JKL issues Area Forecast Discussion (AFD) at Jan 27, 12:35 PM EST
077
FXUS63 KJKL 271735
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1235 PM EST Mon Jan 27 2025
.KEY MESSAGES...
- Temperatures should remain near, if not a few degrees above,
normal into next weekend.
- A system will approach the area towards the end of the work
week, with rain the favored precipitation type.
&&
.UPDATE...
Issued at 1124 AM EST MON JAN 27 2025
The forecast is on track for the most part. The only real change
of note is a minor update to the Sky grids over the far southern
part of the forecast area. The latest observations were used as
the starting point for the hourly grid forecasts.
UPDATE Issued at 703 AM EST MON JAN 27 2025
Flurries have departed to the south and southeast as the
associated upper level disturbance moves east. Clearing continues
to spread south and southeast with most areas north of the Hal
Rogers Pkwy and the KY 80 corridor clear or mostly clear at this
time. The clearing will continue to spread east and southeast as
surface high pressure builds in.
&&
.SHORT TERM...(Today through Tuesday)
Issued at 455 AM EST MON JAN 27 2025
Early this morning, an upper level low was centered over the
Hudson Bay vicinity with troughing south across Quebec and
Ontario as well as the Great Lakes and mid Atlantic to the OH
Valley region. Meanwhile, further south, upper level ridging
extended from portions of the Atlantic across the Caribbean and
central America and into the Pacific. A shortwave trough extended
from the mid Atlantic states into eastern KY and the TN Valley
while another shortwave was upstream nearing the mid MS valley.
Shortwave ridging extended from TX into CO, while a closed low
continues to meander south along the CA coast. At the surface, a
wavy frontal zone extended from the Pacific across VA and into the
Southern Appalachian region to the TX Gulf coast. A surface wave
was moving along the boundary from MS into AL with precipitation
extending north of the sfc wave and boundary into the TN Valley
and Southern Appalachians with some of this lingering over VA and
southern to southeastern KY. This light precipitation has
generally tapered off to flurries or sprinkles in the VA and TN
border counties at this time. Low and mid level clouds linger
across southern and southeastern sections with clearing having
worked into much of western and central KY into northern and
northeastern KY and has reached from a Rockcastle to Johnson
county line attm. Temperatures were in the 20s near and north of I
64 with low to mid 30s common elsewhere. A ridge of sfc high
pressure extended from the Southern Plains across the Ozarks to
the mid MS Valley. Further north and northeast, a surface low was
moving from the James Bay area into Quebec with a cold front
trailing across Ontario and Manitoba into Saskatchewan.
Through dawn, any lingering flurries and sprinkles near the VA
and TN borders are expected to end, as the shortwave trough
working into and across eastern KY at present moves east of the
area and the next upstream shortwave enters the Lower OH Valley.
Sfc high pressure sliding further south and southeast in the
Southern Plains to Lower MS Valley will also build across the
Commonwealth today. Further north the surface low in Canada will
move further into Quebec with the trailing cold front dropping
into the Northern Great Lakes to upper MS valley region in advance
of an upper low meandering from Hudson Bay across the James Bay
area and into Quebec. Another shortwave trough in northeast flow
between the upper low and the associated upper trough extending
into the eastern Conus and upper level ridging building from the
interior Northwest to Northern Rockies should near the western
Great Lakes and move into the Upper MS valley area this afternoon
and into this evening. The pressure gradient between the front
dropping further south across the Great Lakes tonight and the sfc
high pressure ridge in the Southern Plains to Lower MS Valley that
builds into the southeast will increase a bit by later today and
into tonight. The pressure gradient should remain near the same
magnitude on Tuesday as another shortwave moves into the trough
extending from eastern Canada into the Great Lakes and portions of
the eastern Conus with an associated clipper moving along the
boundary reaches the Great Lakes late Tuesday.
Overall other than any initial flurries or sprinkles around dawn
along the TN or VA borders, dry weather is anticipated through the
near term period. Highs today and Tuesday should be near normal
with a bit of an upward trend as well. Lows tonight are a bit
uncertain with high pressure nosing into eastern KY though the
pressure gradient will also be of significant enough magnitude to
lead to uncertainty in timing of, degree of, and areal extend of
decoupling in valleys. Drier air arriving today leading to
dewpoints in the afternoon from the mid teens to mid 20s suggests
valleys could fall well into the 20s if not the upper teens.
However, some mixiness may keep several if not most valley
locations out of the teens. Clouds should generally decrease today
from northwest to southeast with skies averaging mostly sunny to
sunny areawide. The clear skies linger into tonight, but an
increase in mid and upper level clouds should result in an
increase in clouds at those levels late tonight and lingering into
Tuesday morning.
