Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS62 KGSP 221425

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1025 AM EDT Thu Jun 22 2017

Cindy will drift north across extreme western Louisiana today,
spreading tropical moisture across the South through tonight. A cold
front will approach our area Friday and move into the region early
Saturday, before crossing to the Atlantic coast Sunday through
Monday. Cooler and drier weather will follow behind the front for
the middle of next week.


As of 1000 AM EDT: Widespread precipitation crossing the region from
the southwest with passing upper vorticity and divergence late this
morning is keeping temperatures locked in close to dewpoints in most
areas. This will require trimming a few degrees off maximum
temperatures in many areas, especially across the foothills, and a
slight uptick in PoPs. There is still some potential for temperature
recovery this afternoon as a lull develops between this
precipitation area and upstream convection near the AL/GA border.

The persistent deep tropical moisture plume will keep precipitation
coverage and efficiency high through late tonight. Precip amounts
still do not appear to be sufficient, however, to warrant Flood
Watches as most main stems and streams are at fairly low stages
today. Severe storms also appear unlikely with the poor lapse rates
and weak sfc-based CAPE, however deeper layer shear does increase
this evening and the tropical bands arriving from the SW toward 00Z
will have to be closely monitored. Temps will remain mild overnight.


As of 300 AM EDT Thursday: the remnants of T.S. Cindy will begin to
be picked up by a northern stream trough over the Midsouth on
Friday. Meanwhile, the western edge of a large subtropical ridge
will build slightly westward into the Carolinas. This will advect
some slightly drier air and keep weak mid-level lapse rates atop the
CWFA. Guidance is in pretty good agreement on the deepest moisture
associated with Cindy staying west of the area thru the day, while
piedmont, in particular remains largely capped. So PoPs were trimmed
back, esp in the east. Bulk shear will increase thru the day, and if
we manage to get enough CAPE, could see at least a few strong to
severe storms. The CAMS that go thru Friday do show some multicell
segments with convection across the TN Valley. Some of this activity
will try to move into the NC mountains Friday evening. Temps will
rebound with more sunshine and influence from upper ridge to near
normal, making for a muggy day.

Friday night, the models agree that the remnant vort max associated
with Cindy will likely track across the Central Appalachians
overnight thru Saturday morning. This will bring a trailing vort
lobe and associated sfc front across the CWFA. This front should
have good moisture and forcing to work with. But model guidance is
not excited with instability and QPF response. So PoPs will range
from categorical along the TN border to mid-chc to the southeast.
The NC mountains could pick up some decent rain, but unless they get
a lot of rain Thursday, I don`t think there will be much of a flood
threat. Temps will remain above normal.

Saturday thru Saturday night, with the models trending faster with
the front and upper wave, the bulk of the afternoon convection may
be mostly east of the area. Have trimmed PoPs back and start drying
things out in the west by early Saturday evening. With that said,
bulk shear still looks decent for late June, and if the front ends
up being slower and there is better overlap of CAPE, there may be
some severe storms across the area. Highs are still tricky due to
the fropa, but guidance shows little change in thicknesses, so
expect near or slightly above normal temps.


As of 330 AM EDT Thursday: the medium range looks really nice and
pleasant for the forecast area, as a long wave trough persists
across the Great Lakes and digs into the TN Valley thru the middle
of next week. At the surface, a continental high pressure system
will gradually slide southeast across the Midwest Sunday-Monday and
settle over the southern Appalachians by Wednesday. Given the
gradual drying over the first couple days of the medium range, some
slight chc to low-end chc PoPs will linger, but expect basically dry
conditions for Tuesday and Wednesday. Temps will be as much as 5-8
deg below normal, coolest Tuesday thru Tuesday night. Dewpts will
fall into the 50s, which will feel nice after the humid conditions
we`ve had the last few days.


At KCLT: Despite the developing rainfall, ceilings around KCLT and
in upstream areas have remained stubbornly VFR and see no reason for
restrictions going forward as the boundary layer warms ever so
slightly. Thunder chances are too small to mention given the clouds
and precipitation and general lack of any steeper lapse rates.
Confidence is not great after sunset, but with a light upslope flow
and substantial low level moisture, an MVFR to IFR stratus deck
should develop across the Piedmont. Winds should stay S to SW and
light through the period.

Elsewhere: Showers continue to cross the terminals from the
southwest late this morning, but with all ceilings at VFR levels and
this should be the case going forward today as the boundary layer
warms slightly. The guidance suggests that upslope flow will develop
this evening with ceilings in the lower end of MVFR along with light
rain. We will then likely end up IFR in the early morning hours.
Expect mainly light SW winds throughout.

Outlook: Abundant moisture will remain over the area through
Saturday, enhanced by remnants of Cindy which will approach from the
west on Saturday. Associated restrictions can be expected, as well
as the potential for morning fog/low stratus. Some drying may occur
on Sunday.

Confidence Table...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       Med   71%     High 100%     High  94%     High  90%
KGSP       High  88%     High  95%     High  87%     High  88%
KAVL       High  95%     Med   71%     High  82%     Med   71%
KHKY       Med   71%     High 100%     High  83%     High  88%
KGMU       High  88%     Med   78%     High  85%     High  88%
KAND       Med   67%     Med   71%     High  80%     Med   79%

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:




AVIATION...HG/PM is the U.S. government's official web portal to all federal, state and local government web resources and services.