Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 250215
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1015 PM EDT Mon Jul 24 2017

.SYNOPSIS...
A surface front will become stationary from west to east across our
region and dissipate into mid week.  High pressure moving by to the
north is expected to provide cooler temperatures on Wednesday.
Another front will move in from the northwest late in the week.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 10:15pm EDT Monday:  Showers have ended across the region this
evening with a few isolated showers possible again Tuesday
afternoon.  As upper northeast CONUS wave lifts northeast ward,
weakly forced pattern becomes even more weakly forced with weakening
surface features.  CAPE advances slightly as weak northwesterly
850mb flow becomes more variable; however, MLCAPE values only reach
800 j/kg near the North/South Carolina border, with greater amounts
still further southeastward.  With no forcing and some CIN, storms
will be few in number, but a bit of downdraft potential will exist
Tuesday afternoon should anything get going.  Temperatures will
continue the recent history of slightly above normal levels with
excess humidity.

Mountain valley fog and stratus, some dense, will develop once
again. Fog and stratus should develop in the normally more foggy
areas outside of the mountains as well. Lows will remain above
normal similar to this morning`s readings.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 215 PM Monday: The short term will feature rising heights, as
the upper trough axis pushes away from the area and weakens, while
the upper ridge associated with SW Conus subtropical high builds
back into the area, only to become suppressed again by the end of
the period. Despite this, Wednesday is expected to see temps a
little below climo, as a weak surface boundary associated with a
ridge of high pressure nosing down the East Coast is forecast to
turn the low level flow to the E or SE across the area. This
boundary could provide a focus for diurnal convection, although a
model consensus indicates the wind shift could be south of the
forecast area by the time of peak heating. The highest pops Wed
afternoon will be featured across the extreme southern zones and
along the southern Blue Ridge escarpment, with generally 30 pops
advertised elsewhere.

Height falls commence by the end of the period, as a short wave
trough pushes across the northeast quadrant of the country. Low
level flow is expected to return to the SW across our area by Thu
afternoon, allowing temps to return to normal levels. Otherwise,
standard mid-summer diurnal convective coverage is anticipated Thu
afternoon (40-50% across the Blue Ridge areas, generally 30 percent
elsewhere).

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 155 PM Monday: The medium range begins Thursday evening with
heights falling in the east while the semi-permanent ridge remains
over the desert southwest.  A strong wave or closed 500mb low moving
east to far eastern Canada brings the falling heights to our region
and a surface cold front which will be near the Ohio River early
Friday. As the front approaches from the north on Friday, showers
and storms will be most active with the greatest coverage of any day
in the medium range. The front will be moving slowly south as it
stalls out on Saturday then remain west to east across our region
into the start of next week. 500mb trough becomes rather deep for
this time of the year to start next week and likely give upper
support for moving the surface front south of our area. This would
lower the chances of rain for the Carolinas and northeast GA for
Sunday.  This pattern of amplified trough over the East and big
ridge over the West will result in cooler than normal temperatures
for our area and hotter than normal for Desert Southwest and
Rockies.

Max Temperatures are forecast to be just below normal Friday then
cool to be about 5 degrees below on Monday.  Min Temperatures will
be close to normal with the moisture and clouds.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere.  Convection around the area has all but ceased
this evening, with a slight to outside chance for an afternoon
shower again tomorrow.  As weak northeast upper wave works its way
east and heights rise, effective weather pattern will not change
much. Extremely weak surface pattern will make for light to variable
winds through Tuesday, with a slight northerly to northwesterly wind
direction bias.  Boundary-layer cu generally in the afternoon at
4000 to 5000 ft and a fair amount of high clouds through Tuesday.
Fog will again be possible for awhile Tuesday morning, mostly at
KAND, KHKY, and KAVL, though recent history has been fairly patchy.

Outlook: Scattered diurnal convection can be expected each day this
week across the region. Chances for morning fog and stratus will
also be possible each day in the mountain valleys.

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  95%     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  95%     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

&&

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

&&

$$
SYNOPSIS...DEO
NEAR TERM...WJM
SHORT TERM...JDL
LONG TERM...DEO
AVIATION...WJM


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