394
FXUS62 KRAH 091901
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
301 PM EDT Thu May 9 2024

.SYNOPSIS...
A series of upper level disturbances will interact with an
unseasonably moist airmass over North Carolina through Friday,
bringing unsettled weather. A cold front will move across the region
late Friday, ushering in drier and less humid air for the weekend.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 250 PM Thursday...

The risk of any storms, much less severe storms, is very much in
doubt for the rest of today, given a considerable amount of SBCINH
resulting from the stabilization effects of earlier rain and
outflows along with low-mid level W and WNW flow components. While
the overcast low deck over much of the Piedmont earlier today has
mixed out and lifted, a few low clouds still linger across the area,
topped by anvil cirrus as the most robust and organized convection
continues to propagate ESE over S GA and S/E SC. However, the
existing CINH has shown a waning trend in recent hours with the
increasing filtered sunshine this afternoon, and the deep layer bulk
shear has rebounded to over 35-40 kts as well, leaving us with
marginal CAPE and sufficient mid level flow to support isolated
storms. While the most prominent mid level perturbation will be
pushing E of the area in the next few hours, we`ll still need to
watch our northern sections for a few isolated showers or storms as
CINH there is expected to vanish briefly through early evening with
1000-1500 J/kg SBCAPE, and we`re already seeing some agitated cu
over and north of the Triad. Other than this isolated convection
threat over the next few hours, we should see dry weather from this
evening through the overnight hours as PW aob 1" spreads in from the
west, with diminishing CAPE and flow becoming deeply W to WNW aloft.
Will trend remaining low pops down and out by sundown, with skies
fair to partly cloudy overnight. After rather seasonable readings
today peaking in the upper 70s to lower 80s, expect lows tonight in
the 60s. -GIH

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
As of 300 PM Thursday...

A rather vigorous shortwave trough extending from the eastern
Great Lakes southwest to the western OH Valley on Friday morning
will quickly advance east and swing across central NC during
the afternoon and early evening. A belt of strong mid- level
winds of 60+ kts at 500 mb ahead of the trough will lift across
VA and NC during the afternoon. At the surface, a cold front
will extend from near KORF southwest to near KGSO to west of
KCLT during the early afternoon with the front advancing east
and southeast as it reaches the coast by midnight.

NWP guidance had a notable shift last night slowing the eastward
progress of the front and keeping much of central NC in the
relatively moist and somewhat unstable area ahead of the front.
This trend has slowed but the potential for deeper convection
and some severe weather has increased a bit across the
Sandhills and Coastal Plain for Friday. Higher res guidance
suggests the atmosphere may become weakly unstable for a short
period in the eastern Sandhills and southern Coastal Plain in a
narrow tongue just ahead of the cold front. Modest mid level
lapse rates, the potential for some capping, and perhaps an
initial round of light precipitation early in the afternoon just
ahead of the most favorable time period could hinder convective
development and intensification. If deep convection can
develop, it could tap into 0-6km bulk shear values of 35 to 50
kts supporting storm organization and a couple of supercells.
Hodographs are long and straight which adds additional concern
for large hail. SPC has not surprisingly expanded the marginal
risk north and a little west as the guidance has brought the
threat area northwestward. Feel the coverage of stronger/deeper
storms will still be limited and is more favored to the south
and east of the RAH CWA, but would not be surprised if one or
two stronger cells develop and move across the Sandhills and
southern Coastal Plain with an increased severe weather
potential. The window for convection will shut down around
dinner time with dry weather expected on Friday night. Further
west across the western and northwest Piedmont, the chances for
a shower and perhaps a thunderstorm are much more limited and
deep convection is not expected.

Highs on Friday will range from the upper 70s in the Triad and near
the VA border to the lower 80s in most other locations. Noticeably
drier air will spread into the region on Friday night with dewpoints
falling into the lower 50s with some upper 40s possible across the
northern and western Piedmont. Lows will range in the lower top mid
50s. -Blaes

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 211 PM Thursday...

