Area Forecast Discussion
Issued by NWS Wakefield, VA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 270618
Area Forecast Discussion
National Weather Service Wakefield VA
218 AM EDT TUE SEP 27 2016
A warm front will weaken as it snakes its way across the mountains
tonight. A cold front will move southeast across the region Tuesday
morning, then stall along the coast Tuesday afternoon and night
before moving farther offshore late Wednesday. An upper level low
will track across the area later in the week.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Area of shras w/ isolated tstms progressing E from the
mountains...about to I 95 corridor right now. Cold front arrives
in far NW counties by around 12Z/27. Additional mainly shras will
be crossing the FA...lastly at the coast. Otherwise...mostly
cloudy overnight...lows from the l60s NW to u60s SE.
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
Still a rather complex forecast for Tuesday. Latest data supports
the front sagging SE across the fa during the morning but stalling
across the SE after 18Z. The reason for this is twofold, first is a
weak wave progged to ride NE along the boundary and second is an
area of tropical moisture off the Carolina coast that causes to
boundary to slow its SE movement. Am a bit concerned about this
offshore moisture as to whether any of it gets entrained into the
stalled frontal system along the coast. This could enhance rainfall
across the SE in areas that got drenched a few days ago. Something
to watch over the next 12-24 hours. Upshot here is for a wet day
with likely pops most areas, categorical across the SE after 18Z.
Thunder will shift towards the SE after 18Z closer to the boundary.
Somewhat drier air is progged to filter in behind the front across
NWRN zones. Despite the dry air aloft, enuf moisture noted to
continue chc pops back through the piedmont. Again. some moderate to
lclly heavy downpours possible across the SE. Highs in the low 70s
north to mid-upr 70s south.
Boundary gets hung up along the coast Tues nite then shifts a bit
farther east Wed. Likely pops continue along the coast Tue evening
with chc pops all areas after midnite through Wed as moisture from
the approaching upr level low crosses the mts. Lows upr 50s NW to
near 70 SE. Highs Wed in the mid-upr 70s. Thunder possible across
the SE Wed afternoon.
Models differ a bit with the actual cut off low position by mid
week, but anyway you look at it it appears unsettled with sct shwrs.
NAM slower and further west than GFS/SREF but can`t rule out aftrn
tstrms once the cold pool aloft crosses the mts. Lows Wed nite in
the 60s. Highs Thurs in the 70s.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Long term forecast is complicated by the presence of an upper-level
cutoff low over the E/NE CONUS for the duration of the period. This
will lead to below normal temps and frequent chances for rain.
Difficult to time the precip this far out in time but at this
point the best chances will be Thu night/Fri (30-50% pops). As the
cutoff low slides NE through the period, the chances of rain will
slightly decrease through the end of the week. As for temps, highs
will avg in the mid 70s each day with lows ranging from the mid
50s over the Piedmont to the mid 60s near the coast.
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --Cold front approaching from the northwest will spread showers and
lower ceilings into the region through the overnight hours.
Initial band of scattered light showers expected to impact KRIC
and KSBY, ahead of another line of showers associated with the
cold front. MVFR ceilings expected to spread across the Piedmont
into central Virginia by 07-09Z, remaining over the region through
late Tuesday morning. VFR conditions prevail KORF and KECG. MVFR
(possibly IFR) visibilities expected to light to moderate showers.
Surface winds generally out of the south below 10 knots.
Showers will reach southeast Virginia/northeast North Carolina by
12-15Z as the front pushes across the region. Front expected to
stall along the coast late today, with showers lingering near the
coast. Thunderstorms possible along the coast. Surface winds at
or below 10 knots today.
Unsettled weather conditions expected through the end of the work
week as waves of low pressure lift along the cold front. Showers
are possible each day.
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930 PM Update...Have dropped SCA on the Lower Bay, as current
observations and latest high resolution model forecasts suggest
strongest winds will be across the northern 2 Bay zones. The lower
2 bay zones will remain AOB 15 knots overnight and Tuesday
Late afternoon discussion...Latest sfc analysis shows high
pressure centered offshore with a frontal boundary approaching
from the west. Southerly flow increases tonight ahead of the frnt
as the pressure gradient increases. Maintained the SCA hazards in
place for the entire Bay and Rappahannock River for winds up to
15-20 kt. Conditions will be marginal and winds do not appear to
be high enough to warrant a SCA over the ocean and other rivers.
The front drops into the area Tue with winds decreasing through
the day as the front stalls and weakens in the vicinity. Waves of
low pressure then form along the front through the end of the work
week as an upper-level cutoff low persists over the E/NE CONUS.
Expect mainly 1-2 ft waves over the Bay and 2-4 ft seas over
coastal waters through this period.
-- Changed Discussion --MD...None.
MARINE...Small Craft Advisory until 7 AM EDT this morning for ANZ630-
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