-- Discussion containing changed information from previous version are highlighted. --
481
FXUS63 KJKL 181535 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1135 AM EDT Tue Jun 18 2024

.KEY MESSAGES...

- Hot weather persists through the week. Afternoon heat indices
  may peak around 100 at some locations. A few thunderstorms will
  be possible this afternoon, otherwise it will be dry through
  Friday.

- The upper level high/ridge bringing our heat wave will weaken
  next weekend and allow a cold front to move into the area,
  possibly bringing thunderstorms Sunday and Monday.

&&

.UPDATE...
-- Changed Discussion --
Issued at 1135 AM EDT TUE JUN 18 2024

15Z sfc analysis shows moderately strong high pressure in place
over eastern Kentucky late this morning. A cu field is developing
on track through the area as temperatures warm in this moist air
mass. Currently, readings have soared into the low and mid 80s
most places while dewpoints hover in the lower 70s amid light
southwest breezes. Still can`t rule out a stray shower or storm
later this afternoon despite the high 5h heights in place.
Temperatures are on course to hit the low 90s for highs while
heat indices top out in the 95 to 100 degree range for most. The
forecast has been updated mainly to add in the current obs and
trends for the T/Td/Sky grids along with removal of fog mention
from the text products. These minor adjustments have been sent to
the NDFD and web servers along with a freshening of the zones and
SAFs.

UPDATE Issued at 718 AM EDT TUE JUN 18 2024

The forecast is on track. Just blended in latest observations with
the forecast for continuity purposes.
-- End Changed Discussion --

&&

.SHORT TERM...(Today through Wednesday)
Issued at 317 AM EDT TUE JUN 18 2024

An unseasonably strong upper level low remains positioned over
central Canada. Broader troughing is found west of the Rockies,
while a stout upper level ridge is centered over North Carolina.
At the surface, high pressure is seen across the western Atlantic,
with ridging fanned west across the Eastern Seaboard. A remnant
quasi-stationary boundary is aligned from the Great Lakes through
portions of the Midwest, before transitioning to more of a warm
front through the central Plains. This warm front is tethered to
stronger low pressure for this time of the year across portions of
the Front Range and High Plains region. Partly cloudy to mostly
clear skies are currently in place over eastern Kentucky,
following an afternoon and evening of convection, some of which
was on the stronger-side at times. Current temperatures range
from the upper 60s to lower 70s.

The models remain in excellent agreement through the short term
period, still depicting a strengthening and expanding upper level
ridge that will move north, generally residing from New England
through the Upper Ohio Valley by late Wednesday. At the surface,
high pressure will also expand west with time, allowing for
backing low level flow to the southeast and east, leading to at
least some humidity relief across our area by Wednesday.
The HREF has trended higher with rain probabilities for today over
the past 3 runs; however, given the rising 500 mb heights and
generally lowering PWATs, will only maintain some slight chance
(20%) PoPs across the majority of the area for this afternoon, as
capping may be stronger in reality than currently shown in
forecast soundings. Cloud cover looks to be more prevalent today,
which will keep highs just a bit cooler compared to yesterday,
generally around 90 degrees. Any stray convection that manages to
fire up this afternoon will diminish quickly towards dusk this
evening, with partly cloudy skies overnight and lows ranging from
the mid 60s in the cooler valleys, to around 70 atop the ridges.
Stronger capping will keep a lid on all convection on Wednesday,
with highs back in the lower 90s, although dew points will lower
to the mid to upper 60s, keeping higher heat indices in check.

.LONG TERM...(Wednesday night through Monday)
Issued at 234 AM EDT TUE JUN 18 2024

Models continue in good agreement for the pattern that will affect
our area during the long term period. Strong upper level high
pressure is expected to be centered over the Mid Atlantic states
ridging west southwest over our area through Friday. Surface high
pressure/ridging will be displaced slightly to the southeast. Our
low level flow will emanate from this high/ridge, crossing the
Appalachians and not having trajectories over the warm gulf, and
this will keep dew points from being too excessive. Meanwhile, the
upper level high will bring subsidence and warm temps aloft. This
combination should prevent deep convection, despite the early season
hot temperatures which are expected.

As we move into the weekend, the upper level ridge will break down
and an upper low/trough is forecast to move east to the upper Great
Lakes, sending the southern edge of the prevailing westerlies aloft
back south to our area. At the surface, our flow out of the high
will break down and become amorphous on Saturday. The upper level
system to our north will support a cold front which will approach
the Ohio Valley late Sunday, and our low level flow should then
become southwesterly. As the flow out of the surface high breaks
down, our air mass should begin to modify and see dew points creep
higher on Saturday, followed by advection of moisture into the area
ahead of the front late in the weekend. Along with slight cooling
aloft as the ridge breaks down, the combination may allow for a few
thunderstorms during the weekend. However, the best shot at rain is
on Monday when the cold front should arrive and provide a focus for
development.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 708 AM EDT TUE JUN 18 2024

Isolated convection is possible during the afternoon into early
evening hours today, though confidence is quite low as to timing
and location of storms. Given the isolated nature, just going with
VCTS at this time. Would not be surprised if there was very
little to no convective activity, either. Winds will average less
than 5 kts through the period. The typical valley fog is likely
late tonight, likely only impacting TAF sites significantly
if/where rain occurs this afternoon.

&&

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

$$

UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...HAL/CMC
AVIATION...CMC