JKL issues Area Forecast Discussion (AFD) at Jan 23, 10:40 PM EST160
FXUS63 KJKL 240340 AAB
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1040 PM EST Thu Jan 23 2025
.KEY MESSAGES...
- A cold front passing through overnight brings a chance for
flurries and a few snow showers this evening into early Friday.
A few snow showers may be locally intense with sudden, sharp
reductions to visibility and minor snow accumulations over and
in the vicinity of the Bluegrass region.
- Temperatures gradually moderate back toward normal by this
weekend.
&&
.UPDATE...
Issued at 1040 PM EST THU JAN 23 2025
Based on recent radar trends and updated model data, decided to do
a forecast update for late this evening. Current radar trends have
been showing a slightly faster down tick in snow showers and
flurries across the area. Temperatures across most of the area
have also been running anywhere from a couple of to several
degrees warmer than previously forecast, so adjustments were made
to both hourly temperatures and overnight lows. Still expect
scattered snow showers and flurries to persist overnight, with a
few slick spots possible here and there. The hazardous weather
outlook was also updated as the previous one was segmented and the
current one did not need to be.
UPDATE Issued at 745 PM EST THU JAN 23 2025
Incorporated obs from the past several hours into the forecast
grids, with no appreciable change to the overall forecast
necessary at this time. Temperatures for most of the area have
been running about a degree warmer than forecast, so will continue
to watch this trend to see if any changes need to be made to
tonights lows. Scattered snow showers have begun to move through
our area and, based on current radar trends, are holding pretty
close to forecast precipitation probabilities so far this evening.
No update to the zone forecast text product is planned at this
time.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 332 PM EST THU JAN 23 2025
The primary adjustment to the short-term forecast is to be a bit
more aggressive than the NBM with regards to PoPs for late this
afternoon into Friday, and to lower valley temperatures Friday night
across the area given weak low-level warm advection developing with
clear skies and light winds. It is in these scenarios that we
typically see the most significant ridge-valley splits.
As for the forecast overall, main concern through early Friday is
the potential for snow showers and flurries across much of the
forecast area in association with a passing cold front. The front
will pass through overnight, but snow shower chances will increase
from the west and northwest late this afternoon ahead of the front.
Behind the front, cold advection snow showers will likely be
enhanced by upslope flow across central and southeastern Kentucky.
An SPS will be issued for the activity early to mid-evening, as a
few of the MPAS CAMS and the GFS Snow Squall Parameter indicate that
a few of the snow showers could be locally intense in the far
northwestern part of the CWA. Sudden visibility reductions and minor
snow accumulations up to a quarter-inch are possible in the heaviest
snow showers. Models suggest this activity will weaken while
crossing the forecast area.
Subtle upper ridging builds over and to the west of the area within
west-northwesterly flow aloft Friday into Friday night. Clouds will
scatter first from northwest to southeast during the morning and
early afternoon Friday, with clearing from southwest to northeast in
the afternoon. By evening, optimal radiational cooling conditions
with weak low-level warm advection developing will promote
significant ridge-valley temperature differences/splits Friday night
into Saturday morning.
.LONG TERM...(Saturday through Thursday)
Issued at 416 PM EST THU JAN 23 2025
Finally, some model agreement for this weekend!! High pressure will
take hold for Saturday, but will be moving eastward quickly. This
will result in mostly clear skies through the first part of the day,
followed by return flow, WAA, and some increasing clouds by the
second half of the day. Temperatures will be markedly higher than
recent, with highs in the low to mid 40s.
The system in question comes into play on Sunday. Both the ECMWF and
GFS showed a strong upper level low and associated surface low
traveling across Canada Sunday, while another low pressure system
develops across the Southern Plains/western Gulf. WPC still shows
these systems connected by a cold front, which will move through
Kentucky from late Sunday into Sunday night, exiting Monday. The GFS
has been gung-ho on precipitation across the state with this
boundary passage, though it did notably pull back on the extent
across the state 24 hours ago, leaving just mostly the JKL CWA
covered. Meanwhile, the ECMWF has shown a dry frontal passage, with
no precip chances in the state, for this same period. It has been
consistent with this solution for multiple days now.
