642
FXUS63 KJKL 261856
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
256 PM EDT Wed Jun 26 2024

.KEY MESSAGES...

- Heat and humidity lingers today with heat indices peaking
  between 90 and 100F.

- The next high probability (60-80% chance) of rain comes today
  into this evening with a cold front.

- A few strong to severe storms are possible this afternoon and
  evening, with damaging wind gusts the primary threat.

- Hotter weather is expected to make a comeback by Friday and
  especially Saturday, with afternoon highs in the low to mid 90s
  and heat index values peaking around or in excess of 100F.

&&

.SHORT TERM...(This evening through Thursday night)
Issued at 256 PM EDT WED JUN 26 2024

Current surface analysis is pretty busy as there`s multiple
disturbances moving across the eastern CONUS. The most significant
of them is a surface low moving across the Upper Great Lakes.
Extending southwest from the occluding low is a stationary front.
Also, riding along the boundary is another surface low moving out of
the Ozarks. All of this is forecast to move toward the Commonwealth.
Locally, a weak line of showers is moving across the northern tier
of counties with a couple weak echos showing up along the Mountain
Parkway. Also, temperatures across the area are already climbing
into the upper-80s to low-90s which will maximize ahead of the cold
front.

This afternoon brings an upper-level trough that`ll pivot southeast
toward the CWA this afternoon. That pivoting will push that
aforementioned surface low and cold front toward the Commonwealth.
The SPC has increased our severe weather risk to include much of the
entire CWA minus a few cities along the KY/TN border. Forecast
soundings from across the area continue to show somewhat favorable
severe weather indices. Both MUCAPE, SBCAPE and DCAPE are all
favorable for severe storms, steep low-level lapse rates are in
place as well. Significant shear is slightly lacking but there`s
enough out there to favor a few longer lasting storms. Lastly, PWs
continue to run about 2" which if a storm is efficient enough will
allow for some heavy rainfalls. The front will slowly track through
the area this afternoon and overnight hours before exiting early
early tomorrow morning. Widespread fog is possible tomorrow morning
but will burn off with increasing daytime heating.

Height rises ahead of surface high pressure is expected to build
into the region for Thursday morning and persist through the
remainder of the forecast period. Temperatures for Thursday will be
slightly cooler with highs climbing into the mid-80s and overnight
lows dropping into the upper-50s to low-60s which will bring an end
to an active period.

.LONG TERM...(Thursday night through Tuesday)
Issued at 451 AM EDT WED JUN 26 2024

The 26/00z model suite is in fairly good synoptic agreement through
the long-term period. A forecaster analysis initially shows a
longwave 500H trough extending from a parent ~534 dam low over
Davis Strait down through eastern Canada and into the
Northeast/Mid-Atlantic US. Further west, an elongated ~590 dam
high is found along the US/Mexico border with a ridge axis extending
northward across the Plains and into the prairies of southern
Manitoba/Saskatchewan. At the surface, a large but relatively
weak surface high, centered over the Great Lakes, dominates the
from southeast Ontario down through the Tennessee Valley.
Upstream, an ~558 dam Pacific low is found over the Alberta/
British Columbia/Montana triple-point with a corresponding
surface low over near/over the Black Hills. A upper-level
shortwave disturbance extends from the low southward across the
High Plains. A second disturbance over the Pacific Northwest is
rotating around the parent slow. Additionally, an ~558 dam
low/trough is found further upstream over the North Pacific.

The upper level high over the southwestern CONUS will slosh from
west-to-east through the long-term period while each of the
aforementioned lows/troughs translate across the northern half of
the CONUS. Across eastern Kentucky, the first upper level trough
will depart as heights rise on Thursday night and Friday while the
surface high passes into southern New England. Southerly flow
returns to the Ohio Valley on the back side of the high, causing 850
mb temperatures to rebound to near 20C on Friday. With those
rising temperatures, PWATs will also rise quickly to around 1.75
inches after starting the day near 1.00 inch. Spotty convection
may ignite off of the high terrain of the Central/Southern
Appalachians near peak heating, but rising heights will tend to
minimize coverage and intensity. The first upper-level shortwave
trough then approaches Friday evening with weak height falls; but
by that time, any associated convection will tend to wane due to
the loss of daytime heating. Heading into Saturday/Sunday, the
next upper level low/trough continues to ride the US/Canadian
border eastward while its surface reflection treks into the Upper
Great Lakes by Saturday morning and eventually down the St.
Lawrence Valley on Sunday. PWATs continue climbing to around 2.00
inches (near climatological maximums) on Saturday as the second
upper level shortwave passes, likely firing off more widespread
convection. A cold front, trailing the surface low, eventually
sinks through the Ohio Valley on Sunday with the highest rain
threat of the period. Behind this system, upper level ridging
briefly returns to the Ohio Valley region early next week. Brief
cooling and drying on Monday will give way to renewed heat and
humidity by Tuesday ahead of the next trough and cold front`s
arrival just beyond the end of the forecast period.

Sensible weather will feature a refreshingly cooler and less humid
Thursday night and Friday morning. Low temperatures are forecast to
range from the upper 50s in the northern valleys to the middle 60s
over the thermal belt ridges/slopes. As southerly flow returns,
building heat and humidity will boost temperatures back into the
upper 80s to lower 90s by Friday afternoon while heat indices
reach 90 to 100F. A stray shower or thunderstorm (10-30%) is
possible near the Virginia border during the afternoon and then
north of the Mountain Parkway during the evening or overnight.
Similarly, hot temperatures are expected for Saturday but will
feel more oppressive due to dew points rising into the lower and
middle 70s leading to heat indices of 100 to 105F. There is a
better chance (40-50%) for scattered showers and thunderstorms on
Saturday afternoon which may give some relief. The highest chance
(60-80%) of rain comes on Sunday with the passage of a cold front.
Nights are forecast to be muggy with lows ranging in the upper
60s to mid 70s for most locations. Behind the front, it will be
less muggy and cooler with Sunday night`s low temperatures
returning to the upper 50s to mid 60s. Mostly sunny, dry and
comfortable weather is expected for Monday with highs in the lower
to middle 80s before heat and humidity return on Tuesday as highs
return to the upper 80s and lower 90s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 130 PM EDT WED JUN 26 2024

VFR conditions are prevailing across all TAF sites and will
largely prevail over the next several hours. However, a cold front
diving toward the area will bring increased shower and
thunderstorm activity to all terminals mainly after 21Z/Wednesday.
Terminals could be impacted by strong thunderstorm winds during
cold frontal passage. Precipitation will persist through
06Z/Thursday before tapering off. Lowered CIGS into MVFR is
expected the front approaches the area. Once precipitation tapers
off, fog is forecast to develop bringing categorical MVFR to IFR
visibilities after 07Z and persist through 13Z before CIGS and VIS
improves slightly to MVFR for the remainder of the period. Aside
from thunderstorms winds, light and variable winds are expected
through much of the TAF period.

&&

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

$$

SHORT TERM...VORST
LONG TERM...GEERTSON
AVIATION...VORST