477
FXUS63 KJKL 261142
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
742 AM EDT Sat Jul 26 2025

.KEY MESSAGES...

- Heat indices will approach 100 degrees in many places each day
  through Wednesday, and could be in excess of 105 degrees on the
  warmest days--Monday through Wednesday.

- Scattered shower and thunderstorm chances return area-wide for
  this weekend.

&&

.UPDATE...
Issued at 742 AM EDT SAT JUL 26 2025

Widely scattered convection is noted on radar this morning with a
few rumbles of thunder over far eastern Kentucky. This activity
is serving as an appetizer for more widespread convection later
this morning and afternoon/evening. Otherwise, it is shaping to be
another hot and humid day with high temperatures not far from 90
degrees. Those temperature combined with dew points well into the
70s will lead to peak heat indices within a few degrees of 100 for
most locations.

UPDATE Issued at 1223 AM EDT SAT JUL 26 2025

With the absence of any convection as of 04z PoPs have been
lowered to below 15 percent for the remainder of the overnight
period. A shower or storm cannot be completely ruled out, however,
within a weak warm advection regime.

With several locations forecast to possibly see heat indices approach
or reach 105 degrees later today, a Heat Advisory or Special
Weather Statement may be needed later this morning.

UPDATE Issued at 932 PM EDT FRI JUL 25 2025

Made minor refinements to PoPs and Sky grids based on latest
observed trends, and utilized the most recent hourly observations
as the initialization for the hourly grid forecast.

UPDATE Issued at 658 PM EDT FRI JUL 25 2025

Extended low-end PoPs (generally 10 to 15 percent) well into the
overnight given sufficient instability plus the GFS depicting a
weak low-level southwesterly jet developing toward sunset
providing a little bit of extra warm advection. No other changes
otherwise.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 200 PM EDT FRI JUL 25 2025

The last full work week of July is coming to a close on a hot and
humid note. Thermometers across the JKL forecast area are ranging
mostly in the upper 80s to near 90F early this afternoon. An
extensive cumulus field has also developed, with a few of the more
robust towering cumulus maturing enough to produce small showers
or pin-prick sprinkles. The latest analysis shows a nearly
stationary cold front extending from the Canadian Maritimes
southwest over/near Lake Ontario and Erie and beyond into central
Missouri. Surface high pressure is centered northeast of the
Bahamas but continues to exert its calming influence into
southeastern Kentucky. The surface high is mirrored aloft by a
~596 dam high centered just a bit further northwest along the
South Carolina Coast. Broad, low amplitude ridging extends
northwest from the high across the heart of the nation, though a
vigorous vorticity max and shallow shortwave trough is noted over
the Central Plains.

Through the short-term period, the aforementioned disturbance
will ride east northeast and over the ~596 dam high while the high
itself retrogrades westward to near/over northern Georgia. A weak
wave of low pressure under the disturbance will track toward Lake
Erie and cause the stalled boundary to lift back north as a warm
front. Southerly return flow on the west side of the high (and in
the lows warm sector) will cause PWATs to continue rising into the
1.6 to 1.8 inch range by this evening, and then flirt with 2.0
inches for Saturday and Saturday night. Though the air mass will
be quite juicy, the only forcing mechanisms through Saturday night
appear to be weak upper-level perturbations riding around the 500
hPa high as well as strong differential surface heating. RAP13
MLCAPE values only peak in the 1,000 to 2,250 J/kg range today and
in the 1,500 to 2,500 J/kg range on Saturday. Weak mid-level
lapse rates and shear, as well as abundant mid-level dry air, are
likely to suppress updraft vigor. However, that dry mid-level air
does suggest that if a stronger storm core somehow developed,
there would be a chance of a downburst. Any deep convection could
produce a briefly torrential downpour, but the disorganized/scattered
nature of the convection would not suggest any substantial hydro
concerns at this time. Convective coverage is likely to peak each
afternoon and early evening, coincident with peak diurnal
destabilization, and be a little more widespread on Saturday.
However, an isolated shower or storm cannot be entirely ruled out
at other times of the day.

In sensible terms, look for hot and humid conditions to continue,
with afternoon high temperatures within a few degrees of 90F
while nighttime lows range in the lower to middle 70s. Dew points
in the lower to middle 70s will combine with those hot air
temperatures to produce maximum heat indices in the upper 90s to
lower 100s at most locations. There will also be isolated to
scattered thunderstorms each afternoon and evening. Nights and
mornings should be dry for most, if not all, of the area, but a
stray shower or storm still cannot be ruled out entirely during
those times.

.LONG TERM...(Sunday through Friday)
Issued at 459 PM EDT FRI JUL 25 2025

Our most dominant feature through most of the long term period will
be an upper level high which will start out in the vicinity of GA
on Sunday. It is expected to shift/build westward with time,
becoming most prominent over the lower/middle Mississippi Valley
by Tuesday. Although we will not be directly under the high, it`s
proximity will give us hot and humid conditions and very weak
flow aloft. Models also suggest that enough heat and humidity
will be present to fuel area of showers/thunderstorms around the
high, especially it`s periphery. However, with weak flow aloft
there would be very little movement of any showers/thunderstorms
for our area through early in the week, limiting their coverage,
with much of our local daily activity likely due to subsequent
development along outflows after initial development.

The upper high should weaken mid to late week, while the upper
level prevailing westerlies on the north side buckle and develop a
trough over southeast Canada and the northeast CONUS and a ridge
to the west. This would aid a surface cold front to move
southward and make it through our area. While both the GFS and
ECMWF show this, there is still some model to model and run to
run inconsistency on the timing and how far south the front goes.
At this point, the likely fropa timing for our area is in the
neighborhood of Wednesday night or Thursday. Along with the fropa
would come an increased POP, followed by drier weather with at
least some relief from heat and humidity late week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 720 AM EDT SAT JUL 26 2025

Patchy fog in the river valleys occurred again this morning, but
will have little impact of regional airfields. Isolated showers
were occurring this morning with additional showers or a storm
will possible into this afternoon thanks to continuing weak warm
advection across the area.

PROB30 groups have been included at most terminals beginning
between 17z and 23z Saturday, with scattered showers and storms
expected from midday into this evening.

Winds will remain variable to southwesterly around 6 kts or less
thanks to high pressure southeast of the region.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...GEERTSON
SHORT TERM...GEERTSON
LONG TERM...HAL
AVIATION...HATCH