JKL issues Area Forecast Discussion (AFD) at Jan 24, 6:45 AM EST109
FXUS63 KJKL 241145
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
645 AM EST Fri Jan 24 2025
.KEY MESSAGES...
- A few flurries are expected to linger into early afternoon,
mainly over southeastern Kentucky.
- Temperatures moderate back to normal levels for Saturday
afternoon and then slightly above normal by the middle of next
week.
&&
.SHORT TERM...(Today through Saturday)
Issued at 400 AM EST FRI JAN 24 2025
Chilly temperatures and variable cloud cover are found across the
area this morning. The temperature at 353 AM EST at Jackson, KY
was 27F or about a degree colder than Fairbanks, AK which was at
28F. Readings elsewhere across eastern Kentucky ranged in the
upper teens to mid 20s. The latest surface analysis shows a cold
front extending from the St. Lawrence Valley southward along the
spine of the Appalachian mountains and then southwestward into the
Tennessee Valley. The front precedes a deep positively-tilted
500H trough axis extending from am ~479 dam low over southern
Greenland southwestward across the Great Lakes and beyond into
Texas. A massive 500H ridge remains over the North Pacific and
Alaska.
As the cold front pulls away from eastern Kentucky, low-level
west northwest cold air advection and some very shallow moisture
will keep upslope cloud cover and perhaps a few flurries over
eastern Kentucky through mid-morning. A brief uptick in the
flurries is possible over southern Kentucky, primarily in the
Cumberland River Basin during the late morning to early afternoon
timeframe as the upper level trough axis and an embedded weak
disturbance pass overhead. Very little or no snow accumulation is
expected in any of the flurry activity early this morning or later
in the day. Once the trough axis departs, heights will rise and
the flow will turn more zonal for tonight into Saturday. At the
surface, high pressure passing along the Gulf Coast will nose
northward into the Central Appalachians tonight then drift
slightly southeast on Saturday. This will lead to mostly clear
skies for tonight and Saturday morning. Subtle upper level
disturbances passing on Saturday afternoon should support an
uptick in high cloud cover, but it will still be dry. Temperature-
wise, today's highs will range from the mid 20s north of I-64 to
the mid 30s in the upper portions of the Cumberland River basin
around Middlesboro and Harlan. Favorable conditions for
radiational cooling tonight should lead to a moderate ridge-valley
split with lows ranging from the mid single digits in the colder
northern hollows to the mid/upper teens in the thermal belts.
Temperatures should then rebound nicely on Saturday with afternoon
highs in the lower to mid 40s at elevations below 2,500 feet and
in the 30s above.
.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 12Z TAFS through 12Z Saturday morning)
ISSUED AT 645 AM EST FRI JAN 24 2025
A mix of VFR and MVFR conditions were observed at TAF issuance. In
general, expect MVFR conditions to be more widespread northeast
of US-421 with generally low VFR further south and west. A few
flurries are possible area-wide but the best chance will be over
locations near the Tennessee border and also over the higher
terrain near the Virginia border. Gradual improvement to VFR is
anticipated later this morning and afternoon as any lingering
flurries dry up and ceilings thin/breakup from the west. Winds
will be variable to westerly at around 5 kts or less.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...JMW
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Jan 24, 6:45 AM EST---------------
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