JKL issues Area Forecast Discussion (AFD) at Feb 27, 6:50 AM EST384
FXUS63 KJKL 271150 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
650 AM EST Thu Feb 27 2025
.KEY MESSAGES...
- A cold front will move through the area early this morning with
a few showers.
- Gusty showers and possibly a thunderstorm can be expected again
late this afternoon into the evening with another passing
disturbance. Small hail is a potential with the most intense
activity.
- The next significant rain chances, and potentially some
thunderstorms, will come Tuesday night/Wednesday morning.
&&
.UPDATE...
Issued at 630 AM EST THU FEB 27 2025
The front is progressing steadily through the area with its
showers now clear of the northwest half of the JKL CWA. As such,
no significant changes to the forecast with just the inclusion of
the latest obs and trends for the T/Td grids. These minor
adjustments have been sent to the NDFD and web servers.
&&
.SHORT TERM...(Today through Friday)
Issued at 455 AM EST THU FEB 27 2025
09Z sfc analysis shows a fairly strong area of low pressure
lifting out of the northern Ohio Valley. This is dragging a cold
front through Kentucky early this morning with gusty rain showers
accompanying it - more extensive for the northern parts of the JKL
CWA ATTM. This boundary is switching the winds to the west and
northwest at 5 to 10 mph away from the southwest at similar
speeds in advance of the boundary. It is also cooling the air
with the rain and returning cooler air in its wake. Currently,
temperatures vary from near 50 degrees in the northwest to the
upper 50s and lower 60s on the eastern ridges ahead of the showers
and front. A few of the sheltered valleys area running colder - in
the mid 40s from an earlier drop off in temperatures during the
evening. Meanwhile, dewpoints range from the upper 40s northwest
to the mid 30s in the far east before the showers arrive. A few of
these have been able to tap into the stronger winds aloft to
bring down gusty winds as high as 40 mph early this morning - an
SPS is in effect addressing this through 6 am.
The models, and their individual ensemble suites, are in pretty
good agreement aloft through the short term portion of the
forecast. They all depict a trough digging through the eastern
parts of the Ohio Valley this morning bringing falling 5h heights
and an initial impulse of mid level energy. Later this evening
the core of this negative anomaly pushes through the area as the
5h trough axis crosses eastern Kentucky. Northwest flow at mid
levels follow with much weaker bits of energy passing through the
region overnight and into Friday. However, another substantial
trough then heads this way from the Upper Midwest later Friday
flattening the flow and bringing more energy and height falls to
the Ohio Valley that night. The small model spread aloft supported
using the NBM the starting point for the forecast grids, though
with some adjustments to incorporate the latest CAMs guidance into
the PoPs through tonight.
Sensible weather features a much cooler day in the wake of this
morning's cold frontal passage. It also will be briefly active
late this afternoon and into the evening as the better support
aloft moves into this part of the state along with some skinny
CAPE allowing for a threat of thunderstorms with enough depth for
small hail. The best shot at seeing these thunderstorms will be
generally for the northeast parts of the area, but they cannot be
ruled out just about anywhere in eastern Kentucky this evening.
Drier and cooler weather follows with enough lingering low and mid
level moisture around tonight to limit radiational cooling while
the CAA continues in the wake of the main system moving out of
the area to the east. After a chilly start for Friday morning,
ample sunshine and dry conditions will allow temperatures to
rebound into the mid and upper 50s for highs - though a thicker
cloud deck starts to return from the north by evening. Winds will
also likely be higher than modeled for Friday afternoon given the
tight pressure gradient ahead of the next system.
The changes to the NBM starting point consisted primarily of
adding in some details from the latest CAMs guidance for the PoPs
into this evening. As for temperatures, did not adjust them too
far away from the NBM given the cloud concerns tonight that will
likely hinder radiational cooling and minimize our more typical
terrain effects. Did also tick the winds up this evening and also
Friday afternoon.
.LONG TERM...(Friday night through Wednesday)
Issued at 536 AM EST Thu Feb 27 2025
When the long term forecast period opens on Friday night, longwave
troughing will dominate the upper air charts over the Eastern CONUS.
Out west, a ridge axis will extend from Central Texas up through the
High Plains into Alberta. A southern stream upper level low will be
spinning over Southern California at this time, and the evolution of
that particular feature will play an important role in the sensible
weather forecast for Kentucky over the next seven days. All three of
these features will propagate eastward this weekend, marking the end
of the past week's repetitive clipper-systems and resultant
temperature fluctuations.
On Saturday, a shortwave disturbance will navigate through the
aforementioned mean troughing and nudge one final clipper system
into the Ohio River Valley. Out ahead of its trailing cold front,
temperatures will be fairly mild, with morning lows in the 40s.
Saturday's diurnal temperature curve will be muted by FROPA. There
will be a noticeable NW/SE gradient in daily highs from the
Bluegrass (mid 40s) to Pine Mountain (low/mid 50s), but once winds
shift to a northwesterly orientation behind the front, cold air
advection kicks in. The front is expected to be relatively moisture
starved, although some light precipitation is possible due to the
weak lobes of cyclonic vorticity rotating around the parent trough
aloft. The greatest precipitation chances occur in locales where NW
winds favor orographic lift, although any accumulations will
minimal. A brief changeover to very light snow or flurries is
possible on Saturday night across the higher terrain near the
Virginia state line, but most locales will see a clearing and
cooling trend overnight.
In the wake of Saturday's system, a cold Canadian high pressure
system is expected to build into the Midwest. NW flow will continue
aloft, meaning that a dry, continental airmass will be in place
throughout the entire column on Sunday. Morning lows in the 20s will
struggle to rise above 40, especially north of the Mountain Parkway.
Dewpoints may drop into the single digits in some locales on Sunday,
and cloud cover aloft is expected to be minimal. This favors ridge-
valley temperature splits overnight into Monday; ridgetops will be
in the 20s, with valleys in the upper teens. The eastward
propagation of the entire upper air pattern continues into the
daytime hours on Monday, with noticeable height rises across the
forecast guidance suite. This marks the beginning of a warming
trend, and MaxTs are forecast to rise from the 50s on Monday to the
60s on Tuesday and Wednesday.
Confidence is high that the longwave weather pattern aloft will
favor such a warm up ahead of a rather dynamic mid-week storm
system. Guidance collectively resolves a deep, negatively-tilted
trough over the Central Plains on Tuesday. It will then approach our
forecast area on Wednesday. However, questions linger regarding the
magnitude of moisture return throughout the atmospheric column
beforehand. Surface flow is expected to veer towards the south as
the Canadian high moves east, but southerly surface winds often lead
to downsloping and mesoscale drying in our forecast area. In a
similar manner, models resolve the previously-mentioned southern
stream low opening into a mid-level trough over the Gulf Coast
states on Monday. This would keep winds aloft west-northwesterly for
at least one more day and produce predecessor precipitation in the
Tennessee Valley. Thus, the amount of available moisture will depend
on the forward progression speed of the overarching system. A slower
approach would give the atmosphere more time to moisten and
destabilize. With plenty of shear available, instability will be the
key limiting factor, and the compounding effects of the above
uncertainties precludes the mention of any specific hazard types at
this moment in time. For now, the forecast grids show rain chances
increasing headed into Wednesday and the greatest chances of thunder
in the NW third of the forecast area. We will continue to closely
monitor the potential for thunderstorms and heavy rain over the
coming days. As we do so, interests are encouraged to keep an eye
out for potentially-relevant preparedness and safety information as
we kick off Kentucky's Spring Severe Weather Awareness Week on March
1st. Stay tuned.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 650 AM EST THU FEB 27 2025
Still mainly VFR conditions are ongoing at the start of the
forecast period but some lower CIGs are trailing the front and its
showers. The cold front will move east of the terminals just after
13Z. After the front moves through, a dry period will hold during
the first half of the day, before a passing upper level shortwave
brings a resurgance of scattered showers for a few of the TAF
sites. With the morning, post frontal period: CIGs will linger in
the MVFR range for a time before improving back to VFR later in
the day. Then this evening CIGs and VIS could lower and fluctuate
with a few passing showers, generally staying in the MVFR range,
but increase back to unrestricted once the showers have exited the
area. Winds will be westerly at 5 to 10 kts through mid-morning
before becoming increasingly gusty this afternoon potentially
reaching 25 kts, for a time. The winds will settle later this
evening becoming light and variable into Friday morning.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...MARCUS
AVIATION...GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Feb 27, 6:50 AM EST---------------
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