799
FXUS62 KGSP 120550
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
150 AM EDT Thu Sep 12 2024

.SYNOPSIS...
The remnants of Francine are expected to drift north over the lower
Mississippi River Valley through late week with a broad area of
moisture moving north from the Gulf of Mexico to the Carolinas. This
will result in periods of showers and thunderstorms for our area
mainly Friday and Saturday. Scattered showers may linger through
Sunday with an area of low pressure potentially developing off the
Carolina coast that may keep rain chances across the area into
the middle of next week.

&&

.NEAR TERM /THROUGH TODAY/...
As of 136 AM Thursday: Radars show the leading edge of a precip
band associated with the outer periphery of Francine across the
northern part of metro ATL and extending east along the I-20
corridor, where it bumps up against the drier air to the north
across the Carolinas. Expect this precip to continue having trouble
fighting its way northward and down to the ground for the rest
of the overnight hours. Temps will remain seasonally mild under
thickening cloud cover. No changes.

Otherwise, broad sfc high pressure will continue to ridge down
from the New England Coast east of the Appalachians in wedge-like
fashion.  TC Francine will continue to move northward and over
Mississippi on Thursday. The system is expected to be centered
somewhere over NE Arkansas by the end of the near-term period early
Friday. Mostly dry conditions should continue for our fcst area
thru most of the period. Deeper moisture will steadily increase
from the south thru the day on Thursday along with weak isentropic
lift developing in the SLY mid-level flow. Clouds should lower
and thicken as well.  Precip chances will increase during the
afternoon, but I don`t have any likely PoPs over our area until
roughly 00z Friday. Still expect any QPF that does materialize
to be light thru tomorrow night as the stronger forcing remains
west of our area. With the wedge pattern setting up on Thursday,
high temperatures should remain about 1 to 2 categories below
normal for most of our area.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
As of 123 PM EDT Wednesdsay: Expectations remain similar, in broad
strokes, to similar forecasts going into Friday.  The latest 12z
suite of deterministic guidance has continued to shift the axis of
strongest low-level moisture transport southward, resulting in lower
QPF for the NC zones through the end of Friday.  There remains the
issue of a frontogenetical band possibly resulting in locally-
enhanced rainfall over the western Upstate or extreme southwest NC
mountains, but even this feature is displaced south in the latest
deterministic guidance, and an inspection of the LREF ensembles
lends little additional support for the idea.  Saturday is also
trending drier, with the bulk of long-range ensembles keeping the
stronger moisture transport and surface front displaced south of
earlier forecasts...once again limiting rainfall.

All told, the latest storm total rainfall estimates fall under 2.25"
for all but a few localized areas along the SC Blue Ridge Escarpment
through Saturday.  Even without the dry antecedent conditions amid
ongoing drought in many of these zones, this forecast should keep
concern for hydro issues limited.  Under such a regime, any hydro
issues would almost certainly be related to embedded convection
resulting in locally high precip rates and/or training.  Otherwise,
temperatures will remain well below normal as low-level cool air
filters in from the northeast only to be further cooled by falling
rain.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 154 PM EDT Wednesday: Of somewhat greater interest will be the
potential development of a secondary low off the SC/GA coast Sunday
as cyclogenesis gets going along an extant boundary draped across
SC.  This is a fairly new feature in the long-range guidance, but
one that, over the last 24 hours, has become the favored solution
for the LREF ensemble system.  The loss of strong circulation
associated with Francine`s remnants will temporarily shut off
whatever moisture/forcing are in place at this point, resulting in a
lull in rainfall on Sunday. Then, all the deterministic models and
fully 60-70% of global ensemble members depict the low curving
westward and slamming into the Carolinas with a second round of
rainfall.  It`s certainly too far out to start speculating on
impacts, but should this feature remain in the forecast for a few
more model cycles, it`ll become a point of focus over the coming
days.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: VFR conditions are likely to prevail at
all terminals through the day, even as clouds thicken and light
precip on the outer edge of the circulation around Francine makes
attempts to spread northward. The moisture will be fighting into
dry air, so any ceiling is likely to be mid-level and precip not
restricting vis. There could be a brief fog restriction around
daybreak at KAVL, but confidence is poor. Otherwise, wind will
pick up from the NE this morning and should become low-end gusty
in the late morning to early afternoon. Some shower activity
is shown to lift northward across north GA and far western NC,
missing the terminals. It won`t be until late in the day or this
evening until a plume of deeper moisture is brought to bear in a
SE upslope flow that we will see an increase in precip chances,
but we will step into this with a PROB30 for the end of the period
and expect the prevailing lower vis/cig just beyond the current
period. Watch for it in the 12Z issuance.

Outlook: Restrictions become more likely on Friday and thru the
weekend. Another tropical low may move over our area from the SE
on Monday, bringing more precip and restrictions.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JPT/PM
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...PM