JKL issues Area Forecast Discussion (AFD) at Oct 2, 3:23 AM EDT900
FXUS63 KJKL 020723
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
323 AM EDT Wed Oct 2 2024
.KEY MESSAGES...
- Patchy dense fog in some locations early this morning.
- Areas of dense fog expected again late tonight into Thursday
morning.
- Aside from some patchy drizzle this morning, dry weather should persist
at least through Thursday night.
&&
.SHORT TERM...(Today through Thursday)
Issued at 323 AM EDT WED OCT 2 2024
A mixture of fog and low stratus is found across most of eastern
Kentucky this morning as a weak cold front sags through the area.
Temperatures range from the upper 50s north up to the lower and
middle 60s further south and east. The combination of mostly clear
skies, light winds, and lingering low-level moisture has allowed
areas of fog to form across the Kentucky Coalfields, not only in
the valleys but also impacting many of the ridges as well. The
weak cold front is evident from weak biological radar returns and
surface observations, roughly extending from Paintsville to
Jackson to London line. Boundary layer mixing behind the front is
causing the radiation fog to dissipate or thin at most locations
as a trailing low stratus deck moves in. Model soundings and weak
radar returns suggest that some patchy drizzle is occurring with
this stratus.
Through the remaining pre-dawn hours, anticipate the frontal
boundary to continue pushing southeast and exit into Virginia after
5 AM. Anticipate that the fog, especially on valley bottoms, will
tend to thin or dissipate as the front arrives. However, expect
that the low stratus deck impinging on the higher hills and
mountains will lead to renewed visibility reductions on elevated
terrain through the mid-morning hours. This stratus deck may
produce patchy drizzle at some locations. Minimum temperatures
will bottom out around sunrise, ranging from the mid 50s to lower
60s.
The post-frontal low stratus will only slowly lift and erode from
the northwest during the daylight hours today as drier air gradually
works into our region on a northwest flow; in fact, counties
adjacent to the Virginia border may not see substantial clearing
until late this afternoon or evening. Patchy drizzle may linger
over the higher terrain near Virginia into the afternoon hours.
Temperatures will be cooler with highs mainly in the upper 60s to
lower 70s.
After a day of suppressed high temperatures, high pressure settles
in at the surface and aloft tonight, setting up the ideal
combination of conditions (clear skies and light winds with
lingering low-level moisture) for widespread fog formation, even
impacting many of the ridges. Some of the fog could become dense
late in the night before likely lifting off the valleys floors.
Temperatures are forecast to be cooler, dipping into the upper 40s
in the coolest northern hollows ranging up to the mid 50s in
southern valleys and over thermal belt ridges.
Bright sunshine finally returns for the entire forecast area on
Thursday once the morning fog and any low stratus lift and
dissipate. Forecast highs range from the mid 70s north of the
Mountain Parkway up to the lower 80s in the broader river valleys
south of the Hal Rogers/KY-80 corridor.
.LONG TERM...(Thursday through Tuesday)
Issued at 548 PM EDT Tue Oct 1 2024
During the long term forecast period, a couple of cold fronts will
work their way into Eastern Kentucky. Before and after their
passage, broad ridging will keep dry air in place, which will limit
the ability of these fronts to produce widespread convection.
Forecast guidance generally agrees in the placement and the timing
of these longwave features, so confidence in the synoptic set up for
our sensible weather forecast is quite high. However, mesoscale
trends in the ingredients for instability and fog formation will
need to be monitored as these cold fronts approach.
The period opens with a fairly flat 500mb ridge and its associated
surface high pressure in place over the area on Thursday and early
on Friday. Modeled height rises support the idea that high
temperatures will creep up towards the lower 80s by Friday
afternoon, although the broad and flattened nature of this ridge
means that the weak magnitude and the quasi-zonal orientation of
flow throughout the column will not yield in any meaningful moisture
or warm air advection ahead of Friday evening's cold front passage.
The parent upper level trough for Friday's system is not
particularly amplified, and the best dynamic support will remain
north of the Ohio River as a result. The highest rain chances,
albeit only around 25%, will actually be in far southeastern
portions of the forecast area. There, northwesterly flow may combine
with just enough daytime heating to trigger a few showers. This
activity is expected to die down by the overnight hours as the front
clears.
This cycle of ridging-troughing continues this weekend, with ridging
building back in on Saturday and into the daytime hours on Sunday
and troughing swinging down deeper into the Ohio River Valley than
it did on Friday. Skies should be mostly clear for any daytime
activities this weekend, with temperatures progressively warming up
to near 80 degrees once again by Sunday afternoon. While Sunday
night's cold front will be more dynamically supported aloft than
Friday's, its misalignment with the diurnal heating cycle and
antecedent dry air will relegate its ability to produce any
widespread convection. PoPs on Sunday night into Monday morning have
been capped near 35% at this time, with the greatest chances being
across northeastern counties, closer to the upper level support.
Given how far out this is, we will continue to monitor trends in
forecast guidance and make changes accordingly. For now, the most
impactful sensible weather that will come from this system appear to
be the much cooler temperatures that advect in behind it. High
temperatures may struggle to cross the 70 degree mark early next
week, as northerly surface flow and northwesterly flow aloft will
work to advect some of the driest and coolest air so far this fall
into the area. Low temperatures across the entire area will dip into
the 40s.
Aside from the uncertainty regarding instability, questions linger
regarding valley fog potential in the long term forecast. Typically,
ridging yields in the formation of this radiational fog, but the
nocturnal timing of these cold fronts may disturb this. On the other
hand, wet grounds from the associated showers may work to bolster
fog formation outside of the conventional valley spots. As higher
resolution guidance comes in and the time gets closer, these
details will become more clear. For now, patchy valley fog remains
in the grids on most nights in the long term given the favorable
synoptic set up.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 212 AM EDT WED OCT 2 2024
VLIFR to IFR conditions were reported at terminals across eastern
Kentucky at the 6z TAF issuance amidst areas of fog. Some
improvement to mainly IFR is expected as a cold front continues to
to cross eastern Kentucky from northwest to southeast and exits
into Virginia by 10z. Behind that boundary, a lowering stratus
deck will lead to reduced flight categories of mainly LIFR/VLIFR
east of the Escarpment and IFR to the west for the remainder of
the early morning. A slow improvement to VFR is expected during
the day on Wednesday as skies slowly clear. Fog is expected to
develop again Wednesday night and lead to significant visibility
reductions around and just beyond the end of the TAF period.
Lastly, winds will remain variable around 5 knots or less through
the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...MARCUS
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Oct 2, 3:23 AM EDT---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
