307
FXUS61 KAKQ 170719
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
319 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 THURSDAY NIGHT/...
As of 405 PM EDT Monday...

Key Messages:

- Highs rain chances for the entire region Tuesday morning into
late Tuesday night into Wednesday Morning.

-A flood watch is in effect for NE NC, tomorrow morning and
 into the evening.

-A flood watch is is in effect along and east of I-95 across
Virginia tomorrow morning into Wednesday morning.

The low will then continue NW or N across NC very late tonight
through Wed. This will result in bands of showers (isolated tstms),
possibly heavy at times nwrd across the CWA tonight into Wednesday
morning. Based from the latest 12z model guidance the risk of
possible flooding has been increased across the CWA. A flood watch
has now been issued along and east of I-95 for both North Carolina
and Virginia. Latest Hi-Res guidance is suggesting heavy bands of
showers and possible thunderstorms tracking across portions of NC
and VA tomorrow morning and into the afternoon. Models have
suggested that a strong and long enough fetch of 850 mb winds will
align itself from the coast continuing to fetch in an abundance of
moisture. This fetch of wind would allow for training showers to
continue throughout the day  producing heavy amounts of rain. Based
on what happened today across southern North Carolina with training
showers and thunderstorms it is highly possible that can happen
tomorrow. Over these next 48 hours the higher QPF totals could
be stretching from the Northern Neck to South Central Virginia
and Tidewater. There could potentially be wide spread rainfall
from 2-3 inches with isolated heavier amounts in excess of 4
inches. This again all depend on where the band of training
showers align. The only uncertainty with this system is where
these heavier rain bands set up. Temperatures for the day will
remain on the cooler side with highs in the middle to upper 70s.

After Tuesday an upper level low will continue to linger across the
region. With this low lingering Pops will remain in the forecast.
However, these chances will be lower than the previous days with
Pops ranging between 25-35% for both Wednesday and Thursday.
There will not be wide spread rain with these pops as it is the
potential for scattered to isolated showers. Temperatures will
be slightly for both Wednesday and Thursday as highs reach into
the lower 80s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 345 PM EDT Monday...

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 15-20% PoPs Fri and 20-35% PoPs Sat
through Mon (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 upper 70s to around 80F Fri, mid-
upper 70s Sat, low-mid 70s Sun, and 70s Mon. 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) Thu-Sat nights and mid-
upper 50s west to lower 60s east (mid 60s along the coast) Sun and
Mon nights.

&&

.AVIATION /07Z 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...
As of 345 PM EDT Monday...

Key Messages:

- Small Craft Advisories remain in effect for all of the marine
  area through Tuesday. A few gusts to 35 knots are possible
  south of Cape Charles this afternoon through tonight.

- Small Craft Advisory conditions are likely to linger well into
  this week, especially for seas.

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

Low pressure is just pushing onshore near the NC/SC border this
afternoon while the surface high to our north has shifted east to
just off the New England coast. The gradient between these two
features continues to result in a ~20 kt NE wind (with frequent
gusts to 25 kt...and occasional gusts to 30 kt). Seas remain in the
6-7 ft range N and are 7-9 ft S. SCAs remain in effect for all
marine zones.

The low is progged to track to the WNW across northern SC from
tonight-Tue while the associated warm front slowly approaches from
the north. The persistent 15-25 kt NE wind will continue through
much of Tuesday. Winds veer to the east and diminish to 10-15 kt
late Tue evening-Tue night (as could become southerly over the far
southern coastal waters) as the front approaches and the pressure
gradient slackens. There is still the potential for a few gusts of
~35 kt (especially at elevated terminals) from this evening-tonight.
All SCAs run through Tuesday, with the lower bay/coastal waters in
effect through Tuesday night. Winds remain onshore on Wed/Thu (with
speeds ~10 kt) as what`s left of the low very slowly tracks near the
central Appalachians. Seas remain 6-10 ft through tonight and a
High Surf Advisory remains in effect through Tue AM for the NE
NC Outer Banks and VA Beach. Seas slowly subside later Tue/Tue
night and should fall below SCA criteria by Wed evening. The
high rip current risk continues through Tue.

High pressure drops south from Canada into New England this weekend.
This will push a backdoor cold front across the local waters Fri
night into early Sat, with a tightening pressure gradient behind it.
As such, expect a prolonged period of NE onshore flow this weekend
into early next week. Confidence is increasing in SCA criteria winds
during this time with winds 15-25 kt and gusts up to 30 kt possible.
Will note that the GFS is the most aggressive model, but enough
consensus in at least 15-20 kt sustained winds exists between models
and in the ensemble guidance to include in the forecast.

&&

.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...
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.
     High Surf Advisory until 4 AM EDT early this morning for
     NCZ102.
VA...Coastal Flood Advisory until 4 PM EDT this afternoon for
     VAZ075>078-085-522.
     High Surf Advisory until 4 AM EDT early this morning for
     VAZ098.
     Flood Watch from 7 AM EDT this morning 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 AM EDT Wednesday for ANZ650-652-
     654-656-658.

&&

$$

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