Area Forecast Discussion
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FXUS62 KILM 260535
Area Forecast Discussion
National Weather Service Wilmington NC
135 AM EDT Mon Sep 26 2016
A cold front will stall across South Carolina tonight before
returning north Monday. A stronger cold front will move across the
Carolinas late in the week though its timing is highly uncertain.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 1025 PM Sunday...Have dropped pops for the overnight period
with the latest update as showers have faded with loss of diurnal
heating. Relevant portion of previous discussion from this
This morning`s cold front has nearly stopped moving southward and
is stalled over eastern South Carolina in the vicinity of
Georgetown, Florence, and Hartsville. With northeast winds on both
sides of the boundary it`s a bit nebulous exactly where the front
is. Dense low clouds never burned off across northern and central
North Carolina, but fortunately the post- frontal airmass never
became that well established here before the sun rose this
morning. Northeasterly low-level flow should push these lower
clouds southwestward after sunset.
Weak cool advection should be felt most strongly across coastal
SE North Carolina tonight as the high over New England points its
ridge axis down in that direction. Broken low clouds will help to
hold heat in overnight and my forecast lows are close to the
warmer NAM MOS guidance, except at ILM where a slug of dry air
after midnight associated with the ridge may allow better
radiational cooling to occur. Lows mainly upper 60s with some
lower 70s on the beaches.
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...The 500 mb ridge over the Southeastern U.S.
will get beaten down over the next two days as an upper level trough
begins to dig southward across the Great Lakes. The surface high
will move off the New England coast Monday; return flow behind this
high should lift today`s cold front back to the north again, with
the boundary moving back into Virginia by Monday evening. A weak low
in the northern Bahamas will get lifted northward by the same low
and mid-level flow. While this feature should remain 50-75 miles off
the coast as it moves northward Monday into Tuesday, its closest
approach late Monday night into Tuesday morning could enhance
rainfall potential, at least along the coast.
By Tuesday, attention will shift to a cold front entering the
western Carolinas, preceding the upper level trough over the Great
Lakes. This front should stall as the upper trough deepens and cuts
off. With a humid tropical airmass in place Tuesday ahead of this
stalled front, scattered showers and t-storms appear quite possible,
especially inland. Assuming there are no unresolved upper level
disturbances present, precipitation should diminish Tuesday evening
with the loss of daytime heating.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 3 PM Sunday...Interesting weather early in the period with a
very large trough on Wednesday turning into a major cutoff low well
into the weekend. Trouble is, models are not in agreement regarding
the longitude of the cutoff. As a result it is difficult to
determine whether we see a FROPA locally or spend most of the long
term in the warm sector of the deeply occluded surface low. Even
FROPA model solutions do not push the boundary very far offshore so
either way the weather appears to be unsettled. The main
ramifications of the aforementioned uncertainties then will likely
affect temperature/dewpoint forecast. The ECWMF has been seemingly
leading the way in figuring out how this system will evolve and it
has been showing the least progression. It now delays the front
until about Saturday morning and it is not indicative of any
significant airmass change. The GFS looks like it is trending in the
direction of the EC so the forecast will be hedged in that
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
As of 06Z...Stalled cold front is draped across NE SC this morning,
with high pressure building down the coast from the NE. Moisture is
pooling along the leading edge of this ridge of high pressure and
behind the front, creating increasing stratus across the area. This
stratus will likely become more widespread overnight, but should
remain at MVFR levels, and no IFR is forecast. Best chance for
persistent stratus will be at the inland terminals, and while
confidence is lower at the coast, have included MVFR at all sites
through dawn. Winds will remain 5-10 kts overnight, highest near the
coast, so no visibility restrictions are expected.
The front will waver across the area again during Monday, with
showers and isolated tstms possible at all terminals. Have not
included any mention of TS in the TAFs attm, but VCSH has been
introduced to all terminals. Winds are expected to rise to around 10
kts, while veering to the SE through the aftn/eve. Any showers will
wane after dark Monday night, with more stratus possible at the end
of this valid period.
EXTENDED OUTLOOK...Chance for SHRA/TSRA each day through
Wednesday, with morning fog/stratus also possible. VFR Thursday
NEAR TERM /THROUGH TONIGHT/...
As of 1025 PM Sunday...Latest obs continue to show E to NE winds
of around 15 kts in the wake of the recent cold front, with seas
of 3 to 4 ft. This fits in well with the latest forecast, of which
there is no change. Previous discussion from this afternoon
This morning`s cold front has made it only a short distance down
the South Carolina coast this afternoon. The boundary will settle
somewhere near the Santee River tonight where it should remain
stalled through Monday. A healthy northeast breeze around 15 knots
with gusts to 20 knots should continue most of the night as high
pressure builds south across New England. Seas 3-5 ft across the
NC waters and 3-4 feet across the SC waters consist of a mix of
11-second easterly swell from former Tropical Storm Karl and 4-5
second wind waves.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...As high pressure moves off the New England
coast Monday and out to sea Tuesday, our synoptic wind direction
will veer from northeasterly Monday morning to southeasterly by
Monday night. Normally it would hold this direction, however it
appears that a weak area of low pressure in the Bahamas will move
north along the Gulf Stream Monday, approaching to within 50-75
miles of Cape Fear Tuesday. Circulation around this feature may turn
our winds back to the northeast for at least the first half of
Tuesday before the southeasterly winds redevelop Tuesday afternoon
or evening. Wind speeds should average 10-15 kt Monday, but lighter
through Tuesday and Tuesday night.
LONG TERM/WEDNESDAY THROUGH FRIDAY/...
As of 3 PM Sunday...Confidence is very low for the long term. A cold
front driven southward by a cutoff upper low is being handled very
poorly by various models. Solutions range from a somewhat clean
FROPA on Thursday to the front lingering to our west until Saturday
morning. Have trended the forecast towards the slower timing since
models do tend to be gravitating in that direction. While the
current wind direction forecast may be way off given the
uncertainties at least that is some confidence that both wind speeds
and seas will remain quite manageable for most mariners.