505
FXUS63 KJKL 020738
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
338 AM EDT Tue Jul 2 2024

.KEY MESSAGES...

- Temperatures 5 to 10 degrees below normal will continue through
  tonight, before temperatures warm to near or slightly above
  normal on Tuesday.

- Humidity will increase through midweek and afternoon heat
  indices may approach 100 in some locations Wednesday through
  Friday

- The potential for showers and thunderstorms returns by Thursday,
  Independence Day, and lasts through the weekend. The highest
  probability of rain is on Thursday and Friday.

&&

.UPDATE...
Issued at 1145 PM EDT MON JUL 1 2024

No significant changes to the forecast with just the inclusion of
the latest obs and trends for the T/Td/Sky grids with this update.
These minor adjustments have been sent to the NDFD and web servers
along with a freshening of the zones and SAFs.

UPDATE Issued at 740 PM EDT MON JUL 1 2024

23Z sfc analysis shows pleasant high pressure in place over the
region providing for light northeast winds and mostly clear skies.
Temperatures were 10 to 15 degrees cooler today than yesterday
thanks to this air mass change along with much dry conditions.
Currently, temperatures are running in the mid 70s while dewpoints
are noted in the comfortable upper 40s to lower 50s, most places.
Have updated the forecast mainly to just add in the latest obs and
trends for the T/Td/Sky grids. These minor adjustments have been
sent to the NDFD and web servers.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 410 PM EDT MON JUL 1 2024

Late this afternoon, an upper level ridge extended from portions
of the Southern Plains/Arklatex region northeast into the mid MS
Valley to Great Lakes regions. Meanwhile, an upper level trough
axis extended from western Canada across MT and portions of the
Northern Rockies into southwest Conus. At the surface, a ridge of
high pressure extended from the Great Lakes to the OH Valley to
Arklatex regions. Behind the front that crossed the region on
Sunday, the high has ushered in a cooler and drier airmass and
only a few passing cirrus were moving across the region at
present. Highs so far today have been 5 to 10 degrees below normal
for early July.

Tonight and Tuesday, the upper level ridge is expected to build
across the Southeastern Conus with the axis of the 500 mb ridge
remaining west of eastern KY. However, the sfc high pressure ridge
will slide to the eastern seaboard through Tuesday evening.
Meanwhile, the trough extending across the western Conus at
present will move east into the upper MS Valley to Plains region
to the south of an upper level low that evolves from Saskatchewan
and into Manitoba to far western Ontario. Tuesday night, the axis
of the ridge will gradually shift to the east of the area as the
upper low reaches the northern Ontario/James Bay vicinity and an
associated shortwave trough reaches the western Great Lakes to mid
MS Valley areas. The cold front associated with this system will
remain well northwest of the area through the short term period.

The high shifting east across the Great Lakes and the OH Valley
region tonight, will lead to another night with low temperatures
on the order of 5 to 10 degrees below normal. As this high moves
further east on Tuesday, return flow will begin to usher a warmer
and more moist airmass into eastern KY. PW is forecast to rise
from present levels of below 0.50 inches to about 0.65 inches in
the southeast to around 1 inch near Lake Cumberland near dawn on
Tuesday per the HREF mean and then further to around 0.9 to 1
inch east and southeast to about 1.3 near Lake Cumberland on
Tuesday evening followed by an increase to 1 to 1.3 inches
areawide by late Tuesday night.

The pattern will favor a moderate ridge/valley temperature split
with afternoon min dewpoints in the upper 40s to low 50s
supporting some lows in eastern and northeastern valleys in the
low 50s with a 49 or so in some of the typical cold spots. Fog
should also form not long after midnight along the larger creeks
and especially portions of the Big Sandy and Kentucky Rivers as
well as lakes in those basins. Temperatures will warm up nearly 10
degrees from what has been observed so far today on Tuesday with
some fair weather cumulus probable by the afternoon as moisture
increases. Any cumulus that develops on Tuesday should dissipate
by sunset on Tuesday evening and with the upper ridge axis working
across the area yet another ridge/valley split should occur with
a lesser magnitude than tonight. Valley fog should again occur,
but may be more confined to right along the rivers.

.LONG TERM...(Wednesday night through Monday)
Issued at 338 AM EDT TUE JUL 2 2024

An active forecast period is expected as multiple disturbances are
expected to move across the area. At the start of the forecast
period, an upper-level shortwave is forecast to be tracking across
southern Canada with a surface low and associated cold front moving
through the Great Lakes. The aforementioned cold front will be on
the doorstep of the CWA at the start of the forecast period with
increasing showers and storms Wednesday night into Thursday morning.
Upper-level flow is forecast to outrun the front thus leaving a
stationary boundary draped across the CWA. To the west, another
shortwave is forecast to develop over the mid-Mississippi Valley
with surface cyclogenesis occurring. Models are in agreement with
this low moving northeast into the Great Lakes while dragging a cold
front through the Commonwealth beginning early Friday morning and
persisting through the day Friday before the front slowly exits by
Saturday afternoon. Between the two fronts moving through the area,
forecast QPF through 00Z Sunday is expected to range from over an
inch in the Bluegrass to two-thirds of an inch near the KY/VA/TN
state line. High pressure builds into the region for Sunday into
Monday before another upper-level shortwave brings another front
through the area beginning Monday afternoon and continue through the
end of the forecast period.

Overall, the period will highlighted with periods of showers and
thunderstorms. Temperatures will return to more seasonal ranges as
daytime highs in the mid-80s to low-90s and overnight lows ranging
from the upper-50s to upper-60s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 300 AM EDT TUE JUL 2 2024

Fog was evident developing in some valleys at the start of the
period, but was not affecting any reporting airports. The fog will
continue to spread in valleys until dawn, but probably still avoid
TAF sites. It will bring localized IFR or worse conditions.
Outside of fog, VFR conditions are expected through the period.
Winds will be less than 10 kts.

&&

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

$$

UPDATE...GREIF
SHORT TERM...JP
LONG TERM...VORST
AVIATION...HAL