Scientific Forecaster Discussion
fxus62 kilm 291028
Area forecast discussion
National Weather Service Wilmington NC
628 am EDT Sat Apr 29 2017
high pressure will extend across the area from offshore through
Sunday. Expect warm temperatures and isolated sea breeze
showers or storms, mainly Sunday. The next cold front will
bring a chance of showers and thunderstorms late Monday into
early Tuesday. High pressure will follow for the mid-week
period. A low pressure system will impact the region Thursday
into Friday with possible soaking rain.
Near term /through tonight/...
as of 300 am Saturday...low stratus was covering much of the
local forecast area early this morning as evident on the 11-3.9
micron satellite imagery. A very moist southerly flow has
remained up around 10 mph keeping fog out of the picture, but
allowing the development of stratus mainly along the coast and
then moving inland. Model guidance does not have a good grip on
the clouds, but sounding data does show a saturated layer
between 500 and 1500 ft through early this morning.
A very humid air mass will continue to maintain dewpoint temps
in the 70s with temps holding in the low to mid 70s through
early this morning. This is very unusual for April. Although
there is a moist saturated shallow layer of moisture, the
atmosphere aloft remains very dry as mid to upper ridge builds
over the eastern Carolinas. This dry air and subsidence aloft
will maintain a lid on convection and therefore once the stratus
lifts there should only be some cu around this afternoon and
possibly some cirrus streaming high in the sky. Expect a good
amount of sunshine across the area once the low clouds dissipate
as drier air mixes down this morning. Temps will soar into and through
the 80s today reaching around 90 inland with overnight lows
holding up around 70 tonight once again. Overall, temps are
running about 15 degrees above normal.
Climate note: a new all-time record warm low temperature of 74
degrees was set for the month of April in Wilmington. Records
extend back to the year 1874.
Short term /Sunday through Monday night/...
as of 3 am Saturday...chances for convection increase through the
period as a cold front moves east across the coastal Carolinas, with
a deep upper trough descending upon central Continental U.S.. high pressure
over the western Atlantic will retreat east as the cold front
approaches, with Sunday being generally dry other than some spotty
afternoon sea-breeze related convection. Pops increase on Monday,
maxing out in the likely category Monday night as the front moves
across the forecast area. Steady SW flow in advance of the front
will maintain above-normal temperatures for both days, with highs in
the mid 80s (lower at the coast) and lows in the 60s.
Long term /Tuesday through Friday/...
a cold front will move off the coast Tue morning and high
pressure along the Gulf Coast will slide east and then offshore
to our S during Wed. This should bring a dry period. Deep low
pressure will move out of the mid south and Gulf Coast states
Wed, lifting slowly to the NE. Its associated cold front will
move into the southeast states Thu-Thu night, bringing the risk
for robust thunderstorms.
Aviation /12z Saturday through Wednesday/...
as of 12z Saturday...main forecast uncertainty regards when
patchy stratus currently blanketing area will break up.
Although overall confidence low that stratus will lift by mid-
morning, satellite loops show myr and cre will likely be most
affected due to a large and persistent area of offshore stratus.
A return to IFR/MVFR conditions possible again overnight.
Extended outlook...periods of IFR/MVFR conditions are possible
in showers and thunderstorms late Monday into early Tuesday.
near term /through tonight/...
as of 300 am Saturday...southerly return flow around 10 kts will
maintain seas between 2 and 3 ft most waters. The winds and seas
will kick up this afternoon as sea breeze develops. It will also
help to back the winds a bit through the aftn. A very warm and
humid air mass is helping to bring water temps up into the 70s.
Short term /Sunday through Monday night/...
as of 300 am Saturday...increasing SW flow in advance of the
next cold front will make it likely that a Small Craft Advisory
will need to be issued on Monday for winds gusting up to around
30 kts. By Monday night seas will have built to 4 to 7 ft
although winds may slacken in the pre- dawn hours of Tuesday as
the front makes its close approach. Sunday looks to be the
better day for boating, with seas of right around 3 ft and winds
of 10 to 15 kts.
Long term /Tuesday through Wednesday/...
as of 300 PM Friday...in the wake of the cold frontal passage
early Tuesday, offshore winds will slowly diminish. The offshore
trajectories will knock seas down and should drop below Small
Craft Advisory levels by Tuesday afternoon. There are no
concerns for Wednesday into Thursday.