Area Forecast Discussion
Issued by NWS Wakefield, VA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KAKQ 050134
Area Forecast Discussion
National Weather Service Wakefield VA
834 PM EST Sun Dec 4 2016
Low pressure passes south of the region late tonight and Monday.
A complex area of low pressure crosses the region Tuesday. A strong
cold front crosses the area Thursday.
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
-- Changed Discussion --830 pm update...Afternoon forecast in good shape. Have tweaked
POPs/WX to account for current trends, which show precip
spreading eastward a little faster than earlier thought. Also
tweaked hourly temps overnight some based upon current
observations and hi-res model trends. Biggest change was to back
off on the amount of fog expected. Best chance for fog development
appears to be SE half of CWA, and that appears to be patchy and
not widespread. Warm front remains far enough that widespread fog
should not occur.
Late afternoon discussion...Sfc high will slide off the NC coast
this evening. Current sfc obs to the ssw are showing light rain
beginning to fall out of a 6-8K ft cloud deck so will carry
chc/likely pops mainly south of I64 through 00Z to account for
High res data continues to show a rapid increase in moisture SW-NE
across the region between 00Z-04Z. 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 this
evening before the column wet bulbs out above freezing. However,
this to be rather insignificant and has been left out of the grids.
Weak low pressure tracks east along the trof later tonite with the
best lift progged between 03Z-10Z. Strongest lift noted across the
south where the highest QPF will be (1/2 to 3/4 inch with 1/4 to 1/3
inch across the north). Thus, confidence high enough to max out pops
(90-100%). Expect areas of fog given the stratiformed pcpn. Lows
in the mid-upr 30s northern most zones to the lwr 40s across the se.
-- End Changed Discussion --
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Models take the sfc low off the Mid Atlantic coast Monday morning
with high pressure building south from the Ohio valley. Thus, pcpn
quickly ends w-e between 12-17Z. Will carry pops across the east
through noon then dry as the high quickly dries out the column.
NAM more aggressive than the GFS in decreasing the cloud coverage,
but will lean toward clouds giving way to pt sunny skies across
the north during the aftrn. Temps respond to the sunshine given
no real CAA seen. Highs in the mid-upr 50s.
Models are now even slower in returning the moisture across the
area Monday night as the high slowly drifts ene across PA into
New England. Won`t get to fancy here given how the models generally
underestimate just how fast pcpn breaks out in and overrunning
scenario. Clouds thicken in the evening with rain overspreading
the fa SW-NE after midnight. Lows upr 30s north to upr 40s SE.
Tuesday remains a challenge as low pressure rides NE along the mts
with a scendary low pressure tracking NE along the Carolina coast.
Coupious amounts of both GOM/Atlantic moisture become entrained and
track across the region. Models consistant 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 stratiformed 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 insitu-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
mstly sunny in the aftrn. Highs in the mid-upr 50s.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Long term period starts off Wed night with dry weather as the
aforementioned low pressure system pushes farther offshore and high
pressure briefly builds into the Mid Atlc. Low temps in the mid 30s
to lwr 40s under a partly/mostly cloudy sky. A strong cold front
crosses the area on Thu. ECWMF continues to be slower than the GFS
with the fropa, which would delay the precip until late in the
day/eveng hours. Pcpn amounts are expected to be lower than with the
system Tue. There is also a chance that some of the light pcpn could
mix with or change to snow showers late Thu. Hi temps Thu in the
low/mid 50s most areas. Dry weather thereafter for Fri into the
weekend as sfc high pressure builds in from the west. Cold nighttime
temps expected Thu night through Sat night, with lows in the low/mid
20s most locations.
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
A low pressure system located near the Gulf Coast will continue to
lift northeast through Sunday night. Rain will continue to
overspread the area from the southwest through the first half of the
night. Low pressure moves off the coast early Monday morning leading
to VFR conditions returning.
VFR conditions at all terminals as of 00Z, but rain is just on our
doorstep. Showers should impact RIC and ECG first and will continue
to spread across the area from the Southwest. Ceilings will continue
to fall through the evening, am anticipating a period of IFR
ceilings at all TAF sites closer to sunrise. All rain should clear
the area by 12Z and VFR conditions will return to the area by Monday
Outlook: Rain moves out early Monday, with VFR conditions returning.
High clouds once again thicken and lower through the afternoon on
Monday 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.
Latest sfc analysis shows high pressure sliding off the Mid Atlc
coast with disorganized low pressure near the Gulf coast. Weak low
pressure will pass through the Carolinas tonight and allow for
increasing northerly winds behind the low Mon, though still below
sca criteria. A much stronger low pressure system affects the area
Tue, with east winds/waves/seas increasing ahead of the low. Will
hold off with any headlines attm with this as it`s fourth period and
still some uncertainty over the timing of the increase of winds.
Winds then shift to the W/NW Tue night/Wed. A strong cold front then
crosses the region by late Thu, with gale conditions possible over
at least the coastal waters and Bay Thu night through Fri night
behind the front.