528
FXUS62 KGSP 150234
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
934 PM EST Thu Nov 14 2024
.SYNOPSIS...
Dry weather and a warming trend are expected Friday through Tuesday.
Rain may return to the area for Wednesday and Thursday with mild
temperatures Wednesday and near normal temperatures Thursday..
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 925 PM EST Thursday: A weak cold front currently extends from
northwest GA through the southern Appalachians, and is poised to
cross the forecast area relatively quickly tonight. NWLY 850 mb flow
will continue to ramp up in the vicinity and in the wake of the
front, with enough moisture for a few upslope showers along the
TN/NC border tonight, but temps should remain too warm for anything
but rain in light of weak cold advection. So far, the low stratus
associated with residual in-situ cold air damming has been stubborn
to scour this evening, and guidance continues to show mixed signals
on the timing and extent of any erosion overnight. It seems there
will be some break up of the cloud cover, but with the initial
post-frontal air still rather moist, any decoupling of winds could
result in at least patchy...possibly locally dense fog and low
stratus forming late this evening thru the overnight. In the
interim, a Special Weather Statement for patchy dense fog has been
issued for the Blue Ridge escarpment based upon spotter reports of
such...a fairly common occurrence during weakening CAD events. Still
think widespread dense fog is unlikely given expected light mixing.
Temps will drop only a few degrees tonight, resulting in slightly
above normal lows.
Dry air and CAA should scour out any morning stratus and fog by
late morning. Then a stratocu field will likely form within some
wrap-around moisture associated with low pressure off the Outer
Banks. A few NW flow upslope showers may linger into the aftn near
the TN border, but otherwise, Friday looks dry. Temps will rebound
nicely, with highs mainly in the mid 60s east of the mountains,
near to slightly above normal. But will be near to slightly below
normal with breezy conditions in the mountains.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 145 PM Thu: Ridging surface and aloft will build over the area
through the period. Any lingering NW flow rain showers will end by
Friday evening with dry conditions remaining in place through the
rest of the period. NW flow clouds will linger in the usual
locations across the mountains before dissipating by early Saturday.
Gusty winds continue across the area, with the strongest winds
across the mountains, Friday night and dissipate through the morning
Saturday. With rising heights and thicknesses, along with mainly
clear skies, a warming trend takes place through the period as well.
Lows will be near normal Friday and Saturday nights. Highs range
from near to 5 degrees above normal Saturday rising to 5 to 10
degrees above normal Sunday.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 215 PM Thu: A short wave tops the ridge Sunday night but the
associated cold front never makes it this far south as the ridge
rebuilds through Tuesday. The ridge axis moves eastward Wednesday
and Thursday as a deep upper low develops over the central CONUS.
The GFS moves the low into the OH Valley by Thursday with short
waves rotating around the low and across our area. The ECMWF is a
little slower and not as far east but does bring short waves into
the area by Thursday. Despite the slower upper feature movement of
the ECMWF, it is more aggressive bringing in moisture on southerly
flow ahead of the associated cold/occluded front. The GFS is slower
less aggressive, but it has some precip for Wednesday and both do
for Thursday. Both of these and the Canadian agree that any remnant
low from Sara will remain to our south, and any significantly deep
tropical moisture. The GFS and the Canadian bring in significantly
colder air for Thursday but the ECMWF holds it off until Friday.
Given the uncertainty, leaned heavily on the model blend. This means
a dry forecast until late Tuesday with chance of slight chance PoP
through Thursday. Highs will remain nearly steady 5 to 10 degrees
above normal until Thursday then the fall to near normal. Lows rise
steadily to 10 to 15 degrees above normal.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: A very messy/low-confidence aviation forecast
over the first 6-12 hours of this forecast period, as there are a
number of competing factors that render cig/visby forecast trends
rather complex. Low stratus (primarily IFR) lingers at the TAF sites
in association with weakening cold air damming this evening.
However, weak NW downslope flow is developing above the surface, and
this will increase slightly and deepen as a weak cold front passes
through the area overnight. Therefore, there`s a good chance (but
far from a certainty) that clouds will lift and scatter at some
point this evening. However, near-surface moisture will remain high,
especially in light of the soaking rainfall that occurred earlier
today. With winds expected to remain generally light, there is
strong potential that low stratus and/or fog (IFR or worse) will
fill in shortly after any clearing occurs, with the period from
07-11Z being the most likely time frame for visby restrictions.
Again how all of this will evolve is quite controversial at this
time, so have generally made liberal use of tempo/s to address the
uncertain, but possibly impactful trends. Otherwise, VFR/mostly SKC
conditions should develop at all sites by late Friday morning. Light
NNE winds this evening are expected to become NNW (and even lighter)
overnight, increasing to 5-10 kts between sunrise and early
afternoon.
Outlook: High pressure brings dry and VFR conditions back Friday
into early next week.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...RWH
NEAR TERM...ARK/JDL
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...JDL
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