952
FXUS61 KRNK 260823
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
423 AM EDT Thu Sep 26 2024

.SYNOPSIS...
Rounds of scattered showers and thunderstorms will continue
across the area through today with the rainfall resulting in
increasingly saturated soils. Then tonight and Friday moderate
to heavy rain around Hurricane Helene will greatly enhance the
threat of flooding in the mountains and foothills. Over the
weekend the remnants of the tropical system will be trapped over
the Tennessee Valley with a lower probability and coverage of
showers.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 200 AM EDT Thursday...

Key Messages:

1) Pre-Helene rain continues to fall, mainly over the mountains
today.

2) Moderate to heavy rain bands from Helene will enter the area
tonight.

3) Winds become breezy and gusty tonight into Friday morning.

An upper level low will wobble in the vicinity of Memphis TN
while an upper level ridge sits off the southeast coast. These
two systems will help guide Hurricane Helene as it enters the
Gulf of Mexico. Hurricane Helene is expected to intensify and
become a major hurricane as it moves over the warm waters of the
eastern Gulf of Mexico today. Helene is expected to move inland
around the Big Bend area of Florida this evening, then turns
northward towards the southern tip of the Appalachian mountains
(NW GA) tonight.

Shortwaves coming around the upper level low will keep the
chance for showers and a few thunderstorms over the area through
this evening. The chances for moderate to heavy rain will be
over the Mountain Empire of SW Virginia, the Grayson Highlands
and NW North Carolina mountains and foothills. This area is
currently under a Flash Flood Watch through this evening. Rain
bands from Helene will enter the current Flash Flood Watch area
and spread across the rest of the area overnight into Friday.
Rainfall amounts of 1 to 3 inches fell across the area last
night. An additional 1 to 2 inches are possible for most of the
area and another 2 to 6 inches are likely over the current Watch
area tonight into Friday. A new Flood Watch with respects to
Helene`s rainfall covering the entire RNK`s forecast area is a
good possibility.

Winds from Helene will range between 15 to 30 MPH with gusts as
high as 45 MPH late Thursday night into Friday morning. The
higher end of the range will primarily be across the NW North
Carolina High County, the Grayson Highlands and the Mountains
Empire of SW Virginia between midnight and noon Friday. Even
though winds speeds will not reach advisory criteria, trees
could topple as ground will be saturated.

High temperatures today will range from the mid 60s to lower
70s across the mountains and in the mid to upper 70s over the
foothills and piedmont. Humidities will remain high with a
tropical airmass over the region.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
As of 200 AM EDT Thursday...

Key Messages:

1) Hurricane Helene will quickly weaken and mostly dissipate
Friday night into Saturday.

2) Rain chances significantly decrease for Saturday, but
increase once again on Sunday.

Hurricane Helene will have mostly moved through the area by
Friday night, with only scattered showers remaining over the
region. However, the airmass will still remain tropical, with
dewpoints in the 60s to near 70, especially in the piedmont
locations. Despite this, there is increasing confidence that
PoPs will be significantly lower on Saturday, due to drier air
in the mid-levels. Even some sunshine is expected to return for
parts of Saturday afternoon as cloud cover will lessen. The
remnant low of Helene will continue to meander through the
weekend in the Ohio River Valley, with no significant weather
systems expected to pick the storm up and move it. It will then
slowly begin to drift back to the east and into the Mid-Atlantic
on Sunday, though models differ on how quickly this will occur.
Nonetheless, this track to the east will allow showers to
develop once again on Sunday.

There is moderate confidence that QPF totals for the weekend
will generally be under 0.25" for most of the RNK CWA, according
to the NBM, with isolated areas possibly seeing up to 0.50" in
the heaviest showers. High temperatures on Saturday will be in
the 70s to low 80s, due to the break in cloud cover. Sunday will
see slightly cooler temperatures, as clouds and showers move
back over the region with highs in the 70s. Nighttime lows will
be around 60 degrees both days.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
As of 200 AM EDT Thursday...

Key Messages:

1) Scattered showers persist for the early week as the remnant
low of Helene slowly begins to move east.

2) Drier and quieter weather finally returns for the midweek.

As the remnant low of Helene moves back over our area Sunday
night and Monday, showers will remain in the forecast as the
tropical airmass remains in place. The Ensemble Situational
Awareness Table keeps precipitable water amounts around 1.5
inches through Tuesday night. Because of this, PoPs still remain
modest for both Monday and Tuesday, though there is uncertainty
in the coverage of the rainfall across the CWA. Temperatures
will be around normal, with highs in the mid 70s, with 60s for
the higher elevations. A cold front begins to approach the area
on Tuesday, though confidence remains low on the timing as
models disagree on this. Once the front passes, much drier
conditions will move into the area, with high pressure building
back in place. This will also cause temperatures to fall below
normal, with lows possibly in the 40s across most of the CWA for
Wednesday night.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
As of 140 AM EDT Thursday...

Showers and isolated thunderstorms will continue for locations
along the western slopes (KBLF/KLWB) through 10Z, then light
spotty showers for the rest of the morning. IFR to MVFR ceiling
and visibilities expected through this morning. For the rest of
the area, light spotty showers with MVFR ceilings and
visibilities into this morning.

Another round of rain enters this afternoon, then rain bands
from Hurricane Helene enter the forecast area overnight. IFR to
MVFR ceilings and visibilities this afternoon, becoming LIFR to
IFR tonight.

Light easterly flow through this afternoon, increasing to
10-15kts with gusts up to 25kts across the mountains. Stronger
winds possible over the KTNB area.

EXTENDED AVIATION OUTLOOK...

Widespread moderate to heavy showers and isolated thunderstorms
will cover the mountains and foothills with light rainfall
amounts in the piedmont tonight and Friday. Wind speeds will
increase in the mountains. Gusts of 25 to 40 kts are likely at
the higher elevations. Wind gusts at local TAF sites will remain
at or below 40 knots.

Moderate in flight conditions and diminishing winds are
expected Saturday through Tuesday. A chance of light showers
will continue around the remnants of Helene.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flood Watch through Friday evening for VAZ007-009>020-022>024-
     032>035.
NC...Flood Watch through Friday evening for NCZ001>003-018-019.
WV...Flood Watch through Friday evening for WVZ042-044.

&&

$$

SYNOPSIS...RCS
NEAR TERM...RCS
SHORT TERM...JCB
LONG TERM...JCB
AVIATION...RCS