384
FXUS62 KRAH 160534
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
132 AM EDT Fri Aug 16 2024

.SYNOPSIS...
High pressure will persist over the Carolinas today then shift
offshore late today and tonight. A cold front will approach
the region from the west on Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 910 PM Thursday...

Quiet weather continues tonight as upper level trough proceeds to
shift offshore. Some mid-level clouds moving into the region from VA
overnight will limit fog potential for the most part, but could
partially clear resulting in a low chance for some patchy fog over
the eastern portion of the CWA. Otherwise, overnight lows will be a
few degrees below climo ranging in the 60s with a few cooler spots
getting down into the upper 50s again.

As of 200 PM Thursday... Central NC will remain under the influence
of NW flow aloft with modest height rises aloft as the upper trough
exits offshore and ridging begins to build in from the west. The dry
air sfc ridge extending south into the area will continue to keep
humidity at comfortable levels.

Underneath some wispy cirrus clouds and scattered diurnal stratocu
field, a projected increase ~5 m in low-level thicknesses should
translate into a 1-2 degrees of added warmth, which will place most
of central NC near to slightly below the 30 year norm. Highs in the
mid to upper 80s.

Hi-res CAMs suggest an isolated shower or two is possible along the
seabreeze and higher terrain this afternoon, which is very plausible
given the agitated cu field in both these regions. Otherwise, a
capping inversion coupled with dry, below-normal PWATs should
preclude diurnal convective rain chances today.

Aside from increase in mid and high clouds across the nw Piedmont,
upper impulses spilling east atop the building ridge should prove
rather inconsequential overnight. Lows 60-65.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 200 PM Thursday...

Embedded in the W-NW flow aloft between the upper ridge centered
over the south central CONUS and the large troughing over the Great
Lakes and Ohio and Tn Valleys, moisture/PWATs will steadily increase
from west to east across central NC through Friday night as weak
perturbations traverse the area. Steered by W-NWLY flow, convective
initiation just upstream across the mountains and foothills will
likely progress eastward, in weakening fashion, into the western
Piedmont between during the afternoon and evening, and potentially
into central and eastern portions, in widely scattered fashion
overnight. Given both weak shear and instability, severe storms are
not expected.

The onset of SWLY low-level flow will result in continued warming
and a slight uptick in humidity levels. Highs 85-90. Lows 65-70.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 350 PM Thursday...

Mid-latitude flow will become and remain amplified through at least
the middle of next week, anchored by a sub-tropical high with 500 mb
heights of 3-5 sigma (near 600 dam) forecast to develop from the srn
High Plains to the Southwest. A surrounding ridge will extend across
the Plains and be flanked by a reloading negative height anomaly off
the Pacific Northwest coast and a trough that will progress into and
persist over ern NOAM.

At the surface, high pressure and residual continental air will
linger along the Middle and South Atlantic coast Saturday, then
yield to a cold front that will approach from the west and move
slowly ewd across NC Sun through Mon night. While high pressure will
follow, it may be initially slowed by the Appalachians and allow for
lee trough development on Tue, before more-overwhelmingly building
ewd and across the Middle Atlantic and Carolinas Wed-Thu.

The pattern described above will favor a good chance of diurnally-
maximized convection over mainly the wrn half of cntl NC Sat, where
low-level moisture/instability will be more plentiful away from the
lingering dry air ridge along the coast. A high to likely chance of
convection will result as the cold front edges into cntl NC on Sun,
with chances gradually shifting across the Coastal Plain and toward
the coast through Mon night. Mainly dry conditions will follow for
the rest of the week. Temperatures will generally be around to
slightly above normal ahead of the front through Sun, then trend
below average Tue-Thu.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
As of 132 AM Friday...

A semi-persistence forecast continues with best chance for sub-VFR
fog at RWI, with a lesser chance at FAY. Lack of rainfall, warmer
high temperature, and lower crossover-temperature, should confine
fog to the climatologically favored time of 05z-12z. Showers/storms
will be possible (15-30% chance) at INT/GSO during the late
afternoon into the evening hours as upstream convection leaks across
the mountains, although likely in a weakening state.

After 06Z Saturday: A slow moving cold front will approach this
weekend, producing increasing convective rain chances through the
weekend with Sunday being the most active/widespread. Showers/storms
will potentially linger into Monday as the front finally moves
through the area.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...PWB
NEAR TERM...CA/CBL
SHORT TERM...CBL
LONG TERM...MWS
AVIATION...PWB/Swiggett