Clemson, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

588
FXUS62 KGSP 152340
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
740 PM EDT Fri May 15 2026

.WHAT HAS CHANGED...
The aviation forecast was updated to reflect the recent 00z TAF
issuance.

&&

.KEY MESSAGES...
1. A summer-like pattern will gradually evolve through early
next week, with hot/above-normal temperatures and steadily
increasing moisture resulting in slowly increasing chances for
diurnal convection.
2. Mainly diurnal showers and thunderstorms are expected Tuesday
and Wednesday before a cold front brings better rain chances
Thursday into Friday. Well above normal temperatures stick around
ahead of the front before cooler and near normal temperatures
return behind the front on Friday.

&&

.DISCUSSION...
Key message 1: A summer-like pattern will gradually evolve through
early next week, with hot/above-normal temperatures and steadily
increasing moisture resulting in slowly increasing chances for
diurnal convection.

Heights will rise along the East Coast and across the western
Atlantic through the weekend, supporting establishment of a
summer-like Bermuda high pattern by the end of the weekend. As a
result, after another relatively cool night under strong radiational
cooling conditions tonight, temperatures will warm quite quickly
over the weekend, with Saturday highs forecast at around 5 degrees
above climo...further warming to almost 10 degrees above normal
Sunday/Monday. Low level moisture will also increase, albeit slower
than the heat. Nevertheless, enough moisture may be in place
by Sunday afternoon to support development of isolated, diurnal
deep convection in western areas, primarily across the mountains,
with another round of isolated activity possible Monday afternoon.

Forecast soundings suggest a remnant elevated mixed layer will be
in place across the Southeast...as mid-level lapse rates of 7.5-8
C/km are forecast during the Sunday/Monday time frame. Therefore,
low level moisture will not need to be too rich to yield significant
instability, and around 1500 J/kg of sbCAPE appears likely both
afternoons. Upper flow and therefore shear parameters are forecast
to be rather weak, but a few strong pulse-type updrafts are possible
each afternoon.


Key message 2: Mainly diurnal showers and thunderstorms are expected
Tuesday and Wednesday before a cold front brings better rain chances
Thursday into Friday. Well above normal temperatures stick around
ahead of the front before cooler and near normal temperatures return
behind the front on Friday.

Upper ridging remains centered offshore the Southeast coast while
gradually breaking down as an upper trough approaches out of the
west Tuesday through Thursday. The trough should track over the
forecast area Thursday, dragging a surface cold front across the
region with it, before pushing east Friday. Mainly diurnal
convection is expected ahead of the front Tuesday into Wednesday
before better rain chances return ahead of the front on Thursday.
Shower and thunderstorm activity appears to remain confined to the
mountains on Tuesday, possibly spreading east of the mountains on
Wednesday as the front inches closer. Global models show the
potential for convection to linger through Friday but this will
depend on the speed of the cold front. For now, NBM PoPs look
appropriate through the period. Unfortunately, with only light
rainfall amounts expected ahead of and along the front, not
expecting much if any relief from the ongoing drought. Well above
normal temperatures will linger across the region ahead of the front
before cooler and near normal temperatures return behind the front
on Friday.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: VFR still expected to prevail through the
new TAF period as a dry air mass stays in place.  SKC continues
through tonight at most sites, with increasing FEW/SCT cirrus
expected to develop everywhere on Saturday morning.  Light and
variable winds overnight will return become steady and SW at 6-9kts
by late Saturday morning and continue into the afternoon.

Outlook: VFR conditions expected to persist through the first
half of next week, except in mountain valleys, where as moisture
increases, the potential for morning fog/low stratus will increase
each night.  Isolated diurnal convection is possible early in the
week, primarily across the mountains.  Another active system may
return by Wednesday.

&&

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

&&

$$

AR/JDL/MPR