832
FXUS63 KJKL 010710
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
310 AM EDT Wed May 1 2024

.KEY MESSAGES...

- Fog this morning mixes out after sunrise.

- Very warm Wednesday, followed by near-record highs on Thursday.

- Showers and thunderstorms return to the forecast Friday through
  Sunday.

&&

.SHORT TERM...(Today through Thursday)
Issued at 308 AM EDT WED MAY 1 2024

A very foggy start this morning for most of the forecast area; areas
along the escarpment are the exception as of this writing. However,
satellite trends show some subtle westward expansion of fog.
Therefore, there is still time for the likes of Somerset and
Morehead to experience fog. Conditions were ripe for fog given
rainfall that occurred during the day followed by clearing skies
and calm wind. While we will mix out nicely this afternoon
(temperatures soaring well into the 80s with dew points in the
50s), ensemble forecast soundings indicate the low-level
inversion will come roaring back overnight. Due to the anticipated
daytime mixing, we think the fog will be less widespread.
Therefore, we`ve introduced fog to the river valleys tonight to
start. This can be finessed further by day shift.

An upper-level ridge in place over the Southeast US amplifies on
Thursday, resulting in a hot afternoon. High temperatures will be
close to records. Jackson`s record is 87 set in 2012 while London`s
is 88 set in 1959. Relative humidities will plummet in the
afternoon which raises a non-zero fire weather concern (similar
conditions today, though RH value will be slightly higher). Of
course, recent rain will squelch the concern overall, as will
light wind.

One last item to consider on Thursday is a non-zero chance of an
isolated pop-up thunderstorm. The forecast remains dry at this time,
but this possibility was noted in the CAMs. Dew points in the 50s
will result in significant dew point depressions which will be
challenging to overcome. Ensemble soundings indicate marginal
instability of about 500j/kg and virtually no shear. However,
convective temperatures will likely be met which could afford at
least some cumulus clouds attempting to bubble up. Forcing may come
in the form of a weak perturbation rippling atop the ridge, ahead of
an incoming trough digging in over the lower Mississippi River
Valley.

.LONG TERM...(Thursday through Tuesday)
Issued at 327 PM EDT TUE APR 30 2024

The period begins with good agreement in the deterministic and
ensembles on the mid-level ridging the Southeast US and high
pressure off toward the Atlantic Coast line. This will keep the
weather quiet, with very dry low levels and capping inversion
aloft. This could lead to some flat cumulus in the afternoon, but
very warm afternoon high temperatures in the mid-80s to near 90
degrees. This could eclipse record high temperatures, with JKL 87
degrees set in 2012 and LOZ 88 degrees set in 1959. The ridging
does push east as a mid-level wave rides toward the Ohio Valley
Thursday night into Friday. This will aid in giving way to showers
and thunderstorms Friday afternoon, as moisture surges northward
and small amount of instability comes with it. This as multi-model
ensembles show 40-50 percent chance of greater than 250 J/kg of
CAPE.

Overall guidance, including ensembles are in good agreement with
best chance of rain (around 60-70 percent) Friday night into
early Saturday. There seems to be a little uncertainty on Saturday
in terms of timing, with first wave and next shortwave pushing
into the Midwest, Saturday night into Sunday. The deterministic
and ensemble data are disagreeing on the amplitude of this wave
too and leads more uncertainty by late weekend into early next
week. Particularly as there could be some shortwave ridging in
between these features. Therefore, the PoPs drop back into the
40-50 percent range mainly in the afternoon hours Sunday into
Tuesday. It will remain 10 to 15 degrees above normal through this
time range.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 118 AM EDT WED MAY 1 2024

Highly variable conditions are noted at the TAF sites as of this
writing. Fog has developed through the valleys per RGB satellite
imagery. An expansion westward is noted beyond JKL and LOZ.
Therefore, I do think all sites will see some BR or FG through the
early morning hours. Confidence in time of arrival (for those
VFR or MVFR) is low. Conditions improve after sunrise, but fog is
probable again early Thursday morning and will need to be wrestled
into the next TAF issuance.

&&

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

$$

SHORT TERM...BROWN
LONG TERM...DJ
AVIATION...BROWN