JKL issues Area Forecast Discussion (AFD) at Sep 15, 7:59 AM EDT524
FXUS63 KJKL 151159
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
759 AM EDT Sun Sep 15 2024
.KEY MESSAGES...
- After high temperatures well into the 80s in most places this
weekend, a slight cool-down arrives for the upcoming weekdays.
- Dry weather lasts through Monday, followed by a small potential
for showers at times Monday night through Friday.
&&
.UPDATE...
Issued at 757 AM EDT SUN SEP 15 2024
Updated the grids to maintain fluidity in hourly diurnal
temperature grids.
&&
.SHORT TERM...(Today through Monday)
Issued at 433 AM EDT SUN SEP 15 2024
A Rex-block pattern, high pressure north of a low, continues to
usher in slightly above average temperatures today with mostly
sunny skies, light winds, and drier air. A fairly strong 590dm
high over the northeast will dry things out even more heading into
Monday, while keeping moisture over the southeastern CONUS from
progressing away from the area. Eastern Kentucky remains far
enough north to escape the active rain to the south. Highs today
will generally be in the mid to upper 80s. Tonight, with drier
air advecting in across eastern Kentucky, and clear skies, areas
may radiate out more than model guidance, with ridge valley
splits likely falling outside the 5th percentile of the NBM. Lows
will likely be in the lower 50s in the valleys, and upper 50s to
lower 60s across ridges.
Currently, an offshore low off the southeastern US coast, has been
given a 50% chance of forming into a cyclone in the next 48 hours,
as forecasted by the National Hurricane Center. This low pressure
according to model and ensemble guidance is expected to move
onshore over the Carolinas Sunday night, and continue westward
towards Eastern Kentucky during the day Monday. The area will see
increasing cloud cover from east to west throughout the day. This
will also keep high temperatures closer to average for this time
of year, forecasted in the upper 70s to lower 80s across the area.
.LONG TERM...(Monday night through Saturday)
Issued at 335 AM EDT SUN SEP 15 2024
The period begins Monday evening with an upper level low and
potential tropical or subtropical cyclone moving inland across the
Carolinas, with models varying on the location and strength of the
parent upper low as well as the surface feature for subsequent
periods through the mid to late week period. For instance, at 12z
Wednesday, the 00z GFS operational model depicts the parent upper
low over southern Indiana, while the 00z ECMWF depicts the upper
low over western North Carolina, while the 00z NAM has the parent
low over eastern Kentucky. This makes for a somewhat difficult
temperature and precipitation forecast, especially Tuesday, with
less uncertainty with time through the remainder of the week.
However, models attempt to build ridging over the Midwest toward
the weekend, though there are significant discrepancies between
the operational models in how this is achieved.
Monday, ensemble and model guidance shows a coastal area of low
pressure
For Tuesday, we decided not to be as aggressive as the NBM with its
deterministic forecast highs in the lower 70s, opting instead for
mid to upper 70s given uncertainties with the track and strength of
the aforementioned low pressure system. For the rest of the week,
the generally decreasing cloud coverage and PoPs will allow for
MaxTs to climb back into the 80s for the second half of the week
into the weekend, while MinTs are expected in the upper 50s/lower
60s. The potential for ridge-valley splits and radiational fog
will be mitigated by clouds and precipitation chances mid-week,
but both may still materialize in southwestern portions of the
area. Places such as London, Monticello, and Somerset will be the
furthest removed from the moisture and forcing associated with the
tropical system and will thus see less cloud coverage and lower
rain chances throughout the long term forecast. On the other hand,
eastern and northern portions of the forecast area that are
closer to this developing system will be more likely to see some
rainfall and enhanced cloud coverage. Given the slightly better
model alignment than previous days, the NBM has categorically
upped PoPs from less than 25% slight chances to about 40% chances
in the eastern third of the forecast area Tuesday, with gradually
diminishing PoPs through the remainder of the week within an
overall diurnal trend based on the diurnal heating cycle. It is
important to note that the positioning of this particular tropical
or subtropical system will translate to flow with northerly
components. As a result, while downsloping appears less likely
than it did with Francine, if the system retrogrades westward,
orographic lift could locally enhance rain chances in northward-
facing terrain. This system will be working against some dry air
leftover in the column from this past weekend's ridging, and
forecast rain totals reflect this. Any rain that falls from this
system will likely be more stratiform in nature than the
intense/convective type that one might associate with tropical
cyclones. Significant impacts from this system across Eastern
Kentucky are not expected at this time. Instead, we will see
chances for some beneficial rain, and these chances might increase
further as higher-resolution guidance comes into perspective. We
once again encourage interested parties to stay tuned to future
forecast updates as confidence increases and the exact details
regarding this system's evolution are nailed down.
&&
.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
ISSUED AT 759 AM EDT SUN SEP 15 2024
Mostly sunny conditions are expected today, with VFR conditions
being the prevailing flight category. Some lingering valley fog
should dissipate by 14Z this morning. This fog may briefly reduce
visibilities to MVFR to IFR conditions, but should not affect TAF
sites and is expected. Winds will be less than 10 kts from the
east or southeast.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GINNICK
SHORT TERM...GINNICK
LONG TERM...CMC/MARCUS
AVIATION...GINNICK
Source:
JKL issues Area Forecast Discussion (AFD) at Sep 15, 7:59 AM EDT---------------
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