Area Forecast Discussion
Issued by NWS Wakefield, VA-- Remove Highlighting --
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FXUS61 KAKQ 050912
Area Forecast Discussion
National Weather Service Wakefield VA
412 AM EST Mon Dec 5 2016
Low pressure passes south of the region this morning. A complex
area of low pressure crosses the region Tuesday. A strong cold
front crosses the area Thursday.
.NEAR TERM /THROUGH TONIGHT/...
Latest wx analysis features weak wave of sfc low pressure lifting
ne along Coastal front just off the Coastal Carolinas. Meanwhile,
High pressure is now in place over New England, with weak high
pressure nosing south into the Delmarva. Another area of sfc high
pressure continues to build east from the Lower Mississippi River
Valley into the Mid-south this morning. Aloft, potent upper
disturbance embedded in opening upper trough aloft lifting NE
from Northern Mexico into Southern Texas this morning, with an
associated sfc wave developing over the Western Gulf Coast.
Regional Radar mosaic showing swath of light rain associated with
sfc low and slug of isentropic overrunning now rapidly pushing
east across the coastal plain, with drier air aloft slowly
filtering in from the west. Categorical to high end likely rain
chances continue through mid morning for NE NC/SE VA zones,
tapering back to chc/slight chc well inland. Downslope flow and
subsidence behind the departing wave will allow for partial
clearing and dry wx for the balance of the morning through late
this evening. Highs warm slightly into the low-mid 50s.
Rain chances ramp back up late tonight, as wind fields back to the
SSW as sfc low pressure deepens over the Gulf Coast. Isentropic
lift similarly ramps back up late this evening through the
overnight hours, and rain chances increase from SW to NE during
this period. Meanwhile, sfc high pressure builds across the
Interior northeast, with weak CAD setting up as sfc high noses
down into the piedmont. CAMS indicating increase in pops after 06z
but have increased pop after midnight, as deterministic models
generally underestimate just how fast pcpn breaks out in and
overrunning scenario. Clouds thicken/lower once again in the
evening with rain overspreading the fa SW-NE after midnight. Lows
upr 30s north to upr 40s SE.
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
-- Changed Discussion --Tuesday remains a challenge as low pressure rides NE along the
Southern Appalachians with a secondary low pressure tracking NE
along the Carolina coast. Given the current temp/dp temp scheme,
it is not out of the question to see a few sleet pellets mix in
with the rain at the beginning across northern most zones early
Tuesday morning before the column wet bulbs out above freezing.
While this won`t result in any significant impacts, have allowed
for a brief period of sleet mention across far NW zones Late
Tonight and early Tuesday morning. Deterministic models and
majority of NCAR ensembles indicating period of moderate rainfall
Tuesday morning through afternoon as Gulf/Atlantic moisture become
entrained and track across the region. 00z/05 models consistent in
tracking the triple point low across the northern outer banks
keeping the center ivof eastern Albemarle sound. This track will
likely keep pcpn type mainly stratiform across the fa but may
become convective across the extreme sern zones for a few hours
during the afternoon. Temp forecast tricky due to a strong in-Situ-
wedge holding readings arnd 40 most of the day across the nwrn
most zones (LKU) ranging to the low-mid 60s ivof the northern
outer banks (ONX). Forcing strong enough for a several hour period
of mdt to psbly heavy rainfall with widespread rainfall amounts
between 1/2 to 1 inch. Pcpn slowly ends SW-NE Tuesday night as the
best lift moves NE. Lows 35-40 west, 40s east.
The low slowly pulls away from the region Wednesday with deep
layered SW flow behind it. Decreasing clouds in the morning bcmg
mostly sunny in the aftn. Highs in the mid-upr 50s.
