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Area forecast discussion 
National Weather Service Wilmington NC
647 PM EST Sat Nov 28 2015

high pressure will persist across the area one more day
maintaining dry weather through Sunday. A cold front will drop
south across the area late Sunday night bringing a chance for
showers into Monday. This front will lift back north on Tuesday
bringing a return to warmer and drier weather. This front will
return once again Wednesday...crossing offshore with another
chance for showers. Cool but cloudy weather will then develop for
the end of the week behind this front.


Near term /until 6 am Sunday morning/...
as of 645 PM changes to the forecast with the latest
update. Previous discussion follows:

A fair and mild late November evening on tap across NE SC and southeast both daytime maximum temperatures today and overnight lows
tonight end up 7-9 degrees above normal for Thanksgiving weekend
by climatological standards.

At the surface...high pressure will remain ridged from west-southwest to east-northeast
across the region...establishing light to calm winds overnight.
Above the surface...arid air will remain sandwiched between 5 and
12 thousand feet in west wind flow. Above 12 kft...clouds will
spill over-top a dampening upper-level ridge sending a variable
smattering of high and patchy middle-level clouds over the region.
This will offset ideal long-wave heat escape but only partially
and minimums will drop to 49-52 across most locations...middle
50s near the beaches and icw passageway. Weak to calm surface wind
and partial clearing may lead to mist banks and fog pockets late
tonight and very early Sunday.


Short term /6 am Sunday morning through Monday night/...
as of 300 PM Saturday...difficult forecast for the short term as a
variety of features interact across the southeast. Large upper ridge
and surface high which have kept the southeast weather beautiful the
past several days will weaken this period. Upper flow becomes zonal
as a series of shortwaves moves overhead and squashes the
ridge...and this causes the high to weaken and shift off to the
east. Strong baroclinic boundary that has been almost stalled well
west of the area...will pivot...with a piece of the cold front
dropping southward as a back door type boundary late Sunday into
Monday. This will then drive surface wedging across the Carolinas
while west/SW flow remains in place aloft. The biggest question Marks
involve how far south the precipitation will be able to get into this well as the strength of the isentropic lift forced to
develop atop The Wedge.

While guidance is in good agreement with the overall
pattern...differences in intensity of The Wedge and duration of the
more flat upper flow create forecast challenges...especially on
Monday. The GFS appears to weaken the upper flow the fastest and
push the back door front furthest south...thus explaining its wetter
solution. The ecm/NAM both are drier and keep the ridge more
strongly in place...driving most of the precipitation and middle-level vorticity
energy off to the northwest. Wpc seems to favor this solution...and will
hedge in that direction by keeping pop in the low-chance
category...schc southeast zones. Best precipitation chances occur late
Sunday night and into Monday as determined by sref plumes and
forecast profiles...with the highest quantitative precipitation forecast confined to the northern
zones...and even then only looking at 1/10 of an inch or so. While
light drizzle is possible within the isentropic remains
possible that only clouds will be the result across southern zones
before ridging tries to Blossom once again late in the period as
troughing amplifies to the west and the front lifts back to the

Still anticipate above normal temperatures Sunday...becoming cooler Monday
within The Wedge of high pressure. Highs Sunday will exceed 70 most
areas...and then be about 5-10 degrees cooler Monday. If the GFS
turns out to be the better verification...highs Monday could be even
cooler thanks to the stronger wedge. Lows both nights will remain
be above normal...Sunday night in the middle 50s due to the continued
warm air mass...and Monday a degree or two either side of 50 thanks
to cloud cover and the slow return of the front.


Long term /Tuesday through Saturday/...
as of 300 PM Saturday...two weather systems will make the long-
term portion of the forecast rather difficult. Reviewing the
various 12z GFS ensemble members shows significant spread with
timing of the frontal passage with wednesday's system...and also
with the northward advance of stratiform rain as a low develops
across Florida and the eastern Gulf Friday.

