582
FXUS63 KJKL 110833
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
433 AM EDT Sat May 11 2024

.KEY MESSAGES...

- Some showers and perhaps a storm or two are possible, at times,
  Saturday afternoon.

- Precipitation free weather is anticipated from Saturday night
  into Monday morning, before unsettled weather returns.

- Expect cooler temperatures through the weekend, with milder
  weather then returning.

&&

.UPDATE...
Issued at 210 AM EDT SAT MAY 11 2024

Just a quick touch up to the forecast through morning, mainly
beefing up the valley fog and adding in the latest obs and trends
for the T/Td/Sky grids. These adjustments have been sent to the
NDFD and web servers along with a freshening of the zones, SAFs,
HWO, and also an SPS for areas of dense valley fog for much of the
area through 9 am.

UPDATE Issued at 1048 PM EDT FRI MAY 10 2024

A roughly once-in-a-generation geomagnetic storm event is
underway, resulting in a spectacular view of the aurora borealis
across eastern Kentucky currently. Note that you do not have to
looking north to see it as usual. There are reports of it being
seen currently in southern Florida.

As for the weather update as to what is occurring in the
troposphere, where most weather occurs, there is very little to no
change for the forecast through the remainder of the overnight.
Did blend in latest hourly observations with the forecast.

UPDATE Issued at 703 PM EDT FRI MAY 10 2024

There are a few isolated showers remaining over far eastern
Kentucky where PoPs are currently less than 15, but these showers
are expected to dissipate in the next 1 to 2 hours with the loss
of daytime heating. Also lowered forecast lows in many of the
sheltered valleys another degree or two for tonight. Otherwise,
the forecast is on track and no significant changes are needed.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 322 PM EDT FRI MAY 10 2024

Shortwave trough, embedded within broader troughiness across much of
the county, is clearing our region this afternoon. Shortwave ridging
will replace it briefly, providing equally brief clearing skies,
good enough for aurora watching, per Space Weather Prediction
Center`s severe geomagnetic storm warning! Not certain it will be
visible this far south, but worth a look. Relatively light winds and
these clear skies should promote valley fog formation late tonight.
In the wake of this morning`s cold front, expect low temperatures to
fall into the 40`s for most locations.

Saturday, another shortwave trough will cross the region,
reinforcing the cold front and bringing another night with lows in
the 40s Saturday night. Along the front, we`ll see another potential
for light rains, similar to today. Also similar to today, the
deepest moisture and thus potential for storms look to be in far
eastern KY. Forecast soundings west of Jackson show a fairly stout
inversion above about 700 mb, but it`s weaker east of Jackson.

.LONG TERM...(Sunday night through Friday)
Issued at 433 AM EDT SAT MAY 11 2024

Operational models are in good agreement through the first half
of the extended with synoptic features, and diverge from there. In
general, eastern Kentucky resides in a split flow pattern through
the period, with stronger wind fields (westerlies) across the
Deep South and to our north along the Northern Tier and Great
Lakes. Because of the weaker wind fields aloft, one main trough
only manages to crawl through the OH/TN valley regions from late
Monday through Wednesday. A second southern stream trough tracks
through the region late in the period, Dy7...or Friday. At the
surface, low pressure lifts out of the Great Plains and through
eastern Kentucky Tuesday into Wednesday, then a second low
pressure system moves into the TN valley by the end of the
forecast window.

Sensible weather features generally unsettled weather through the
extended with two main rounds of weather to deal with, the first
from late Monday through Wednesday, then a second round from
Thursday night through Friday. There are two periods of dry
weather, or at least a lull in shower activity, at the start of
the extended...Sunday night into Monday and then again Wednesday
night into Thursday. Due to a general lack of instability and
shear across the area through the period...and relatively weak
flow aloft, thunderstorm activity will likely be limited and occur
primarily during peak heating, or during the afternoon and early
evening time frame. Not seeing signals that would suggest much
hazardous weather through the period, though WPC does have eastern
Kentucky within a marginal risk for excessive rainfall Tuesday
and Tuesday night. Thinking is that this risk is primarily due to
the slow speed of the first system`s progression through the Ohio
and Tenn valleys. With limited instability and shear, and by
extension a lower risk of strong and/or severe thunderstorms over
our forecast area, it is difficult to see convection being a
primary ingredient to an overall hydro risk. Freezing levels are
not particularly high, generally below 11 kft through that portion
of the forecast. Wind fields are on the lighter side, but storm
motion is still greater than 10 kts until Tuesday night. By late
Tuesday night steering winds do drop to between 5-10 kts. PWATS
are up close to 1.4 inches, or 75th percentile of climatology.
Thus, while the threat of hydro issues is low at this time, it
would appear that if there were any problems, a Tuesday through
Tuesday night window of time would be most likely time frame of
concern.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 220 AM EDT SAT MAY 11 2024

VFR conditions are still holding at all sites at the start of the
forecast period. With mostly clear skies and light winds, though,
valley fog formation is kicking into overdrive, some of which
may impact the TAF sites with IFR or lower conditions for a time.
To account for this, a TEMPO group for fog down as low as 1SM
visibility was kept in the forecast along with low CIGs. Expect
west to west-southwest winds to increase through the morning
ahead of a cold front and upper disturbance that brings showers to
the area from late morning through much of the afternoon.
Sustained winds up to 12 kts will transition to a more
northwesterly direction with passage of that boundary in late
morning and afternoon - then diminishing after dark.

&&

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

$$

UPDATE...GREIF
SHORT TERM...SHARP
LONG TERM...RAY
AVIATION...CMC/GREIF