214
FXUS63 KJKL 010518
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
118 AM EDT Wed May 1 2024

.KEY MESSAGES...

- Following recent rain, high pressure builds in leading to
  clearing and light winds setting the stage for dense fog
  potential tonight and Wednesday morning.

- Dry and trending warmer Wednesday to Thursday, with near record
  highs on Thursday.

- Unsettled weather returns for Friday and lingers through early
  next week.

&&

.UPDATE...
Issued at 1025 PM EDT TUE APR 30 2024

Radar shows a couple of showers lingering over portions of Pike
and Floyd county at update time. They should sink southeastward
and dissipate within the next couple of hours. Otherwise, the
Night Fog satellite imagery product is already showing tendrils of
fog expanding through the river valleys. With plenty of low-level
moisture in place and clearing skies, the fog is likely to become
fairly widespread overnight and also dense in many valley
locations. Individuals traveling overnight may want to allow
extra time to reach their destinations.

UPDATE Issued at 735 PM EDT TUE APR 30 2024

Hourly grids were updated based on recent observations as well as
radar and satellite trends. This mainly ended thunder chances
near the VA border that were in the previous forecast. Clearing is
still anticipated late this evening and overnight, likely setting
the stage for fog.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 440 PM EDT TUE APR 30 2024

A mid and upper level shortwave trough is moving across portions
of the OH Valley and Appalachians at this time while riding
extended north from the Gulf of Mexico into the Lower OH Valley
region with broad troughing extending south across the western US
from an upper level low near the Northwest Conus/Canadian border
area. A weak cold front/surface trough is crossing the eastern KY
region at this time. Showers are moving across the area in advance
of these features with only very minimal in cloud activity briefly
detected over the past hour or so. West of the area, a ridge if
high pressure extends from the lower MS Valley to the Lower OH
Valley region. Further west, an area of low pressure was tracking
from portions of the Central Plains toward the Upper MS Valley.

This evening and tonight, the upper level trough and weak surface
boundary will move east of eastern KY this evening with the upper
level ridge building in behind it. Meanwhile, a shortwave trough
will move from the Plains to upper MS Valley and then across the
Great Lakes through Wednesday and toward the St Lawrence Valley
through Wednesday night. A general trend of height rises is
anticipated from tonight through Wednesday across the
Commonwealth. At the same time, the sfc ridge of high pressure
will build into eastern KY and the Southern Appalachian region.
The axis of the upper level ridge will shift east across the area
on Wednesday night while sfc high pressure remain in place across
the southern Appalachians. Further to the north and west, a
shortwave trough is expected to move from the Central Plains
toward the Upper MS Valley.

Shower activity across the south and east will gradually decrease
from west to east during the evening as the shortwave trough and
sfc system pass. Sfc and upper level ridging will build in behind
this for tonight and lead to a clearing trend and slackening
winds. This will also occur following recent rainfall and set the
stage for fog formation and perhaps a few areas of low stratus as
well. There is uncertainty in the areal extent and intensity of
the fog, but some dense fog has been included in the grids,
especially for valley locations. The fog may affect the morning
commute and this potential is highlighted in the HWO.

Under high pressure, a drying and warming trend is anticipated
into Wednesday with mixing leading to lower afternoon dewpoints
in the east and south compared to today. The pattern will be
favorable for a moderate ridge/valley split as valley should
decouple by sunset on Wednesday evening and fall to near or even
below the afternoon mixed dewpoints. Lows in the deeper valleys
should be near the 50 degree mark with coalfield ridges near 60.

.LONG TERM...(Thursday through Tuesday)
Issued at 327 PM EDT TUE APR 30 2024

The period begins with good agreement in the deterministic and
ensembles on the mid-level ridging the Southeast US and high
pressure off toward the Atlantic Coast line. This will keep the
weather quiet, with very dry low levels and capping inversion
aloft. This could lead to some flat cumulus in the afternoon, but
very warm afternoon high temperatures in the mid-80s to near 90
degrees. This could eclipse record high temperatures, with JKL 87
degrees set in 2012 and LOZ 88 degrees set in 1959. The ridging
does push east as a mid-level wave rides toward the Ohio Valley
Thursday night into Friday. This will aid in giving way to showers
and thunderstorms Friday afternoon, as moisture surges northward
and small amount of instability comes with it. This as multi-model
ensembles show 40-50 percent chance of greater than 250 J/kg of
CAPE.

Overall guidance, including ensembles are in good agreement with
best chance of rain (around 60-70 percent) Friday night into
early Saturday. There seems to be a little uncertainty on Saturday
in terms of timing, with first wave and next shortwave pushing
into the Midwest, Saturday night into Sunday. The deterministic
and ensemble data are disagreeing on the amplitude of this wave
too and leads more uncertainty by late weekend into early next
week. Particularly as there could be some shortwave ridging in
between these features. Therefore, the PoPs drop back into the
40-50 percent range mainly in the afternoon hours Sunday into
Tuesday. It will remain 10 to 15 degrees above normal through this
time range.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 118 AM EDT WED MAY 1 2024

Highly variable conditions are noted at the TAF sites as of this
writing. Fog has developed through the valleys per RGB satellite
imagery. An expansion westward is noted beyond JKL and LOZ.
Therefore, I do think all sites will see some BR or FG through the
early morning hours. Confidence in time of arrival (for those
VFR or MVFR) is low. Conditions improve after sunrise, but fog is
probable again early Thursday morning and will need to be wrestled
into the next TAF issuance.

&&

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

$$

UPDATE...GEERTSON/JP
SHORT TERM...JP
LONG TERM...DJ
AVIATION...BROWN