.LONG TERM...(After midnight Tuesday night through Sunday)
Issued at 639 AM EST Mon Jan 27 2025
Relatively quieter and warmer weather is expected at the start of
the long term forecast period. Persistent southwesterly flow will
yield low temperatures well above freezing across the entire
forecast area on Tuesday night. Clear skies may foster modest ridge-
valley temperature splits, but expect temperatures on Wednesday
morning to start off in the mid to upper 30s. These seasonably mild
lows will combine with efficient diurnal warming/mixing to yield
widespread highs near or above 50 degrees on Wednesday afternoon.
Forecast guidance does resolve a weak disturbance moving through the
Ohio River Valley on Wednesday, but it continues to look rather
moisture starved. Precip chances have trended down as a result, and
skies will remain mostly clear due to the dominance of dry air in
the column. Collectively, these conditions are expected to
melt all leftover snow on the ground in Eastern Kentucky before
the well-advertised late week storm system arrives.
While forecast guidance continues to disagree on the exact evolution
of said system, the trend towards a faster and warmer event onset
has continued. Sub-freezing low temperatures on Thursday morning
will quickly rise into the upper 40s/lower 50s as surface flow
shifts towards the south and flow aloft backs towards the
west/southwest ahead of the closed upper low's approach. The
resultant warm air advection and moisture return will allow clouds
to stream into the area on Thursday afternoon/evening. This would
insulate Thursday night's temperatures and reduce the risk of winter
precipitation ahead of the system's warm frontal passage. In fact,
the previously-observed 10 to 15 degree spread between the 25th and
75th percentiles of Thursday night's temperature guidance has
significantly narrowed. These percentile values are now both above
freezing, and confidence is increasing that rain will be this
event's predominant precipitation type.
Rain chances enter the forecast on Thursday evening as isentropic
lift increases out ahead of the aforementioned warm front. These
chances peak on Friday as flow aloft backs further to the SW and
access to Gulf moisture increases. An intensifying low/mid level jet
and modeled upper level directional divergence supports the idea
that the rain could be heavy at time. Probabilistic long range
ensembles (both the NBM and the LREF) depict a 50-70 percent
chance of at least 1 inch of rain from this system, with the
greatest chances along and west of the KY-15 corridor. The
probabilities of seeing storm totals greater than than 1.5 inches
are much lower across our forecast area, although a signal for
higher QPF does exist further to the west closer to the I-65
corridor. It is plausible that these reduced rain amounts in our
forecast area are due to the downsloping effects of persistent
southerly surface flow. As parcels of air descend down the
northern slopes of the higher terrain along the Virginia state
line, some degree of downwind drying is likely to reduce
precipitation intensity and totals in our forecast area. These
mesoscale effects and the buffer between the previously-
discussed early week snow melt and the best precipitation chances
will reduce the likelihood of widespread hydrological impacts with
this system. Probabilistic NAEFS river guidance resolves 30 to 40
percent chances of exceeding action stage on the Kentucky River
at Ravenna and Heidelberg in the next 10 days. A closer look at
the QPF plumes of the respective ensemble members reveals that
this is likely an artifact of a few more aggressive models, and
the probability of seeing minor flood stages is less than 10
percent. Due to this system's prolonged rain chances and the
potential for moderate to heavy precipitation rates, however,
localized areal/urban flooding cannot be entirely ruled out. The
Weather Prediction Center has issued a Marginal (Level 1/4)
Excessive Rainfall Outlook for Eastern Kentucky on Friday to
account for this.
Beyond Friday, the long term forecast remains shrouded in
uncertainty. The latest model runs portray a faster ejection of the
parent features aloft, while past runs keep the upper low around for
longer on Saturday. Both of these solutions would generally reduce
precipitation chances on Saturday, with more scattered activity
possible on Saturday afternoon/evening. The greatest amounts of
lingering model spread are in the cloud coverage and temperature
guidance. The amount of cloud coverage on Saturday will play a large
role in how warm it gets on Saturday afternoon and thus how cold it
gets later that evening. NW flow on the backside of the system will
reintroduce CAA, but if drier air wraps around the back side of the
system and there is less cloud coverage, temperatures on Saturday
could reach the 50s once again. If this materializes, temperatures
would be less likely to approach freezing on Saturday night as
precip wraps up. As models come towards a consensus, the sensible
weather specifics for Saturday and beyond will come into focus. For
now, interests with outdoor plans on Friday and Saturday are
encouraged to prepare for potentially wet, but relatively warm,
weather.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1235 PM EST MON JAN 27 2025
VFR conditions under clear to mostly clear skies are expected
through the TAF period. An approaching disturbance from the
northwest will cross the area between 09z and 15z Tuesday. Ahead
of this disturbance, an increasing pressure gradient will promote
modest wind speed increases generally from the west. Aloft, the
stronger low-level warm advection will produce LLWS across the
terminals during the overnight.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CMC
SHORT TERM...JP
LONG TERM...MARCUS
AVIATION...CMC
Source: JKL issues Area Forecast Discussion (AFD) at Jan 27, 12:35 PM EST (https://mesonet.agron.iastate.edu/p.php?pid=202501271735-KJKL-FXUS63-AFDJKL)
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