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515
FXUS62 KGSP 050620
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
220 AM EDT Sun May 5 2024

.SYNOPSIS...
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A general summertime pattern sets up today through Wednesday,
keeping scattered thunderstorm chances around each afternoon. A
strong cold front will approach out of the west on Thursday before
tracking across the western Carolinas on Friday, leading to better
coverage of thunderstorms towards the end of the workweek. Highs
will remain above normal through the workweek but will climb well
above normal Tuesday through Thursday.
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&&

.NEAR TERM /THROUGH TODAY/...
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As of 215 am EDT Sunday: Numerous-to-widespread showers continue
across the eastern half of the CWA early this morning in conjunction
with a passing upper shortwave, which is now located over the
western half of the CWA.  Still expect coverage to gradually
diminish and move east through the overnight as the shortwave exits
the area. Precipitable water values remain very high within deep
moisture plume, so locally heavy rainfall remains possible despite
weak instability. However, the potential for excessive rainfall is
quite low. Min temps will be around 10 degrees above normal.  At
least patchy morning fog will likely be an issue, at least for
locations that have received appreciable rainfall this evening.

Scattered convection, numerous across the mountains, will return
this afternoon as instability redevelops. An isolated severe storm
will be possible as mid level dry air returns and DCAPE values
increase with heating. The mid level dry air will decrease PW values
limiting the flood threat. That said, isolated heavy rainfall will
be possible. Highs should end up a few degrees above normal.
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&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
As of 145 PM EDT Saturday: Short term period will be generally
dominated by building mid-level ridge, but with a shortwave embedded
in the pattern lifting up from the MS Valley and traversing the area
through the period. Meanwhile a strong system will be gearing up
over the northern Rockies and push off into the northern Plains to
impact us into the extended. We`ll see a warming trend Monday into
Tuesday afternoon as the ridge builds aloft and surface high off the
New England coast slides south toward Bermuda, with moist southerly
flow rounding the base into the Southeast. A summerlike pattern will
set up as moisture and instability increase Monday, but very little
deep-layer shear to work with. Categorical pops pretty much area-
wide but highest in the mountains.

Shortwave pushes east on Tuesday and ridging builds in with stronger
SW flow aloft. NAM is a little faster with bringing some deep-layer
shear in ahead of the next system. Pops are a little lower on
Wednesday as moisture is not quite so widespread, but with warmer
temperatures (mid 80s in the Piedmont as opposed to lower 80s on
Tuesday) instability is a little higher as well, 1500-2000 J/kg so
could be looking at isolated strong to potentially severe with some
wet microburst potential.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 215 PM EDT Saturday: Active period for the extended as the
upper system moving across the northern plains drags a front through
the country Wednesday into Thursday. Should see continued low-level
WAA Wednesday with temperatures across the Piedmont climbing again
into the upper 80s, even flirting with 90 in the Charlotte Metro
area. Best pops will be in the mountains closer to the deep-layer
shear and moisture, but cannot rule out isolated activity elsewhere.
With the increased heating and better upper dynamics approaching the
area, SBCAPEs will climb again from Tuesday, now reaching 2000-2500
J/kg with over 30kt of deep-layer shear across the area, so where we
can get a storm going certainly can`t rule out isolated severe
activity with a very summer-like microburst feel, though there will
at least be movement in the storms so expect some organization.

Things get a little more interesting Thursday as the cold front will
begin to push into the area. Although the front will be stretched
out somewhat rather than just blasting through, strong DPVA combined
with the upper jet provide plenty of synoptic lift. It`s a little
far out for details but at least the GFS is trying to show a decent
850mb jet as well midday Thursday. Timing of the instability surge
and juxtaposition with strongest deep-layer shear might be critical,
but somewhere in our forecast area we are currently progged to have
2000-2500 J/kg lined up with >50kt deep layer shear, which is
impressive. Forecast trends will need to be monitored. SPC`s Day 6
outlook is vague on the area but mentions the possibility of needing
to introduce an one or more 15% areas for Thursday when guidance
comes into better agreement.

Upper shortwave actually begins to approach later on Friday so pops
remain in the forecast until then. However, depending on the actual
timing of the front itself, cannot rule out an insitu increase in
instability right along the front where there would be a local
enhancement in deep layer shear, but uncertainty is quite high on
when the front would push through. Pops remain high as in line with
the blends but timing will likely change in subsequent forecasts.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
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At KCLT and elsewhere: Showers remain widespread across much of the
NC foothills and Piedmont (i.e., near KHKY and KCLT) early this
morning, but will continue to slowly push east through the morning.
Occasional periods of brief heavy rain will be possible at the above
sites, and can`t completely rule out a rumble of thunder. Otherwise,
low cigs will fill in across the Terminal Forecast Area through
daybreak, with cigs in the 002-005 range expected at all sites.
Visby of 2-4SM is expected in SHRA or BR at all sites as well. Visby
of 1SM...possibly even less is expected at KAND and KGMU, where
mid-level drying is expected atop very moist lower levels. Can`t
rule out visby <2SM at other sites, but confidence is low.
Otherwise, cigs are expected to begin improving late in the morning,
with VFR conditions expected at all sites during the afternoon.
While widespread SHRA are expected to move east of the area during
the morning, scattered convection is expected to develop across the
mountains during early/mid afternoon and move E/SE. Prob30s for
afternoon/early evening TSRA are warranted at all sites.

Outlook: Enhanced moisture will combine with a weak/stalled front
through the middle of next week, resulting in a period of
active/mainly diurnal convective weather each day. There will also
be the potential for restrictions associated with widespread fog
and/or low clouds each morning.
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&&

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

&&

$$

SYNOPSIS...AR
NEAR TERM...JDL/MPR/RWH
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...JDL