780
FXUS62 KRAH 171501
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1100 AM EDT Fri May 17 2024

.SYNOPSIS...
An upper level disturbance will move across the area this afternoon
and tonight. An upper level trough will slowly move eastward through
the mid-Atlantic and Carolinas on Saturday and Sunday before moving
off the coast on Monday. High pressure will build into the area for
the first part of the work week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1100 AM Friday...

A shortwave over OK/TX will move east to the lower MS Valley through
tonight, as mid/upper ridging remains just off the southern Mid-
Atlantic coast, with central NC under the influence of WSW flow
aloft in between these two features. The latest surface analysis
shows a weak boundary/convergence axis stretching from the NW
Piedmont into the southern Coastal Plain, accompanied by a wind
shift from E/NE to W/SW. Meanwhile a quasi-stationary frontal zone
extends across the northern Gulf Coast, which is being overtaken by
an MCS across southern MS/AL/GA. This MCS will continue to move east
and off the coast by this evening, weakening as it does so. Weak
perturbations in the WSW flow aloft will help generate scattered
showers and maybe a few storms this afternoon and evening. Today`s
mid-level lapse rates look very unimpressive, which will limit
instability, as guidance shows MLCAPE in the 500-1000 J/kg range.
Furthermore, the MCS to our south may end up choking off our
moisture feed, and it is bringing widespread mid and high clouds
across the area which will continue through the day. Thus not
expecting any storms today to be widespread, and not concerned about
anything severe. POPs are slight to chance today, highest across the
north and west. As another perturbation aloft approaches and the MCS
to our south moves away, shower coverage may actually increase in
the evening and overnight hours, still highest in the north and west
where POPs are likely. However, with the nocturnal timing any
instability looks limited and elevated, and only carry a slight
chance of thunder overnight. Today`s forecast highs look on track,
still in the upper-70s to mid-80s. Lows tonight will be mild (in the
60s) with the overcast skies and precipitation.

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 345 AM Friday...

* Lots of uncertainty with the evolution of convection on Saturday
  and Saturday night after a lull on Saturday morning.
* The chance of convection increase on Saturday afternoon,
  especially across the south where there`s an increased risk of
  strong to severe storms.

The mid and upper air pattern on Saturday and Saturday night is
complicated with multiple shortwave troughs embedded in an elongated
trough axis that extends along and a little west of the Appalachian
mountains on Saturday morning. The trough axis will shift east on
Saturday with the embedded disturbances spreading across the mid-
Atlantic and Carolinas with the trough axis extending northeast to
southwest across VA and the western Carolinas by Sunday morning.
Guidance is highlighting the potential for a weak wave of low
pressure to develop across the Deep South, ahead the trough, and
move across southern NC on Saturday afternoon evening. This will
provide a focus for convection and introduce a surface boundary
separating slightly cooler and more stable air across the northern
Piedmont and northern Coastal Plain with a more humid/unstable air
mass to the south near the SC border. Further complicating the
forecast is the potential for deep convection to spread across the
Deep south on Saturday which may complicate and disrupt the
downstream environment. The southwesterly flow across the Carolinas
strengthens ahead of the approaching trough on Saturday afternoon
and evening with 0-6km bulk shear values of 30-40kts possible across
southeast areas. Accordingly, SPC has introduced a level 2 slight
risk across southern/southeastern NC which just skims into our
southeastern Counties. The primary severe weather risk will be
damaging winds but given the location of the frontal zone and
enhanced shear near a surface wave, will need to closely monitor the
location of the low and front which could increase the tornado
potential. With a decent amount of forcing for ascent in the area
thanks to the upper trough, scattered convection may continue well
into Saturday night.

Highs on Saturday will range from the lower 70s near the VA border
to the lower 80s across the south. Expect a good deal of cloudiness,
but if more intervals of sunshine occur, highs could jump into the
mid 80s across the south which would enhance instability and add to
the threat of strong to severe storms. Lows on Saturday night will
range from around 58 across the north to 64 across the south. -Blaes

&&


.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 356 AM FRIDAY...

Upper level trough axis will move over the region Sunday bringing
another day of increased upper level moisture to the region. Ridging
will push in from the west by late Monday resulting in drier
conditions for Tuesday and most of Wednesday. At the surface, a low
pressure system will continue to push offshore as high pressure
builds into the region by late Monday. For now, have likely PoPs for
Sunday across the region with Slight chance PoPs for the first half
of Monday. Models are showing some instability across the region
especially over the Piedmont. SPC has introduced D3 outlook with the
western half of our CWA in General Thunderstorms for Sunday. Will
keep an eye on the instability and moisture values as storms on
Saturday could deplete our chance for severe storms developing on
Sunday.  As things progress, and models begin to lean towards a
consensus, Monday could be completely dry across the region. Expect
a trend of lowering PoPs on Monday as time gets closer. As high
pressure builds into the region from the north Monday into Tuesday,
temperatures will be slightly below normal with highs ranging from
mid 70s to around 80. As dry conditions persist on Wednesday,
temperatures continue to warm up a tad with highs ranging from low
80s NW to upper 80s SE. An approaching cold front from the west will
result in increased chance of showers and storms Thursday especially
in the afternoon. Highs will be in the mid/upper 80s.

&&

.AVIATION /11Z FRIDAY THROUGH TUESDAY/...
As of 615 AM Thursday...

Generally fair weather with VFR conditions is expected across much
central NC this morning with deteriorating aviation conditions
during the afternoon and especially evening hours. A couple
lingering and persistent small showers/sprinkles were moving across
the northeast Piedmont and northern northern Coastal Plain. These
showers should diminish over the next hour or two but could produce
a brief VSBY reduction near KRWI. Also, some patchy fog has
developed in a few spots in the Coastal Plain and eastern Piedmont.
The fog should also dissipate over the next hour or two.

VFR conditions with increasing mid and high clouds are expected this
morning into this afternoon. An approaching upper level disturbance
will spread scattered showers and a few thunderstorms northeast
across the area from the west and southwest during the afternoon and
tonight. Precipitation coverage will increase with MVFR CIGS and
some VSBY restrictions becoming increasingly likely from west to
east tonight with some IFR CIGS possible across the western Piedmont
late tonight.

Looking beyond 12Z Saturday, an unsettled weather pattern is
expected with period of showers and some thunderstorms over the
weekend. Coverage will likely be the greatest tonight into early
Saturday and again late Saturday afternoon and evening with a
lingering risk on Sunday. Areas of sub VFR conditions are likely
during this period. Improving conditions and mainly VFR conditions
are expected Monday into Tuesday. -Blaes

&&

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

&&

$$

SYNOPSIS...Blaes
NEAR TERM...Danco
SHORT TERM...Blaes
LONG TERM...CA
AVIATION...Blaes