Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1241 am EST Thursday Dec 18 2014
high pressure builds into the area from the northwest through
Friday. One low pressure area will track from the Gulf Coast
states east northeast to just off the North Carolina coast
Saturday morning into Sunday morning. Another low will move
northeast off the southeast and middle Atlantic coast late Sunday
night through Monday.
Near term /until 6 am this morning/...
surface trough remains over the local area with light low-level west-
northwest flow over the region. High pressure builds into the
region tonight as the surface trough weakens. This will allow drier
and colder air to advect into the region. Low level thicknesses
drop of 30m tonight with temperatures expected to fall into the low to
middle 30s. Some locals over the Piedmont expected to fall into the
upper 20s. Increasing winds aloft and a passing upper low to the
north will result in high clouds through much of the
overnight...thinning late. Cloud cover not expected to be thick
enough to limit temperatures. Drier air will inhibit any fog development
Short term /6 am this morning through Saturday/...
dry conditions will prevail Thursday into early Friday night...as dry/zonal
flow dominates the region and surface hi pressure builds across the Great Lakes
into southeast Canada. Shortwave energy tracking from west-east in fast flow aloft
will produce a little more cloudiness Thursday night into Friday morng.
Otherwise...mostly clear or partly cloudy Thursday through Friday...with hi
temperatures ranging through the 40s both days. Lows Thursday night mainly in the
upper 20s to lower 30s.
Friday night through Sat...leaning closer to the slightly faster GFS...esply
regarding onset/overspreading of precipitation across the region. At this
time...went closer to the GFS thicknesses/model soundings...esply
during Sat morng with the onset of precipitation...where a chance of sleet
(maybe some snow) was added generally north of a South Hill to
Williamsburg line. By late morng or early afternoon...precipitation will become
just rain everywhere...as layers warm and surface temperatures climb into
the upper 30s to middle 40s. Highest quantitative precipitation forecast amts with this system could
end up across extreme southern/southeast Virginia and NE NC.
Long term /Saturday night through Wednesday/...
drier air filters in from the northwest Saturday night behind the departing
low. Low temperatures should eventually fall to around 30 northwest to the
upper 30s southeast. However...any light rain should end prior to any
surface temperatures falling to at or below 32f. Weak high pressure should
prevail Sunday...before another low forms off the southeast coast
and tracks NE Sunday night into Monday. At this time temperatures
appear warm enough for only rain. However...there could be a brief
mix of rain and sleet across the northwest Piedmont Sunday night. Middle-level
ridging builds in behind this system with milder conditions expected
by Tuesday. Low pressure tracks west of the mountains Tuesday night
into Wednesday bringing the potential for rain.
Aviation /06z Thursday through Monday/...
VFR condition through the forecast prd with only broken cirrus clouds
expeceted. Winds will or shortly shift to the north (aob 10 kts) as trough
moves easta cross the region.
Outlook...high pressure dominates Friday. The next low pressure
system impacts the Middle Atlantic States Saturday with a chance for IFR
cndtns in lght rain. High pressure builds to the north of the area
Sunday but easterly flow could maintain MVFR ceilings.
went ahead and hoisted a Small Craft Advisory for the lower & mouth of the ches Bay
given the latest data suggests winds increase to between 15-20 knots
once the weak trough passes across the area over the next few hours.
Bumped up waves as well through the Erly morning hours. Otw...no oth
changes with Erly am update.
surface high pressure builds in from the northwest tonight through
Friday. A trough of low pressure slides by to the north tonight followed
by shallow cold air advection across the northern portion of the marine area. The
current Small Craft Advisory for the northern ocean zones was expanded to include the northern
two Bay zones. A 20-25kt northwest wind is expected across the northern ocean
zones...which could briefly build seas to 4-5ft out near 20nm.
Generally expecting low-end (15-20kt) Small Craft Advisory conditions in the Northern Bay
zones. Similar conditions persist Thursday and Friday with the wind
gradually decreasing. Low pressure tracks east-northeast to immediately off the
Carolina coast Saturday morning through Sunday morning. Another low
tracks NE off the southeast and middle Atlantic coasts late Sunday
night into Monday. There is too much uncertainty at this point to
speculate on the potential of Small Craft Advisory conditions.
Marine...Small Craft Advisory until 10 am EST this morning for