-- Discussion containing changed information from previous version are highlighted. --
439
FXUS63 KJKL 241451
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1051 AM EDT Mon Jun 24 2024

.KEY MESSAGES...

- A fleeting sampling of drier and somewhat cooler air will be
  noticed today.

- Heat and humidity climbs Tuesday and Wednesday before another
  cold front arrives with a decent shot at thunderstorms
  Wednesday evening.

- The midweek cold front will be less impressive, with even hotter
  weather expected to make a comeback by Friday and Saturday.

&&

.UPDATE...
-- Changed Discussion --
Issued at 1051 AM EDT MON JUN 24 2024

The surface analysis this morning reveals that a cold front has
moved south of the area and high pressure has pushed into the Ohio
Valley in the wake. This leading to mostly sunny skies and cooler
northwest flow. Outside of some minor updates for the latest obs
and trend this was a very minor update.

UPDATE Issued at 803 AM EDT MON JUN 24 2024

Cold front is exiting into far southwest Virginia at 1145z.
Lingering areas of fog and low cloud cover will lift into a fair
weather cumulus field later this morning and persist into the afternoon.
Going forecast has the current trends well captured and was only
adjusted to incorporate the latest observations.
-- End Changed Discussion --

&&

.SHORT TERM...(Today through Tuesday)
Issued at 416 AM EDT MON JUN 24 2024

Cooler and drier air continues to slowly filter into eastern
Kentucky early this morning behind the passage of a cool front.
Rainfall varied widely from nothing to over an inch. Fog has formed
in many locations, especially in valleys, where rainfall occurred.
Temperatures presently range from the upper 60s in the cooler
northern valleys and in the lower to middle 70s elsewhere. At 730z,
a surface analysis suggests that the poorly defined cold front is
pressing southeast of the Hal Rogers Parkway/Highway 80 corridor. A
500H analysis shows a trough axis extends from the Ottawa Valley
down into the Mid-Ohio Valley/Central Appalachians. Further west, a
positively-tilted, upper-level ridge axis extends from an ~593
dam high centered over New Mexico, northeastward through the
Central Plains into Northern Ontario and is reflected at the
surface by high pressure extending from the Upper Midwest down
into the Mid-Mississippi Valley.

The 500H trough over our region will shift off to the east today
while the upstream ridge axis will drop southeastward and cross the
Ohio Valley late tonight. Precipitable water falling to between 0.6
and 0.8 inch and 850 mb temperatures falling to between 13 and 16C
will allow for a very comfortable late June afternoon. Heading
into tonight, the corresponding surface high crests over the
eastern Kentucky Coalfields around 3z tonight; with weak westerly
return flow commencing by early Tuesday morning and continuing
throughout the day tomorrow. This will buoy 850mb temperatures
back to around 20C by late in the day. The next trough will drop
into the Great Lakes late Tuesday evening/night, sending another
cold front toward eastern Kentucky early in the long-term.

In sensible terms, look for patchy low clouds and fog (especially
in southeastern valleys) this morning. After sunrise, the fog
should lift and the patchy low clouds will become an extensive
cumulus field. It will be cooler and less humid with highs in
lower to middle 80s. Mostly clear skies follow for tonight along
with fog forming in the favored valley locales and low
temperatures in the mid 50s cooler northern hollows to the mid
60s on the thermal belt ridgetops/slopes. Abundant sunshine and
hotter temperatures follow on Tuesday with highs in the upper 80s
and lower 90s. However, moderate dew points in the lower to middle
60s will prevent the heat from being to oppressive -- heat
indices generally peak in the upper 80s to lower 90s.

.LONG TERM...(After midnight Tuesday night through Sunday)
Issued at 610 AM EDT MON JUN 24 2024

Pattern aloft is best described as low amplitude and progressive
through the extended. The core of the westerlies remain generally
along the Northern Tier and Great Lakes with an occasional
incursion southward into the eastern CONUS. The first intrusion of
westerlies southward occurs on Wednesday as energy carves out a
trough that sweeps through the Ohio Valley late Wednesday into
Thursday. The second drop of the core westerlies southward is with
a second trough (low amplitude) at the end of the forecast
window, or possibly just beyond. Otherwise we fall under the
influence of persistent high pressure, or ridging across the
southern and especially southeastern CONUS. At the surface, our
area will experience the passage of a series of surface cold
fronts that appear to provide brief single day reprieves from the
summer heat and humidity, first on Thursday and then again on
Sunday...or the day after.

Sensible weather features a continuation of our seasonably hot
weather, with a temporary break in the heat from time to time
courtesy the passage of a series of surface cold fronts and the
increased threat of rain provided to the area with the passage of
each system. The exception will be Saturday where heat and
humidity will combine for a hot, muggy day (the warmest of the
period) along with scattered afternoon and evening showers and
thunderstorms. Hazards are limited to the heat throughout the
period and the potential of strong storms on Wednesday. The
Weather Prediction Center also include eastern Kentucky in an
excessive rainfall outlook for Wednesday.

For hazards, MLCAPES increase to around 1500 J/kg on Wednesday.
However, shear is marginal with bulk shear of 20-35 kts over
portions of the area. Thus it is difficult to imagine anything
more than some isolated severe storm potential unless these
environmental parameters change. PWATS, while elevated are not
impressive and only approach the 90th climatological percentile.
In addition, the bulk of energy and dynamics with this mid week
system remain generally to our north. Consequently, at this time
our most likely threat would appear to be from the heat. That
being said, afternoon highs on Saturday rise into the low to mid
90s. NBM guidance has tended to be high based on recent trends.
Combined with surface dew points in the mid 70s, heat indices
would climb to around 100 degrees, possible higher on
Saturday...again, at this time the hottest day during the extended
period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 803 AM EDT MON JUN 24 2024

Fog and and patchy low clouds are lifting at TAF issuance and will
become an extensive cumulus field later this morning and afternoon.
High pressure, light winds, and clear skies will set the stage for
fog to develop in the river valleys and possibly impact one or
more TAF sites late. Otherwise, expect VFR conditions to prevail.
Winds will be northwesterly around 5 kts or less today then
become light and variable tonight.

&&

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

$$

UPDATE...DJ
SHORT TERM...GEERTSON
LONG TERM...RAY
AVIATION...GEERTSON