Matthews, North Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

256
FXUS62 KGSP 152151
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
551 PM EDT Thu May 15 2025

.SYNOPSIS...
Warm high pressure settles over our area through Friday. A cold
front will approach from the northwest and may bring a line of
showers and storms into the North Carolina mountains late Friday
night into early Saturday. The front will become stationary over our
region into early next week as the next storm system organizes over
the plains states.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 5:45 PM EDT Thursday: We remain shower free across our CWA
early this evening, despite a Severe Thunderstorm Watch now in
place just to our NE. An upper ridge will continue to build over
the region thru the evening. Rising heights and a notable capping
inversion will keep convection at bay with the exception of maybe
a few stray showers over the northern mtns. Benign weather should
continue into tonight with increasing high clouds and mild overnight
low temperatures with a couple fast moving showers potentially tran-
secting the mtns. The fcst becomes more complex tomorrow as the upper
ridge axis shifts offshore and subtle height falls return as a potent
wave slowly slides across the Mississippi Valley. This will allow for
a period of quasi-zonal westerly flow to become established into the
Southern Appalachians downstream of the base of the mean trof. A rather
pronounced Elevated Mixed Layer (EML) will get advected into the region,
which should largely keep most of the area capped. Fcst confidence
decreases in regards to whether just enough forcing will be present
to overcome the cap and either initiate deep convection across the
NC mtns/foothills or maintain upstream convective complexes into the
area.

The 12z suite of CAM guidance depicts a wide range of solutions
ranging from too capped with no convection to the potential for
vigorous deep convection across northern portions of the forecast
area. While confidence is lower than usual, the most likely location
for storms, should they occur, would generally be along and north of
the I-40 corridor where the cap will be somewhat weaker. While
conditional, should any storms impact the area the ceiling is very
high regarding severe potential. The parameter space depicted in
forecast soundings is definitely on the higher end for the Carolinas.
The capping inversion/EML will support moderate to high instability
with surface-based CAPE on the order of 3500-4000 J/kg along with
steep mid-level lapse rates of 7-7.5 C/km. Deep-layer wind vertical
wind shear of 50 to 60 kts with straight hodographs will support
clusters of splitting supercells within a robust thermodynamic
environment. Thus, any storms that are able to develop (if at all)
would easily become severe with the potential for very large hail
and intense downdrafts. Once again, this is a very conditional svr
threat and it`s definitely possible that no storms impact the area
owing to the strong cap. But given the previously mentioned parameter
space, very close attention will need to be paid to the potential for
even just one or two storms.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
As of 100 PM Thursday, key messages:

1. Confidence has increased for organized convection to move from
KY/TN into the southern Appalachians late Friday night into early
Saturday morning, translating to a nonzero threat of severe weather
at that time.

2. Per the above, confidence is slightly higher for a cold pool to
overspread the area and suppress convection Saturday. The cold pool
also would bring lower humidity to much of the area Saturday,
although temperatures will remain above normal.

As a mature low pressure system crosses the upper Mississippi Valley
Friday night and Saturday morning, a shortwave will cross the lower
Ohio Valley. A convergence axis, arguably a dryline, will move into a
strongly unstable and sheared environment invof western KY/TN Friday
evening. It looks likely at least one linear MCS--maybe two depending
on how well the forcing mechanisms overlap--will take shape and
progress to the western slopes of the Appalachians overnight or early
Saturday morning. That suggests a widespread threat of damaging wind
across the lower OH and TN valleys with potential for large hail as
well. The track of the first MCS shown on some runs has generally
been such that it misses us to the north. However, the dryline
activity continues to be depicted as pushing across the TN/NC border
between 06-12z Sat, with the earlier timing more likely given the
potential for the cold pool to be driving development. We will be
coming off a remarkably unstable afternoon, but MUCAPE still is
likely to be greater than 1000 J/kg over our mountain zones. Thus it
is plausible the line will at least make it partway into the CWA
before weakening enough for the severe weather threat to diminish.
SPC has included our mountains in the Day 2 Marginal Risk area.

Many aspects of the forecast for Saturday remain contingent on how the
convection plays out during the early morning, but with that looking
more likely than it had been, confidence is not as low as before. PoPs
will be retained over a good portion of the area Saturday morning as
the convection decays along the edge of the cold pool and stratiform
rain fizzles. Most models show little to no QPF response east of the
mountains Saturday, The NAM shows some scattered response seemingly
progressing with the cold pool thru the Piedmont late morning to
afternoon, but that would be somewhat atypical; usually we experience
a complete lull for a time with diurnally forced redevelopment late in
the day, if the cold pool doesn`t completely work us over. PoPs are
being shown to taper from NW to SE during early to mid aftn. The cold
pool is associated with an appreciable drop in dewpoints following the
same trend; temperatures should be a few degrees cooler than Friday
although potentially will be offset by downsloping. Maxes remain at
least a few degrees above normal.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
As of 215 PM Thu: The actual cold front associated with the Great
Lakes system should push into the CWA Saturday night. Still cooler
conditions and lower dewpoints are forecast Sunday in the wake of the
front. Ridge will be building in the lower MS Valley by that time,
however, and the cold front stalls and gets reactivated to our west.
Stable post-frontal airmass is most likely to persist over the NE
half of the CWA.  Seasonable CAPE of at least a few hundred joules
will redevelop in the other half of the area, nearest the front; T/Td
may actually be a little warmer in the Savannah Valley compared to
Saturday.  Furthermore, NW flow into the Appalachians will also
provide weak forcing along the TN border so small PoPs extend along
there.

The ridge to our west and NW-SE oriented warm front may put us in the
path of another MCS if one develops Sunday night or Monday. The
deterministic global models, plus a number of members of the NAEFS
and ECMWF ensembles, show precip developing variously in AR, MO, KY,
TN Sunday and/or Monday and carry it into our area as an apparent MCV
rounds the ridge. Per the pattern, that would appear possible Monday
night or Tuesday as well, although there appears less support for
that idea from the models. The MCS possibility notwithstanding,
spotty diurnal convection may develop over the mountains Sunday, with
climatological 20-40% chances Monday as dry air aloft should be less
of a limiting factor that day. 0-6km shear will be supportive of at
least an isolated severe threat if storms do develop either day.

Early in the week, cyclogenesis is probable in the central CONUS as
upper low moves across the Rockies.  By late Tuesday we may enter the
warm sector of that system if the front is able to shift far enough
north. Shortwave/cold fropa potentially will occur Wednesday. Precip
chances are highest those days but confidence on the extent of any
severe threats is limited by spread in timing and the position of the
front.

&&

.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
At KCLT and elsewhere: An afternoon cumulus field has developed
across the area with cloud bases currently in the MVFR range. So
far, coverage has mainly been scattered but a couple instances of
broken coverage cannot be ruled out at any given terminal.
Otherwise, high clouds will increase in coverage through the period
with a few wind gusts possible this afternoon. A few showers may
move across the area early Friday morning, but both confidence and
coverage is too low to warrant mention at this point.

Outlook: A couple scattered thunderstorms cannot be ruled out Friday
afternoon and a decaying line of storms is expected to move through
at least the mountains early Saturday morning. In addition, fog and
low stratus will be possible each morning, primarily in the mountain
valleys and in areas that receive appreciable precip the previous
day.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$

SYNOPSIS...DEO
NEAR TERM...JPT/TW
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...JPT/TW