JKL issues Area Forecast Discussion (AFD) at Feb 27, 5:39 AM EST457
FXUS63 KJKL 271039
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
539 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.
&&
.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 06Z TAFS through 06Z Thursday night)
ISSUED AT 1255 AM EST THU FEB 27 2025
VFR conditions are ongoing at the start of the forecast period but
will start to deteriorate at most terminals, shortly. A cold
front moves through the forecast area overnight, generally between
07 and 13Z, bringing with it some gusty rain showers. Went with
PROB30 along and ahead of the boundary. After the front moves
through, expect a dry period during the first half of the day,
before a passing upper level shortwave brings a resurgance of
scattered showers for some of the TAF sites. As the sfc system
approaches through the rest of the night, expect CIGS to begin
deteriorating into the MVFR range, 15-30k ft AGL, where they will
likely remain for most of the day. VIS will probably also lower
and fluctuate with the passing showers, generally staying in the
MVFR range, but increase back to P6SM once the showers have
exited. Winds will start out from the southwest direction early
this morning at 5 to 10 mph, becoming more westerly when the
front passes through into dawn - but with gusts up to 35 kts in
any heavier shower. As we head into the daytime hours, can't rule
out some increased mixing, which would result in gusts between 15
and 20 kts during the afternoon. Also, look for some LLWS through
the first part of the overnight with winds up to 45 kts off the
sfc from the southwest.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GREIF
LONG TERM...MARCUS
AVIATION...JMW/GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Feb 27, 5:39 AM EST---------------
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