Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 280217

Area Forecast Discussion
National Weather Service Raleigh NC
1017 PM EDT Fri May 27 2016

.SYNOPSIS...A low pressure system developing off the Southeast coast
will drift toward the northwest, approaching the Carolinas and
Southeast coast over the weekend.


.NEAR TERM /through tonight/...
As of 1005 PM Friday...

Little change required to the near term forecast.

Latest data analysis shows high pressure (both at the surface and
aloft) continuing to ridge into the region from the east. This has
kept the area free of any convection tonight. Given very little
change in the air mass over the past 24 hours, persistence will be
key to the forecast tonight. Therefore, under mostly clear skies,
overnight lows are expected to be mostly in the low/mid 60s.


.SHORT TERM /Saturday and Saturday Night/...
As of 325 PM Friday...

An area of low pressure north of the Bahamas will slowly gather
strength and likely organize into a tropical or sub tropical system
by Saturday. This system will approach the southeast U.S. coast
Saturday afternoon. Bands of moisture associated with the low will
begin to affect  southeast NC by Saturday afternoon, and more so
Saturday night. This will lead to increasing cloudiness over our
southeast counties by Saturday morning with an increasing threat for
showers, mainly south of a Laurinburg-Fayetteville-Goldsboro line,
late Saturday into Saturday night.

Main uncertainty revolves around max temps for Saturday. While feel
fairly certain that increasing/thickening cloud coverage will limit
sunshine/heating over the southeast, presence of a mid/upper ridge
over the northern Piedmont may suppress cloud coverage enough to
allow for decent heating, warming temps into the mid 80s in the
Triad and Triangle areas. If clouds come in faster/thicker than
current thinking, max temps may end up a few degrees cooler. High
temps lower 80s se to the mid 80s nw.


.LONG TERM /Sunday Through Friday/...
As of 305 PM Friday...

Sunday through Tuesday: The likely tropical/sub-tropical low is
expected to be located very near the South Carolina coast Sunday
morning, shown by nearly all of model guidance. However, where the
sub-tropical/tropical/remnant low tracks after approaching/moving
onshore is still in question. Given the approaching system and
influx of tropical moisture into central NC, we should see numerous
to widespread showers and thunderstorms on Sunday as the inverted
surface trough pivots westward and into our area. This will lead to
the potential of heavy rain with any showers and storms as PW`s are
expected to surge to around/over 2 inches, along with at least some
threat of at least isolated severe storms. With regard to the severe
threat, there is still some uncertainty about how much instability
we will have and how strong the deep and low level shear will be,
with the eventual track and intensity of the system playing a major
role. High temps Sunday should be limited to around 80 degrees
thanks to the convection and mostly cloudy/overcast skies, but with
quite humid conditions.

The latest GFS and NAM shows the system lifting northward across the
coastal plain of the Carolinas on Monday night into Tuesday and
being absorbed in a passing northern stream s/w. The latest ECMWF is
hinting at this potential now as well, which differ some from its
previous run and has more of a drier solution across most of central
NC by Monday, with any heavy rain/rain generally from the I-95
corridor and eastward. However, will maintain continuity for now
with previous forecasts and still show at least likely pops across
the eastern half of the area. Chances for showers and storms are
expected to decrease further Monday night into Tuesday with any
lingering trough axis located along the coast (higher chances east
vs west for central NC). High temps on Monday and Tuesday are
expected to be in the lower to mid 80s, with lows in the mid to
upper 60s.

Tuesday night through Friday: Will trend chances for showers and
storms more towards climo with poor run to run model continuity,
along with model differences. This will yield generally diurnal
chance pops with high temps in the lower to mid 80s and lows in the


.AVIATION /00Z Saturday through Wednesday/...
As of 740 PM Friday...

24-Hour TAF period: High confidence that VFR conditions will persist
across central NC through Saturday. The exception would be a small
possibility for some MVFR visbys between 09Z and 12Z in sections of
the sandhills and the coastal plain. Otherwise...will see gradually
lowering cigs through the aft/eve Saturday generally from southeast
to northwest as the tropical depression approaches the area. -KC

Looking ahead: Aviation conditions will deteriorate late Saturday as
increasing low level moisture overspreads the region from the
southeast. This will result in ceilings lowering into the MVFR
category along with an increasing threat for showers. Adverse
aviation conditions appear highly probable across central NC
Saturday night through Sunday night.

Low confidence in the forecast Memorial Day through Wednesday as
weather conditions will be dictated by the position and movement of
an area of low pressure in vicinity of the southeast U.S. Aviation
conditions will vary between VFR and MVFR though tough to determine
which category will be most likely during this period. -WSS





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