477
FXUS63 KJKL 270555 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
155 AM EDT Fri Sep 27 2024

.KEY MESSAGES...

- The remnants of tropical system Helene will bring a widespread,
  soaking rain event through today.

- Flash flooding could result from the remnants of Helene, but the
  overall potential will probably be limited by its quick movement.

- Wind gusts of generally 40 to 60 mph are expected at times into
  Fri as the remnants of Helene pass.

&&

.UPDATE...
Issued at 140 AM EDT FRI SEP 27 2024

The overall forecast is on track with the dynamic night of weather
upon us. Have mainly updated through dawn to track times of the
heaviest rain as it surges north through the area and also the
increasing wind field for the area. Did incorporate the current
obs and trends for the T/Td/Sky grids with this update, as well.
These adjustments have been sent to the NDFD and web servers along
with a freshening of the zones, HWO, and SAFs.

UPDATE Issued at 1200 AM EDT THU SEP 26 2024

Showers continue across eastern Kentucky at midnight and are
still expected to increase in intensity from southeast to
northwest through 4 AM EDT. Forecast is on track.

UPDATE Issued at 847 PM EDT THU SEP 26 2024

Showers, mainly light, continue to stream northward across eastern
Kentucky this evening while Hurricane Helene, now a category 4
hurricane, churns toward the Florida Panhandle. Expect waves of
showers to continue drifting across eastern Kentucky. The overall
intensity of the rainfall should tick up gradually from the
southeast, especially after midnight, as Hurricane Helene lifts
across the Florida Panhandle and through Georgia. Overnight PoP/T
forecast has been refined with the latest hi-res model solutions.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 455 PM EDT THU SEP 26 2024

Late this afternoon, an upper level ridge was centered to the
west of Bermuda with another upper level ridge extending from the
Southern Rockies to the upper MS Valley. An upper level low was
centered near the confluence of the MS and OH Rivers while Major
Hurricane Helene continues to move north in the northeastern Gulf
of Mexico and headed toward northwest portions of FL. A nearly
stationary frontal zone remains from low pressure in Quebec to
the upper OH Valley to eastern KY to northwest FL to the
northwestern Gulf of Mexico. The upper level low continues to
interact with the boundary and moisture transported into the
region for a continued precursor rain event (PRE). Rain continues
to move from eastern TN north into much of eastern KY at this
time.

Tonight and Friday, the upper level low is expected to move south
to northeastern MS/northwest AL with this upper low and Hurricane
Helene more or less moving into Fujiwhara fashion with Helene
tracking quickly across northwest and FL and southern and central
GA. This will then move across the Southern Appalachian region
and then to the Cumberland Plateau through early to mid afternoon
on Friday, gradually weakening and becoming extratropical. Bands
of rain more closely associated with Helene are expected to cross
the region tonight through Friday morning as the pressure
gradient also increases between Helene and high pressure north of
the eastern Great Lakes vicinity. These winds will have a
downslope component a times, but PW will rise near or in excess of
2 inches tonight remain at those levels into the morning before
dry slotting works northwest on Friday afternoon. As Helene nears,
a general additional soaking rainfall should occur areawide. Some
locally more intense rain of 3 or more inches could occur in a
band somewhere across eastern KY per some CAM runs, though a
general 1 to 2.5 inches of rain expected through Friday evening.
Winds and wind gusts are also a concern and in addition to a flood
watch in effect generally south of the Mtn Pkwy. Areas generally
south of the Mtn Pkwy have either had more rain over the past 3
days and/or are expected to have the highest totals on average.

