-- Discussion containing changed information from previous version are highlighted. --
044
FXUS61 KAKQ 250556
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
156 AM EDT Wed Sep 25 2024

.SYNOPSIS...
A series of shortwave troughs will slide across the region in
northwest flow aloft bringing unsettled conditions through
midweek. The remnants of Helene likely pass well west of the
area on Friday. Temperatures will gradually moderate through
midweek.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 940 PM EDT Tuesday...

Key Messages:

- Showers and isolated thunderstorms overspread the region
  overnight into early Wednesday morning.

- A Flood Watch is in effect for our southwestern counties from
  this evening into Wednesday morning.

Late this evening, showers and sctd tstms associated with a warm
frontal boundary (shortwave energy) were moving into the
Piedmont counties. Temps were ranging from the mid 60s to the
lower 70s. These showers and isolated tstms will push across the
region overnight into Wed morning, with showers or tstms
possibly producing locally heavy rainfall. Many of the CAMs
are hinting showing higher QPF amounts across our far SW counties.
As a result, WPC has highlighted these locations with a slight
risk for excessive rainfall for overnight. Thus, a Flood Watch
has been issued for Prince Edward, Nottoway, Brunswick, Lunenburg,
and Mecklenburg counties. Scattered instances of flash flooding
are possible, esply in any poor drainage areas. There is a
marginal risk for excessive rainfall for much of the remainder
of the area, roughly around I-95 and west. Lows tonight will
generally be in the mid to upper 60s.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/...
As of 350 PM EDT Tuesday...

Key Messages:

- Continued cloudy conditions with additional chances for showers or
thunderstorms on Wednesday, especially west of I-95.

- The remnants of Helene move north Thursday night through Friday,
bringing additional rain chances to the area.

A warm front lifts north through the area tomorrow, bringing warmer
and more humid air back into the region. Additional shower and
storms will be possible Wednesday afternoon, especially along and
west of I-95. Heavy rainfall and potentially gusty winds will be
possible with any storms that develop. High temperatures tomorrow
will range from the mid-upper 70s north to the lower 80s south.
Drier on Thursday, with only low-end PoP chances (mainly west), but
still remaining fairly cloudy. Highs will range from the upper 70s
to lower 80s. Rain chances increase again Thursday night into Friday
as Helene moves north (remaining well west of the forecast area).
The best rain chances will likely be late in the day and Friday
night, with locally rainfall again a possibility (especially west).
Highs on Friday range from the mid 70s NW to lower 80s SE.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 350 PM EDT Tuesday...

Key Messages:

- Multiple low-end chances of rain late this week into the
  weekend from Tropical Storm Helene

- Drier and cooler air coming mid next week

There is some uncertainty about impacts from newly-named Tropical
Storm Helene for the weekend. The 12z ECMWF and GFS suggest remnants
split from Helene`s original track up GA to the W near the TN/MO
border and E over the ocean late Friday. The splitting of the low
pressure system could allow chc showers from residual energy and
moisture on Saturday, Sunday, and Monday. Temperatures Saturday and
Sunday will have highs in the upper 70s and lows in the low to mid
60s. The last of the moisture will be squeezed out on Tuesday by a
frontal passage which will bring drier and cooler conditions Tuesday
and Wednesday with highs in the mid 70s and lows around 60F.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
As of 200 AM EDT Wednesday...

A batch of Showers and isolated tstms are continuing to move
across southern Virginia. These showers and thunderstorms will
bring some MVFR and IFR conditions for ECG, ORF, and PHF this
morning. Later this morning there will be another chance of
isolated showers and thunderstorms across all TAF sited bringing
in more MVFR and IFR conditions. Then by this afternoon as the
warm front propagates north mainly MVFR and VRF conditions
across all taf sites as the chances of showers decrease.
Thursdaywill be drier, but chances of showers return on Friday
and Saturday.
-- End Changed Discussion --

&&

.MARINE...
As of 400 PM EDT Tuesday...

Key Messages:

- Elevated seas persist through most of this week and into the
coming weekend. Small craft advisories have been extended on the
coastal waters through Thursday.

- The remnants of Tropical Cyclone Helene pass well inland Friday,
with impacts locally limited to gusty SE winds Friday-Friday night.

A warm front is located SW of the waters this afternoon, with low
pressure well offshore and high pressure ridging into the area from
New England. Tropical Storm Helene is situated over the NW Caribbean
Sea and is expected to track northward into the Gulf Mexico tonight,
per the latest NHC forecast. Locally, a relaxed pressure gradient is
leading to light-moderate winds as of 3 PM/19z, generally E ~10
kt. Seas remain elevated in the 4.5-7 ft range, highest N.
Small craft advisories remain in effect for all coastal water
zones and have been extended through most of Thursday as
confidence is high in these elevated seas continuing.

