Area Forecast Discussion
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FXUS62 KGSP 012358
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
758 PM EDT FRI JUL 1 2016
An upper trough will push a cold front south across the region
through Saturday. The front will stall just to the south of the
area, but then will lift slowly back north late in the weekend into
the beginning of next week.
.NEAR TERM /THROUGH SATURDAY/...
As of 750 PM: A few cells have redeveloped over the srn NC Foothills
over the past hour, though none have yet grown tall enough for
lightning. These likely formed along some sort of convergence axis
or other local boundary, tapping instability that was not realized
during the day when LCLs were higher. Meso model runs would suggest
these are the last cells of the day, but seeing how much CAPE
developed this afternoon, any outflow they produce might fire up
a new isolated cell over the next hr or two in the Hwy 221 corridor.
As a weak upper trough exits the region tonight, drier air already
in place over the northwest zones will certainly try to make it
farther south, but as the flow flattens tonight the front will
stall across the area making the attempt of dry air intrusion
futile across most of the Piedmont, with not much change in
overnight lows from what we`ve been seeing.
The front will sort of stall and then wash out across the area
Saturday, and with a shortwave approaching from the west (more on
that below), should see a decent increase in instability across the
area with just a bit of an enhancement to the normal summertime
diurnal pattern, with initial convection over the mountains
but possibly increasing in coverage across the NC Piedmont in
closer proximity to the upper forcing. Thermodynamics tomorrow
look similar to today but with just slightly stronger flow aloft
could see a bit of jet-level synoptic lift, and thus the SPC Day2
Marginal Risk for eastern zones looks reasonable. Highs Saturday
are progged to be a degree or two warmer than those today.
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 230 pm EDT Friday: Mid level ridging will be in place to the
south of the area through this period, keeping conditions warm and
muggy. The southern end of the westerlies will allow weak
disturbances in the flow to kick of mainly afternoon and evening
showers and thunderstorms. As usual, initiation will begin across
the higher terrain then pushing into the Piedmont during the late
afternoon and evening. High temperatures will be in the lower 90s
outside the mountains with heat indices reaching the mid to upper
90s each afternoon. Lows will likely remain above 70 degrees outside
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 230 pm EDT Friday: Weak troffing will develop during this
period across the region allowing for a general increase in shower
and thunderstorm activity. The peak in the activity will be in the
typical late afternoon/evening but overnight activity should
increase during the period as well. Conditions will remain hot and
muggy with heat indices approaching 100 outside the mountains before
storms cool it off each day.
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: VFR expected tonight at the TAF terminals,
but outlying areas might see some patchy and shallow fog. Low
cigs are not expected to develop either, given low-level winds
veering to westerly or northwesterly in the predawn hrs, and the
fact that there was so much less convection Fri aftn compared to
the previous two aftns (recall low clouds plagued the sites the
following mrngs). Winds veer around as noted, being NE-ly after
daybreak and southerly in the aftn, except at KAVL where the usual
channeling will occur. Characteristically unstable conditions are
likely to redevelop Sat aftn; TS chances are in the PROB30 range
over western NC and too low to mention over SC.
Outlook: A weak frontal boundary stalls across the region Sunday,
and persists into the middle of next week. Afternoon/evening showers
and thunderstorms will continue, and restrictions could occur the
following morning wherever heavy rain falls in the afternoon. A
wave of low pressure moving east along the boundary will enhance
TSRA potential Mon-Tue.
00-06Z 06-12Z 12-18Z 18-00Z
KCLT High 100% High 100% High 97% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL High 100% High 97% 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 schedule TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link: