764
FXUS63 KJKL 101146 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
746 AM EDT Thu Oct 10 2024

.KEY MESSAGES...

- Mainly rain free weather is expected through Wed with only a
  20-30% chance of rain Sun into Sun night.

- Patchy frost is possible tonight to early Fri morning as well as
  Fri night to early Sat morning, mainly in the sheltered hollows
  away from larger bodies of water.

- Patchy to widespread frost is forecast Mon night to early Tue
  morning and again Tue night to early Wed.

- A freeze is possible in some spots Mon night to early Tue and
  with a widespread freeze possible on Tue night to early Wed.

&&

.UPDATE...
Issued at 743 AM EDT THU OCT 10 2024

Minor adjustments were made to hourly temperatures to account for
recent observations. This led to a slightly milder start for a few
locations. Valley fog should gradually lift and dissipate through
the 9 to 10 AM EDT timeframe and give way to sunny skies areawide
today. Highs should be within a couple of degrees of normal for
this time of year.

&&

.SHORT TERM...(Today through Friday)
Issued at 500 AM EDT THU OCT 10 2024

Early this morning, Milton was starting to pull away to the east
of the FL peninsula while upper level ridging was in place from
portions of the eastern Pacific into the southwest Conus to the
Four Corners vicinity to the Dakotas/upper MS Valley to Hudson
Bay. Further east and northeast, an upper level low was centered
in the vicinity of the Gulf of St Lawrence with an associated
trough axis extending to near Cape Cod to the mid Atlantic coast.
Mutably disturbances were moving around the extensive area of
ridging moving across BC and Alberta into the Northern Rockies
vicinities at this time. PW is currently analyzed in the 0.3 to
0.6 range across the area from west to east or from the Tug Fork
to areas near Lake Cumberland. At the surface, an area of sfc high
pressure was centered in the mid MS Valley with another sfc ridge
extending from the Great Lakes to upper OH Valley. In between a
weak sfc trough/frontal zone extended into VA to the Lower OH
Valley and then north to a low pressure system in
Alberta/Saskatchewan. Locally, near the trough/frontal zone sfc
dewpoints were higher than 24 hours ago with temperatures a few
degrees milder on average. Valley fog was again present per
satellite imagery along the Big Sandy, Kentucky, and Cumberland
River and their forks as well as large tributaries and lakes in
their reach.

Today, the boundary/sfc trough is expected to become diffuse with
the stronger sfc high over the Great Lakes become dominant and
merging with the sfc high in the mid MS Valley area leading to a
sfc ridge extending from the eastern Great Lakes to OH Valley and
mid MS Valley south to the northwest Gulf of Mexico through
evening. This will occur as the upper low to the northeast of
eastern KY continues to gradually work northeast with the
associated upper trough axis working east of the Northeast to Mid
Atlantic coast with Milton also moving east of the Fl peninsula
to the north of the Bahamas. A gradual trend of rising heights is
expected today across the OH Valley as upper level ridging builds
into portions of the eastern COnus including the OH Valley and
Appalachians region. This will continue tonight and into Friday
morning with 500 mb heights forecast to continue to rise through
midday on Friday across the area. Late in the period,
disturbances/shortwaves moving around the ridge will lead to its
continued flattening and more neutral 500 mb height tendencies in
the OH Valley. Accompanying the trend of rising heights today and
into Friday, the airmass will dry with the 00Z HREF ensemble mean
having mean PW forecast dropping to the 0.3 to 0.5 inch range
areawide through late afternoon and evening, drying further to 0.2
to 0.4 tonight and then changing little or having a slight
increase for Friday.

Valley fog may increase in coverage a bit through day, before
gradually mixing out/lifting/disipating by the 9 to 10 AM EDT
timeframe. Sunny skies are expected again as the entire column
becomes drier today. Mixing and some dry advection as well should
result in dewpoints during peak mixing dropping into the mid 30s
to around 40 range. This will result in min rh in the upper 20s to
mid 30s percent ranges for most today. Sfc and upper high pressure
will dominate tonight and into Friday, with fog along the rivers
and larger tributaries and lakes anticipated. Locations removed
from the larger bodies of water should drop into the mid 30s with
some of the normally coldest spots nearing 32 or 33. This may
result in patchy frost in these areas nearer to and in the head
of drainages/hollows late tonight to early on Friday. Fog and
frost will lift and dissipate on Friday, with a bit of moderation
in temperatures while the airmass remains dry and changes little.
Peak mixing afternoon dewpoints into the 30s will again be common
with min rh generally between 25 and 35 percent anticipated.

For both this afternoon and Friday afternoon, the NBM
deterministic dewpoints seemed unrealistically high and downward
adjustments were made areawide in coordination with surrounding
offices. Forecast values were more in line with the lower
percentiles of the NBM with some Consshort and HRRR blended in and
resulted in values nearer to MAV MOS.


.LONG TERM...(Friday night through Wednesday)
Issued at 409 AM EDT THU OCT 10 2024

High pressure looks to deliver warm temperatures for the upcoming
weekend, with highs in the upper 70s; the warmer of the two days
looks to be Sunday. Winds will be light and out of the southwest
Saturday. Lows will generally be in the upper 40s to lower 50s.

Sunday, southwesterly winds will pick up and veer to more of a
westerly wind through the day. Winds will be 10-15 mph with gusts up
to 20 mph during the afternoon. This coincides with an approaching
cold front, and deepening upper level low, that may produce
scattered rain showers across eastern Kentucky into the evening.
Lows Sunday night will be slightly cooler in the mid 40s.

Once the cold front moves through A big cooldown in temperatures is
being forecasted by models and ensembles. Highs Monday will be
notably cooler, in the upper 50s to lower 60s across eastern
Kentucky. Winds will have veered to a northwesterly to northerly
direction, reinforcing the Canadian air mass with cold air
advection. Models such as the GFS and the Euro have 500mb heights
under or around 540dm, which is one of many good indicators of a
column of air that is cold enough to support temperatures around
friezing. Lows are being forecasted in the lower 30s to the
valleys, with ridgetops in the upper 30s. Widespread frost is
possible Monday night, and more so Tuesday night, which may lead to
any uncovered outdoor plants or garden items dying.

A ridge of high pressure starts to build into the region by midweek,
with the ridge axis over eastern Kentucky Thursday morning. A slight
warmup in daytime temperatures heading into the end of the week.
Overnight lows Wednesday morning will still be cold enough in the
30s to support areas of frost.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 745 AM EDT THU OCT 10 2024

High pressure will remain in control through the period with VFR
largely prevailing. VFR is expected throughout the period for all
the TAF sites. However, deeper valleys will experience fog through
13Z to 14Z with reductions to MVFR and IFR, if not locally lower
initially for locations such as K1A6 and KI35. The potential for
valley fog with generally MVFR to IFR reductions should return to
end the period in the 04Z to 12Z Fri period, but TAF sites are not
expected to be affected at this time. Winds will be light and
variable to begin the period, before trending to the east to
northeast from 14Z to 23Z between 4 and 8KT for the TAF sites,
before again becoming light and variable to end the period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...JP
SHORT TERM...JP
LONG TERM...GINNICK
AVIATION...JP