The eastern fringes of a LLJ overspreads the Chesapeake Bay tonight
and winds likely increase to 10-15 kt for a time after sunset. There
could be a few gusts to 20-25 kt in this timeframe, especially
across the northern bay. The duration and marginal wind speeds
precludes a small craft advisory at this time. Into Wednesday,
the high over New England retreats into the Canadian Maritimes
as TS or Hurricane Helene gets pulled northward through the
central and eastern Gulf. This will turn the flow to the SE or
SSE through at least Thursday, though wind speeds should average
10 kt or so. Helene makes landfall in the FL Big Bend region
Thursday, tracking inland along the southern Appalachians
Friday. The remnant low will probably lead to an increase in SE
winds by Friday afternoon and winds could approach low-end SCA
criteria of 15-20 kt with gusts to 25 kt. This appears most
likely over the southern coastal waters and lower Chesapeake
Bay, with lower chances further N. There is higher uncertainty
into Saturday as a cold front potentially pushes into the area
from the N or NW. The timing is overall slower with the 12z
guidance, delaying any increase in winds to Saturday night or
early Sunday. SCA conditions are possible behind this front as
NE winds make a return.

Seas remain 4-6 ft through most of this week and into the weekend
and SCAs will likely be needed for most of this period. Waves in the
Chesapeake Bay will average 1-2 ft through the weekend, except ~3 ft
at the mouth of the bay. Per the latest 12z NWPS output, 3-4 ft
waves are possible at the mouth of the bay tonight w/ the brief
increase in SE winds. Not enough confidence at this time to issue a
SCA, however. Depending on the frontal timing Sat-Sun, waves in the
bay could increase to 3-4 ft at times.

A high rip current risk is forecast through at least Wednesday.

&&

.TIDES/COASTAL FLOODING...
As of 400 PM EDT Tuesday...

Key Messages:

- Long duration coastal flood event continues across the region (see
section below for info on this being a record at a few sites).

- Water levels are forecast to gradually subside over the next few
days.

- Coastal Flood Warnings remain in effect from Windmill
Pointt/Tappahannock northeastward to the bay side of the MD Eastern
Shore, with advisories elsewhere (see CWFAKQ for more details).

- Minor flooding likely persists into Wednesday across the middle
and upper bay.

Tidal departures are averaging 1.5-2 ft above astro tides this
afternoon. Only changes to the ongoing headlines was to refine the
timing with the ongoing or approaching afternoon/evening high tide.
High-end minor or low-end moderate tidal flooding is forecast in the
upper bay and along the Potomac/Rappahannock, including on the bay
side of the MD Eastern Shore, with this upcoming high tide cycle.
Accordingly, Coastal Flood Warnings remain in effect through this
evening (early Wed morning on the MD Eastern Shore).

Elsewhere, Coastal Flood Advisories are in effect across the lower
bay and York and James Rivers through this evening. Here, confidence
is low in exceeding minor flood and current tidal departures argue
water levels should peak within or below minor thersholds. Elsewhere
in the advisory area, only minor flooding is expected today. Also,
included MD Beaches in the ongoing advisory through 6 PM as Ocean
City crested just above minor flood w/ this afternoon`s high tide.

Water levels should gradually fall this week with decreasing
astronomical tides, but minor flooding is expected through much of
the week in areas near/adjacent to the mid/upper bay. Over the lower
bay, only nuisance/action-level at worst is expected.

As of 400 PM EDT Tuesday:

Consecutive high tides reaching at least Minor Flood with this event:

- Lewisetta (P.O.R. since 1979): 16 (with several more to come),
previous record was 8 in Oct 2021, Oct 2019, Oct 2015.

- Cambridge (P.O.R. since 1980): 10 (with several more to come),
previous record was 5 in Oct 2021, Oct 2019, Sep 2018, Oct 2011.

Consecutive high tides reaching at least Moderate Flood with this
event: (this event may tie the record at Lewisetta).

- Lewisetta (P.O.R. since 1979): 6 (so far) ***record is 7 in Oct
2015***

- Cambridge (P.O.R. since 1980): 1 (so far and unlikely to occur  on
consecutive tide cycles)  ***record is 4 in Oct 2019***

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
MD...Coastal Flood Warning until 2 AM EDT early this morning for
     MDZ021>023.
NC...None.
VA...Flood Watch until 8 AM EDT this morning for VAZ060-065>067-079.
MARINE...Small Craft Advisory until 7 PM EDT Thursday for ANZ650-652-
     654-656-658.
-- End Changed Discussion --

&&

$$

SYNOPSIS...AJB
NEAR TERM...AJB/TMG
SHORT TERM...AJB/HET
LONG TERM...KMC
AVIATION...HET/TMG
MARINE...MAM/SW
TIDES/COASTAL FLOODING...