JKL issues Area Forecast Discussion (AFD) at Sep 6, 7:16 AM EDT
394
FXUS63 KJKL 061116
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
716 AM EDT Fri Sep 6 2024
.KEY MESSAGES...
- After another warm day today, a cold front passing tonight will
bring a noticeable cool-down for the weekend. This is followed
by a gradual warm-up next week.
- Showers or thunderstorms are possible late this afternoon into
this evening in association with the passing cold front.
Otherwise, there's no rain in the forecast for the next week.
&&
.SHORT TERM...(Today through Saturday)
Issued at 352 AM EDT FRI SEP 6 2024
An energetic upper trough will push from the Upper Great Lakes
region this morning to the Mid-Atlantic region Saturday evening. A
cold front will move south and southeast through eastern Kentucky
tonight, ushering in an unusually cool and dry air mass for early
September by Saturday afternoon.
Ahead of the front, a broken line, or lines, of showers and
thunderstorms will enter our northwestern counties late this
afternoon, then move through the remainder of the forecast area from
north-northwest to south-southeast through the evening and early
overnight tonight. Models suggest instability rapidly weakens with
the loss of daytime heating, with the most likely locations to see
thunder being along and north of the Interstate 64 corridor, with
chances diminishing to the south and instability wanes. Clouds
begin to diminish Saturday morning from northwest to southeast
Saturday morning as an unusually cool and dry air mass moves in
for Saturday afternoon.
It is interesting to note the larger than usual temperature spread
in MOS guidance for high temperatures Saturday behind the cold
front. The MET guidance for Saturday at KJKL is only 64 degrees,
which would be unusually chilly for so early in September and only
one degree above the record low maximum for the date set in 2011.
The ECMWF and GFS MOS forecast highs for KJKL Saturday are higher,
but still quite cool for early September, at 69 degrees and 72
degrees, respectively. Will stick with the NBM forecast high of 70
degrees for now, but note there is room for the forecast to trend
cooler than this.
.LONG TERM...(Saturday night through Thursday)
Issued at 352 AM EDT FRI SEP 6 2024
This particular long term forecast package is defined by a rather
quiet weather pattern. Around the backside of ejecting upper level
troughing and within a post-FROPA surface regime, cool and dry air
advection will yield in mostly clear skies and seasonably cold
temperatures through Monday morning. Expect one more day of
afternoon highs around the 70 degree mark on Sunday as a surface
high pressure with Canadian origins settles into the Commonwealth.
Overnight MinTs in the low to mid 40s appear likely on both Saturday
and Sunday nights as clear skies and calming winds combine to
produce efficient radiational cooling. Topographic temperature
splits and the development of AM valley fog near bodies of water are
common when patterns like this settle into Eastern Kentucky. As
such, both of these remain in the forecast for much of next week.
Perhaps the highlight of the long term forecast is the potential to
rewrite the existing temperature records at our climate sites in
Jackson and London. On Saturday night into Sunday morning,
probabilistic ensemble guidance returns a 65% chance of temperatures
less than 49 degrees across much of the forecast area. Thus, the
minimum temperature record in Jackson for September 8th (49 degrees)
appears poised to break. The record MinT of 45 degrees in London
will be harder to reach, but given the potent post-FROPA cold air
advection and a forecast that favors efficient radiational cooling,
it certainly cannot be ruled out. In fact, if the current forecast
grids for both locations verified, they would tie or break the
existing records, with both sites forecast to drop down to 45
degrees on Sunday morning. On Sunday afternoon, the record minimum
high temperature (69 degrees) at Jackson could be broken or tied.
DESI depicts a 55% chance of afternoon highs less than 70 degrees on
this date at KJKL, with much lower chances at KLOZ, where the record
is 68 degrees. For Sunday night into Monday, the record lows are 46
in Jackson and 45 in London. Guidance is less aggressive with its
forecast lows on this second cool night, although efficient
radiational cooling could once again yield in broken records. Stay
tuned to future forecast updates to see if these climate records are
broken!
Throughout next week, the aforementioned surface high pressure
system and related upper level ridging gradually propagate eastward.
As it does so, temperatures moderate back into the 80s (afternoon
highs) and 50s (overnight lows), and shifting winds slowly
reintroduce a little bit of moisture aloft. Some models resolve the
development of an inverted troughing feature over the area by
midweek. Given the similarities of the forecast synoptic pattern to
the one we witnessed this past week, this solution appears
plausible. If it comes to fruition, some mid/high clouds would
stream into the area on Wednesday, and the forecast grids reflect
this. However, the continued dominance of dry air/subsidence and a
lack of any real synoptic forcing means that PoPs remain suppressed
for the foreseeable future. In short, expect rather tranquil
sensible weather next week.
&&
.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 716 AM EDT FRI SEP 6 2024
VFR conditions are expected through 21z Fri with the exception of
valley fog this morning resulting in IFR or worse visibilities in
some locations. Beginning after 21z showers and thunderstorms in
association with an approaching cold front will begin to move into
the area from the north and northwest, with KSYM and then KSME the
most probable of the TAF sites to be impacted by thunderstorms
producing some gusty winds. Showers and perhaps a few thunderstorms
will then move south and southeast through the remainder of the
TAF sites after 00z, with the chances of thunderstorms diminishing
through the evening as the activity moves through the remainder
of the area. Sub-VFR conditions are expected with the arrival of
showers and thunderstorms, and then again for much of the
overnight immediately along and behind the cold front passage.
Skies will begin clearing from northwest to southeast at the end
of the TAF period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CMC
LONG TERM...MARCUS
AVIATION...CMC
Source: JKL issues Area Forecast Discussion (AFD) at Sep 6, 7:16 AM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202409061116-KJKL-FXUS63-AFDJKL)
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