Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
509 am EST Tuesday Feb 9 2016
an area of low pressure deepens well off the middle Atlantic coast today
as an upper level trough swings through the region later this through
tonight. High pressure slowly returns Wednesday through Friday.
Near term /through tonight/...
current analysis indicating ~998 mb surface low pressure deepening off
the southeast Virginia coast with a surface trough extending to the west-northwest through
central Virginia. Another surface low is over Lake Huron. Aloft...low
pressure is situated over Ohio. The offshore system is prognosticated to
continue to intensify today...but will rapidly move farther out to
sea. As the upper low drifts east later today and this evening...shortwave
energy will help develop a weak surface low per the 00z GFS/NAM across
Maryland/northern Virginia and push off the Delaware-Maryland-Virginia this evening. Some light
rain is ongoing across mainly the Eastern Shore with only spotty light
rain or drizzle elsewhere near the coast and mainly dry conds
inland. Skies have actually cleared across south central Virginia.
Overall trends in the models continue to be warmer/slower to wrap
the cold air into the region from the northwest. Boundary layer flow
looks to be west or even west-southwest today...and this will keep deeper
moisture north of most of the County Warning Area and should promote some late
morning through middle afternoon sunshine for all but the north. With
this in mind...have raised high temperatures a few degrees most
areas compared to the previous forecast. Did however stay firmly
on the cold edge of guidance favoring the met numbers which yields
highs ranging from the upper 40s across far southeast Virginia/NE NC...to the
lower 40s across the northern zones. As for probability of precipitation...will have chance a
confined to the north later this morning...then raise probability of precipitation to low
end likely NE later in the afternoon as the upper energy
arrives...tapered to 20-30% farther south. Still only rain or a
mix through middle afternoon...trending colder late.
By this evening...colder air will overspread the County Warning Area as critical
thicknesses drop well below 1300 M. Overall though...trends are
weaker in the models with respect to forcing and deep
moisture...now prognosticated to stay primarily north of the County Warning Area. Still
anticipate a 3-6 hour window for scattered snow showers across the Northern
Neck/Eastern Shore...but accumulations are expected to be up to 1" at
most (generally little to no accumulation for the rest of the
cwa). Lows m20s west to lower 30s along the coast.
Short term /Wednesday through Thursday/...
a deep upper level trough prevails across the eastern Continental U.S. On Wednesday as
a strong ridge persists along the West Coast. Overall...should
have drier air in place across the region with decent subsidence
present in the wake of the exiting shortwave located well to the
northeast. Steep lapse rates still present due to the cold pool
aloft so expect partly sunny/variably cloudy conditions. Kept
20 percent probability of precipitation for snow showers across northestern areas through the
morning hours. Otw...pt sunny and cold. Highs u30s north to l40s
south. Mainly dry and cold Wednesday night with lows falling into the
teens west to the 20s elsewhere. As colder air spills in...could
see a few Bay enhanced snow showers across mainly the Virginia Eastern Shore
so will carry 20-30% probability of precipitation there. Colder but mostly sunny on Thursday
(partly sunny eastern shore) with highs in the lower 30s north to the
middle- upper 30s south.
Long term /Thursday night through Monday/...
an upper level low pressure system will head northeast and away
from the eastern Continental U.S. Wednesday into Thursday...only to be
replaced by a strong upper level trough late Friday into the
coming weekend. Precipitation chances will be limited through the period...
although a round of snow showers is possible on Friday with an
Arctic frontal passage. Bay/ocean effect snow showers along the
coast will be possible Saturday and Sunday as very cold air aloft
(-20 to -25 850 mb temps) settle in. Although a low confidence
forecast at this time...there are some indications that low pressure
develops along the Carolina coast Friday/Friday night which could
provide additional moisture for the Arctic front to work with. If
this ends up being the case...then accumulating snow would be
possible across a portion of the area late in the week. Of more
significance at this time is the very cold air settling over the region by
the weekend. Highs in the 30s Thursday- Sat...but then only 20s to
maybe low 30s Sunday. Lows temperatures in the teens and 20s...with
single digits Saturday night.
Aviation /10z Tuesday through Saturday/...
weak cold front with scattered rain showers associated with it...will
swing off the CST this morng into early this afternoon. Low pressure will
form well off the Delaware-Maryland-Virginia CST later this morng into early this
afternoon also. Expect mainly VFR and MVFR ceilings through the morng hours
with isolated IFR ceilings at ric/sby/phf if some clearing occurs.
Drier (and eventually colder) west-northwest surface flow will then filter into
the region this afternoon through Wednesday. Expect scattered to broken SC (vfr cigs) across
most of the area...esply ric/sby/phf through the period...with the
best chance for snow showers (and some lower cigs) this eveng into
Outlook...VFR conditions should prevail Wednesday night into Friday...as
hi pressure builds into the middle Atlantic region.
a weak cold front was lifting through east-northeast portions of the County Warning Area early
this morng...while low pressure was developing well east of the Virginia/NC CST.
That low will move quickly away to the NE today into
tonight...resulting in winds shifting to the west and increasing to 10
to 20 knots over most of the marine area. However...west winds will
increase to 20 to 25 knots with gusts to around 30 knots expected over the
southern coastal zones tonight. Seas were still between 7 and 12 feet early this
morng...and will finally subside from later this morng into
tonight...due to offshr west winds. Another round of Small Craft Advisory conditions
appear likely for the entire marine area Wednesday eveng into Thursday
night...as strong northwest winds are expected. Gale conditions may be
possible by the weekend...as some very cold air settles over the
river flood warnings remain in effect for the Blackwater above
Franklin and Nottoway at Sebrell. See flsakq for details.
a high surf advisory remains in effect along the entire Atlantic coast
through 8 am this morning...as nearshore waves remain high (8-11 ft).
Water levels have risen quite high across the Bay as elevated seas
are preventing water from exiting the Bay and tidal rivers. In
most areas the surge has risen to 2 feet or greater. Thus...coastal
flood advisories have been issued for all zones adjacent to the
ches Bay (both the western and eastern shore) as well as the tidal
rivers through the upcoming high tide cycle (see cfwakq for
details on times). The coastal flood advisories have been
maintained for the Atlantic coast areas through the upcoming morning
high tide cyle.
Maryland...high surf advisory until 6 am EST early this morning for
Coastal Flood Advisory until 10 am EST this morning for mdz024-
Coastal Flood Advisory until 7 PM EST this evening for
NC...high surf advisory until 6 am EST early this morning for
Coastal Flood Advisory until 10 am EST this morning for ncz102.
Virginia...coastal Flood Advisory until 1 PM EST this afternoon for
High surf advisory until 6 am EST early this morning for
Coastal Flood Advisory until 10 am EST this morning for
Coastal Flood Advisory until 7 PM EST this evening for
Marine...Small Craft Advisory until 10 am EST Wednesday for anz650-652-
Small Craft Advisory until 7 am EST this morning for anz634.