Finally, with the latest model runs since overnight, the GFS is
coming more into line with the ECMWF, keeping the CWA mainly dry. It
does slide some pops just above the TN border into the far SE
portion of the state during the day Monday before it exits. The NBM
is markedly drier this last run, as well. That being said, it does
still bring some light pops into the high terrain of the far eastern
CWA Sunday night. After another day of highs in the low to mid 40s
across much of the area Sunday, temperatures are expected to drop
down to the 20s overnight as the precipitation starts. Based on the
latest model guidance, it's entirely possible that if any
precipitation does fall, it could become isothermal for a brief
period of time as temperatures drop below freezing. It also shows
much of the moisture below 850mb, making it harder to efficiently
generate snow. As such, it's not entirely out of the question that
we may see some rain changing over to freezing rain, with possibly a
few snow flakes mixed in. Thankfully the pop chances only top out
around 20 percent at this point, and seem to be trending drier. And
the chance of freezing rain is also on the low end, but will be
something to keep an eye out for nonetheless.
Once this system moves out Monday, Kentucky will find itself in the
reigns of another longwave trough across the eastern U.S., with
split flow to our south. As of yesterday, this pattern was shifted
farther north, with KY in the split warmer flow, but latest trends
now show us in the strong NW flow region. It is very interesting,
therefore, that the NBM still has post frontal high temperatures in
the low to mid 40s, not much different than the pre-frontal
environment the day before. The only explanation may be the
continued SW flow at the surface, though wouldn't be surprised if
these temperatures started to trend down a bit if this troughing
does in fact impact the state.
This upper level pattern will persist through Wednesday, as another
surface low pressure system passes to our north. Meanwhile, a
secondary system will be developing across the Southern Plains and
slowly shifting eastward. Again, both the GFS and ECMWF show
Kentucky between these two systems to close out the extended period
Wednesday into Thursday, keeping us dry (with precip to our north
and south) and strong NW flow which would likely promote CAA.
However, the NBM has a different idea, showing scattered pops
related to these systems starting Wednesday night and continuing
through the day Thursday. It also keeps the warm trend in place,
with highs generally in the 40s (topping 50 in some locations on
Wednesday). Obviously, this far out, there is still much to change
and a lot of uncertainty, so will be interesting to see how it
trends.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 630 PM EST THU JAN 23 2025
VFR conditions should hold through the first several hours of the
TAF periods, but will trend toward MVFR later this evening and at
times during the overnight, as a cold front moves through the
region. This boundary will bring BKN to OVC CIGs to our airports
as it moves through, along with scattered snow showers and
flurries. The snow could reduce VSBYs to MVFR, or perhaps even IFR
for brief periods, at the TAF sites. The MVFR CIGs could persist
through the night, before improving after the sun comes up on
Friday and the front moves off well to our east. Due to the
scattered nature of the snow showers and flurries, decided to
continue with PROB30 groups at each TAF sites overnight, to handle
any periods when snow actually occurs at or near an airport.
Winds should remain light and variable overall, but could increase
to 5 to 10kts, with gusts of up to 15kts, as the cold front and
snow moves through. It still appears that the airports that will
be most affected will be JKL, SJS, and SYM, as the best snow
shower activity will likely occur well north of the Highway 80/Hal
Rogers Parkway corridor. The snow should finally begin to taper
off towards dawn Friday, with flurries lingering south of the
Mountain Parkway until late Friday afternoon.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AR
SHORT TERM...CMC
LONG TERM...JMW
AVIATION...AR
Source:
JKL issues Area Forecast Discussion (AFD) at Jan 23, 10:40 PM EST---------------
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