069
FXUS61 KAKQ 030258
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
958 PM EST Thu Jan 2 2025

.SYNOPSIS...
A weak system moves through the region later tomorrow, bringing
a chance for showers mid to late Friday afternoon and evening.
Cold and dry conditions then follow for most of the upcoming
weekend. Low pressure is expected to bring winter precipitation
to much of the area Sunday night into Monday.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 955 PM EST Thursday...

Key Message:

- Dry and chilly tonight with lows in the 20s to low 30s.

The forecast remains on track. The only change made during the
evening update was to lower overnight lows a bit as temps have
already fallen into the upper 20s to lower 30s in many spots.
Clear and cold overnight with widespread mid 20s inland.

Previous Discussion as of 345 PM...

Afternoon analysis shows high pressure centered over MS/AL with a
stronger surface ridge over the western Canadian Prairies. Skies are
mostly clear this afternoon with some orographically enhanced
stratus forming along and east of the Blue Ridge this afternoon.
Temps this afternoon are mainly in the 40s.

Remaining mostly clear and cold tonight with clouds increasing from
west to east toward sunrise as a developing shortwave trough in the
NW flow aloft dives SE toward the area. Low temps dip into the mid
20s to low 30s over the area.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
As of 345 PM EST Thursday...

Key Messages:

- More clouds Friday. A disturbance brings a chance for showers
  by mid to late afternoon, potentially changing to snow
  showers before ending Friday evening. Light snow accumulations
  are possible in the Virginia Northern Neck and especially the
  MD Eastern Shore.

- Dry and cold Saturday between systems.

- Increasing moisture and overrunning ascent move into the
  region late Sunday afternoon ahead of the next system.
  Initially dry low levels will limit any daytime snowfall
  accumulations.

The disturbance aloft amplifies through the morning and especially
during the afternoon tomorrow, resulting in a focused area of lift
with steepening lapse rates aloft. Not much moisture to work with
across the area but lift should prove sufficient to allow some
shallow convective showers to move across the area from mid
afternoon into the evening hours. Given very cold temps aloft, some
graupel may mix in with the rain showers in any of the more intense
cells across central VA. Lift will be focused across the N and NE
portions of the area where more graupel may accompany the showers
through the afternoon. Afternoon high temps top out in the mid to
upper 40s. Heading into the evening hours, colder air will move into
the region and allow precip to end as a rain/snow mix or potentially
all snow showers for NE portions of the area. Have light snow
accumulations of around 0.5" for the MD Eastern Shore with a
trace/quick dusting possible across the Northern Neck and adjacent
portions of the VA Eastern Shore. The column dries out quickly
towards midnight with any lingering precip coming to an end. Cold by
sunrise Saturday with temps ranging from the low 20s W to the mid
20s E. Winds will be breezy behind the surface cold front,
(especially near the coast) with wind chill readings in the teens
across the region.

Dry and chilly Saturday with mostly sunny skies. It will also stay
breezy across the region through mid afternoon before winds calm
down toward sunset. High temps only rise into the mid and upper 30s
with wind chills in the 20s through the afternoon. Clear and cold
overnight with low temps in the mid teens in the typically colder
rural spots to the low 20s for the remainder of the area.

Clouds increase from west to east Sunday as the next system
continues to amplify across the central CONUS. Have increased
afternoon temps a few degrees with highs in the upper 30s to low
40s. Clouds increase further across the west in the afternoon with a
slight chance of light snow/flurries for the Piedmont before sunset.
Very dry low levels will limit any accumulation potential during the
afternoon and will serve to begin cooling surface temperatures
through evaporation/sublimation along with loss of daytime
heating.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 330 PM EST Thursday...

Key Messages:

- We continue to keep a close eye on the Sunday night-Monday
  night timeframe for an impactful winter storm, especially
  over northern and central portions of our area.

- Models trends have continued to trend toward a significantly
  warmer solution. A period of snowfall is still possible over
  the northern third of the area. However, for much of our area,
  a brief period of snow at the outset yields to a wintry mix of
  snow/sleet/freezing rain mix, which eventually transitions to
  rain across central zones with mainly rain SE.

Overall, the 12Z/02 guidance and their respective model ensembles
continue to smooth out previous timing issues. Models have also
come into better alignment with placement of surface and upper
level features for the Sunday night/Monday event, though some
differences remain. Generally speaking, Miller B` type evolution
looks increasingly likely, entailing the initial area of low
pressure crossing the mid-south/TN Valley on Sunday, then lifting
ENE just west of the higher Appalachian Mountains Sunday night
and early Monday as it weakens. Meanwhile, a secondary area of
low pressure develops and becomes dominant over coastal E NC or
SE VA Monday morning. The ECMWF continues to be on the faster
end of the global deterministic models, though it has slowed
slightly toward the remainder of guidance (12z GFS/UKMET and
Canadian) for the secondary low to become the dominant surface
feature.

What all of the models have in common is a more aggressive
handling with the mid-level warm nose, despite pesky cold air
wedge hanging on into the late night/morning hours of Monday,
especially across the VA piedmont and northern neck. This leads
to the continued concerns for mixed precip. There are still a
few ensemble members showing the potential for a significant
snowfall over the far northern CWA (see ensemble probs listed
below), but for much of the area, probabilities for heavy snows
locally are lower across the board, significantly so for central
VA. It does appear that SN will be more short-lived, likely
confined to the WAA-aided onset of precipitation near or just
after sunset Sunday evening into the early morning hrs Monday.
Low temperatures have trended up several degrees (especially
south) for Sun night with a quicker arrival of the clouds and
moisture, though it will still get below freezing for the
region, with lows ranging from the mid 20s to lower 30s.

