JKL issues Area Forecast Discussion (AFD) at Oct 14, 1:36 PM EDT652
FXUS63 KJKL 141736
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
136 PM EDT Mon Oct 14 2024
.KEY MESSAGES...
- Colder and breezy conditions occur today on account of fall
high pressure moving in from the northwest.
- Patchy to widespread frost is expected each night from Tuesday
night through Thursday night.
- Freezing temperatures could be rather widespread Tuesday night
and again Wednesday night.
&&
.UPDATE...
Issued at 1135 AM EDT MON OCT 14 2024
Not many changes made to the forecast grids as they have been on
track through this morning. However, loaded in the latest surface
obs and made a touch-up or two based on those trends. Lastly,
updated mornings text and radio products to reflect the changes.
Grids have been saved and sent.
UPDATE Issued at 738 AM EDT MON OCT 14 2024
Very little changes made to the forecast grids as they have been
on track through this morning. Only loaded in the latest surface
obs and made a touch-up or two based on those trends. Grids have
been saved and sent.
&&
.SHORT TERM...(Today through Tuesday)
Issued at 320 AM EDT MON OCT 14 2024
07Z sfc analysis shows a cold front now southeast of the state as
high pressure is arriving from the northwest. This transition is
occurring on northwest winds of around 10 mph with gusts up to 20
mph - bringing the colder and drier air mass into this part of
the state. A smattering of mid and high level clouds are working
into the area from the north, post frontal. Currently,
temperatures vary from the lower 50s northwest to the mid 60s in
the far southeast. Meanwhile, dewpoints range from the mid 30s
northwest to near 50 degrees in the south. The stirring northwest
winds and drier air are keeping any fog at bay despite the input
of some rainfall in the southeast parts of the state last evening.
The models, and their individual ensemble suites, are in
excellent agreement aloft through the short term portion of the
forecast. They all depict a descending western lobe of the
large northeast 5h gyre working south into the Ohio Valley today
and tonight whipping through eastern Kentucky into Tuesday
evening. The core of the mid level energy will accompany this push
working over the JKL CWA during the day Tuesday. The small model
spread warranted using the NBM solution as the starting point for
the grids along with some limited adjustments for more terrain
distinctions in temperatures tonight. The CAMs ideas on pcpn
chances on Tuesday were also incorporated into those grids in the
later part of the short term.
Sensible weather features a much chillier and breezy day compared
to the past weekend. Layered clouds arriving from the north
through the afternoon will contribute to below normal temperatures
in conjunction with the CAA on northwesterly winds of around 10
mph with gusts up to 20 or 25 mph today. Look for a very chilly
night amid variable clouds and a small ridge to valley temperature
split. The upper levels will support a batch of showers - mainly
east - developing through the day, Tuesday, as a secondary cold
front brings in a reinforcing bout of cold air and enough lift for
shallow convection.
The changes to the NBM starting point mainly consisted of
adjusting the hourly T grids for more terrain distinction and a
faster valley drop off after dark tonight. As for PoPs - the NBM
values were enhanced (both timing and placement) with the latest
guidance from the higher resolution CAMs for Tuesday.
.LONG TERM...(Tuesday night through Sunday)
Issued at 514 AM EDT Mon Oct 14 2024
The long term forecast period opens on Tuesday evening with a
shortwave disturbance moving out of the Ohio River Valley. At the
surface, this feature is represented by a reinforcing cold front,
which may continue to produce a few showers across far eastern
portions of the forecast area through early Wednesday morning. Then,
northwesterly to northerly flow on the backside of persistent
longwave troughing aloft will advect colder and drier air into the
area. These advective processes will set the stage for the primary
sensible weather concern in this long term forecast package:
widespread frost potential on Tuesday, Wednesday, and Thursday
nights.
Post-FROPA temperatures on Tuesday night will easily drop into the
30s across the entire forecast area, but lingering cloud coverage
may preclude temperatures from dropping below freezing across the
eastern third of the area. Further west, sub- or near- freezing lows
will produce the first of three nights of widespread frost. On
Wednesday, a surface high pressure system will slide into the
region, fostering clear skies and efficient radiative cooling at
night. MaxTs will only reach the mid 50s on Wednesday afternoon, and
low temperatures across the entire area will near or surpass 32
degrees. Wednesday night looks to be the coldest night in the
forecast period, so the greatest coverage of frost will occur then.
Record low temperatures will likely be challenged this week,
especially at the Jackson climate site, where the existing records
are relatively paltry (38 for Wednesday the 16th and 33 for Thursday
the 17th).
As the aforementioned surface high slides east later in the work
week, southerly surface flow will return. At the same time, upper
level ridging builds back in, leading to height rises and the
persistence of mostly clear skies. This will allow temperatures to
gradually moderate. After one more cooler than average day and
continued overnight frost potential on Thursday, highs will return
to near/just above 70 degrees on Friday, Saturday, and Sunday. This
synoptic pattern favors nocturnal ridge-valley temperature splits,
so MinTs will vary greatly based on terrain on these three nights.
Valleys, especially sheltered ones and those with seasonally reduced
exposure to sunlight, will remain much cooler (30s) than the ridges
(40s). This will allow patchy frost potential to linger in valleys
through Saturday morning. By Sunday, it will be warm enough across
the entire forecast area for these diurnal differences to produce
patchy valley fog rather than valley frost.
Confidence in the above forecast is greater than usual; the
available forecast guidance generally agrees upon both the placement
and timing of the parent synoptic weather features. Due to this
enhanced level of confidence, the only major changes made to the
forecast grids were related to local geographic knowledge. Ridge-
valley temperature splits and an enhanced diurnal mixing cycle in
the Td/RH/Wind grids were manually added each day. Thus, other than
the frost potential, the long term forecast is defined by fair
weather. Next weekend's forecast looks ideal for any planned outdoor
autumn activities, with relatively warmer temperatures and the
persistence of mostly clear skies. Before then, frost headline
products may be needed, so interests are encouraged to pay attention
to future forecast updates accordingly.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 136 PM EDT MON OCT 14 2024
VFR conditions are prevailing across all TAF sites with this
issuance. A deck of stratus clouds has moved south into the area
and terminals are VFR but could fluctuate between VFR and MVFR
through much of the forecast period as this cloud deck remains
overhead. Terminals are also experiencing west-northwest winds
that are sustained around 10 knots with gusts upwards of 20 knots.
These winds are forecast to persist over the next couple of hours
but will slowly diminish toward sunset. Scattered showers are
forecast to develop late tonight/early tomorrow morning and will
begin impacting terminal KSYM after 10Z/Tuesday with the
remaining terminals seeing VCSH chances increase through the
remainder of the TAF period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...VORST
SHORT TERM...GREIF
LONG TERM...MARCUS
AVIATION...VORST
Source:
JKL issues Area Forecast Discussion (AFD) at Oct 14, 1:36 PM EDT---------------
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