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000
FXUS61 KAKQ 242341
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
641 PM EST Fri Jan 24 2020

.SYNOPSIS...
Low pressure and an associated cold front track across the region
tonight into Saturday morning. High pressure builds in for the end
of the weekend. Another area of weak low pressure potentially tracks
across the area on Monday.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 640 PM EST Friday...

Early evening weather analysis shows an upper trough stretching
from south-central Canada SSE to the Lower Mississippi River
Valley. A well-defined upper low was slowly moving eastward over
IL/IN. At the surface, ~1010 mb low pressure was centered over
nrn IL/IN, with a trailing cold front stretching southward into
WV, western VA/NC, and GA. Latest radar mosaic shows the main
area of showers (ahead of the trailing cold front) now advancing
through SW VA and entering the Piedmont of NC with scattered
showers reaching our western FA. The main area of pcpn will
likely remain W of the CWA until late evening.

A secondary triple point low is progged to develop over the
western Carolinas before tracking to the northeast across our
CWA overnight. This happens as the aforementioned upper low
tracks ENE toward the srn Great Lakes. Timing of the main line
of convection looks to be around 03z/10 PM across the Piedmont,
07-10z/2-5 AM for the I-95 corridor (including the RIC metro),
and 10-16z/5-11 AM for the VA peninsula and MD/VA/NC coastal
areas. Winds slowly veer to the SE then S tonight as the
secondary triple point low approaches our CWA. This will allow
temperatures to warm into the mid 50s-near 60F E of I-95 during
the latter half of the night (prior to the arrival of the main
line of showers). Still looking like there will be some elevated
instability as the line of showers moves across the area. In
addition, kinematic fields are fairly robust (as is often the
case during the cool season). A 50 kt southerly 925 mb jet is
progged to be over ern portions of the area overnight-Sat AM
while the mid-level flow will be out of the SSW-SW at 50-70 kt.
The one factor that will likely keep this line from producing
severe wx is the fact that surface-based instability will be
non-existent across the area (as temperatures will struggle to
reach 60F...with dew points likely no higher than the mid 50s
in most areas). Nevertheless, any of the stronger showers could
produce wind gusts of ~40 mph (highest chances across the SE).
This is in line w/ the convective outlook from the Storm
Prediction Center, which has our area in general thunder (w/ a
marginal risk to our south). Still expecting very little in the
way of thunder w/ this line as any convection will be fairly
shallow. However, cannot rule out a rumble of thunder or two
across NE NC.

While rainfall rates will be fairly impressive for late January, the
line will be moving quick enough that flooding should not be a
concern, outside of nuisance poor drainage areas. Highest rainfall
totals will be out to the west with totals decreasing as you head
southeast. Expect 1-1.25" west of I-95, 0.75-1.0" from the
Richmond metro up to the Lower MD Eastern Shore, and ~0.5" for
NE NC and the Tidewater area.

The cold front associated with the low clears the area by midday
Saturday. Despite the frontal passage, Saturday will remain
mild with high temps ranging from the mid 50s NW to low 60s
across the SE. Cannot rule out some re-development of showers
across the VA Northern Neck/Lower Ern Shore Sat aftn as
temperatures rapidly cool aloft (as the upper trough axis
approaches the region), but any remaining showers should
dissipate during the evening hours.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 330 PM EST Friday...

High pressure builds to our SW Saturday night before weakening and
moving offshore on Sunday. Slightly cooler/drier air will filter in
from the W, but temperatures are expected to remain at or just above
seasonal averages. Lows Saturday night will be in the low-mid 30s in
most areas, with highs in the upper 40s-low 50s on Sunday.

Models have come into better agreement that an upper-level shortwave
will track from the TN Valley to northeast North Carolina from
Monday-Monday night. While this system will be lacking
moisture, models have some light QPF across the southern half of
the CWA on Monday. 12z/24 EPS probabilities of at least 0.1"
from 00z Mon-00z Tue are 30-40% across srn VA/NE NC. Therefore,
went ahead and added slight chc PoPs across central/srn zones
on Monday. These PoPs may need to be trended upward over the
next day or two if the models continue to trend wetter on
Monday. Temperatures will start out in the 30s Monday morning
with highs warming into the upper 40s-around 50F.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 330 PM EST Friday...

