JKL issues Area Forecast Discussion (AFD) at Oct 6, 8:39 PM EDT322
FXUS63 KJKL 070039 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
839 PM EDT Sun Oct 6 2024
.KEY MESSAGES...
- A cold front passing through tonight will bring a chance of
showers and thunderstorms to mainly eastern portions of the
forecast area.
- Noticeably cooler and drier air will arrive behind the cold
front and persist through next weekend.
&&
.UPDATE...
Issued at 839 PM EDT SUN OCT 6 2024
Hourly grids were updated to account for deeper eastern valley
locations experiencing temperatures dropping off a bit more
quickly as sunset passed. However, an increase in cloud cover and
mixiness at the very least is expected with a frontal passage
later this evening into the overnight. Some convection may also
develop as the front passes and the anticipated mixing should
lead to temperatures in those deeper valley locations leveling off
it not rising a bit before dropping off again behind the front.
No other changes were needed at this time.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 506 PM EDT SUN OCT 6 2024
A cold front is entering KY from the northwest late this
afternoon, supported by a potent upper trough moving east across
Ontario and the Great Lakes region. Low level moisture is briefly
increasing before fropa, with low to mid 60s dew points over KY as
of late afternoon. A cap is currently in place, preventing deep
convection. NAM forecast soundings show a narrow window just ahead
of the front when the cap may weaken and allow showers and
thunderstorms to occur, mainly over the northeast part of the
forecast area. Have maintained a chance of precip there tonight,
tapering to sub-20% POP over our far southwestern counties.
Once the front passes, notably cooler and drier air will begin to
flow into the area, and skies will clear. Cold air advection and
the arrival of drier air and will limit fog potential tonight,
but a bit of fog won't be ruled out toward dawn, mainly in the
deeper valleys of far southeast KY. Clear skies then last for
Monday and Monday night as surface high pressure builds southeast
toward us under west northwest flow aloft. Easing cold air
advection should allow for some fog in the valleys of southeast KY
on Monday night, but the arrival of a much drier air mass could
limit the fog potential elsewhere.
.LONG TERM...(Tuesday through Sunday)
Issued at 506 PM EDT SUN OCT 6 2024
Dry weather and slightly below normal temperatures will persist
throughout much of the upcoming work week. A building surface high
pressure system and continued northwesterly flow aloft will work
together to advect dry, cool air into the area. Subsidence will keep
skies mostly clear, leading to a pattern that generally supports
nocturnal ridge-valley temperature splits. Expect Tuesday to
Thursday's afternoon highs to hover around 70 degrees in most
locations, with a few areas slightly below this in the upper 60s. At
night, radiative cooling will easily allow temperatures to drop into
the lower 40s, with some particularly sheltered and shadowed valleys
making it down into the upper 30s. Conventionally, this synoptic
pattern supports overnight valley fog formation, but antecedent
dryness may limit coverage. For these reasons, fog chances have been
limited to places where our deepest valleys and larger sources of
water overlap. Such places are mostly located in the southeastern
third of the forecast area and close to the Cumberland, Kentucky,
and Big Sandy Rivers.
Due to the local impacts experienced during Hurricane Helene, we
understand that there may be some concern regarding now-Hurricane
Milton in the Gulf of Mexico. The same synoptic features that will
cause our dry and cool weather this week will block this hurricane
from coming our way. Local impacts, if any, will be limited to
cirrus-type clouds streaming off its outflow, and a few past model
runs have resolved this for Thursday. With the recent southward
trends in the tropical models, the latest deterministic NBM sky
grids do not necessarily capture this. If a northward track trend
comes to fruition, the resultant high clouds might make Thursday
slightly cooler than Wednesday. Other than these minor temperature
forecast fluctuations and perhaps some vivid sunrises/sunsets, no
major local impacts are expected from Milton.
Confidence in this long term forecast is greater than average, as
captured by the relatively compressed model spread box and whisker
plots for the next week. Greater uncertainty enters the forecast
just past the end of the period, when a northern stream disturbance
and associated frontal boundary will approach the Ohio River Valley.
Ahead of this system, expect a warming trend. Upper level ridging
will build back in from the Plains by the end of the work week,
allowing temperatures to moderate back towards 75 degrees under
sunny skies on Friday and Saturday. The corresponding wind shift
will lead to some degree of moisture advection into the column,
although it does not appear to be particularly robust at this
moment. Thus, the sensible weather here in the Commonwealth looks to
be seasonably appropriate and quite pleasant for the next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 835 PM EDT SUN OCT 6 2024
VFR conditions prevailed at the start of the period and will
largely prevail through the period. The exception will be within
any stronger showers and storm in more eastern and northeastern
locations that may affect the area through about 06Z with brief
MVFR to IFR reductions are possible as a cold front passes.
Between 08Z and 14Z, limited valley fog developing is anticipated
for some of the deeper valleys south of the TAF sites. Once any
fog dissipates by 14Z, VFR will return to all areas as high
pressure builds in. Winds will average southwest to west to begin
the period at less than 10KT, before becoming northwest from the
northwest portion of the area to the southeast at around 5KT or
less between 02Z and 07Z. By the last 12 hours of the period,
winds will become generally north at 5KT or less.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...HAL
LONG TERM...MARCUS
AVIATION...JP
Source:
JKL issues Area Forecast Discussion (AFD) at Oct 6, 8:39 PM EDT---------------
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