Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 251914

Area Forecast Discussion
National Weather Service Raleigh NC
314 PM EDT Fri May 25 2018

High pressure centered over the western Atlantic will extend
westward across the Carolinas today. The resulting wind flow from
the south, along with an upper trough approaching from the west,
will lead to increased cloud cover and unsettled weather over the


As of 310 PM Friday...

Latest surface analysis shows surface high pressure centered
off the Mid-Atlantic coast with a light southerly flow across
the Carolinas. Further aloft, a ridge of high pressure extends
from the subtropical Atlantic northwest across the Carolinas
into the southern Appalachians. A shortwave riding north on the
backside of the ridge will slowly lift north across western NC
this afternoon and evening.

Isolated to widely scattered convection developed this
afternoon in a region of weak to perhaps moderate instability
in the southern Coastal Plain with just a few showers to the west
across the Sandhills into the western Piedmont. As the short
wave lifts north, expect convective coverage to increase across
the western Piedmont late this afternoon and continue into the
early evening before diminishing later this evening. SPC has
central NC outlined in generally thunder and don`t expect any
severe weather given weak instability and light southeast to
southwest flow with bulk shear values of around 10kts. Given a
weak flow and slow storm motion, locally heavy rain could be an
issue. Only an isolated shower is expected after midnight with
areas of stratus likely developing toward daybreak, especially
in the west and south. Lows should range in the upper 60s to
around 70. -Blaes


As of 310 PM Friday...

Moisture will continue to increase across the region on Saturday
as the deep southerly flow increases. After a period of morning
stratus, skies should develop some breaks allowing temperatures
to warm into the mid to upper 80s. This will support perhaps a
moderately unstable air mass and scattered showers and
thunderstorms, mainly during the afternoon and evening. The best
chance for storms once again appears to be across the western
Piedmont and in the southeast. Convection will wane a bit during
the evening but a shower can`t be rules out overnight,
especially in the west. Lows will range in the upper 60s to
lowers 70s. -Blaes


As of 235 PM Friday...

Latest longer range forecast generally on track.

Sunday will start out fairly dry for central NC as the area will be
between a frontal zone to the north and Alberto to the south.
That frontal zone to the north will become more active with the
heating of the day and possibly impinge upon our northern and
western counties by late afternoon.

Overnight Sunday night into Monday morning the first wave
of tropical moisture will arrive from the south with some upper
level support and this could linger in the area through early
Tuesday morning. Periods of heavy rain can be expected during this
time, particularly across southern and eastern areas. This wave will
move out to sea on Tuesday morning with drier conditions later
Tuesday. The next wave of tropical moisture will enter the
region Wednesday into Thursday, but this will depend upon the
actual track of the remnants of Alberto. Drier weather returns
Friday, but with more sunshine, temperatures will rise to
around 90F.

With deep tropical moisture in place from Sunday through
Thursday, torrential rainfall with any convection will have the
potential to produce flash flooding across central North
Carolina. Urban and small stream flooding risk will be highest
early on with river flooding possibly becoming a problem later
in the period depending on actual rainfall totals.


As of 230 PM Friday...

VFR conditions are noted across much of central NC this afternoon
with the exception of some MVFR cigs across the Triad and in a
few locations in the Sandhills and southern Coastal Plain where
some scattered convection is ongoing. Scattered showers and an
isolated thunderstorm or two will develop in an arc from the
southern Coastal Plain west and northwest across the Sandhills
into the western Piedmont, potentially impacting the FAY, GSO
and INT terminals with a much more limited threat at the RDU and
RWI terminals. Convective coverage will wane this evening with
a period of VFR conditions expected to dominate late this
evening and overnight. However, sub-VFR conditions, mainly with
low cigs are expected to return overnight after around 06Z at
the FAY terminal and a little later, maybe after 08Z at the
other terminals with the greatest confidence of MVFR to IFR cigs
at INT, GSO and FAY. Surface winds from 160 to 200 degrees at 5
to 10kts today will decrease to less than 5 kts overnight
before increasing to around 10 kts on Saturday with a few gusts
to near 15 kts possible during the afternoon.

Looking beyond 18Z Saturday, low clouds and reduced cigs will
lift giving way to a period of VFR conditions before scattered
afternoon and evening storms develop. After a period of morning
stratus another round of scattered storms on Sunday. Widespread
adverse aviation conditions are expected Monday into Wednesday
as widespread showers and thunderstorms are expected. -Blaes




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