Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 252047
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
347 PM EST Tue Feb 25 2020

.SYNOPSIS...
A warm front will linger over the area tonight into Wednesday
morning. A strong cold front will approach from the west Wednesday
afternoon, and then track through the region Wednesday evening.
Cooler, drier weather returns Thursday and Friday.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 330 PM EST Tuesday...

Latest MSAS has the warm front now into srn VA and will meander
across the area tonight. Most of the steady pcpn has pushed
offshore but can`t rule out a shwr ivof the bndry this eve.

Main forecast challenge tonight will be fog development as most of
the data suggests widespread fog developing not only across the land
but over the waters as well. Have added fog to the grids attm.
Lclly dense fog is also possible late. Lows in the 40s-lwr 50s se.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY NIGHT/...
As of 330 PM EST Tuesday...

Rather interesting forecast ahead for Wed/ Wed nite. Key for
Wed will be how long it takes for the morning fog / low clouds
to burn off and will there be any partial sunshine before clouds
/ shwrs overspread the area during the aftrn ahead of the
apprchg cold front. Given the position of the frontal bndry and
the amount of low- level moisture seen in the models, based this
forecast off the cooler MET MOS values vs the higher MAV
values. Therefore, will have morning clouds / fog giving way to
mstly cldy aftrn skies with shwr chcs increasing from west to
east. Highs in the 60s.

A triple-point low is progged to track across nrn VA into PA
late Wed with the trailing cold front crossing the area Wed
eve before exiting off the coast after midnite. Models have its
passage across the wrn half of the fa btwn 01Z-04Z, ern half
btwn 03Z-06Z then quickly pushing offshore. SPC has the wrn two-
thirds of the local area in a marginal svr risk for damaging
wind gusts with a narrow line of convection with the actual
fropa. Given time of day, think the best chc for this to occur
will be to the nw (where the mid level jet will be the strongest)
closer to the track of the triple point low, otherwise high res
data supports convective wind gusts arnd 40 mph as they push
east. Will carry likely PoPS thru 06Z, then rapidly ending and
clearing west to east. CAA behind sends lows into 30s west, 40s
east.

Sunny and cooler Thurs as high pressure builds in from the nw.
Deepening low to the north combined with the high results in a
breezy to windy day (25-30 mph except 30-40 mph along the ern shore)
despite the sunshine. W-NW downsloping winds will offset the CAA a
bit, with highs in the upr 40s-lwr 50s. Mstly clr with diminishing
wind Thurs nite. Lows mid 20s-lwr 30s. Fri starts out mstly sunny,
with increasing aftrn clouds ahead of the next s/w "clipper" system
tracking ese. Highs in the mid-upr 40s.

Models show some weak moisture/lift crossing the mts with the s/w
Fri nite. Will carry slght chc rain/snow shwrs with this feature at
this time. Lows mid 20s-lwr 30s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 330 PM EST Tuesday...

Shortwave axis moves offshore on Saturday and high pressure will
build in for the remainder of the weekend resulting in drier and
cooler conditions. High temps in the 40s, with lows in the 20s to
near 30 SE for Saturday and Sunday. The high shifts east on Monday
to off the southeast coast resulting in a warmer S/SE flow. Lows
Monday morning mid 20s NW to mid 30s SE. High temps 50-55. Next
chance for precip will be late Monday into Tuesday as the first of a
series of disturbances crosses the area.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
As of 1245 PM EST Tuesday...

A warm front has lifted north into srn VA this aftrn with most
of the rain with the leading trof pushing up the ern shore and
of the coast. Meanwhile, abundant low-level remains in the form
of a SCT-BKN IFR ST layer south of the boundary and a solid ST
IFR deck north of it. Expect these conditions to continue through
most of the forecast period as little in the way of synoptic
movement is noted until Wed aftrn. Data all points to a foggy
night ahead with the potental for some locally dense fog early
Wed morning. Did not want to take VSBYS that far down attm, so
went no lower tha 1SM for now. Conditions will be slow to improve
Wed morning.

OUTLOOK...
A cold front will approach from the west Wed aftn and cross the
region btwn 00Z-06Z Thurs bringing a good chc of showers. Could
even see some gusts aoa 35 KTS in some of the shwrs with the
actual fropa. Dry and breezy/windy conditions develop Thur/Fri
as an upper trough spreads across the region. A quick moving
trough will bring a very minimal chc of light rain or snow
showers Friday night, before dry conditions return Saturday.

&&

.MARINE...
As of 330 PM EST Tuesday...

A broad area of low pressure is centered over the Appalachians late
this afternoon. The pressure gradient ahead of the low is relatively
weak, so S-SW winds are averaging ~10 kt over the waters. Seas are
around 3 ft. The low is expected to weaken as it crosses the
mountains tonight through the first part of Wednesday, but will
rapidly deepen as it tracks from Virginia north to upstate NY during
the Wed aftn-Thu AM timeframe. Wind will remain light (aob 10 kt)
from this evening through the first part of Wednesday as a frontal
boundary lingers INVOF the waters. Have seen some patchy fog over
the waters today, and guidance is hinting that the fog may become
dense over parts of the marine area this evening-tonight. Will keep
1-3 NM VSBYs in the forecast for now, but Marine Dense Fog
Advisories may be required by tonight.

The boundary retreats north on Wednesday before a strong cold front,
crosses the waters from W to E Wednesday night/early Thu AM (most
likely between 04-08z Thursday). The wind will shift to the W behind
the cold front. Could see a brief (< 3 hour) period of ~35 kt gusts
as a broken line of showers accompanies the frontal passage.
Prevailing sustained wind speeds increase to 18-23 kt on the bay/~25
kt over the ocean (highest north) by Thu AM as the pressure gradient
tightens in the wake of the rapidly deepening low (with relatively
decent CAA following the FROPA). While there are differences in the
models with respect to the wind speeds, confidence is high enough to
issue SCAs for the Ches Bay, ocean, Lower James River, and Currituck
Sound from Wed night-Thursday evening. Will likely see a few 35 kt
gusts across the nrn coastal waters on Thu, but the best chc of
frequent gale gusts will remain N of our area. Cannot rule out a 3-6
hour period of frequent low-end gale gusts over the far nrn coastal
across waters (especially 20 nm offshore) on Thursday, but this
would only occur if the high-end model forecasts for wind speed
verify. Therefore, not enough confidence to issue Gale headlines
this far out but will allow future shifts to re-evaluate. In
addition, SCAs appear increasingly likely for the upper rivers on
Thu, but will hold off on issuing headlines attm.

The aforementioned surface low will slowly track NE into Quebec from
Thu night-Sat AM as a cold upper trough remains in place across the
ern CONUS. W winds are forecast to average 20-25 kt (sustained) Thu
night over the bay/ocean, so SCAs will likely be extended in future
forecast packages. Winds may diminish to just below SCA thresholds
during the day on Fri before a nocturnal CAA surge allows wind gusts
to increase to around/just above SCA thresholds by early Sat AM.
Could see one last nocturnal CAA surge Sat night before sub-SCA
conditions return on Sunday. Seas are not expected to build to more
than 4-6 ft during the Thursday-Saturday timeframe due to an
offshore component to the wind, with 2-4 ft waves on the Ches Bay.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory from 10 PM Wednesday to 7 PM EST Thursday
     for ANZ630>632-634-650-652-654-656-658.
     Small Craft Advisory from 1 AM to 7 PM EST Thursday for ANZ633-
     638.

&&

$$
SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...MPR
LONG TERM...CMF
AVIATION...MPR
MARINE...ERI



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