A front stalled near the Savannah River Tuesday will crawl northward
into North Carolina by Wednesday. With this point at least the 12z
GFS and European model (ecmwf) are now in agreement! Tuesday/Tuesday night should
see little precipitation as synoptic forcing remains off to the north and
west and a good deal of dry middle-level air should be in place. Probability of precipitation
have been lowered to only 10-20%. Thinning low clouds should allow
highs Wednesday to climb into the 70s...although I am still on the
low side of the last two (00z & 12z) gfsx MOS runs. The European model (ecmwf)
remains slower than the GFS with the cold frontal passage Wednesday
evening/night...and my forecast lows remain warmer than the GFS as a

High pressure should build in from the west Thursday...however dense
high cloudiness from the southern branch of the jet stream could
still lead to mostly cloudy skies. This cloudiness may obscure our
chance to view a Cape Canaveral rocket launch scheduled for 555
PM Thursday evening. A wave of low pressure developing in the
eastern Gulf Thursday night will cross Florida on Friday. While we
should keep middle and high cloudiness overhead...dry low-level air
advecting southward from surface high pressure near the Great
Lakes will try its best to keep the precipitation shield from advancing
as far north as the Carolinas. The European model (ecmwf) shows dry weather as a
result...although the 12z GFS brings rain to the South
Carolina/Cape Fear coast Friday. Given plenty of GFS ensemble
spread I have maintained a small 20ish pop for Friday.


Aviation /00z Sunday through Thursday/...
as of 00z...potential for areas of MVFR due to fog development late
overnight into the early morning hours continues. Otherwise expect

VFR continues tonight across the area with few to scattered coverage
of cirrus and light winds. Will keep the potential for areas of fog
late overnight into the early morning hours...which could create
brief periods of MVFR. However...if cloud coverage is more scattered
to possibly broken in may inhibit fog development. For now
have kept with tempo MVFR at all terminals. On Sunday...VFR will
prevail with few/sct/bkn coverage of cirrus. Winds will be light and
variable...becoming southeast in the afternoon hours along the
coast...increasing to at or below 8 kts.

Extended outlook...unsettled weather Monday night through late
Tuesday with possible MVFR/IFR conditions from ceilings and reduced
visibility from precipitation and areas of fog. Otherwise expect VFR.


near term /through tonight/...
as of 645 PM changes to the forecast with the latest
update. Previous discussion follows:

The long period east swell continues to slowly dampen...and much of
the energy is being dissipated by bottom friction on the near-
shore shelf waters along the 0-20 nm marine zones. As a
result...the Small Craft Advisory will be cancelled at 3 PM this
afternoon. With light exercise caution statement will
be needed...and the 3-5 foot waves will have very little steepness
given the 12-13 second intervals. Wave heights will subside to 2-4
feet by daybreak Sunday. No showers or thunderstorms are expected on the
0-20nm waters overnight. Sea surface water temperatures currently
are in the low to middle 60s.

Short term /Sunday through Monday night/...
as of 300 PM Saturday...high pressure across the southeast will give
way to a back door cold front dropping south late Sunday night into
Monday. This front will waver across the waters Monday before
beginning to lift back north late in the period. This creates north
to northeast winds both days...primarily around 10 kts except for a
northerly surge behind the back door front Sunday night and the
first half of Monday...when speeds will reach up to 15 kts. Seas
will be formed by a combination of a deamplifying 10 second easterly
swell and a NE wind wave...creating wave heights of 3-4
feet...slightly lower in the wave shadowed region SW of Brunswick
County in amz252 and amz254.

Long term /Tuesday through Thursday/...
as of 300 PM Saturday...a front stalled over South Carolina Tuesday
will return northward Tuesday night...allowing light NE winds to
turn southerly by Wednesday morning. This period of south winds
won't last long however as a cold front will push offshore Wednesday
night. Northerly wind developing behind the front will persist into
Thursday. Wave heights of 2-3 feet will probably build to 4 feet 10-
20 miles from shore Wednesday in the southerly wind...but should
diminish back to 2-3 feet again Thursday.


Ilm watches/warnings/advisories...



near term...mjc/rek
short term...jdw
long term...tra

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