313
FXUS63 KJKL 090836
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
436 AM EDT Thu May 9 2024

.KEY MESSAGES...

- A few thunderstorms with brief torrential rain is the biggest
  concern for convection today in areas near the TN border, with
  this activity winding down this morning.

- Some showers and perhaps a storm or two are possible at times
  from this afternoon through early next week.

- Above normal temperatures are forecast today. However, a cold
  front passing today will usher in cooler temperatures from
  Friday through early next week.

&&

.SHORT TERM...(Today through Friday)
Issued at 436 AM EDT THU MAY 9 2024

Early this morning, an upper level trough extended from the
Maritimes across portions of Ontario and Quebec to the Great
Lakes to southwest Conus. West southwest flow was in place
between this trough and upper level ridging, the axis of which
extended across Central America to portions of the Caribbean. A
shortwave trough was approaching eastern KY at this time. At the
surface, An area of low pressure was tracking across the Lower OH
Valley region with the associated frontal zone extending east to
the mid OH Valley to the mid Atlantic coast. Meanwhile an
instability gradient associated with outflow from rounds of
convection since Wednesday was in place southwest of eastern KY.
Recent mesoanalysis had very limited instability in place north
of this boundary with MUCAPE 250 to 500 J/kg in the southwest
portion of eastern KY, mid level lapse rates area wide no more
than 6 to 6.5C/km, and best shear parameters from the TN border
and locations to the south of the area. PW as high as 1.3 to 1.5
inches was in place from central KY to areas generally near and
west of Interstate 75. Convection was occurring across the OH and
TN Valley with the more robust/deeper convection from nearer to
the TN border and south in the instability gradient though
lightning was occurring into portions of central KY in a
stratiform rain regime.

The shortwave trough is expected to move east of eastern KY this
morning while the trough axis at 500 mb remains north of the the
OH Valley today. The western portion of the trough is progged to
close off/be left behind over the Four Corners region today and
then meander to the west and southwest through Friday. Meanwhile,
the 500 mb trough axis is expected to move south and southeast
across the Great Lakes and near the OH Valley and mid MS Valley
tonight, before this trough axis axis rotates across the OH Valley
and into the Appalachians to end the period. Shortwave ridging
should enter the OH Valley to end the period while another
shortwave trough moves into the evolving trough over the eastern
Conus and into the western Great Lakes and Upper MS Valley.

Chances for convection today should be greatest through the
morning though after a possible late morning to early afternoon
lull, a slight uptick in activity may coincide with peak heating
and the cold front crossing eastern KY. Recent convective
allowing models forecast as much as an inch or more over the next
few hours through about dawn in the southernmost tier or two of
counties nearest to the TN border. At this point have held onto
the Flood Watch through 8 AM across the south.

Chances for at least isolated convection will linger into the
evening and tonight as the 500 mb trough axis lingers upstream
though a lull during the evening into a part of the overnight is
possible. If and where clouds can clear out, fog may become a
concern following recent rainfall though a general increase in
cloud late tonight and toward dawn on Friday leads to uncertainty
in location and duration. Some patchy fog was included in the
grids for tonight, with somewhat lower visibilities for deeper
valleys. Chances for convection will increase on Friday during
peak heating as the trough nears with the best chances in the
southeast. Temperatures on Friday will be notably colder than
recent days with highs not expected to get out of the 60s. Friday
highs should be nearly 10 degrees below normal for this time in
May.

.LONG TERM...(Friday night through Wednesday)
Issued at 436 AM EDT THU MAY 9 2024

The long term discussion will be issued shortly.


&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 235 AM EDT THU MAY 9 2024

A lull in convection was occurring at issuance time across the
region with a few showers near the TN border and some storms to
the west and south of eastern KY. Convection to the west of the
area should arrive around 08Z or 09Z and track east, though the
strongest convection should remain west and south. In the lull,
varying amounts of clouds are leading to some fog or status in
some locations and MVFR or even IFR reductions while other areas
were experiencing VFR. As the convection moves into the area, at
least brief reductions to VFR ceilings and or visibilities are
anticipated a few hours either side of 12Z for most locations.
Improvements to VFR should then follow for most areas as coverage
of convection decreases. Some increase in coverage could occur
again during peak heating as a cold front approaches. Behind this
activity, reductions down to MVFR or perhaps lower are
anticipated in the north to end the period. Some fog would also
be possible with visibility reductions if clouds were to thin
enough falling recent rain. Winds will average between southeast
and southwest tonight at generally 10KT or less before becoming
southwest to west as the cold front moves through on Thursday into
Thursday evening.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 8 AM EDT this morning for KYZ058-059-068-069-
079-080-083>088-108>118-120.

&&

$$

SHORT TERM...JP
LONG TERM...HAL
AVIATION...JP