Area Forecast Discussion
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FXUS62 KILM 201447 CCA
Area Forecast Discussion
National Weather Service Wilmington NC
652 AM EST Fri Jan 20 2017
A warm front will lift north across the area today. The front
will then remain in close proximity through the weekend. Waves
of low pressure will move along this boundary with the last and
deepest Sunday night and Monday. This will result in a wet
weekend with total rainfall amounts of one to three inches.
Thunderstorms will have the potential to produce severe weather
Sunday and Sunday night. As the deep low departs, high pressure
will build toward the area Tuesday and Wednesday. A weak cold
front will stall in the region on Thursday.
.NEAR TERM /THROUGH TONIGHT/...
As of 600 AM Friday...The main surge of showers were quickly moving
across the I-95 corridor near daybreak. The rain was very light.
A front will approach from the S and should sneak into the
Forecast area before stalling. A weak wave of developing low
pressure on the front will skirt the coast as it moves N of the
area today. The front will then have a tendency to sag S tonight
as the wave moves NE and well offshore.
An upper trough will pivot across the Southeast states around an
upper low in the Northern Plains through midday. As the upper level
support pulls away, the showers are expected to become increasingly
diffuse. A large area of showers across the upstate of South
Carolina was moving toward the I-95 corridor as of 07z. Will carry
highest pops across the I-95 corridor this morning, up to a likely
risk across Marlboro and Darlington counties. The risk for showers
will decrease as you move eastward toward the coast. The risk will
also be highest this morning, but will remain above threshold in
most areas into the afternoon. Rainfall amounts will be light.
Clouds today should keep temps rather uniform across the area, lower
70s. However, an onshore flow will keep the beaches in the mid and
We do not expect measurable rainfall tonight, although will show
POPs beginning to increase to slight chance near daybreak for
southern and westernmost areas. Can not rule out some spotty drizzle
tonight. Model soundings continue to support low stratus and fog
development and have included areas of fog in the grids at this
time. Widespread fog may turn dense overnight as dewpoints remain
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 400 AM Friday...A front will be in close proximity
through the period. A wave of surface low pressure is expected
to move NE along this front coincident with mid-level shortwave
energy Sat. Precipitable water values ramp up Sat, especially
by/during the afternoon and will show POPs ramping up in kind.
This wave moves by and if the timing holds, and this of course
is not a certainty, we should experience a lull in the coverage
of convection sometime Sat eve. However, our Forecast Area will
remain ripe for more significant rainfall as another wave moves
NE along the front. A 50 to 60 kt low level jet at 2-3 kft will
impinge on the area overnight Sat into Sun morning and
precipitable water values again peak near 1.5 inches. This
supports another round of categorical POPs. Then perhaps a lull
before the vertically stacked area of strong low pressure
reaches the area Sun night and Mon.
As you can see, the forecast is froth with complexity. However,
the bottom line is we are expecting a very wet and stormy
weekend with bouts of showers and some thunderstorms. Our
current storm total rainfall forecast through Sun night is 1 to
3 inches of rain and this will be enough to cause localized
ponding and perhaps some flooding in the most urbanized areas
where drainage is poor.
The other major concern is whether any of the thunderstorms will
produce severe weather. Here the signals are a bit mixed with
the strongest low-level jet not quite in sync with the strongest
lift nor the better instability and shear. The strongest low-
level jet is currently slated to arrive during Sun morning, a
diurnal minimum. Still the severe weather potential late in the
weekend exists with mixed layer CAPE values on the order of 500
J/kg with significantly higher instability not too far to our S
where the warm sector will be deepest. However, as is often
the case in the winter season with these powerful systems, there
will be very strong shear. The 0-6 km Bulk Shear values reach
up to 70-80 kt Sun and Sun night and these are very high. These
values heighten the tornado risk. So it still remains to be seen
whether there will be sufficient instability in the lowest
levels of the atmosphere to produce damaging winds or tornadoes
in our area. SPC currently has a good portion of the eastern
Carolinas in a slight risk for severe weather Sun and Sun night.
We continue to highlight the weekend hazards in the Hazardous
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 300 AM Friday...A complex storm system will be on the
move to the east/northeast Monday with some residual moisture
and forcing aloft continued to advertise good chance pops
winding down in the evening.
In the wake of this system a broad and deliberate pattern change
begins to take shape. Brief mid level ridging moves across Tuesday
as strong troughing takes shape out west. This feature will deepen
and move east with a full cyclonic flow in place by the end of next
At the surface, weak high pressure Tuesday and Wednesday will give
way to a cold front Thursday. A decent southwest flow of moisture
with this system warrants at least some mention of pops for
Thursday. Colder temperatures arrive for next weekend with the
expectation of below freezing readings (overnight lows) returning
for the first time in a while.
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
As of 12Z...A warm front will sweep north across the region between
now and 16Z, veering surface winds from east to southwest. A little
light rain is possible inland along with patchy MVFR ceilings as the
front moves through. VFR conditions should prevail through tonight,
however as low-level moisture continues to increase we expect
widespread IFR/LIFR conditions in fog and low ceilings to develop
late tonight, mainly after 06Z-08Z.
Extended outlook...IFR/LIFR likely continuing Saturday morning.
Tempo MVFR or lower ceilings and visibility expected in showers and
thunderstorms Saturday afternoon through Sunday night. Thunderstorms
will have the potential for strong to severe wind gusts Sunday
afternoon and night.
NEAR TERM /THROUGH TONIGHT/...
As of 600 AM Friday...A front, approaching from the S, will
move across the waters as a warm front this morning. SE winds
will veer to SW with its passage, but speeds will not exceed 10
to 15 kt. Seas of 1 to 2 ft this morning will build to 2 to 3 ft
this afternoon. Tonight, the front is expected to sag southward
as weak low pressure along the North Carolina coast moves NE
and away from the area. A SW or WSW wind should hold across the
waters, but wind speeds will be 10 kt or less with seas holding
near 2 to 3 ft. There is some concern for sea fog development
and reduced visibility late tonight and have included in the
gridded forecast at this time and through the day Sat.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 AM Friday...Sea fog may result in reduced visibility
through a good portion of the day Sat. A front will be in close on
Sat and a wave of surface low pressure is expected to move NE along
this front. This will bring widespread showers and some
thunderstorms across the waters, especially Sat afternoon. Then on
Sun, another wave will be moving along this wavering front and then
finally the strongest and deepest area of stacked low pressure will
make its way across the area beginning Sun night. Waves of
widespread showers and some thunderstorms are expected with each of
these features. Convection will have the potential to produce at
least gale force gusts Sun and Sun night. Small Craft Advisory
conditions are expected to get underway Sun morning and then to
persist into the early part of the work week. Sustained winds will
peak around 25 kt with higher wind gusts expected. Seas will peak in
the 6 to 9 ft range.
LONG TERM /MONDAY THROUGH TUESDAY/...
As of 300 AM Friday...Low pressure will be departing to the northeast
leading to a continuation of strong southwest winds at least for a
few hours Monday. Expect speeds of 20-25 knots through midday
dropping to 15-20 by the evening. A more offshore flow develops
Tuesday with similar speeds of 15-20 knots although leaning toward
the lower end of the range most of the day. Significant seas will
show a similar trend with very high values early in the period (7-10
feet) dropping considerably Tuesday.