Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 261935
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
335 PM EDT Thu May 26 2016

.SYNOPSIS...Bermuda high pressure will extend over the area through
Friday. Meanwhile, a storm system will develop over the sub-tropical
Atlantic and drift toward the Southeast U.S. coast through the
holiday weekend.

&&

.NEAR TERM /through tonight/...
As of 335 PM Thursday...

A slightly unstable low level air mass coupled with a weak upper
disturbance stalled over the western Piedmont may support the
development of an isolated shower or storm through sunset. The
approach of another disturbance (responsible for the convection
crossing the lower oh valley this afternoon) may trigger a few
showers overnight across the far northwest-northern Piedmont. Not
expecting any strong or severe convection at this time as parameters
for sustained updrafts virtually non-existent as the shear is very
weak and instability weak/marginal.

The continued modification of the low level atmosphere along with
patchy mid level cloudiness will support mild overnight
temperatures. Min temps in the mid 60s.

&&

.SHORT TERM /Friday through Friday Night/...
As of 335 PM Thursday...

A narrow ridge of high pressure aloft will extend west-east across
central NC. This feature will maintain a mid level cap and inhibit
convective development over most of the region. The exception may be
the far west-nw where outflow boundaries from overnight convection
and linger weak upper level disturbance may enable an isolated
shower or storm to develop during the heat of the day.

Low level thicknesses comparable to today, supportive of afternoon
temps well into the 80s, near 90 in the sandhills and coastal plain.
Continued mild overnight with min temps in the mid 60s.

&&

.LONG TERM /Saturday through Thursday/...
As of 230 PM Thursday...

The main forecast concern for this period continues to be the
potential tropical/sub-tropical development of an area of low
pressure between the Bahamas and Bermuda this weekend.

The upper level ridge responsible for the recent quiet weather will
break down as the coastal low develops. To the west, an upper level
trough will linger for the weekend. A shortwave will progress from
the southern Rockies northeastward along the trough axis toward the
Great Lakes.

As the upper level short wave moves through the Great Lakes, the
northeastward moving coastal (tropical) low will progress toward the
SC coast. As of the most recent runs, the models indicate these two
features interacting Sunday night/Monday. The upper level shortwave
could absorb the coastal low (possible tropical system) on Monday.
There is still a fair amount of uncertainty on whether the low will
move up the Mid-Atlantic coast or hand out along the Carolina coast
before slowly moving inland. Regardless of this, the majority of
this period appears to be fairly unsettled, with chances for
convection, highest in the aft/eve, everyday. Much of the coverage,
duration, and timing of convection will depend on how the system evolves
and thus confidence is still somewhat low. With the strong advection
of Atlantic moisture into the region on the northern edge of the
low, expect increasing clouds from the east on Saturday, though much
of the day will remain dry. Cloudy skies could persist through much
of the period.

Temperatures through the period: with the increasing clouds and
chances for rainfall, expect highs to decrease from the mid 80s on
Saturday, to upper 70s to low 80s Sunday. Highs should slowly
moderate back into the mid 80s by the middle of the week. Overnight
lows will remain fairly steady in the mid to upper 60s.

&&

.AVIATION /18Z Thursday through Tuesday/...
As of 115 PM Thursday...

It`s highly likely that VFR conditions will persist across central
NC through Friday. The exception will be a small risk for early
morning fog, limiting the visibility to MVFR criteria for a brief
period. In addition, isolated convection late this afternoon through
this evening, and again Friday afternoon through the evening, will
produce instances of MVFR ceiling and visibility.

Aviation conditions on Saturday will vary between VFR and MVFR
criteria as increasing moisture results in lowering cloud bases and
an enhanced threat for afternoon and evening scattered convection.
Sub VFR conditions appear more likely Sunday and Memorial Day due to
an area of low pressure projected to be positioned off the GA/SC
coast. Circulation around this feature could send abundant moisture
into central NC, resulting in widespread cloud cover and scattered
to numerous showers and thunderstorms. Aviation conditions may
slowly improve by Tuesday, though periods of MVFR conditions are
probable.

&&

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

&&

$$

SYNOPSIS...CBL/BLS
NEAR TERM...WSS
SHORT TERM...WSS
LONG TERM...KC
AVIATION...WSS



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