875
FXUS63 KJKL 050045 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
845 PM EDT Sat May 4 2024

.KEY MESSAGES...

- Shower and thunderstorm potential lasts through the next 7
  days.

- Above normal temperatures are forecast through most of the next
  week. A cold front should pass late in the week and bring
  readings down to near or below normal.

&&

.UPDATE...
Issued at 845 PM EDT SAT MAY 4 2024

00Z sfc analysis shows low pressure to the northwest of Kentucky
with some weak high pressure found nearby. This was not enough to
prevent mainly unorganized showers and storms from developing
through the area earlier in the afternoon and evening. These
continue but their magnitude appears to be fading as we get
further removed from peak heating and instability lessens. Even
so will keep the threat of convection going into the night
incorporating the latest radar and CAMs trends - but with just a
slight chance for thunder after midnight. Currently, temperatures
are generally from the mid 60s to lower 70s across the area.
Meanwhile, amid south winds of 5 to 10 mph, dewpoints are running
in the low to mid 60s. Did also include the current obs and
tendencies for the T/Td/Sky grids with this update. These
adjustments have been sent to the NDFD and web servers along with
a freshening of the zones and SAFs.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 537 PM EDT SAT MAY 4 2024

The latest upper level map features ridging aligned from eastern
Canada through New England, Cape Hatteras, and then offshore. A
deeper low is centered over the western part of Hudson Bay, with a
trailing trough positioned southwest and then south through the
Midwest. At the surface, low pressure is located near central
Wisconsin, with a cold front laid out south southwest through the
middle Mississippi Valley and then more southwest across the
southern Plains. A weaker surface trough/quasi-stationary front
branches east southeast across the Ohio Valley and then over the
central Appalachians. Bouts of scattered to numerous convection,
some producing locally heavy rainfall at times, and plenty of
cloud cover kept temperatures in check today across eastern
Kentucky. Readings range from the mid to upper 70s at most
locations.

The models are in fairly good agreement aloft through the short
term. The Hudson Bay low will gyre its way east with time, taking
the more defined trough to its south southwest with it. Meanwhile,
a short wave trough will emerge from the southern stream and
deepen as it moves out of the Arklatex region by late Sunday. This
feature will continue to trek over the middle Mississippi Valley
by Sunday night. At the surface, a cold front will gradually move
southeast across the Ohio Valley, eventually stalling near our
area by end of the short term period.

Unsettled weather will remain in the forecast, although as we lose
heating tonight, convection should gradually diminish in
coverage. Depending on clearing trends, fog will develop in the
valleys, becoming locally dense where enough clearing is
coincident with locations that saw heavier rainfall today. Lows
will average in the lower 60s. Most models show some 500 mb height
rises during the day on Sunday, which should keep convective
coverage more scattered and less organized in nature. Less clouds
should allow temperatures to climb to the upper 70s and lower 80s.
Any activity should quickly die off Sunday evening, before PoPs
ramp back up towards dawn from the southwest out ahead of the
approaching short wave trough. Lows should be similar to tonight,
generally lower 60s, with valley fog likely once again.

.LONG TERM...(Monday through Saturday)
Issued at 253 PM EDT SAT MAY 4 2024

The long term period continues to look wet. Prevailing
large scale flow aloft will be persistent from the west southwest
through at least Thursday, while low level flow is out of the
southwest off the Gulf of Mexico. This pattern of warm/moist
advection will favor precip whenever there are triggers/forcing
mechanisms. A wavering frontal boundary will approach from the
northwest at times, but being largely parallel to the upper level
flow until near the end of the period it is not likely to make a
forceful passage until then. This will leave us in a modestly humid
air mass with surface dew points mainly in the lower to mid 60s. The
main drivers for precip will be mid/upper level waves along with
diurnal heating/destabilization cycles. The mid/upper level waves
with the most agreement in the models are ones that would affect us
on Monday, and also Wednesday night into Thursday, and these time
frames contain the highest POP area wide at mainly 70%+.

There are some model discrepancies in the Thursday-Friday time frame
concerning timing of an eventual cold frontal passage. In the 00Z
and 12z deterministic/operational runs, the GFS is faster than the
ECMWF with the passage of the primary cold front, and this results
in lower forecast confidence mainly from Thursday onward. The
current forecast is a model blend, but temperatures are likely to
end up being either warmer or colder, depending on timing of cold
fropa. It should be noted the 13z NBM trended a few degrees cooler
for both Thursday night/Friday morning and Friday night/Saturday
morning. Additionally, a faster fropa would result in the POP
dropping off faster, and a slower passage would allow precip to
linger longer.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 815 PM EDT SAT MAY 4 2024

The current batch of scattered showers and thunderstorms will
diminish by late evening, but still a threat into early Sunday.
There is the potential for some MVFR fog/stratocu to develop
between 09 and 13Z at most sites, as well. Any lower deck will
then mix out by the mid to late morning, Sunday, with a return to
VFR conditions. South to southwest winds at 5 to 8 kts will
diminish to less than 5 kts later this evening, before upticking
once again by late Sunday morning to between 5 and 10 kts from the
southwest.

&&

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

$$

UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...HAL/CMC
AVIATION...GEOGERIAN/GREIF