Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 141050
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
650 AM EDT Thu Mar 14 2024

.SYNOPSIS...
Daytime temperatures will be warm and springlike through the
weekend. Showers will occur in many areas Friday ahead of a cold
front, possibly including some thunderstorms. Rain chances taper
off by Saturday morning, and that is likely to be the last rainfall
for several days. Expect cool temperatures Monday and Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 6:35 AM EDT Thursday: Other than a couple of thin patches
of cirrus moving over the area, we remain clear this morning with
light to calm winds. Low temps appear to have just about bottomed-
out across the area with most locations about 4 to 8 degrees above
climatology.

Otherwise, upper ridging will continue to build over our area today
and then flatten towards the end of the period early Friday. At the
sfc, high pressure will remain nearly stationary and centered off
the SE Coast thru the end of the period. SWLY low-level flow becomes
more entrenched with increasing thickness values allowing temps to
climb higher today. Highs are expected to top-out about 15 degrees
above normal, and reach 80 degrees across much of the lower terrain.
Dewpts should also trend warmer in response to the SWLY flow and less
overall mixing this aftn. Nonetheless, there`s a good chance that
minimum RH values will at least approach critical values for a few
hrs this aftn/evening. Any showers and/or thunderstorms associated
with the approaching frontal boundary will likely not reach our fcst
area until the very end of the near-term period. As such, I do have
some slight to solid chance PoPs for roughly the western third of our
CWA for the last few hrs of the period.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 200 AM Thu: HRW-FV3 and ARW, along with the HRRR, are in
agreement with global model consensus in depicting semi-organized
convection to reach the SW NC mountains by 12z Friday, leaving
behind abundant debris cloud shield or possibly (for the SW CWA) a
cold pool, either of which would inhibit convective development
later in the day. However, dynamic lift increases by afternoon due
to jet streak skirting by to the north, and if/where such factors do
not transpire, it is plausible that convection could fire.  The 12km
NAM now appears to have trended more like the other solutions but
still doesn`t bring activity in during the morning, thus giving most
of the area a chance to destabilize diurnally. This type of solution
is backed up by the 3km NAM as well. Even then, coming out of three
dry ridge days, PWATs will start off low and a subsidence inversion
may persist particularly in our east. The dynamic support could
allow any remaining elevated CAPE to be realized, and most models
respond with at least some evening QPF near our southeastern border.
GFS soundings show chaotic low-level wind profiles on account of the
convective debris, but the NAM does develop long if not nearly
unidirectional hodographs.  Its profiles do basically saturate, so
CAPE still remains somewhat muted, but the respectable shear
parameters and possibility of upscale organization led SPC to expand
Day 2 marginal risk over a large portion of the CWA. Given current
CAM output and questionable instability, that may be a bit
generously sized, but agree there could be a small severe threat
with cells that form in the late afternoon, most likely in our far
south/southeast.

Winds will turn NW by Friday night and some NW flow precip could be
generated, perhaps enhanced by elevated instability before CAA really
sets in at lower levels. Sfc front should reach the mountains by
mid-morning Saturday. A few sprinkles could continue after 12z in the
lower Piedmont if any trailing upper vort blobs drift across.  How
much further the weak front can ooze into the area is questionable,
with downslope warming across the CWA and likely a fair amount of
sunshine, the main cloud cover looking to be diurnal cu in shallow
convective layer under inversion. Aside from the mountains near the
TN border, Saturday potentially will be nearly as warm, perhaps even
warmer than Friday, given potential for cloud cover to suppress highs
Friday.  At any rate, still above normal for highs, and mostly in the
70s in lower elevations. Front should sag further south Saturday
night, keeping PoPs unmentionably low and allowing cooler temps than
the past two mornings, but still probably remaining above normal.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 300 AM Thu:  Shortwave embedded in longer trough over eastern
Canada will rotate south across the Ohio Valley on Sunday. Although
we will have already experienced drying behind the previous front,
true airmass change doesn`t look to have occurred; downsloping and at
least some sunshine should permit highs only a category or so cooler
than Saturday. Sharper height falls occur Sunday night with the
shortwave, driving a reinforcing cold front through the area.  Height
falls continue thru Monday night. A few ensemble members and the
operational ECMWF still show some precip developing in our south
along the old front late Sunday, but most sources keep us dry aside
from a very quick shot of NW flow precip near the front. That precip
is expected to be all rain, and the remainder of the period should be
dry. Temps trend a little below normal for highs Monday, and look to
be as much as 10 below normal Monday night and Tuesday.  Frost/freeze
headlines would appear likely if we activate the program. The front
also will induce gusty winds Monday, especially over the mountains.
Critically low RH potentially will develop with diurnal mixing; on
top of the breezy or gusty conditions, elevated wildfire danger may
develop particularly if rain totals remain as low as expected this
weekend. Temps should rebound to near normal Wednesday.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Expect VFR conditions to continue thru
the 12z taf period with mostly clear skies thru this evening.
High clouds will increase from the west tonight as a cold front
approaches the area. Precip associated with the fropa may reach
KCLT just before 18z on Friday, so I included a PROB30 for SHRA
for the last few hours of the fcst and some low-end wind gusts
as well. Otherwise, I`m not expecting any showers and/or tstorms
to impact the other terminals until after 12z Friday. Winds should
remain light to calm thru most of the morning. They will pick back
up from S to SW this afternoon and remain S to SW thru the evening.
There`s a decent chance that KAVL will see some sporadic low-end
gusts this aftn as stronger winds aloft mix down over the area.
So, I kept a TEMPO for gusts from 18 to 22z for the terminal.

Outlook: A moist frontal system will bring rain and associated re-
strictions back to the area as early as Friday morning. Restrictions
could linger into Saturday. Another front will cross the area on
Sunday with more precipitation and restrictions possible, along
with gusty winds.

&&

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

&&

$$

SYNOPSIS...Wimberley
NEAR TERM...JPT
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...JPT


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