-- End Changed Discussion --
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
-- Changed Discussion --Upper trough tracks into the Northeast states Thursday, with an
associated cold front quickly pushing across the local area
Thursday. Medium range guidance now in better agreement with the
frontal timing and evolution of the upper wave. Moisture will be
limited along the front as the best dynamics lag behind. As a
result, have maintained only a slight chance to low end chance POP
Thursday morning for the Piedmont into central Virginia, and then
pushing toward the coast Thursday afternoon. Highs Thursday in the
mid/upper 40s northwest to the mid 50`s southeast. Better chances
expected in the north/northeast forecast area nearest the deepest
moisture. Front and moisture quickly push offshore late Thursday as
a cold and dry arctic air mass surges into the region. Lows drop
into the 20`s Thursday night. Cool, breezy, and dry Friday as
surface high pressure builds in from the west. Latest GEFS still
indicates 850mb temperatures of -10 to -12C (-2 standard
deviations). Highs are expected to warm only into the upper 30`s to
low 40`s. Add in a breezy northwest wind and wind chills will
struggle to reach the mid 30`s. High pressure centers over the area
Friday night as temperatures drop into upper teens to low 20`s
inland to mid/upper 20`s near the coast. 850Mb temperatures progged
to moderate slightly Saturday (-6 to -8C) as cold high pressure
centers over the region. Less mixing will result in another cool
day, with highs back around 40 under a mostly sunny sky. High
pressure slides offshore Sunday as return flow and quasi zonal flow
aloft results in moderating temperatures. Highs Sunday forecast in
the mid to upper 40`s to low 50`s southeast.
-- End Changed Discussion --
.AVIATION /09Z MONDAY THROUGH FRIDAY/...
MVFR to LCL IFR conditions at area terminals early this morning.
All rain should clear the area by 12-14Z, with Ceilings recovering
thereafter through mid morning. VFR conditions will return to the
area by early Monday afternoon.
Outlook: High clouds once again thicken and lower through Monday
evening ahead of the next system. Steady rain to overspread the
area from southwest to northeast late in the evening and overnight
on Monday. High confidence of MVFR to IFR ceilings and
visibilities (and potentially LIFR conditions) during this period.
Rain continues through the day on Tuesday before tapering off
Tuesday night. Widespread MVFR/IFR returns Tuesday night, with
conditions recovering to VFR behind the system on Wednesday.
-- Changed Discussion --High pressure located just offshore this morning, with an area of
weak low pressure along the Southeast coast. Observations indicate a
light south to southeast wind over the waters, generally at or below
10 knots. Waves 1-2 feet and seas 2-3 feet. The low lifts off the
Outer Banks early to mid morning as high pressure builds in from the
northwest. Winds in the southern waters become north to northwest 10-
15 knots early morning, then northwest 10-18 knots all waters by
late morning. With a brief period of increasing onshore flow in the
southern waters, seas will build to 3-4 feet, possibly reaching 5
feet briefly out 20nm. High pressure builds into the region this
afternoon as the low slowly pushes offshore. A northwest wind around
15 knots in the coastal waters expected to keep seas in the 2-4 ft
range. High pressure centers over the Northeast tonight through
Tuesday as another area of low pressure lifts along the Southeast
coast. Flow becomes onshore late tonight and Tuesday. Pressure
gradient strengthens as height falls spread northward over the
coastal waters. Seas expected to build to 4-5 feet in the southern
waters, then 4-6 ft all waters Tuesday afternoon as east winds
increase to 15 to 25 knots. Waves 2-3 feet in the north and 3-4 feet
in the lower Bay. SCA headlines have been issued for the Bay,
Atlantic waters, and Sound. The low lifts northeast away from the
coast Tuesday evening with flow becoming northerly. Speeds remain 10
to 20 knots and seas 4-6 feet. SCA headlines for the Atlantic waters
run through 4th period. The low pushes farther offshore Wednesday
with northwest winds decreasing to 10-15 knots in the afternoon.
Seas subside to 3-4 feet late. A strong cold front pushes across the
waters Thursday, with strong SCA conditions (or low end Gale
conditions) possible Thursday night. SCA conditions expected to
linger into the weekend.
-- End Changed Discussion --
MARINE...Small Craft Advisory from 10 AM to 6 PM EST Tuesday for
Small Craft Advisory from 1 PM Tuesday to 6 AM EST Wednesday
Small Craft Advisory from 10 AM Tuesday to 6 AM EST Wednesday