Area Forecast Discussion
Issued by NWS Wakefield, VA

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FXUS61 KAKQ 200320
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
1020 PM EST Sat Jan 19 2019

.SYNOPSIS...
A warm front lifts north through the Mid Atlantic region late
tonight, as low pressure and an Arctic cold front approach from
the west. The Arctic front quickly crosses the area Sunday
morning, followed by dry and much colder weather Sunday night
through Monday night.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 1015 PM EST Saturday...

Latest analysis features potent low pressure system aloft is
lifting across the upper TN Valley into the Ohio Valley this
evening. At the surface, high pressure is departing to the NE,
with a 996mb low over eastern KY/TN, and a warm front extending
across central and eastern NC.

Broad swath of showers pushing NE across the Piedmont and I-95
corridor with WAA aloft. To the SE, sct showers just offshore of
the Mid-Atlantic coast this evening, associated with the trough
off the coast. Otherwise, mostly cloudy to overcast across the
region. Temperatures to slowly rise overnight, as the warm front
lifts north across the area, as steadier rain over the NW
Piedmont pushes east to I-95 and over to the MD Ern Shore
overnight.

Surface low pressure is expected to track from the central
Appalachians to the nrn Mid- Atlantic overnight through early
Sunday morning, with an arctic cold front approaching the
Piedmont. Temperatures will soar into the mid 50s to low 60s
by morning, (with the exception of the NW Piedmont) and
dewpoint depressions will only be on the order of 1-3F. A SE
wind will become S and increase to 12- 20 mph with gusts to
25-30 mph toward the coast. A band of moderate to heavy rain
will precede the cold front, a few rumbles of thunder are
possible for SE VA and NE NC. The bulk of the rain is expected
to exit the coast by mid-morning Sunday, with a quick drying
trend arriving from the W. QPF ranges from 0.5-0.75".

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
As of 355 PM EST Saturday...

A drastic change in sensible weather will occur late Sunday
morning into the aftn as the arctic cold front sweeps across the
area. High temperatures to begin the day range from the upper
40s far NW to the mid 50s to low 60s elsewhere. However, by late
aftn temperatures will generally be in the 30s to low 40s
across the region. The threat of any wintry precip as the cold
air arrives and moisture exists looks minimal to zero, and
therefore only have lingering rain shower chances east through
18z. Strong wind, and a rapidly drying airmass (plummeting
dewpoints) behind the front Sunday aftn will lead to most liquid
evaporating before the bulk of the sub-freezing air arrives.
Therefore, a "flash freeze" is not expected.

A strong NW wind will develop Sunday aftn and evening within
CAA behind the front. The wind along the coastlines is expected
to increase to 20-30 mph with gusts up to 40-50mph and a wind
advisory is in effect from the wrn shore of the Bay to the Ern
Shore, and far SE VA and coastal NE NC. Farther inland, the wind
speed is expected to reach 15-25 mph with gusts of 30-35 mph.

The sky clears for most areas Sunday evening and overnight,
just in time for the lunar eclipse. There may some stratocu
develop along and south of the Bay and out over the ocean, but
not expecting any streamers at this time as the depth of
moisture will be lacking. The wind will slowly be diminishing as
well, except near the coast where gusts 30-40 mph will
continue. Temperatures will continue to fall through the night
with overnight lows in the teens for all except the far
southeast where low 20s are possible. Mostly sunny and cold
Monday. Highs will struggle to reach the mid 20s in the north
and low 30s across the south. A wind chill advisory for the nrn
1/3rd of the area is likely Monday morning as wind chill values
should fall to 5 below zero (0 to 10 above elsewhere).

The arctic high builds over the area Monday night into Tuesday
morning, and then gradually slides offshore by aftn. Monday
night will likely be the coldest night with lows ranging from
the upper single digits over the NW Piedmont, to the low/mid
teens from central/s-central VA to the MD Ern Shore, and upper
teens for far SE VA/NE NC under a clear sky. Highs Tuesday range
from the mid 30s N to near 40F S under a sunny sky with perhaps
an increase in high clouds late.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 355 PM EST Saturday...

Still favoring the ECMWF for the extended period. High pressure is
sliding off the coast for the beginning of the forecast period
Tuesday night into Wednesday. An area of low pressure and associated
frontal boundary will also be beginning to approach the region from
the WNW during this time period. Rain showers may work into the far
western Piedmont by Wednesday morning and will slowly overspread the
area into Wednesday afternoon. Rain chances pick up further
Wednesday afternoon into Thursday evening as low pressure from the
Gulf coast states tracks NE along the boundary into the Mid Atlantic
region. Rain showers linger into Thursday night before potentially
changing over to a few snowflakes by early Friday morning. Drier and
cooler conditions are expected for Friday as NW or N flow takes hold
over the region.

Moderating temperatures to start out the extended period as the flow
becomes more southerly. Highs Wednesday will likely be quite mild,
reaching up into the mid/upper 50s to even lower 60s across the
area. Mild temperatures stick around into Wednesday night with
precipitation across the region, expect lows in the 40s to lower
50s. One more mild day on Thursday (highs in the 50s to low 60s)
before much colder temperatures work back into the region Friday and
Saturday. Highs on Friday will generally range from the mid to upper
40s and highs Saturday will struggle to make it out of the 30s. Lows
Thursday night range from the upper 20s NW to mid 30s SE and lows
Friday night range from the low 20s NW to low 30s SE.

&&

.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
As of 710 PM EST Saturday...

