514
FXUS61 KRLX 261010
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
610 AM EDT Thu Sep 26 2024

.SYNOPSIS...
Daily chances for showers and thunderstorms continue this week
in response to a stationary disturbance over the Ohio Valley and
a tropical system sailing up from the Gulf coast.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 245 AM Thursday...

Cloudy skies with rain showers and periods of steady rain will
be the theme for today. Thunderstorm probability is very low,
therefore elected to leave mention of them out of the forecast.
Cannot rule an isolated one out, but for the most part this
period will endure stable stratiform rain. The rain could be
heavy at times, especially across southern WV and southwest VA.
Parts of these areas are under a flood watch still and we may
need to expand the watch further north when day shift
reevaluates. According to just the EURO we would likely expand
as the plume of higher QPF does not change path too much and
goes through Friday. Although other guidance seems to be on a
slightly drier solution which justifies the reason to hold off
for now.

The pressure gradient will start to tighten later on in the
evening in response to Hurricane Helene coming up from the
south. This feature will raise winds to near advisory criteria
along the peaks and ridges of southeastern WV and southwestern
VA. Depending on the track, southerly flow looks to be the best
solution which will create downsloping to enhance wind speeds
across those mountains. Forcast soundings indicate 50KT+ at
2000FT elevation so a watch or an advisory may be needed.
However, most guidance (other than the NAMDNG) is not
indicating or showing any signal for high wind, therefore
elected to pass this on to the next shift so they can evaluate
with newer guidance. The time frame we are looking at is Friday
at around 9Z to Saturday at 03Z.

It looks like most of the QPF will fall along the southern half
of our CWA and this is where the most rainfall has gathered in
the past several days to where some locations have seen several
inches of rainfall. Flooding will be the main threat today if
these areas are inundated with more heavy rainfall or exceed
certain rain rates which could lead to flooding issues from low
lying areas, flood prone areas or even smaller creeks coming
out of their banks.

With all the cloud coverage expected and rain cooled air,
temperatures were tweaked toward slightly lower than guidance
with much of the area not expected to surpass the 75 degree
mark, with slightly cooler temperatures in the mountains.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 430 AM Thursday...

Key Points

 * The remnants of Hurricane Helene, coupled with a stationary
   system over the Ohio Valley, will promote periods of heavy
   rain on Friday and into this weekend.

 * An additional half an inch to an inch of rainfall is possible
   through Saturday.

 * A tightened pressure gradient inflicted by this system may
   yield strong wind gusts along the higher terrain Friday
   morning into the early afternoon.

After Hurricane Helene makes landfall Thursday evening, the
system will march northward through the Mississippi Valley and
congeal with the stationary upper level low positioned just west
of the forecast area. This transformation will continue to
usher in a plethora of moisture up into Central Appalachia and
maintaining active weather for Friday and into the start of the
weekend.

A resultant tightening pressure gradient from this stacked
disturbance will impose strengthening winds in the low to mid
levels, especially along the mountain range. One of the many
challenging pieces with this forecast will be whether this
strong winds aloft can be pulled down to the surface. Forecast
soundings depict a predominantly moist profile, which could keep
these stronger winds capped above, but could also be dragged to
the surface with showers and potentially strong thunderstorms.
The motion of Helene as the storm lifts over land will also
dictate wind uncertainty as it takes a sharp western turn and
becomes absorbed with a baroclinic system over the Tennessee
Valley. Forecast offices to the south have already hoisted a
High Wind Watch for their mountain range on Friday, but with
some uncertainty still prevalent with gust potential, will hold
off on jumping on headlines with this issuance.

In regards to rainfall, the best opportunity for higher QPF
amounts will occur Friday morning into the afternoon as Helene
takes the aforementioned western trajectory across the southern
Appalachians into the the middle Ohio Valley. An additional inch
of rain could be achieved during this time through the Tug Fork
river basin and up into the Ohio River Valley. Localized
flooding is still feasible, but the higher flash flooding threat
remains progged to be south of the forecast area down into the
Tennessee Valley and Carolinas.

At the start of the weekend, the tail end of precipitation
associated with a nearby frontal boundary will detach from the
Ohio Valley upper level low. The forecast area enters into a
rain shadow period, where lessening POPs overtake the area as
the low deepens southward and pivots showers further away to the
west, and the eastern flank of moisture pushes offshore.
However, this should be short-lived on Saturday as rejuvenated
moisture wraps around the stacked upper level low and the system
slowly drifts back to the east.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 430 AM Thursday...

The second half of the weekend features the strong upper level
disturbance becoming an open wave and slowly shifting into the
Central Appalachians. Rain bands circulating the center of the
system will become less impressive as the long term period
marches on, but still could produce chance to likely (50-75%)
POPs. This trend will hold through the first half of the work
week as the open 500mb wave and the remnants of the surface low
continues to pivot over the Mid-Atlantic region.

The last batch of rain departs the forecast area late Wednesday
night into Thursday, with the forecast becoming dry under
establishing high pressure. Temperatures will be around
seasonable for this time of year throughout the period, with
afternoon highs ranging in the 60s along the higher terrain and
mid to upper 70s across the lowlands.

&&

.AVIATION /10Z THURSDAY THROUGH MONDAY/...
As of 630 AM Thursday...

For the most part, this period will generally accompany MVFR
CIGs with some minimal VIS restrictions and temporary low
stratus under heavier rain. Periods of fog will affect some of
the sites with VIS restrictions and low stratus until 13Z-14Z
(CRW/EKN). Thereafter, stratocu with rain showers will be the
theme for the day with very low probability for thunderstorms,
therefore elected to leave out mention in the TAFs. Winds will
be fairly light and easterly except for down by BKW where winds
will start to climb tonight in response to the Hurricane Helena
coming up from the south. LLWS will certainly become a concern
for Friday as intense upper level winds associated with Helena
will cause llws if surface flow is weak. Currently, no sites
will be affected if the forecast winds stay similar, but note
that HTS/BKW will likely have some Friday morning if winds are
less than anticipated.


FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...

FORECAST CONFIDENCE: Medium to high.

ALTERNATE SCENARIOS: Timing and extent of low CIGs will vary
somewhat from the forecast.

EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH:   TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW:    TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.

DATE               THU 09/26/24
UTC 1HRLY       09   10   11   12   13   14   15   16   17   18   19   20
EDT 1HRLY       05   06   07   08   09   10   11   12   13   14   15   16
CRW CONSISTENCY  L    L    M    L    M    H    H    H    H    M    M    M
HTS CONSISTENCY  M    H    H    H    M    M    H    H    H    H    H    L
BKW CONSISTENCY  M    M    M    M    H    H    H    H    H    H    H    H
EKN CONSISTENCY  L    L    L    L    L    H    H    H    H    H    H    H
PKB CONSISTENCY  M    L    L    L    H    H    H    H    H    H    H    H
CKB CONSISTENCY  M    H    H    H    H    H    H    H    H    H    H    H

AFTER 12Z FRIDAY...
Brief, but repetitive periods of IFR conditions possible in
showers and storms throughout the week and into the weekend.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Flood Watch through this evening for WVZ033.
OH...None.
KY...None.
VA...Flood Watch through this evening for VAZ003-004.

&&

$$

SYNOPSIS...MEK/JZ
NEAR TERM...JZ
SHORT TERM...MEK
LONG TERM...MEK
AVIATION...JZ