Given a high confidence that this will not just be a snow to
rain event, have tried to get into a bit more specificity with
the progression of P-type, with the understanding that this will
need to be refined in later forecasts, and as the system itself
is finally sampled by the RAOB network over the next day and a
half. Still expect have a rapid changeover to all rain in NE NC
and far SE VA, probably as early as midnight late Sunday
night/early Monday. The typical transition zone looks to be
interior SE VA and south central VA and into metro RIC during
the later evening/early morning period. Across the far NW, it
still appears likely that highs Monday will struggle to get
above freezing, per decent model agreement with respect to Tw
temperatures. As for freezing rain, the area of most concern
will be the piedmont, probably along and W-NW of US-15 from
Farmville to Louisa, though early on south central VA and
interior NE NC could see at least a few hrs with freezing rain
as well. The eastern shore/northern Neck will have the best chc
for seeing a significant snowfall accumulation...but once again
model trends are toward more freezing precipitation than frozen.
Highs into the mid/upper 40s and even the 50s seem likely.

Cold air is expected to rush back S and E Monday evening, but
as the vertical column rapidly dries, the trends are generally
for a faster exit with only chc PoPs mainly over the east by
Monday aftn and early evening. Have therefore changed to
showery/convective wording with measurable snow unlikely in this
time range.

Snow Probs from the 12Z/02 ensembles:

- The ECWMF (ENS) shows a 90%+ chc for 1" of snow and ~60-70%
  for 3"+ across the far N (Louisa to SBY). A general downward
  trend in snow probs continues for central and southern
  portions.

- The GFS and Canadian ensembles are lower, generally ~90% for
  1"+ across the north and ~30-40% for 3"+ across the north
  with decreasing probabilities again with southward extent.

Lows Monday night fall into the mid teens NW to the low/mid 20s
with upper 20s for Hampton Roads and points south, with a flash
freeze of any slush/rain Monday night. Drying out and likely
getting even colder for the remainder of the week. Highs Tue-
Wed mostly in the 30s (and probably barely above freezing for
the northern zones). Lows will mostly be in the teens, but is
northern areas do receive even a modest snowpack, it will be
significant colder, in the single digits and Cold Weather
Advisories may be necessary.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
As of 615 PM EST Thursday...

VFR conditions prevail this evening with clear skies outside of
high clouds. Clear outside of high clouds through most of
tonight. Then, clouds will thicken and lower from NW to SE
as a fairly strong cold front approaches the area (in
association with a shortwave aloft). CIGs lower to 3000-6000 ft
by the late aftn. Strong lift with the shortwave will result in
scattered showers across the area Friday afternoon with very
cold temps aloft. Some graupel/rain is possible at RIC with
graupel and snow possible at SBY. Low confidence in seeing
measurable precip at the southern terminals. Went ahead and
introduced rain/snow showers into the TAF at SBY right at the
end of the period. Could see brief IFR VSBYs at SBY tomorrow
evening (and even a light coating of snow) if one of the
stronger showers directly impacts the terminal. The cold front
crosses the terminals from NW-SE between 22-02z. Skies quickly
clear behind the front, but winds become WNW and may gust to
~30 kt for a few hours following the FROPA. Gusty WNW winds (to
20-30 kt) will continue near the coast through much of Friday
night.

Outlook: Dry for Saturday and most of Sunday. A large system,
likely with some wintry precip, moves in Sun night through
Monday. The highest chc for impactful winter wx is at RIC and
SBY, but flight restrictions will be possible at all terminals.

&&

.MARINE...
As of 850 PM EST Thursday...

Key Messages:

- Sub-SCA winds expected tonight through Friday morning.

- Gale Watches have been upgraded to Warnings for the coastal
  waters, Chesapeake Bay, lower James River, and the Currituck
  Sound for Friday evening into Saturday morning.

Winds have relaxed this evening to 10-15kt with a slackening
pressure gradient. Continued improvement is expected overnight,
albeit temporary, with westerly winds of ~10kt. Winds turn to
the SW through the day Friday, increasing to 15-20kt by the
afternoon ahead of a cold front.

Another round of strong NW winds is expected behind the cold front
Friday evening through Saturday morning. A tight pressure
gradient and strong CAA will allow for NW winds of 20-30 kt
with gusts up to 40-45 kt. Locally higher wind gusts are
possible along the immediate front. Given we are now within 24
hrs and there is high confidence in the forecast, upgraded
previous Gale Watches to Warnings for most of the marine area,
including the coastal waters, Chesapeake Bay, lower James River,
and Currituck Sound with this evening`s marine update. Warnings
go into effect starting at 21z/4 PM Friday. Maintained Gale
Watches for the upper rivers given the shorter duration of
higher winds and lower overall confidence. The next shift will
make the determination on whether to transition to Gale Warnings
or SCAs. Elevated winds persist through Saturday and there is
some possibility that the Gale Warnings will need to be extended
through the day Saturday, especially on the coastal waters.
Waves increase to 3-5ft in the bay and 2- 3ft in the rivers
during this period. Seas of 4-7ft expected, highest 10-20 NM out
due to the offshore wind direction. Winds gradually ramp down
Sunday though remain 15-20 kt through the early afternoon.
Another period of degraded marine conditions is likely later
Monday and Tuesday.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Gale Warning from 4 PM Friday to 7 AM EST Saturday for
     ANZ630>634-638.
     Gale Watch from Friday afternoon through Saturday morning for
     ANZ635>637.
     Gale Warning from 4 PM Friday to 10 AM EST Saturday for ANZ650-
     652-654-656-658.

&&

$$

SYNOPSIS...RHR
NEAR TERM...ERI/RHR
SHORT TERM...RHR
LONG TERM...LKB/MAM
AVIATION...ERI
MARINE...KMC/SW