area on
Friday.

An upper low gradually stalls south of the area on Wednesday and
gradually drift off to the northeast on Thursday, leading to the
continued potential for unsettled conditions. Shower and
thunderstorm chances will not be nearly as high on Wednesday as
compared to today, with activity expected to more isolated to
scattered in nature (best potential across the western half of the
area). Continued onshore flow and widespread cloud cover will
continue to keep temperatures cool (especially across the northwest)
with highs expected to range from the lower 70s NW to the lower 80s
SE. Cool and cloudy conditions continue on Thursday with decreasing
cloud cover late. Highs on Thursday will generally be in the mid to
upper 70s. A weak backdoor cold front will push SE across the region
during the day Friday, which will bring a slight chance for an
afternoon shower. Highs on Friday will range from the upper 70s to
around 80.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
As of 345 AM EDT Tuesday...

Key Messages:

- Potentially unsettled weather continues into early next week,
mainly along the coast.

- Below normal temperatures are expected this weekend into early
next week.

Aloft, an upper level trough remains in place across the Southeast
underneath a tall upper level ridge extending well into Canada and
even to Greenland. Given the very tall ridge, the trough over the
Southeast should remain in place through this weekend, allowing for
potentially unsettled weather to continue. At the surface, high
pressure remains centered in Quebec through Sat before dropping
south into New England by Sun or Mon. Meanwhile, a stationary front
remains well offshore. Given forecast uncertainty, will largely
maintain NBM PoPs which show 20-35% PoPs Saturday through Monday
(highest along the coast). Will note that given high pressure moving
closer to the area by late this weekend, confidence is low in any
precip, particularly inland. Temps begin a gradual cooling trend
with highs in the mid-upper 70s Saturday, low-mid 70s Sunday, and
70s Monday. Lows also gradually cool with lows in the upper 50s to
around 60F across the Piedmont and lower 60s east (mid 60s along the
coast) on Friday night and mid-upper 50s west to lower 60s east (mid
60s along the coast) Saturday night through Monday night.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
As of 200 AM EDT Tuesday...

To start off the forecast period, primarily IFR conditions
inland with low MVFR closer to the coast. Widely scattered,
primarily light rain showers, are over the area early this
morning. Expect rain to pick up in intensity over the next few
hours and become more widespread at ECG, ORF, PHF, and RIC and
remaining scattered around SBY. IFR CIGs will tend to be the
most widespread across inland portions of the area after, but
some IFR VSBYs are likely to accompany the heavier rainfall as
it spread in from the S through 12Z. All sites may briefly try
to become MVFR (potentially VFR at SBY) during the late morning-
early afternoon hours, before all sites fall back to IFR this
evening through tonight. ENE flow continues across the area in
between the strong high off the coast of New England, and low
pressure across northern portions of SC. ENE winds will average
10-15 kt with gusts up to 20kt inland, and 15-20kt with gusts to
~25kt near the coast through the period.

Outlook: Unsettled weather continues Wednesday through Friday,
but the degree to which this leads to flight restrictions is
uncertain.

&&

.MARINE...
-- Changed Discussion --
As of 410 AM EDT Tuesday...

Key Messages:

- Small Craft Advisories remain in effect for most of the marine
  area today.

- Small Craft Advisories linger into tomorrow for the coastal
  waters due to elevated seas.

- Another round of Small Craft Advisory conditions is possible
  this weekend into early next week.

Early morning sfc analysis shows an area of strong high pressure to
the NE and an area of low pressure (formerly PTC 8) to the SW over
the Carolinas. The tight pressure gradient between these features
has allowed for elevated winds and waves to continue. Latest obs
reflect easterly winds of 15-25kt with a few gusts up to 30kt. Winds
have been showing a downward trend, however, over the southern
coastal waters/Currituck sound. Seas there are slowly diminishing as
well, but are still up around 7ft. Elsewhere, seas are 6-8ft and
waves are generally 3-5ft. The sfc low will weaken as it lifts to
the NW today, allowing the pressure gradient to relax and winds to
gradually improve from S to N through the day and into tonight.
Winds will be 15-20kt (occasionally 20-23kt) through the afternoon.
Should see greater improvement after sunset as a weak area of
secondary low pressure passes over the coast overnight. By ~midnight
tonight, winds will be down to 10-15kt, which will continue through
Wednesday. Seas will improve through Wed, but the onshore winds will
make this improvement gradual. Expect 5ft seas will linger in the
northern waters through most of Wednesday, so have extended the SCAs
there accordingly.

The coastal low then exits to the NE as high pressure builds in from
the NW. Winds flip around to the N/NW for Thurs-Fri at ~10kt. Should
get a couple of days of sub-SCA conditions in for the end of the
week. Seas will be 3-4ft, waves 1-2ft. Could potentially see more
SCAs over the weekend due to a tight pressure gradient between high
pressure pushing in from the N and low pressure just offshore.
-- End Changed Discussion --

&&

.TIDES/COASTAL FLOODING...
As of 345 PM EDT Monday...

Astronomical tides will continue to increase tonight with the
approach of the next full moon. Widespread minor tidal flooding is
expected for much of the area with the upcoming high tide this
evening/tonight along the immediate Chesapeake Bay/adjacent tidal
rivers, with the best flooding potential on the western shore of the
bay. Coastal Flood Advisories remain in effect for much of these
areas, in addition to MD/VA eastern shore (except for Worcester
County/Ocean City where water levels should crest a couple tenths
below minor flood thresholds). Note that minor tidal flooding is
likely along the Atlantic coast this evening/tonight across Eastern
Currituck County. All sites are expected to remain below moderate
flood thresholds tonight, but will have to watch Jamestown and
Oyster as there is a chance that levels at these sites touch
moderate flood thresholds. Finally, have issued a Coastal Flood
Statement for Chowan/Perquimans for nuisance flooding from tonight-
Tue as winds become more E than NE.

Tides remain elevated through midweek with additional rounds of
minor flooding continuing at many of the same locations. For now,
have only extended the advisories out to tonight for most areas and
through Tuesday from Cambridge, MD to the Rappahannock River.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
MD...Coastal Flood Advisory until 4 PM EDT this afternoon for
     MDZ021>023.
NC...Flood Watch through this evening for NCZ012>017-030>032-102.
VA...Coastal Flood Advisory until 4 PM EDT this afternoon for
     VAZ075>078-085-522.
     Flood Watch through late tonight for VAZ064-075>078-080>090-
     092-093-095>098-511>525.
MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ630-
     631.
     Small Craft Advisory until 4 AM EDT Wednesday for ANZ632-634.
     Small Craft Advisory until 10 AM EDT this morning for ANZ633.
     Small Craft Advisory until 7 PM EDT this evening for
     ANZ635>637.
     Small Craft Advisory until 1 AM EDT Wednesday for ANZ638.
     Small Craft Advisory until 7 PM EDT Wednesday for ANZ650-652-
     654.
     Small Craft Advisory until 7 AM EDT Wednesday for ANZ656-658.
-- End Changed Discussion --

&&

$$

SYNOPSIS...AJB
NEAR TERM...AJB/HET
SHORT TERM...AJB
LONG TERM...AJB/RMM
AVIATION...AJB
MARINE...AM
TIDES/COASTAL FLOODING...