079
FXUS62 KCAE 300741
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
341 AM EDT Mon Sep 30 2024

.SYNOPSIS...
The remnants of Helene along with the upper level trough axis will
be north of the area today while continuing to slide slowly
eastward. The system will finally move off the coast on Tuesday
as a weak cold front approaches. This will keep the area under
southwesterly flow aloft with a few showers possible this
afternoon and evening, especially in the Northern Midlands and
Pee Dee. This will be followed by the passage of a weak cold
front mid-week but the chance of precipitation is low. High
pressure then builds in behind the front with continued dry
conditions Thursday and Friday. Temperatures remain near or
above seasonable values through Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Message(s):

- Heed road closures and DO NOT drive around barricades.
- Avoid unnecessary travel as utility crews continue restoring
  power and clearing downed trees and powerlines.
- Flooding on area river levels will continue with some
  locations at major flood level.
- Isolated showers possible this afternoon and evening.

Currently clouds blanket the the CSRA and much of the southern
Midlands and will continue moving northward through daybreak.
There is some potential for fog to develop mainly in the eastern
Midlands and southern CSRA where skies remain mostly clear
however fog which develops will generally be patchy with limited
visibility restrictions. Low temperatures will be in the mid 60s
to around 70.

Synoptic situation will be slow to change today as the remains
of Helene along with the upper level trough will be north of the
area while gradually sliding eastward. By this evening the
remains will have reached WV and by daybreak Tuesday be nearing
the Delmarva region. This will keep the area under WSW to SW
flow and with plenty of moisture across the area potential for a
few showers this afternoon and evening. With forecast
soundings again showing some dry air in the mid levels along
with weak lapse rates expect mainly showers as the cumulus will
be vertically limited. The exception will be in the northern
Midlands and Pee Dee where there is a bit more instability and
there could be a thunderstorm or two late this afternoon into
this evening when the upper trough axis begins swinging through
the region. Expect the thunderstorm threat to end with sunset.
Overnight partly to mostly cloudy skies will again be over the
area which will limit the fog and stratus potential. High
temperatures this afternoon will generally be in the mid 80s
along and north of I-20 and the upper 80s south of I-20. Low
temperatures tonight will be in the low 60s in the far western
Midlands with mid 60s elsewhere.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Key Messages:
- Upper low continues eastward, moving offshore on Tuesday.
- Low (10-30 percent) chance for showers on Tuesday, mainly in
  the Northern Midlands and Pee Dee.
- A weak cold front approaches on Wednesday but rain is not
  expected.
- Daytime temperatures above normal.

There continues to be little change in the overall weather
pattern during the mid-week period. The upper low will be
located in the Mid-Atlantic region at daybreak on Tuesday,
slowly moving east, passing offshore during the daytime hours.
Southwesterly flow aloft keeps us warm and moist and there is a
low (10-30 percent) of showers across the Northern Midlands,
especially Chesterfield County. A cold front will follow behind
the upper low on Wednesday but is not expected to produce
precipitation in our forecast area. Temperatures during the
period remain above normal.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Key Messages:
- Warm and mainly dry conditions through Friday.
- Uncertainty increases this weekend ahead of the next system.

High pressure will be in control of the weather on Thursday
while the axis of an upper ridge passes overhead. This will
result in another warm and dry day with above normal
temperatures favored once again. Forecast confidence decreases
this weekend as model guidance has not come into agreement
regarding a potential tropical cyclone in the Gulf of Mexico.
Opted to favor the GFS solution with this forecast package which
shows an upper trough and strong high pressure diverting any
tropical moisture to our south. Having said that, the best rain
chances in this scenario should be over our southern and eastern
counties where there are Slight Chance PoPs on Friday and Sunday
afternoons, though again confidence in any one solution is low
at this time and will need to be refined as the week goes on.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
VFR conditions expected except for possible brief VIS/CIG
restrictions around sunrise.

Satellite imagery shows mid clouds continuing to move across the
area with some clouds around 3.5 kft embedded with the mid
clouds. Through daybreak the main concern will be potential for
MVFR to IFR cigs and vsbys however with increasing clouds from
AGS to CAE expect the threat to be lowering however have kept
mention at prone AGS around daybreak fro MVFR vsbys. OGB remains
clear and potential for sunrise restrictions remains possible
however mid clouds moving toward the terminal may disrupt that
and will continue to monitor. With sunrise any restrictions will
mix out with the remainder of the period VFR with winds westerly
to southwesterly at 8 knots or less.

EXTENDED AVIATION OUTLOOK...No significant impacts to aviation
expected through Friday.

&&

.HYDROLOGY...
Key Message:

- Widespread moderate-major flooding underway and will continue over
the next several days.

Heavy rainfall associated the the pre-Helene event combined with
rainfall associated with Helene has produced high flows and flooding
on many of the streams and rivers across the Midlands and Central
Savannah River Area. Rainfall amounts ranged from 3 to 6 inches
across much of the area with some counties reporting rainfall
amounts from 6 to 12 inches. Many of the area rivers continue to
rise as rainfall across western NC and the Upstate of SC continues
to move down the river basins. Most river forecast points will be
reaching at least Moderate Flood, with several locations in the
Major Flood Category. Stevens Creek at Modoc set a new crest record
just over 43 ft. The pool elevation at Lake Wateree is expected to
crest just under 107.0 feet which is approaching the record lake
level height set back in 1989 with Hurricane Hugo. The Congaree
river at Columbia is forecast to crest at 31.0 feet, near the 2015
level. It will take several days for the rivers across the Midlands
and CSRA to return to more normal flows. Those working around area
rivers and creeks are urged to monitor levels and use caution near
flooded areas for underwater and unseen hazards.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...None.
GA...None.

&&

$$