Scientific Forecaster Discussion
fxus62 krah 252347
Area forecast discussion
National Weather Service Raleigh NC
747 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
Near term /until 6 am Saturday morning/...
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. Storm Prediction Center 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
Short term /6 am Saturday morning through Saturday night/...
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
Long term /Sunday through Friday/...
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
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.
Aviation /00z Saturday through Wednesday/...
as of 747 PM Friday...
Through 00z sunday: scattered showers and thunderstorms expected to
gradually diminish over the next few hours, with VFR conditions
across most of central NC during the late evening and early
overnight hours. Flight conditions will then locally diminish to
MVFR or IFR Saturday morning between 06-12z due to development of
stratus and low cigs. These cigs will lift after sunrise, but will
be followed by scattered shower and tstm development from late-
morning through the evening hours. Flt conditions will locally lower
to IFR in and near shower/tstm activity. Winds generally aob 10kt
tonight, then SW around 10kt after 26/13z.
Looking beyond 00z sunday: after a period of morning stratus,
another round of scattered storms are expected on Sunday. Widespread
adverse aviation conditions are expected Monday into Wednesday as
widespread showers and thunderstorms are expected.