412
FXUS63 KJKL 052151
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
551 PM EDT Wed Jun 5 2024

.KEY MESSAGES...

- Showers and thunderstorms will affect the area again late this
  evening into the overnight tonight.

- Relatively cooler and drier weather will arrive behind a cold
  front passing through eastern Kentucky on Thursday.

&&

.UPDATE...
Issued at 550 PM EDT WED JUN 5 2024

With the first round of convection exiting east into West Virginia
and Virginia, lowered PoPs and Sky cover grids this evening before
the next round of showers and thunderstorms arrive late this
evening into the overnight hours.

&&

.SHORT TERM...(This evening through Thursday night)
Issued at 420 PM EDT WED JUN 5 2024

Late this afternoon the axis of a mid and upper level ridge
extended from off the southeastern U.S. coast across the mid
Atlantic states into Quebec. Further west, an upper level low was
centered near the Saskatchewan and Manitoba border with an
associated trough axis through the MS Valley. A lead shortwave was
moving across the OH Valley and TN Valley with shower and some
thunderstorms with heavy downpours working across the region
preceding it. At the surface, an area of low pressure was located
in the Manitoba into Ontario region with the trailing cold front
south into the Great Lakes to mid MS Valley to Southern Plains. A
secondary cold front extends from western Ontario to the central
Plains and then into the western Conus.

This evening and tonight, the lead shortwave will depart to the
east by early this evening with the next shortwave/500 mb trough
axis will continue east across the central and eastern Great
Lakes and OH Valley into the Southeastern Conus and the
Appalachians. Meanwhile the upper level low to the northwest will
meander into Ontario and then to the northern Great Lakes through
Thursday. Another shortwave trough will move into the OH Valley on
Thursday. The first cold front will work across the Commonwealth
and enter eastern KY late tonight and move southeast of the area
on Thursday followed by the secondary cold front that nears
eastern KY during the day on Thursday and then across the area on
Thursday evening.

The airmass is rather moist across the region, PW is analyzed in
the 1.6 to 1.85 inch range while instability is rather weak with
MLCAPE generally around 500 to 1000 J/kg at present, with low
level lapse rates of about 6 to 7C/km. Mid level lapse rates are
generally weak as well, 6C/km or less. The airmass will remain
moist with deep moisture persisting ahead of the front, as PW
remains in the 1.5 to 1.8 inch range ahead of the first cold
front. MLCAPE is forecast by the RAP to be in the 500 to 1000 J/kg
range ahead of the boundary before diminishing later tonight with
lapse rates becoming meager. Locally heavy rain will remain the
primary threat with any additional convection behind the
convection that will depart into WV and VA within the next hour
and another area of convection anticipated ahead of the next
shortwave trough and the cold front. This second round of
convection area of convection should taper off from northwest to
southeast late tonight. A drier airmass will be in place behind
the first front on Thursday, however, some shallow showers or
sprinkles may accompany the secondary front and shortwave on
Thursday afternoon and Thursday evening.

Some fog will be possible as well tonight with low dewpoint
depressions especially if showers end in a location and winds
slacken. Fog will probably be more prevalent in the valleys on
Friday night behind the secondary front as high pressure begins to
nose into eastern KY.

.LONG TERM...(Friday through Wednesday)
Issued at 333 PM EDT WED JUN 5 2024

We begin the period quiet, as cold front will have passed through
the area. In the mid-levels, we see a low set up near the Great
Lakes and high set up in the Southern Plains, with solid agreement
in the ensembles and deterministic guidance. This will lead to
west to west northwest flow at the surface and much drier airmass.
This will usher in an airmass that will lead to highs in the
upper 70s to lower 80s, which is right around normal for this time
of year. This drier weather will extend into Saturday with with
highs sticking around 80 degrees.

By later Saturday into Sunday, there is good agreement on
increasing moisture, as the the mean of the EPS/GEFS/GEPS ensemble
models show PWAT increasing toward the 1 inch range. This will be
ahead of another southward moving frontal boundary, the a low
forms on near the Lower Ohio Valley. This will spark of showers
and perhaps a few thunderstorms Saturday night into Sunday, with
peak chances on Sunday in the 30-50 percent range.

In the wake of this weaker front, we don`t see quite as much of
moisture drop off and given a mid-level trough axis hangs around
during this time. This could lead to additional chances of showers
and thunderstorms on Monday at around the 30-40 percent chance
range. The the guidance begins to show divergence in the mid- and
upper level pattern. The leads to a fair amount of uncertainty in
the forecast for Tuesday into Wednesday. So we will continue to
see small chances (around 20 percent or less) of showers and
thunderstorms mainly Tuesday and Wednesday afternoon. It looks
like much of the period we will see afternoon highs near normal in
the mid to upper 70s in most cases.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 214 PM EDT WED JUN 5 2024

Showers and some thunderstorms were moving across the region at
issuance time as a disturbance works across eastern KY. Periods
of reductions to MVFR and IFR and with the heaviest showers
briefly to around airport minimums. Thunder on station is most
probable in the first few hours at JKL, KSYM, and KSJS. This
initial round of showers and thunderstorms will move across the
area over the first 3 to 4 hours of the period, before a likely
brief lull. Another round of showers and thunderstorms in
association with the next disturbance and cold front is expected
during the 00Z to 12Z timeframe. However, the predictability of
timing these beyond the first 3 to 5 hours of the period is too
low to specify it in the TAFs, and VCTS has been used after that
point. Winds will average south to southwest at 10KT or less
through the first 12 hours of the period, before winds become more
westerly to end the period behind the front. Some gusts as high as
25 to 30KT may occur with the stronger thunderstorms.

&&

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

$$

UPDATE...CMC
SHORT TERM...JP
LONG TERM...DJ
AVIATION...JP