338
FXUS63 KJKL 112027
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
427 PM EDT Tue Jun 11 2024

.KEY MESSAGES...

- Slightly cooler than normal to near normal temperatures,
  comfortable humidity, and pleasant weather will hold through
  tomorrow.

- Hot weather arrives late this weekend, with highs in low to mid
  90s and heat indices peaking out around 100 degrees at some
  locations on Sunday and Monday.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 427 PM EDT TUE JUN 11 2024

Short term is fairly straight forward. Pattern aloft will become
less amplified as the core westerlies retreat northward to wards
the Northern Tier. At the surface, high pressure will be centered
over the Commonwealth one more night before shift off to the east
Wednesday. Return southerly flow around the western periphery of
the surface high will initiate a warm up beginning Wednesday.

Sensible weather features dry, fair weather for the short term.
With dry air in place (surface Tds generally around 50) and mostly
clear skies, temperatures will drop off quickly in our sheltered
valley locations tonight. Guidance has temperatures falling into
the mid 40s tonight in our cooler valley locations. Elsewhere
temperatures will fall into the mid 50s, especially along our
thermal belt. Boundary layer moisture will begin to increase
Wednesday with return flow, but Tds will only climb back into the
mid to upper 50s. At least that will make for relatively
comfortable weather Wednesday as afternoon high temperatures climb
back up into the 80s. However, moisture return will be enough
that fog will become a bit more prevalent Wednesday night in our
valley areas, especially where a readily available water source
(lakes, rivers, streams) is nearby. We should experience a great
ridge valley split Wednesday night as well, with the thermal belt
only dropping into the lower 60s for overnight lows, while the
cooler valleys drop into the low to mid 50s, especially across our
east.

.LONG TERM...(Thursday through Tuesday)
Issued at 427 PM EDT TUE JUN 11 2024

The period will start with upper level ridging over the southwest
CONUS, very weak troughing over the southeast CONUS, and fast
relatively zonal flow immediately to the north from the Pacific
Northwest to New England and the Mid Atlantic states. Broad
surface ridging will extend from TX to the Mid Atlantic states.
Although little in the way of low level advection will be
occurring in our region, continued rising geopotential heights and
air mass modification will result in further rises in temperature
and dew point on Thursday.

A couple of shortwave troughs moving through the flow to our
north will bring a return of upper level troughing over the
northeast CONUS by Friday, while at the same time the southwestern
ridge begins to move east. The resulting northwest flow aloft
over our area will send another cold front through on Friday. The
GFS and ECMWF generate some very light precip with the front, but
forecast soundings look only marginally supportive of convection.
Will opt to include nothing more than a 20% POP. Unlike recent
frontal passages, the cool and dry air mass behind this front will
skirt by our area, remaining mostly to our northeast.

By Saturday, the northeast CONUS trough will be departing
eastward and the aforementioned upper ridge will be building into
the Ohio Valley and southeast CONUS. This brings us continued dry
weather with climbing temperatures and dew points during the
weekend.

Model differences come into play on Monday and Tuesday concerning
the evolution of the upper ridge. The ECMWF holds onto the upper
level ridge and strengthens it with a center over the central
Appalachians on Monday and Tuesday, resulting in continued dry and
hot weather. However, some recent runs of the GFS move the upper
ridge axis to our east and develop very weak, broad troughing to
our west, with a weak southerly flow in between sending a plume of
deep tropical moisture northward over KY. This would be
supportive of unorganized, slow moving thunderstorms, with clouds
and precip restricting high temperatures somewhat. The GFS
ensemble mean looks like a compromise. With all that said, a model
blend/compromise seems like the best path to go down at this
time, with only minimal POPs on Monday and Tuesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 115 PM EDT TUE JUN 11 2024

CU field that developed across our far east and provided some
temporary MVFR CIGS is showing signs of eroding as drier air
continues to mix down through the boundary layer. However, VFR
CIGS (030-035 AGL) will continue to impact SJS for a another hour
or so into the new forecast period, probably no later than about
20Z. Otherwise, VFR flight conditions are expected outside of the
most sheltered valley areas where fog will develop late tonight
into Wednesday morning. Valley fog is not expected to impact any
terminals at this time. There will be an increase in thin high
level clouds overnight into Wednesday. Light winds are expected
through the period, averaging less than 5 kts but having a
predominant north-northeast flavor in general.

&&

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

$$

SHORT TERM...RAY
LONG TERM...HAL
AVIATION...RAY