JKL issues Area Forecast Discussion (AFD) at Jun 21, 8:43 PM EDT462
FXUS63 KJKL 220043
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
843 PM EDT Fri Jun 21 2024
.KEY MESSAGES...
- Hot and mainly dry weather will continue through the weekend.
Afternoon heat indices will peak near 100 at some locations.
- The upper level high heights/ridge bringing our heat wave will
weaken during the weekend and eventually allow a cold front to
move into the area, with the PoPs peaking in the 50 to 70
percent range from late Sunday afternoon and into the evening.
- Uncertainty still exists concerning the progress of the cold
front next week and whether or not a substantially drier air
mass will arrive. For this package, Monday night through Tuesday
morning were left dry, but with precipitation and thunderstorm
chances returning late Tuesday and continuing through Thursday.
&&
.UPDATE...
Issued at 843 PM EDT FRI JUN 21 2024
Sprinkles have dried up and have timed out of the forecast. Have
made adjustments to the rate of temperature drop in valleys this
evening, with obs showing a more rapid fall in eastern valleys.
UPDATE Issued at 535 PM EDT FRI JUN 21 2024
Cu have built to the point that some light radar returns are
showing up in Bell and Harlan counties. Don't think any place will
measure, but have added a chance of sprinkles early this evening.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 400 PM EDT FRI JUN 21 2024
19Z sfc analysis shows high pressure in place over eastern
Kentucky and this is keeping skies at least partly sunny with
light winds. Accordingly, temperatures have climbed to the upper
80s and lower 90s most places while, amid light winds, dewpoints
are running in the mid 60s. This is yielding heat indices in the
mid to upper 90s along with a tinge of haze in the air due to this
stagnant weather pattern. So far, no showers have been able to
develop across the higher terrain in the southeast parts of the
area, but this may yet happen though with minimal impacts and
a potential around 10 percent or less as subsidence and dry
conditions likely prevail.
The models, and their individual ensemble suites, remain in very
good agreement aloft through the short term portion of the
forecast. They all depict a dominant 5h ridge centered over
Kentucky today shifting southwest into Saturday. This will occur
as the mid level pattern to the north becomes more active through
the Great Lakes. The waves moving west to east at this level will
impinge deeper into the Ohio Valley later Saturday night with
some true 5h height falls working into Kentucky by dawn Sunday. As
this happens, the associated mid level energy will not be far off
in renewed northwest flow affecting eastern Kentucky early
Sunday. The model spread through the short term is still rather
small so the NBM was used as the starting point for the short term
grids with little deviation aside from the incorporation of some
terrain distinctions for temperatures tonight - and to a lesser
extent Saturday night. The latest CAMs runs were also incorporated
into the PoP grids for Saturday afternoon.
Sensible weather features the heat, humidity, and dry weather
continuing through the first part of the weekend. Look for just a
small chance for relief in the higher terrain of far southeast
Kentucky on Saturday afternoon in the form of spotty convection as
temperatures for the majority top out in the low 90s and heat
indices again threaten triple digits. Most places will stay dry,
though - awaiting a better chance starting Sunday when a much
anticipated (and needed) cold front slips into the area. Both the
upcoming nights will be very mild and muggy as mainly just the
valleys see lows in the mid to upper 60s by dawn Saturday - and
even fewer places end up on the cool side of 70 for Sunday
morning. Both nights mainly river valley fog will be noted.
The main changes to the NBM starting point consisted of adjusting
the temperatures in order to better reflect terrain details
tonight and a tad on Saturday night. PoPs were nudged up in the
higher southeast terrain on Saturday afternoon per the latest
guidance from the CAMS.
.LONG TERM...(Sunday through Friday)
Issued at 339 PM EDT FRI JUN 21 2024
The extended period will start off unsettled, as an area of low
pressure moves quickly through the Great Lakes and into New England
Sunday through Monday. A cold front trailing southward from the low
will be the trigger for showers and storms across eastern Kentucky
late Sunday and Sunday night, as it moves through and interacts with
the warm, moist, unstable air that will be in place. The best chance
for rain will be Sunday night, as the surface cold front moves
through. A few showers and storms will linger behind the front in
the eastern half of the forecast area, on Monday, but should be out
of the area by the end of the day. A ridge of high pressure will
settle over the region Monday night through Tuesday, and will bring
dry weather to eastern Kentucky, although we will can still expect
extremely warm and muggy conditions in the only slightly modified
air mass behind the departed front.
Another weather system will be poised to move through the region
Tuesday night through Thursday. This system will bring a more
prolonged period of the rain to the area, as its surface cold front
may be slow to exit the area. This second front will be a bit more
potent the the previous one, so we should see noticeably cooler
temperatures around the area. In fact, Thursday's highs may only
reach the mid 80s for most location's, which would much cooler than
the hot conditions experienced the previous several days. The cool
down will be short lived, however, as another dome of high pressure
settles over the region Thursday night and Friday, and brings highs
in the upper 80s to perhaps 90 back into the fray late Friday.
The models were in pretty good agreement with the overall upper
level flow pattern, with the GFS Ensemble and operational models
used for this. No weather hazards to speak of in the extended. We
will have periods of thunderstorms Sunday afternoon and night, and
again by the middle of the week, but nothing severe is anticipated
at this time. Temperatures will be warm and muggy on average, but
not nearly as impactful as the values experienced leading into the
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 843 PM EDT FRI JUN 21 2024
Valley fog will affect the region with IFR or worse conditions late
tonight and early Saturday, but should avoid TAF sites. A few
thunderstorms with sub-VFR conditions are possible in far southeast
KY on Saturday afternoon. Otherwise, VFR conditions are expected
through the period, with light winds.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...HAL
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...HAL
Source:
JKL issues Area Forecast Discussion (AFD) at Jun 21, 8:43 PM EDT---------------
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