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796
FXUS63 KJKL 240157
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
957 PM EDT Sun Jun 23 2024

.KEY MESSAGES...

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

- 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.
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&&

.UPDATE...
-- Changed Discussion --
Issued at 957 PM EDT SUN JUN 23 2024

Cold frontal boundary is just about to enter the forecast area
from the northwest. A few showers/thunderstorms persist just
ahead of the front as our initial round this evening is about to
exit east out of the state. Have updated sky conditions for
tonight based on latest obs and model runs. Decreasing clouds and
ample surface moisture going into the night would favor fog.
However, advection of cooler and drier air into the area behind
the front will fight against fog development. Given the opposing
forces, the extent of fog development is still uncertain. Fog is
the most likely in valleys in southeast KY where it is hardest to
scour out an air mass at night, and where the drier air will be
latest to arrive.

UPDATE Issued at 729 PM EDT SUN JUN 23 2024

Some of the greatest precip coverage has developed in our
southern counties, and the likely POP has been expanded to cover
that area this evening.
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&&

.SHORT TERM...(This evening through Monday night)
Issued at 313 PM EDT SUN JUN 23 2024

The surface analysis this afternoon shows a cold front pushing
toward the Ohio River and low pressure pushing into the New England
region. There is a mid- and upper level trough axis noted and will
lead to some height falls through the afternoon and evening. A line
of left over convection and mostly sprinkles now has pushed toward
far southeast parts of Kentucky this afternoon. We are starting to
see shallow convection develop this afternoon amid increasingly
unstable region mainly northwest of eastern Kentucky. These seem to
be having trouble develop amid capping and increased cloud cover.
SPC did put out and MCD this afternoon highlighting the threat of
severe weather mainly in the form of severe wind gusts for areas
primarily along and north of I-64. The latest trends in the
mesoanalysis data show MLCAPE of of around 1000-1500 J/kg building
into the area amid a less than ideal 20-30 knots of effective
shear. If cells can develop into multicell clusters this could
help promote stronger updrafts, with notable dry air in the mid-
levels that could aid in strong winds gusts given the 90th
percentile 850mb jet for this time of year. However, mesoanalysis
is also showing more ideal DCAPE remains mostly north and west of
I-64. The CAMs want to build activity through the afternoon and
evening, with the experimental MPAS model data showing clusters of
storms mainly later this afternoon and early evening. Leaned
toward the NBM mostly for PoPs with some modifications given it
seemed bullish in the southeast.

This cold front will lag behind the convection expected this
afternoon and evening. Therefore, the front will pass through late
tonight into early morning on Monday. This could spark off a shower
late tonight into early Monday morning, but there remains lots of
uncertainty this will happen as we quickly loose better moisture.
The convection will decrease through the evening and clouds are
expected to clear some through the night. This would lead to a
degree or 2 difference from the Ridges and valleys. There is also
some uncertainty on the amount of fog we see tonight, as there is
uncertainty on the coverage a amounts of rainfall. Even so, valleys
will have a shot of seeing patchy to areas of fog tonight.

Monday will certainly be one of the better days of the week, with
PWATs in the HREF of less than 1 inch. This decrease in moisture,
northwest flow, and high pressure will lead to sunny skies and
seasonable temperatures with highs in the low to mid 80s. This high
pressure and clear skies will go into Monday. Given the dry day
Monday, we will see a little more notable temperatures split of 5
degrees or a little more. This will also lead to another period
of fog in the valleys late tonight into Tuesday morning.

.LONG TERM...(Tuesday through Sunday)
Issued at 330 PM EDT SUN JUN 23 2024

The extended period will start off with an extensive ridge of high
pressure centered over the southwest CONUS and southern Plains.
The ridging will extend northward up the West Coast and into the
Pacific Northwest and into the western Gulf of Mexico on Tuesday.
A fast moving trough of low pressure will make its way east
through the Great Lakes and upper Ohio Valley, with a stronger
trough exiting extreme northern New England into the open
Atlantic. Weaker ridging will be in place across the Tennessee
Valley and Gulf Coast states to begin the period. The models were
in pretty good agreement with this starting set up and were
showing a general eastward progression of a cold front extended
southward from the northern trough and into the Ohio and Tennessee
Valleys Tuesday night and Wednesday. That will be the period where
we see our best rain chances in the extended, as the front moves
through and interacts with a northward surge of warm, moist air
off the Gulf of Mexico. A line of showers and storms is progged to
advance through the region from very late Tuesday night, through
the day on Wednesday, as the cold front moves through and then
slow greatly late Wednesday. In fact, the boundary may even stall
out near the VA border, and keeping scattered showers and storms
around the end of the day on Thursday for our southeastern
counties.

Once the first cold front moves away, another ridge of high
pressure will move in and bring another period of hot and muggy
weather to eastern Kentucky Thursday and Friday. We could see
highs on those days in the low to mid 90s. The ridge will bring
conditions favorable for modest ridge valley temperature
differences to the area Tuesday night, Thursday night, and Friday
night. Another area of low pressure will bring another round of
rain and storms to the area Saturday through Sunday. The primary
weather concerns in the extended will be how strong any storm we
see on Wednesday are able to become and the hot and muggy
conditions that will be returning on Friday and Saturday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 814 PM EDT SUN JUN 23 2024

A cold front is approaching and will move through the region
tonight. A broken line of thunderstorms ahead of the front is
currently moving east through the forecast area at 00Z and will
exit east out of the state by 03Z. Another area of more sparse
thunderstorms closer to the front was in central KY. As these move
east they will keep a potential for thunderstorms over our area
later into the night, even after the initial round leaves. The
passage of the front will put an end to any precip from northwest
to southeast between about 02-06Z. The heavier precip may briefly
bring IFR conditions, but outside of the precip mainly VFR
conditions are forecast.

Fog is forecast to develop in valleys overnight, especially in
southeast KY, but the extent of the fog is uncertain. Moisture
will be present from earlier precip, but drier air will be trying
to advect into the area behind the front, fighting the fog. Have
opted not to include it at TAF sites at this point. Fog will
dissipate on Monday morning and leave VFR conditions through the
remainder of the period.

&&

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

$$

UPDATE...HAL
SHORT TERM...DJ
LONG TERM...AR
AVIATION...HAL