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FXUS62 KGSP 210205
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1005 PM EDT Mon May 20 2019

.SYNOPSIS...
A weak cold front will pass east of the area this evening.
Following the front, a strong area of high pressure will build and
settle over the region resulting in well-above normal temperatures
and limited rainfall for the rest of this week, with near-record
temperatures expected for Memorial Day weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 1005 PM: Can't rule out a lone shower over the piedmont or
eastern Upstate the rest of the evening. However, basically a dry
forecast is expected as a cold front moves east of the area.

The front will cross the area early this evening with winds turning
around the dial from SW to N overnight. Winds will shift ne/ly thru
Tue morning...so a very low threat exists for dense fog or low stcu
thru daybreak, except for mountain valley fog. Lowering td/s will
make for a drier feeling day across the nrn zones Tue...however td/s
remain in the 60s south. No good temp change with the frontal
passage either...so will expect mins to remain abv normal by 3-5
degrees F and max temps ranging from 5 degrees abv normal north and
10 degrees abv normal south.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 300 PM EDT Monday: Tuesday night, a warm front is expected
to be positioned SE to NW across Georgia just south and west of
our coverage area associated with a deep, occluded low pressure
system over the central Great Plains. As the low continues to
lift NNE into the upper Midwest, the warm front will lift quickly
NE to the west of the Appalachians, but guidance is suggesting the
surface high pressure propagating SE in response to this low will
wedge against the Blue Ridge overnight Tuesday into Wednesday.
All available guidance is developing a very weak area of surface
low pressure early Wednesday morning near Augusta along the
developing wedge front and underneath the building upper-level
ridge as the parent surface high approaches the coast. As we
typically experience in the warm season given this pattern, we
are expecting the low-level wedge to counteract the effects of
the building heat ridge aloft and give much of our area a brief
"respite" before a prolonged heat wave settles in beginning on
Thursday. Of course, this translates to high temperatures being
"only" 2-4 degrees above normal for Wednesday with highs in the
upper-70s to mid-80s within the wedge.

Northeasterly to southeasterly low-level (from the surface to 900mb)
flow will advect Atlantic moisture and may result in a stratocumulus
deck across the western Piedmont and Foothills on Wednesday which
would help to suppress daytime heating. The flow will support
isolated to widely scattered shower development, especially over
the Foothills and Blue Ridge. However, along the periphery of the
wedge boundary, generally across the Georgia Piedmont extending
NE towards the southern Charlotte metro where differential heating
could play a factor, there is a chance for some convection if the
bullish NAM is correct on the strength of the wedge boundary, the
instability (SBCAPE > 1200 j/kg), and moisture flux (PWs > 1.50").
Given the meager lapse-rates, 650-700mb weak cap, and the difficulty
forecasting wedge patterns in general, the margin for error in this
environment is high. The official forecast expects some isolated
to widely scattered shower development along the front and has
adjusted PoPs accordingly. Regardless, the wedge is short-lived
as the parent high remains transient with all guidance agreeing
the area will be entirely within the warm sector no later than
Wednesday night.

The heat is on starting Thursday with a 594-596dm 500mb-level ridge
centered over Georgia. High temperatures will rebound quickly into
the upper 80s to near 90 east of the mountains as we begin to feel
the effects of the subsidence aloft and increasing thicknesses. A
mid-level shortwave and attendant weak cool front/surface trough
will be propagating along the NE extent of the heat ridge over the
Mid-Atlantic and the GFS is the most aggressive about developing
showers and a few thunderstorms over the mountains and Foothills.
The official forecast maintains low-end chance pops in these areas,
but again, any convection will have to overcome a modest 650-700mb
cap and lapse-rates will remain poor given the upper-level pattern.
For most of us, it will remain dry.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 245 PM EDT Monday: With upper-level ridging dominating the
weather pattern across the southern U.S., the main story for the
extended forecast will be the heat, which is expected to persist
through Memorial Day. High and low temperatures will generally
run 10-15 degrees above normal through the holiday weekend. As a
result, both high max and high min temperature records will be
challenged at all three climate sites (AVL, GSP, and CLT) this
weekend and these records are included in the Climate section
of the discussion. The only good news here is that dewpoints,
while uncomfortable in the mid-60s, will not be oppressive and heat
indicies are not yet a concern. This is due to the fact that our
mean low-level flow will be westerly and moisture flux from the
Gulf of Mexico will be limited. Of course, with max temperatures
in the mid-90s east of the mountains, the heat will be more than
enough to handle without the humidity.

Over the weekend, the GFS and the ECMWF are at odds about the
predominant center location of the heat ridge, with the GFS
shifting the ridge center S towards the northeastern Gulf coast
while the ECMWF does not weaken and shift the ridge center until
early next week. As a result, the GFS is a bit more bullish about
isolated to widely scattered shower and thunderstorm development
each day initiating over the mountains and advecting east in
the mean flow into the Foothills as it places our area closer to
the shortwave train over the Ohio Valley and Mid-Atlantic and,
due to the marginally lower heights and thicknesses, gives the
region a bit better support for development. Either way, expect
very little in the way of precipitation and the forecast reflects
the largely dry expectations.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Isolated showers ahead of a cold front will
move east of the area early this evening. Expect SW winds to become
NW then N overnight as high pressure builds in behind the front.
Should see mostly clear skies except for some mountain valley fog.
Added only a FEW005 at KAVL for now as it's uncertain if there will
be fog at the airport. Winds turn NE after daybreak as the high
moves across the area with S wind developing for the afternoon.
Winds turn back NE Tuesday evening.

Outlook: The potential for morning valley fog will continue through
the week, but convective chances will remain limited due to
developing upper level high pressure. However, low clouds may
develop by Wednesday morning as cold air damming may move in.

Confidence Table...

02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL High 100% High 100% High 100% High 100%
KHKY High 100% High 100% High 100% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 100% High 100% High 100%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:

www.weather.gov/gsp/aviation

&&

.CLIMATE...

RECORDS FOR 05-24

MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 90 1939 57 1923 65 1953 36 1931
1903
KCLT 95 1939 57 1923 71 1953 43 1931
1903 1903
KGSP 94 1962 60 1923 73 1953 41 1917



RECORDS FOR 05-25

MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 89 1896 57 1979 68 1953 39 1925
1963
KCLT 95 1953 59 1923 73 1953 41 2013
1926
KGSP 96 1962 63 1963 72 1953 46 2005
1953



RECORDS FOR 05-26

MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 88 1989 59 1956 65 1982 34 1925
1916 1953
KCLT 96 1926 64 1992 73 1998 45 1979
1963
KGSP 96 1953 60 1963 70 1989 45 1979
1926 1953
1912

&&

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

&&

$$
SYNOPSIS...JMP
NEAR TERM...RWH/SBK
SHORT TERM...JMP
LONG TERM...JMP
AVIATION...RWH
CLIMATE...JMP
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