Area Forecast Discussion
Issued by NWS Jackson, KY

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719
FXUS63 KJKL 060836
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
436 AM EDT Thu Jun 6 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 1031 PM EDT WED JUN 5 2024

Showers and thunderstorms are developing and moving into eastern
Kentucky from the west, much as predicted by CAMS from earlier
today. The main threat from this round of precipitation will be
downpours producing isolated areas of high water, especially in
poor drainage areas. A few stronger storms are possible,
especially with decent 0-1 km storm relative helicity providing
some potential for rotating storms. Instability will be a limiting
factor, however, especially in areas that were not able to
sufficiently destabilize following late afternoon thunderstorms
earlier.

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 night through Wednesday)
Issued at 436 AM EDT THU JUN 6 2024

The 06/00z model suite begins the long-term period in good synoptic
agreement, leading to a high confidence forecast through the
upcoming weekend, before increasing model spread results in lower
forecast confidence heading into the new work week. Initially,
500H ridging will be solidly in place over northern Mexico and the
Southern Plains. Meanwhile two sub-550 dam lows lie in a
northwest-southeast oriented trough from the Upper Mackenzie
Valley to Lower Great Lakes. Subtle disturbances aloft are riding
through the northwest flow over the Central Plains between the
ridging further south and the troughing further north. At the
surface, a developing wave of low pressure is found over the
Dakotas with a trailing cold front across the northern Rockies,
while high pressure is meanders east of the 500H ridge across the
Lower Ohio/Tennessee and Mississippi river valleys.

The surface high pressure will shift east, cresting over the
Central/Southern Appalachians late Friday night. As that high
continues to press east on Saturday, focus will turn toward the weak
low pressure passing through the Southern Great Lakes and dragging a
cold front into the Ohio Valley. Meanwhile, the more easterly
upper level low (over Quebec) will elongate and rotate toward the
Ohio Valley, shoving the cold front south of the Commonwealth and
allowing cool Canadian air to pour across eastern Kentucky on
Sunday night and Monday. Height rises return Monday night and
Tuesday as the trough axis shifts to our east and high pressure
passes over the Ohio Valley/Central Appalachians. The second upper
level low and/or an associated trough may then impact eastern
Kentucky during the middle of next week but the specifics are
uncertain due to significant model spread.

Sensible weather will feature fair conditions through Saturday along
with seasonably cool temperatures. Morning low temperatures are
forecast to range from the lower to mid 50s while afternoon highs
top out in the mid 70s to lower 80s. A few of the coldest
northeastern valleys could briefly dip into the upper 40s early
Saturday morning. Shower chances rise again Saturday night as the
cold front drops into the Ohio Valley and peak ~40 to 60 PoP as
that cold front passes over eastern Kentucky on Sunday. A weak
thunderstorm cannot be ruled out ahead of or along the front.
Behind that front, diurnally-driven showers (20-30 PoP) are again
expected to bubble up on Monday, along with a possible rumble of
thunder. After one more day with highs in the mid to upper 70s on
Sunday, Monday`s maximum temperatures will be noticeably cooler,
primarily in the lower to middle 70s. A few of the cooler locales
may fail to even reach 70. A downright chilly night for mid-June
is in store for Monday night, likely deep into the lower and
middle 50s for most locations and perhaps even in the 40s through
the more sheltered valleys and hollows. (Normal highs for June
11th at the lower elevations range from ~79 to 83 while normal
lows range from 56 to 64.) Once the high pressure crests overhead,
winds will turn southerly on Tuesday leading to a quick warming
trend -- high temperatures return to the 80s by Wednesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 332 AM EDT THU JUN 6 2024

A band of showers and a few thunderstorms ahead of a weak cold
front was over the northern portion of the forecast area at the
start of the period and was moving slowly southeast. It will
continue its progression, with what`s left of it exiting southeast
out of KY around mid day. It will bring reductions to MVFR
conditions, which will persist for a time after the passage of
the precip and cold front. Localized reductions to IFR may also
occur. A return to VFR conditions is forecast during the
afternoon. Another area of isolated to scattered showers
associated with a second cold front is expected to develop and
move through from northwest to southeast this evening.
Restrictions below VFR are less likely with the last round of
showers and would be expected to be localized.

&&

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

$$

UPDATE...CMC
SHORT TERM...JP
LONG TERM...GEERTSON
AVIATION...HAL