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fxus62 krah 240851 
afdrah

Area forecast discussion
National Weather Service Raleigh NC
351 am EST Sat Feb 24 2018

Synopsis...
a strong sub-tropical ridge aloft situated off the southeast U.S.
Coast will weaken while drifting south toward the Bahamas through
Saturday. Meanwhile, a quasi-stationary front will remain over
central NC through tonight, then retreat northward while dissipating
on Saturday.

&&

Near term /through tonight/...
as of 330 am Saturday...

Latest surface analysis shows a stationary front draped across
central North Carolina separating a rather significant north/S dewpoint
and temperature spread. Currently, dewpoints/temps near the Virginia/NC
border reside in the mid to upper 40s while those along the NC/SC
border are in the lower 60s. Intermittent fog formation is ongoing
across much of the area, with additional fog formation likely,
especially between 4am and 10am on Saturday. Little in the way of
movement with this boundary has been witnessed thus far tonight, but
guidance continues to indicate a slow retreat northward likely
during the predawn hours. This should allow temperatures to steady
to even slightly increase through dawn, with intermittent mid to
upper level clouds overspreading from west to east associated
loosely with the cold front draped west of the Appalachian Mountains.

&&

Short term /Saturday and Sunday/...
as of 330 am Saturday...

Sub-tropical ridging will remain centered in the vicinity or just
northeast of the Bahamas, with associated surface high pressure
extending from just south of Bermuda, westward into the southeaster
U.S. This pattern will maintain unseasonably warm and relatively
humid conditions across central North Carolina both Saturday and
Sunday. Expect afternoon temperatures in the mid 70s to low 80s each
day under intermittent cloud cover, with mild overnight low
temperatures in the lower 60s expected Saturday night into Sunday.
Cloud cover will be thickest across the western Piedmont counties,
where intermittent shower chances will be possible Saturday
afternoon and evening, and again Sunday afternoon as the front
pushes into the western portion of the state. Southwesterly winds
will accelerate Sunday ahead of the approaching cold front, with
sustained winds 10 - 15mph with gusts up to 30mph possible.

&&

Long term /Sunday night through Friday/...
as of 345 am EDT Saturday...

Sunday night through Monday night: models are starting to come into
better agreement with the timing of the cold front through the area
Sunday night/early Monday, that is forecast to slow down and briefly
stall along coastal areas on Monday before finally pushing south and
away from the area Monday night. While a decent area of showers is
expected to accompany the front Sunday evening/night , the better
rain chances and higher quantitative precipitation forecast amounts will likely occur Post-frontal
on Monday, in response to the approach of a well-
defined/significant shortwave trough that will spur the development
of multiple waves tracking NE along the quasi-stationary frontal
zone. Current model timing indicates, rain chances will taper off northwest
to southeast during the late afternoon/evening hours. Widespread rainfall
amounts of a half inch to three quarters of an inch can be expected.

Calendar day highs in most locations will occur before daybreak,
prior to fropa, with widespread rain and clouds keeping daytime
temperatures in the mid/upper 50s northwest to lower 60s. Clearing and cold air advection
on the leading edge of a 1030ish mb high building into the area will
result in some of the coolest overnight lows that we've seen for
some time. Lows in the lower to mid 40s, which is still a good 5 to
7 degrees above normal.

Tuesday through friday: expect dry, slight above normal temperatures
on Tuesday as a progressive surface high builds across the mid
Atlantic states briefly on Tuesday, only to quickly shift off the
southern mid-Atlantic coast Tuesday night.

The later half of the work week is setting up to be wet and
unsettled, with widespread showers expected Wednesday through
Wednesday night, within the warm conveyor feed on the cyclonic side
of the shortwave trough ejecting east out of the southern rockies.
At this time, model spread is high wrt to the eastward evolution of
the this system, more specifically, when/where this system will
phase with northern stream energy as it progresses into the eastern
US. Eventually this system and it's attendant cold front will bring
another round of showers and possibly some thunder to the area
Thursday/Friday. Will continue to monitor. Continued mild, with
highs in the 60s on Wednesday, warming into the 70s ahead of the
front.

&&

Aviation /06z Saturday through Thursday/...
as of 1250 am Saturday...

24-hour taf period: a frontal boundary continues to remain stalled
across central North Carolina, with kint, kgso, krwi, and krdu
remaining north of the boundary and kfay sitting just south. Biggest
difference at this hour between the north side and Southside remains
dewpoints, with 60s prevalent across the sandhills/southwest
Piedmont counties and 50s prevalent further north. Expect this
boundary to slowly lift north overnight, allowing dewpoints to rise
and aviation conditions to deteriorate in the form of reduced visibilities.
VFR conditions remain in place everywhere except for rwi, where br
formation has begun. Each site will likely dip to LIFR overnight,
especially between 4am and 10am Saturday. Confidence of fog formation
is higher at the eastern sites vs the western sites who will see a
layer of mid to upper level clouds spill across the area. Winds will
remain light to variable, becoming predominantly southwesterly around
10mph during the day Saturday as mixing is allowed and conditions
return to vfr+ before mid day. - Jjm

Looking ahead: increasing winds, particularly aloft, will limit fog
potential Saturday night, except for at perhaps Fay and rwi where
winds will be relatively lighter, with overnight-early morning low
stratus anticipated otherwise and elsewhere. Those strengthening
winds aloft may also result in marginal low level wind shear
conditions at Piedmont sites Saturday night, given the likely
presence of a shallow, ~1000 ft inversion, which will tend to
separate a steady and even occasionally gusty SSW wind at the
surface from an abrupt increase in flow within and above the
inversion. The approach and slow passage of a frontal zone will
result in a high probability of showers, and some sub-VFR
conditions, late sun into early next week. -Mws

&&

Climate...

Rdu records:

Date | high year | high min year
------------------------------------------
02/24 81 1982 58 1985

Gso records:

Date | high year | high min year
------------------------------------------
02/24 79 1982 55 1985

Fay records:

Date | high year | high min year
-------------------------------------------
02/24 83 1930 60 1975

&&

Rah watches/warnings/advisories...
dense fog advisory until 10 am EST this morning for ncz009>011-
026>028-041>043-073>078-083>086-088-089.

&&

$$

Synopsis...mws

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