Area Forecast Discussion
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FXUS62 KILM 260724
Area Forecast Discussion
National Weather Service Wilmington NC
324 AM EDT Mon Sep 26 2016
A stalled front will waver across the area today. A stronger cold
front will approach Wednesday before slowly crossing the area
through late in the week although timing of this front is highly
uncertain. Cooler and drier weather is expected by the weekend.
.NEAR TERM /THROUGH TONIGHT/...
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 /TUESDAY THROUGH WEDNESDAY 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 /THURSDAY THROUGH SUNDAY/...
As of 300 AM Monday...Big differences in the extended continue to
cause lowered confidence for late this week. While the guidance all
shows a deep trough closing off across the OH VLY, the evolution
thereafter becomes quite muddled. The ECM continues to be a
strong/slow/west outlier with this feature as it digs into the lower
Appalachians and then actually retrogrades to the NW through
Saturday before finally ejecting late in the wknd. The GFS/CMC are
more in line with a sharp digging through Thursday and then lifting
off to the NE through New England Friday and into the wknd. Although
the ECM has been consistent the last few days, the GFS solution is
still preferred as a retrograde west of the upper low into a +3 SD
ridge seems unlikely. WPC cannot rule out any solution at this time
however, so a blended forecast is preferred with highest weight on
This upper low will determine the passage of a surface cold front
which continues to slow in forecast guidance. Favoring the GFS,
FROPA is now expected early Thursday, with cool and dry weather
expected Fri-Sun. In fact, temps Fri-Sun may fall slightly below
climo for both highs and lows as the first fall-like airmass of the
season advects into the Carolinas beneath Canadian high pressure.
Will note that if the ECM solution verifies, the front won`t cross
until Saturday, leaving much more unsettled weather through the
week, along with continued above normal temperatures.
.AVIATION /08Z 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/THURSDAY THROUGH FRIDAY/...
As of 300 AM Monday...Still some uncertainty in the extended with
respect to a frontal passage, but attm expect FROPA to occur
Thursday with W/SW winds around 10 kts becoming NW late. High
pressure will build in behind this front creating a very weak
pressure gradient, so winds across the waters on Friday will
feature highly variable direction with speeds of 5-10 kts. Seas of
2-3 ft Thursday will fall to around 2 ft on Friday thanks to the
weaker winds, and a continuing 2ft/9-10 sec SE swell.