12Z HREF mean wind gusts increase to 40 mph or higher across the
highest terrain along the VA border toward midnight with the
stronger gusts progression to the north and northeast through the
remainder of the night. Some of this is not expected to be realized
in the deeper valleys before sunrise. However, 12Z HREF mean
brings wind gusts to near or in some instances than 60 mph
northwest across much of the area Friday morning to early Friday
afternoon, before gradually slackening. Momentum is likely to mix
down as a dry slot moves in behind a morning band of rainfall.
Higher elevation locations will experience a longer period where
stronger wind gusts are possible from late tonight into early
Friday afternoon. A High Wind Warning was issued for Bell, Harlan,
and Letcher County from 11 PM tonight to 8 PM on Friday with
another tier of High Wind Warnings to the north and west 2 AM on
Friday to 8 PM on Friday which generally has elevations of 1500
feet or higher or where soil moisture is highest/heavier rain has
fallen over the past 3 days or so. A Wind Advisory was issued for
areas further northwest, but gusts to around 60 mph area possible
especially in the eastern Bluegrass region and on ridges and
further adjustments to headlines may be needed. 12Z HREF
probabilties of 60 mph gusts or higher are significant over much
of the area at 50 to 100 percent. The 18Z HRRR wind gusts are in
general agreement with the HREF values. So in summary, tonight,
the strongest wind gusts of 40 mph or more are expected in the
High Wind Warning area later tonight, especially on ridges, with
wind gusts peaking across the region during Friday morning to mid
afternoon on Friday.

From late Friday into Friday night, the upper level low and Helene
will gradually merge with the combined low meandering over the
Lower OH Valley region. Following a relative lull in chances for
showers on Friday afternoon and evening with the dry slotting,
moisture is progged to increase from west to east late Friday
night with an associated increase in shower chances from west to
east.

.LONG TERM...(Saturday through Thursday)
Issued at 225 PM EDT THU SEP 26 2024

The forecast period begins with the area still largely under the
impacts of the remnants of Hurricane Helene. At upper-levels, the
remnants of Helene will begin to merge with a largely stationary cut-
off circulation that`s been situated over western Kentucky through
much of this week. As the two systems merge into one circulation,
shower and storm chances will persist through the day Saturday and
linger through the weekend. Models continue to remain in rather good
agreement going into next week with the circulation getting picked
up by the mean flow and ejecting out of the area by Monday morning
but lingering PoP chances will exist through the end of the period
as an upper-level trough, moving through southern Canada, drags a
cold front through the region Tuesday afternoon which will then
usher in cooler and drier weather for the middle of next week.

Overall, the forecast period will be highlighted by multiple rounds
showers and storms. Shower and thunderstorm chances drop a little
bit with the merging of the closed circulation and the remnants of
Helene but chances (40-70%) exist through the weekend. Temperatures
through the period will remain rather seasonal as highs are forecast
to in the upper-60s to upper-70s. Overnight lows, will be warmer
with the insulation of the system overhead but with the approach of
a cold front on Tuesday, cooler temperatures and fall-like weather
will be in place for the end of the period.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 155 AM EDT FRI SEP 27 2024

Generally MVFR to IFR conditions were observed at TAF issuance
time as areas of low clouds, fog, and widespread showers continued
to impact eastern Kentucky. A rumble of thunder remains possible
into Friday morning, but confidence in any affecting a particular
TAF site remains too low to mention. An uptick in the rainfall
rates is underway as the bands ahead of Helene push into the area.
Winds will average from the east to northeast at 5 to 10 kts,
with some higher gusts, to begin the period increasing quickly to
10 to 20 kts sustained, with gusts up to around 30 kts by 12Z.
Winds will then continue to increase from the northeast between
12Z to 18Z to as high as 20 to 30 kts and begin to trend to the
southeast for southern locations to end up with gusts in the 35
to 50 kts range through at least 20Z. LLWS will also be a threat
later this night into Friday morning, with winds as high as 60 kts
a thousand feet or so off the sfc generally blowing from the east
to northeast initially - trending toward southeast after 18Z.
Things start to settle toward the end of the aviation period, but
low clouds will likely remain in place for most locations.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 5 AM early this morning to 8 PM EDT this
evening for KYZ044-050>052-058>060-068-069-079-083-104-106>109-
111-112-114-119.

Flood Watch through this evening for KYZ058-068-069-079-080-
083>088-107>120.

High Wind Warning until 8 PM EDT this evening for KYZ080-084>086-
110-113-115>117-120.

High Wind Warning until 8 PM EDT this evening for KYZ087-088-118.

&&

$$

UPDATE...GREIF
SHORT TERM...JP
LONG TERM...VORST
AVIATION...GEERTSON/GREIF