Low pressure is tracking NE over the eastern TN Valley early
this evening, with high pressure anchored well N of the region.
MVFR conditions across area terminals this evening will
gradually deteriorate to IFR conditions late tonight, as low
pressure continues to track newd tonight, reaching sern PA by
12z Sunday, with a cold front trailing back into central VA.
This will bring low cigs and vsby restrictions in RA tonight
into Sunday morning. The best chc for persistent IFR cigs will
be from RIC to SBY with a lesser chc at PHF, and this will begin
mainly after 00z. MVFR cigs are expected to prevail at ORF/ECG,
but occasional IFR cigs are possible. Spotty light showers
could affect the TAF sites beginning later this aftn into the
evening, with steadier RA arriving late tonight into early
Sunday morning. Occasional IFR vsby is expected in periods of
heavier RA, and this will generally occur from 06-12z at RIC,
and 09-15z for SBY/PHF/ORF/ECG. A southerly wind will increase
to 12-20kt as the low tracks N of the area, with gusts to ~25kt
possible toward the coast. Additionally, a strong LLJ will
likely produce a period of LLWS up to 40-55kt overnight into
early Sunday morning. Drier air quickly arrives late Sunday
morning into the aftn, although sct- bkn clouds ~3.5kft could
linger into early aftn. The wind will become quite strong out of
the NW, with speeds of 15-20kt and gusts to ~30kt for most
sites, and potentially 20-25kt with gusts ~35kt at SBY.

High pressure builds in from the NW Sunday night and Monday, and
then passes over the region Monday night into Tuesday. Remaining
breezy Monday, before the wind relaxes by Monday night and
Tuesday. High pressure moves offshore Wednesday, followed by
another low pressure system that affects the area Wednesday
night into Thursday. This system will likely bring more rain and
flight restrictions.

&&

.MARINE...
As of 355 PM EST Saturday...

Latest sfc analysis shows that high pressure is continuing to
move away from the region. At the same time, strong (~996 mb)
low pressure is deepening as it is moving NE through the
Tennessee Valley. Winds over the marine areas are generally out
of the E/ESE at 10-15 kt with a few higher gusts. Seas are
around 3 ft, with 1-2 ft waves on the bay. As the area of low
pressure tracks well to the NW of the waters tonight, winds will
veer to the SSE then S from and increase to 20-25 kt by 06-12z
Sun.

As the low moves from wrn MD to srn New England during the day
on Sun, an Arctic cold front will rapidly cross the region from
NW to SE. This will cause winds to shift to the NW area-wide by
early Sun afternoon as strong CAA increases across the area.
Since winds are expected to rapidly increase Sun aftn (with Gale
Force gusts over all marine zones), opted to cancel the ramp-up
SCA and extend the Gale Warning for all marine zones. Winds are
expected to increase Sun evening, as model soundings show deep
mixing (due to the strong CAA), resulting in 40-45 kt gusts
across the bay/ocean (with gusts up to 40 kt over the rivers).
Gale force gusts will continue through Sun night, but will
diminish to 35-40 kt over the bay/ocean by early Mon AM. Did not
make any changes to headlines with this forecast package, so
have Gale Warnings expiring from 09-15z over the waters.
However, some of the 12z/19 guidance is showing the potential
for Gales through much of the day on Mon across the nrn coastal
zones. However, not enough confidence to extend warnings attm.
Seas build to 4-6 ft tonight before rapidly building to between
to 5-9 ft over the coastal waters (w/ 4-6 ft waves on the bay)
behind the Arctic cold front.

In addition, the gale force gusts combined with temps plunging
into the mid-upper teens N/low-mid 20s S will result in the
possibility of freezing spray across the marine area, including
the rivers. Nomograms show the potential for moderate freezing
spray across the bay/ocean Sun night, with light freezing spray
potentially lasting through Mon night.

Winds and seas slowly improve Monday night into Tuesday as high
pressure builds into the region, but winds aoa SCA thresholds
are possible through early Tue AM over the bay/ocean. Another
low pressure system potentially impacts the region by Wednesday
and Thursday, but it looks like only SCA conditions are possible
with this.

&&

.TIDES/COASTAL FLOODING...
As of 400 PM EST Saturday...

Tidal anomalies are between 1.0-1.3 ft early this afternoon
across much of the bay. However, am expecting anomalies to
increase tonight as winds veer to the SSE then S (and eventually
SW by 12-15z Sun). This (combined with it being during the
higher astronomical tide) will have the potential to cause minor
tidal flooding at on the bayside of the Lower Eastern Shore
during the high tide cycle mid-late Sun AM. However, not enough
confidence to to issue an advisory attm as there is a chance
that anomalies will not increase enough to cause coastal flood
issues.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...Wind Advisory from noon to 10 PM EST Sunday for MDZ021>025.
NC...Wind Advisory from noon to 10 PM EST Sunday for NCZ017-102.
VA...Wind Advisory from noon to 10 PM EST Sunday for VAZ095-098>100.
     Wind Advisory from 11 AM to 7 PM EST Sunday for VAZ077-078-
     084>086-523-525.
MARINE...Gale Warning until 10 AM EST Monday for ANZ650-652-654-656-658.
     Gale Warning until 4 AM EST Monday for ANZ635>637.
     Gale Warning until 7 AM EST Monday for ANZ630>634-638.

&&

$$
SYNOPSIS...AJZ/JDM
NEAR TERM...AJZ/MAM
SHORT TERM...AJZ/JDM
LONG TERM...AJB
AVIATION...AJZ/MAM
MARINE...ERI
TIDES/COASTAL FLOODING...


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