134
FXUS62 KGSP 180433
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1233 AM EDT Thu Jul 18 2024

.SYNOPSIS...
A pattern change begins to evolve by Thursday, as a cold front
approaches from the northwest, then becomes stationary across our
region for several days. This will keep shower and thunderstorm
chances elevated through at least early next week.

&&

.NEAR TERM /THROUGH TODAY/...
As of 1232 PM EDT Thursday: Shower activity is continuing to
diminish as a stubborn cell persists over the Upstate. It`s
running out of steam and should be gone in the next hour or so,
but nothing severe. Satellite shows some scattered cloud debris
from storms earlier and are moving out of the area. Low level
stratus and fog is starting to creep into the mountains and is
expected to expand given the high dewpoints and light winds.
Other than that, no major changes to the forecast at this time.

Otherwise, upper troffing will linger to our north over the Great
Lakes while broad upper ridging persists to our west and to our
east. At the sfc, Canadian high pressure will persist to our NW
while the Bermuda High keeps moist, southerly low-lvl flow to our
south. Between these two highs, a weak frontal bndy will linger
over our region thru the near-term period helping to keep things
convectively active. Overnight/Thurs morning, conditions will
remain muggy with temps expected to remain a few degrees above
climatology with a decent chance for patchy fog to develop in the
mtn valleys and over area that received precip.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
As of 100 PM Wednesday...A pattern change will begin the short range
as a strong Canadian high builds south and traps a frontal zone
against the Bermuda High. The flow around the subTrop ridge will
will allow for very good moist advect each day and cross sections
indicate high saturation thru the mid levels. The high cloud cover
and rather warm mid levels will limit sbCAPE potential each day as
sfc heating is curtailed a cat or so below normal, but diff heating
will allow for robust and longer lived cells. The various guidance
wavers on the exact placement of the sfc convg zone which will be
instrumental in the generation and amt of precip each day. But for
now, expect arnd an inch or so across localized areas FA-wide with
some potential for localized hydro issues depending on where the sfc
convg is enhanced by deeper convec due to mainly to diff heating.
Training cells with high rainfall rates will also be possible as the
mean steering flow aloft aligns with the stationary front thru the
period. Pops were maintained quite a bit abv normal each day with
noctural precip likely continuing to some degree each night.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 200 PM Wednesday...The ext range fcst remains active as the
latest guidance continues to show an activated stationary front
draped across the area. Decent agreement is seen in the mass fields
Sun thru Tue with the GOM wide open for efficient moisture flux each
day. This could be a period of increased hydro issues as antecedent
water level conds by that time may be quite elevated. A lot will
depend on the areas where the front situates as it wafts north and
south thru the period. High PoPs have been maintained thru the
period including abv normal PoPs during the overnight periods. Max
temps will likely be held below normal each day by a few degrees
while mins remain abv normal.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Still dealing with remaining TSRA moving
east from east TN to the mtns of NC, which will necessitate keeping
a TEMPO at KAVL into the middle part of the evening. Otherwise,
most of the area has been worked over with terminals already having
a thunderstorm earlier in the day. Might see lingering light rain
at some spots, but mainly just mid/high level debris cloudiness
through the evening, with a light SW to W wind away from storm
outflows. Expect the convection to die off by late evening and for
conditions to be VFR and quiet afterward. The usual spots in the
mtns and foothills could have a few periods of a fog restriction
in the overnight hours. Thursday looks like another active one,
with the CAMs showing better coverage in the afternoon, enough
to increase confidence in using a TEMPO for the restrictions
associated with storms at all terminals. Wind should stay SW away
from outflows.

Outlook: Expect scattered to numerous showers and thunderstorms
each aftn/ evening thru the weekend. Morning fog/low stratus will
also be possible each day, especially in the mtn valleys and over
areas that received rainfall from the previous day.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...CP/JPT/PM
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...PM