-- Discussion containing changed information from previous version are highlighted. --
479
FXUS62 KRAH 220821
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
421 AM EDT Wed May 22 2024

.SYNOPSIS...
High pressure over the western Atlantic will extend across the
Southeast ahead of a cold front that will approach from the west and
become quasi-stationary from the Middle Atlantic to the lower MS
Valley Thursday and Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 345 AM Wednesday...

A sub-tropical mid-level ridge will extend from the Gulf of Mexico
newd and across the Southeast and Carolinas, while low amplitude,
wswly flow, and embedded convectively-amplified disturbances, will
exist on its northwest periphery from the srn Plains to the cntl
Appalachians and nrn Middle Atlantic.

At the surface,  ~1017 mb high pressure centered just off the Middle
Atlantic coast swwd and along the coast of the Carolinas will
remain, while an Appalachian-lee trough --and axis of weak to
moderate instability-- will develop this afternoon across the srn
Middle Atlantic Foothills/wrn Piedmont.

Sensible weather associated with the pattern described above will
favor warm(er) and dry conditions throughout cntl NC, though with an
isolated shower or storm that may initiate on the surface trough,
then subsequent outflow, and drift toward the far nw Piedmont before
dissipating with nightfall. High temperatures should be a few
degrees higher than those of Tue and generally in the mid-upr 80s,
followed by milder lows mostly in the lwr-mid 60s.
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&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
-- Changed Discussion --
As of 420 AM Wednesday...

A mid-level ridge initially over the Southeast will move east and
off the South Atlantic coast this period and allow low amplitude,
wly flow to extend from the Mid-South to the srn Middle Atlantic.
One or more convectively-amplified disturbances from deep convection
expected from the Ark-La-Tex to the Mid-South Wed afternoon-evening
will be embedded within that flow and likely move across the srn
Middle Atlantic Thu afternoon-night.

At the surface, high pressure over the wrn Atlantic will drift ewd
and further offshore, while an Appalachian-lee surface trough will
sharpen and drift ewd and across the srn Middle Atlantic Piedmont. A
composite outflow boundary and following cold pool/mesohigh may also
develop with a clusters of showers/storms across the srn
Appalachians and srn Middle Atlantic Piedmont.

Sensible weather associated with the pattern described above will
favor continued warm conditions, probably a couple of degrees higher
than Wed and in the mid 80s to around 90 F. Both global and
convection allowing models also depict clusters of showers/storms
developing across the mountains by early afternoon and subsequently
spreading generally ewd, amid 30-40 kts of wly mid-level flow and
into a deeply-mixed/steep lapse rate environment, across the
Piedmont through the afternoon-early evening. The greatest coverage,
possibly in the form of a small, forward-propagating MCS or two,
will probably focus along the path of the convectively-amplified
disturbances noted above. While predictability of those features and
downstream severe potential remains low at this time range, the
overall environment will support a risk of both strong/damaging wind
gusts and hail across cntl NC during the afternoon-evening. Showers
and storms will likely weaken with time and ewd extent as they move
across the Coastal Plain and offshore through early Thu night, with
associated diminishing severe potential. Low temperatures will be in
the 60s.
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&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 251 AM Wednesday...

Broad troughing across the eastern US will maintain a steady flow of
rich swly moisture transport across central NC through the extended.
Embedded short-wave/MCV features will move over our area triggering
periods of showers and storms each successive day.

At the sfc, an offshore high will pump continuous swly flow across
central NC allowing unstable conditions to flourish each day. Further
upstream, a front will stall west of the Appalachians. As the
aforementioned short-wave energy moves through aloft, expect periods
of showers and storms to develop each day.  Ensembles suggest
periods of stronger shear may be possible Friday (across the south),
Sunday, and again on Monday. As such, the kinematics may be strong
enough to support a few stronger storms these days. The CSU ML model
suggests low-end probabilities for severe weather across our area
each of these days as well. However, we are still a few days out and
details should become more clear as we approach the weekend.  For
now, maintain chance POPs through this period.

With no discernible change in airmass expected, temperatures will
remain above normal in the mid to upper 80s each day of the
extended.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
As of 150 AM Wednesday...

High pressure centered along the coast of the Carolinas will
continue to favor dry and primarily VFR conditions, and light sly to
sswly surface winds, in cntl NC. The exceptions to VFR will be a
risk of typical visibility fluctuations in radiation fog at RWI
through 11-12Z (ie. variable between LIFR and VFR) and also an area
of low stratus and fog now over sern NC, which may spread to near
and just southeast of FAY-CTZ between 10-12Z.

Outlook: A chance of afternoon-evening showers/storms will exist
Thu afternoon through the weekend.

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...MWS
LONG TERM...Luchetti
AVIATION...MWS