Area Forecast Discussion
Issued by NWS Wakefield, VA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 242316
Area Forecast Discussion
National Weather Service Wakefield VA
716 PM EDT Mon Oct 24 2016
Cool Canadian high pressure builds in from the northwest tonight and
remains over the region through Wednesday. A cold front approaches
from the northwest Thursday morning and crosses the area during the
afternoon and evening. High pressure returns Friday.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
The current surface analysis depicts a cold front
pushing through VA and the Delmarva this afternoon. Temperatures
ahead of the front have climbed into the low/mid 70s, and should
remain steady later this aftn as downslope nw flow will delay caa
until this evening. The frontal passage will be dry, with sct cu,
mainly across ne portions of the area. 1032mb high pressure will
gradually build in from the nw tonight. There should be enough
mixing tonight with caa to keep lows generally in the low/mid 40s
(upper 40s se). However, the piedmont could decouple late, which
will allow lows to fall into the upper 30s to around 40 under a
clear sky. Localized cloud cover is possible over the Lower Ern
Shore and coastal se VA late as a bay streamer potentially develops.
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Sunny (outside of any streamers along the coast in the
morning) and cooler Tuesday as caa continues, especially across the
ne half of the area. 850mb temperatures drop to 0 to -2C across the
ne Tuesday aftn, with 0-4C farther sw. This will result in highs
ranging from the mid/upper 50s nw, to the low 60s across interior
The high continues to build in from the nnw Tuesday night. This
appears to be the coldest night through midweek (and probably so far
this season), with lows ranging from the mid/upper 30s over much of
the area, to the low/mid 40s for coastal se VA/ne NC. This will
bring the potential for frost except along the coast. Some modest
mid-level (700-850mb) waa is expected to commence late Tuesday
night, which could result in some clouds (mainly w). The potential
for frost will be less if this does occur. Continued cool Wednesday
under a partly to mostly sunny sky with highs in the mid/upper 50s
ne, to low 60s sw. There is the potential for highs to hold in the
50s for much of the area if more cloud cover develops.
Shortwave energy will lift through the Great Lakes Wednesday night
into Thursday morning, with the trailing cold front approaching from
the nw Thursday aftn. Milder Wednesday night with lows generally in
the 40s across the area, with low 50s se with increasing clouds from
w-e late. Clouds continue to increase Thursday with much of the area
becoming mostly cloudy to overcast. Chc PoPs (30-50%) for showers
spread across the nrn 2/3rds of the area by afternoon. Moisture is
limited with this system, so current QPF through 00z Friday is aob
0.1". Highs Thursday range from the low 60s nw to near 70 se.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Cold front forecast to push across the forecast area to begin the
extended period Thursday night. Best dynamics associated with a
potent shortwave trough progged to push across the Northeast
Thursday night, with modest height falls and moisture return
expected over the forecast area. Best chances for showers will be
across the northeast forecast area, tapering off to low end chance
south and west due to limited moisture/dynamics. The front quickly
pushes offshore late Thursday night as high pressure builds in from
the west for Friday. Dry with highs generally in the mid to upper
60`s. The next in a series of northern stream disturbances drops
across the Great Lakes Friday night and into the Northeast states
Saturday. GFS and CMC drop a cold front into the region Saturday and
across the region Saturday night. However, the ECMWF is flatter with
the shortwave and doesn`t push a front through the region until
Sunday night. Will carry a slight chance to low end chance POP`s
across the northern forecast area Saturday and along the coast
Saturday night, but confidence is not high (hence low POP`s). Highs
Saturday expected to push into the low to mid 70`s. Differences in
frontal timing will have a drastic impact on temperatures Sunday,
and possibly Monday. Have opted for a blend of the guidance until
better agreement can be made. Highs Sunday and Monday are forecast
in the 60`s. Will keep POP`s silent Sunday and Monday as any frontal
boundary will likely be dry. Lows generally in the 40`s to low 50`s
through the period.
.AVIATION /23Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --Dry and VFR conditions are expected through Wednesday.
Reinforcing cold front moving southward into southern portions of
the area as of 23z. Other than a few mid clouds, the frontal
passage will be dry, and mainly result in a wind shift to the
north, along with occasional wind gusts up to 20kt. The wind
becomes more northerly overnight as caa begins and this could
result in a bay streamer, which could produce sct- bkn cloud cover
around 3-4kft at ORF late tonight into Tuesday morning. Latest hi-
res guidance has backed off on this potential. Fog and/or low
clouds are possible Thursday morning as high pressure moves off
the coast and moisture increases over the area. Another cold front
crosses the area Thursday/Thursday evening bringing a chance of
showers. Dry weather and high pressure return for Friday.
-- End Changed Discussion --
Latest surface analysis depicts a cold front splitting the waters
this afternoon. The parent low is centered over southeast Canada,
with high pressure building southward into the upper Midwest. A
brief lull in SCA conditions is observed over the waters this
afternoon with west to northwest winds at or below 15 knots. Waves
generally 1-2 feet and seas 2-3 feet. Cold front drops south of the
waters late today, with a quick ramp up in north to northwest winds
between 6pm and 8pm. Expect north to northwest winds of 15 to 25
knots. Strongest gusts expected a few hours either side of 11pm for
the Bay and northern coastal waters with 30 knot gusts expected.
Gusts taper off to 25 knots late tonight. Waves increase to 3-4 feet
and seas 4-5 feet. Seas could reach 6 feet 20nm out. SCA headlines
are in effect for all waters expect the upper James, York, and
Rappahannock Rivers. High pressure nudges over the waters late
tonight with the gradient expected to weaken shortly after daybreak.
Sub-SCA conditions return to the lower James by 7am, the Sound by
10am, and the Bay and coastal waters by early afternoon. Expect a
northwest wind of 10 to 20 knots Tuesday afternoon. High pressure
prevails over the waters Wednesday with a north wind at or below 10
knots. Waves 1-2 feet and seas 2-3 feet. High pressure slides
offshore Wednesday night and Thursday ahead of the next cold front.
Flow becomes southerly and increases to 10-20 knots Thursday ahead
of the front. Cold front drops across the waters Thursday night with
another period of SCA conditions possible.
-- Changed Discussion --MD...None.
MARINE...Small Craft Advisory until 1 PM EDT Tuesday for ANZ630>632-634-
Small Craft Advisory until 10 AM EDT Tuesday for ANZ633.
Small Craft Advisory until 7 AM EDT Tuesday for ANZ638.
-- End Changed Discussion --