Scientific Forecaster Discussion
fxus62 kilm 141946
Area forecast discussion
National Weather Service Wilmington NC
346 PM EDT Mon Oct 14 2019
dry high pressure will build in from the north through Tuesday.
Rain chances will increase Tuesday night into Wednesday as a
warm front lifts north. Cooler and drier air is expected
Thursday and Friday with temperatures moderating for the
Near term /through Tuesday/...
latest sfc analysis shows a weak frontal boundary across the area
with 1019 mb high pressure across the Tennessee Valley. The high slides
east into the area tonight, leading to dry wx and a mostly clear sky
with light north winds. This will allow for temps to cool much further
than last night...lows range through the 50s.
Main forecast change was to slow down timing of pops on Tuesday.
Although models have been known to be late with the onset of pcpn
associated with weak warm air advection ahead of an approaching warm front, most
guidance has slowed the timing of arrival of pcpn to the aftn over
SW areas, and after dark over NE areas. Otherwise, just some
increasing clouds with high temps in the mid/upr 70s.
Short term /Tuesday night through Wednesday night/...
weak surface wave will move east along the front stalled across the
southeast Tue night into Wed. The wave becomes a more defined surface
low Wed morning, passing west of the area and lifting the stalled
boundary north as a warm front. Rainfall chances ramp up Tue night
as deep moisture arrives. Instability is limited due to nocturnal
timing, but combination of convergence and mid-level forcing from
southern stream shortwave should ensure healthy coverage of
rain/showers Tue night into Wed.
Warm front will be north of the area with surface based instability
marginally increasing through midday Wed. Cold front moves across
the forecast area Wed afternoon, ending any rainfall and ushering in
a cooler and drier air mass. Precipitable water in excess of 1.5
inches for an extended period, and in excess of 1.8 inches at times,
will help generate some healthy rainfall totals Tue night and first
part of Wed. Many areas will see in excess of an inch of rain, which
should fall over an extended period of time.
Although cold advection following the cold front will be robust, not
expecting much in the way of strong/severe storms Wed afternoon.
Limited MLCAPE and low shear will not produce an environment
supportive of strong/severe storms. Temperatures well above climo
Tue night and above climo Wed will end up near to slightly below
climo Wed night as cold advection kicks in.
Long term /Thursday through Monday/...
deep 5h trough Thu into Fri gives way to shortwave ridging Sat into
sun. Surface high builds in from the west as deep northwest flow
dries out the region. Deep mixing could make Thu afternoon breezy as
cold air continues spreading over the region. Moisture starts to
increase early next week as southern stream system moves along the
Gulf Coast. Unsure how far north the system will end up, lowering
confidence in rainfall chances. Pattern would tend to keep the
system farther south, crossing northern Florida and moving out to sea sun
-Strong cold advection Thu into Fri will drop temps 5 to 10
degrees below climo to end the week.
-Air mass moderates for the weekend with temperatures becoming
-Weak low moving along the Gulf Coast may spread clouds and
increase rain chances Sun night and Mon.
Aviation /20z Monday through Saturday/...
any MVFR ceilings should scatter around taf time. Winds will be
light tonight. There may be some ground fog after midnight. Tuesday,
VFR conditions are expected. Winds will swing around to the east in
the afternoon in advance of the warm front that will affect the
region by early Wednesday.
Extended outlook...possible heavy rain along the coast on Wednesday,
northwest flow becomes north tonight at ~10 kt as high pressure builds in from
the W, and seas remain at 1-2 ft. Seas become 2-3 ft then for Tue
with 10-15 kt NE winds ahead of an approaching warm front. This will
be primarily 3-4 second NE wind wave, but also includes a ~1 ft 9-10
second east swell.
Southwest flow will be increasing Tue night and Wed as warm front
lifts north of the waters and cold front approaches from the west.
Front moves across the waters later Wed with strong cold advection
resulting in offshore flow in excess of 20 kt Wed night. Small Craft
Advisory conditions are possible Tue night through Wed night,
although confidence on timing and duration is low. Gradient relaxes
as high pressure builds in from the west. Speeds drop to 10 kt or
less later Thu with offshore flow slowly become onshore Fri into
Sat. Seas build from 2 to 3 ft Tue night to 4 to 6 ft on Wed.
Offshore flow Wed night into Thu will drop seas for the end of the
week. Seas will be a mix of 4 to 5 sec wind wave, with a southerly
wind wave through Wed becoming a northerly wind wave Thu through
NC...coastal flood advisory until 1 am EDT Tuesday for ncz107.