In the wake of the departing upper trough Friday night, NW flow will
take hold across the area on Saturday. This will allow for continued
dry advection and noticeably cooler temperatures, as highs will only
reach the low to mid 70s across the area. A weak shortwave trough is
expected to rotate through southern VA/northern NC late in the day
Saturday which will bring about a brief increase in cloud cover and
perhaps a stray shower or two, but that`s about it. Model guidance
has been consistent in showing limited precip across the area thanks
in large part to a dry BL featuring dewpoints in the 40s. PoPs in
the 15-20 percent range across the northern tier of counties still
seems appropriate based on today`s ensemble guidance (but even this
may be overdone a bit). Any showers that do manage to make it into
the forecast area should dissipate quickly after sunset with dry
weather expected Saturday night. Lows will range from the upper 40s
to lower 50s.

Sunday will see mostly sunny skies and continued cool/dry conditions
as weak cyclonic flow aloft gradually flattens out as a ridge builds
to our west. Look for another day of below normal highs (mid 70s)
with low temps once again falling into the upper 40s to low 50s. No
concerns about precip as all forcing will be displaced well to the
northeast of the area.

The overall pattern next week looks to be active once again. An
upper low over the Central Plains will slowly migrate eastward on
Monday, inducing downstream ridging across the Southeast states and
ultimately resulting in a fairly quiet day across NC with near
normal temps and dry weather. This will ultimately change though as
the low migrates into the Ohio Valley on Tuesday. Broad/weak forcing
for ascent will overspread much of the Southeast on Tuesday
coincident with an increase in moisture transport (PW`s will be back
above 1.5 inches by Tuesday morning). Showers are expected across
the area on Tuesday although just how quickly they arrive is still a
little unclear (daybreak Tuesday vs afternoon). Regardless, Tuesday
is likely to see widespread cloud cover and rainfall with cooler
temps as a result. While thunder seems unlikely at this stage
(instability displaced well to the south), precip chances will
likely be maximized during the daytime hours with lesser chances
Tuesday night into Wednesday morning.

Wednesday will see continued precip chances as the upper low opens
up and moves through the central Mid Atlantic. As PW`s will remain
elevated and the area will be well within the warm sector,
instability will be much more readily available on Wednesday ahead
of the trough and shower/thunderstorm chances should be a bit higher
(60-70 percent range) especially during the afternoon hours. It`s
also likely that we`ll have at least some clearing to start the day
and temps should make it up into the low/mid 80s prior to the
arrival of the trough.

Thursday should start off dry in the wake of the departing low, but
this looks to be short lived. While shortwave ridging aloft will
build in early in the day, this will quickly turn southwesterly as
yet another longwave trough sets up across the Central Plains and
kicks out a series of embedded shortwaves across the Southeast
states through the end of the week. This would favor diurnally
driven showers and thunderstorms Thursday afternoon/evening,
followed by drying overnight.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
As of 140 PM Thursday...

The coverage of showers and storms has trended much lower than what
we expected earlier, as the stronger storms have held south of the
NC/SC border, leaving central NC with just isolated showers at most.
Earlier IFR to MVFR cigs over the Piedmont terminals (INT/GSO/RDU)
has lifted and mixed to scattered, and we should see scattered 2-
3kft clouds plus a mix of scattered higher base cu with patchy mid
and high level clouds for the next 24 hours. Another round of
scattered showers and storms is expected across the S and SE Fri,
but this risk will be limited to near FAY and most likely after the
end of the TAF valid period. Surface winds will be around 10 kts or
less from the SW through tonight and from the W Fri, with a few
gusts to 15-20 kts possible this afternoon.

Looking beyond 18z Fri, S and E sections including FAY may see a
storm pass nearby during the mid to late afternoon Fri. Otherwise,
VFR conditions are expected through at least Mon, with a cooler and
less humid air mass moving in starting late Fri. Rain and isolated
storms are expected to move in Tue morning, with an increasing
chance of sub-VFR conditions. -GIH

&&

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

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Hartfield
SHORT TERM...Blaes
LONG TERM...DL
AVIATION...Hartfield