JKL issues Area Forecast Discussion (AFD) at Oct 3, 2:20 AM EDT963
FXUS63 KJKL 030620
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
220 AM EDT Thu Oct 3 2024
.KEY MESSAGES...
- Areas of dense fog expected overnight into Thursday morning.
- Mainly dry weather and above normal temperatures through the
rest of the week.
- A passing cold front brings a chance of showers to the area,
mainly Sunday night.
- More fall-like temperatures next week.
&&
.UPDATE...
Issued at 1115 PM EDT WED OCT 2 2024
Regional satellite is showing an expansion of low stratus from
east to west back across eastern Kentucky from Pike/Floyd, which
is already impacting several airports at ridge top level,
including KJKL, KSJS, KPBX, and KI35. Weather Cams are not showing
much yet, but the nighttime microphysics channel has been showing
a rapid expansion of fog within most of our river valleys.
Considering guidance and trends went ahead and issued a dense fog
advisory for most of our forecast area. After coordination, left
our Bluegrass counties out of the advisory for now. However,
ensemble probabilistic data suggests that our Bluegrass zones may
need to be included late tonight. Will be monitoring trends for
possible expansion of our advisory. Otherwise, hourly grids have
been update based on the latest surface obs. Overall, not much
change in the rest of the forecast package.
UPDATE Issued at 800 PM EDT WED OCT 2 2024
Skies are clearing across the area this evening as high pressure
settles down across the Ohio Valley. Slackening winds, clearing,
and some subsidence above the boundary layer all point to strong
radiative cooling conditions. In addition, expected overnight
lows are 3-5 degrees below crossover temps. Model guidance,
including ensemble solutions, are all jumping on board as well,
pointing to the development of fog and low stratus across a large
portion of the region through the overnight. All indications are
that the fog/stratus tomorrow morning will be gradual and slow to
improve...or slow to lift out and dissipate.
Signals are not as strong for dense fog over our Bluegrass
counties. This is likely because there has been more sunshine and
time across our northwestern zones to mix out the boundary layer
a little better earlier this afternoon. However, at this time, fog
is a pretty sure bet over a large part of the forecast area. Will
be evaluating initial 0Z model output as it becomes available and
watching trends for a possible headline issuance for fog a bit later
this evening.
Have updated grids to include our most recent hourly obs. Will
also be freshening up the zones a bit later in the shift. Updated
grids have been submitted.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 424 PM EDT WED OCT 2 2024
A cold front has passed through the region and is to our southeast
now. However, low level moisture lingers against the higher
terrain in southeast Kentucky in light northerly low level flow,
and skies have not cleared yet there. The clearing line will
continue to progress southeast and east this evening, and
clearing should eventually reach the rest of the forecast area.
Surface high pressure will pass to our northeast tonight, with
ridging extending southwest over the JKL forecast area, bringing
light winds. Ridging aloft will also move in from the west
tonight with very dry air. Moist ground and lingering low level
moisture overlaid by very dry air aloft, along with light surface
winds will be very favorable for fog development. Have already
issued a special weather statement highlighting this. At least
part of the area could end up needing a Dense Fog Advisory, and
oncoming night shifts will monitor the situation.
The ridging, surface and aloft, will shift to our east on
Thursday, but will still maintain control. Once heating dissipates
the fog, plenty of sunshine is expected for the rest of the day.
How quickly the fog leaves is somewhat in question, as the lower
sun angle as we move into autumn makes it harder to mix it away.
Mainly clear skies will last into Thursday night, and valley fog
will develop again. It shouldn't be quite as widespread, with
better heating and mixing expected to occur during the afternoon
compared to today, and also providing a better opportunity to dry
the ground.
.LONG TERM...(Friday through Wednesday)
Issued at 410 PM EDT WED OCT 2 2024
A mainly progressive long wave pattern will be in place through
the end of the week, before more notable amplification occurs
into next week. A short wave trough will start out cruising east
across the Great Lakes and Ohio Valley regions on Friday, with
stouter short wave energy moving in over the Pacific Northwest.
This feature will barrel through the northern Great Basin/Rockies,
intensifying and likely cutting off with time as it moves over
the northern Plains/Upper Midwest region by late Saturday night.
This low will continue to rotate east over Ontario and then Quebec
into next week, with deeper troughing setting up over the eastern
third of the CONUS. At the surface, a weak cold front will push
through the Ohio and Tennessee valleys Friday/Friday night,
providing a small chance (10-20%) of showers across our southeast.
Despite the cold frontal passage, temperatures will continue to
average above normal with highs in the upper 70s and lower 80s,
and lows in the 50s. A stronger cold front will push through
eastern Kentucky Sunday night, providing the area with a better
chance (30-50%) of showers. More fall-like temperatures then
follow this front into next week, with highs retreating back to
the 60s and 70s, and lows in the 40s, under mostly clear skies.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 220 AM EDT THU OCT 3 2024
Low stratus/fog bank with LIFR or worse conditions over southeast
Kentucky is spreading north of I-64 and west of I-75 at 620z.
Terminals not currently impacted by fog/stratus bank can expect
rapid onset of LIFR to VLIFR with its arrival. These poor flying
conditions are forecast to continue through mid-to-late morning.
Conditions should improve to VFR by midday or early afternoon as
low stratus fog lifts and dissipates. Winds will be light through
the period, around 3 kts or less.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM EDT this morning for KYZ058>060-
068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...RAY
SHORT TERM...HAL
LONG TERM...GEOGERIAN
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Oct 3, 2:20 AM EDT---------------
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