A weak shortwave moves through the southern portion of the CWA late
Monday night into early Tuesday bringing with it a slight chance of
a few scattered rain showers before sunrise. High pressure moves in
Tuesday and persists into Wednesday evening. A coastal low moves NE
off the Carolina coastline well offshore on Thursday. There is high
uncertainty with this system as to whether or not it will be close
enough to produce precipitation for the CWA. The Euro is the least
aggressive, the GFS the most, and the CMC a mixture of the two. As
such have kept PoPs at 10-25%. High pressure once again moves into
the region Friday and will persist until early Saturday.

Temperatures will be near seasonal through the period. Lows Tuesday-
Friday morning will range from the upper 20s in the NW to the low-
mid 30s in the SE. Lows on Saturday morning will be slightly warmer
with low 30s in the NW and low 40s in the SE. Highs will range from
the mid-upper 40s Tuesday and Thursday, low-mid 40s on Wednesday
(with the Ern Shore being the coldest in the low 40s), and from the
upper 40s in the NW to lower 50s in the SE Friday.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 640 PM EST Friday...

VFR conditions are expected to prevail through late this
evening (03z). Low pressure and an associated cold front will
approach the terminals tonight before moving east of the area by
midday Saturday. Ahead of the front, a line of SHRAs (w/
moderate-heavy RA) will cross the terminals from west to east.
Rain should only last a few hours in any given location. Timing
of the SHRAs looks to be from 06-11z at RIC, 09-14z at
PHF/ORF/ECG, and 11-15z at SBY.

Periods of degraded flight conditions are expected, especially
during periods of moderate to heavy rain. During the rain, VSBYs
will be MVFR/IFR, while CIGs will mainly be MVFR. Could see some
brief wind gusts to around 30 kt with the strongest SHRAs (best
chc at ORF/ECG). In addition, winds in the 1-2k ft layer may
approach LLWS thresholds at SBY late tonight-Sat AM, with
lesser chances at RIC/PHF. Conditions should improve quickly
behind the passage of the cold front Saturday morning. Could see
a shower or two re-develop near SBY Saturday aftn, but
confidence in this is low-moderate.

Winds veer to the SE-S tonight and may gust to ~20 kt,
(especially near the coast) before becoming SW-W at 5-10 kt on
Saturday. High pressure then builds in from Saturday evening-
Sunday, with mainly VFR conditions expected at all TAF sites.

&&

.MARINE...
As of 330 PM EST Friday...

Departing surface ridge centered between Maine and the Canadian
Maritimes continues away from the region this evening as deep closed
low aloft makes progress toward the area from the west. Easterly
winds ~5-15 knots are in place across the marine zones this
afternoon with a few gusts to 20 knots noted at elevated sensors
along the eastern shore of the Ches bay. Waves are 1-2 feet with
seas ranging from 3-6 ft.

Secondary surface low pressure will form over the western
Carolinas/Virginia tonight and cross the waters through early
Saturday afternoon. The pressure gradient will tighten ahead of the
low/cold front with winds increasing to 15-20 knots with gusts to 25
knots. Waves/seas build further tonight with the persistent easterly
flow, and by Sat morning expect 2-4 ft waves in the Bay and seas 5-8
ft.

Cold front associated with the low pressure system crosses the area
waters Sat morning into early Sat aftn. Westerly flow expected after
the frontal passage. SCAs are currently in effect for all coastal
waters this afternoon, then spread into the Bay, lower James, and
Currituck Sound late this evening through Sat AM. Pressure rises are
fairly minimal Sat aftn/Sat night/Sun as the sfc high builds in from
the Gulf coast as low pressure lingers well off to our N. Not much
in the way of any cold air advection either, so overall do not
anticipate needing any headlines after Sat AM other than for
lingering seas on the coastal waters due to swell and dominant
periods of 9 sec or greater into Sun AM.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory until 1 PM EST Saturday for ANZ634.
     Small Craft Advisory until 10 AM EST Saturday for ANZ630>632.
     Small Craft Advisory from 1 AM to 10 AM EST Saturday for
     ANZ633.
     Small Craft Advisory from 10 PM this evening to 10 AM EST
     Saturday for ANZ638.
     Small Craft Advisory until 6 AM EST Sunday for ANZ650-652-654-
     656-658.

&&

$$
SYNOPSIS...CMF/ERI
NEAR TERM...ERI
SHORT TERM...CMF/ERI
LONG TERM...RMM
AVIATION...ERI/JDM
MARINE...LKB/RHR