JKL issues Area Forecast Discussion (AFD) at May 24, 2:39 PM EDT881
FXUS63 KJKL 241839
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
239 PM EDT Fri May 24 2024
.KEY MESSAGES...
- Showers and thunderstorms are expected from time to time through
the middle of next week, especially during the afternoon and
early evening hours.
- There is a potential for severe thunderstorms on Sunday and
Sunday night, with damaging winds and large hail being the
primary threats.
&&
.UPDATE...
Issued at 239 PM EDT FRI MAY 24 2024
Forecast remains on track, and only minor changes were made to
blend in early afternoon observations.
UPDATE Issued at 1044 AM EDT FRI MAY 24 2024
Our fog and low stratus of early morning is thinning and lifting
into a cu field as expected. This will allow for more heating
today as compared to yesterday. Even so, it's looking like
convection will be very limited. Weak ridging aloft with light
flow and very dry mid-upper levels will not be favorable for it.
The best shot at anything looks to be in our southwest counties
toward evening as a weak ripple in the flow aloft approaches.
Based on latest model runs and MOS, have lowered the POP for
today.
UPDATE Issued at 824 AM EDT FRI MAY 24 2024
Updated the forecast package to hang onto PoPs a bit longer across
our eastern zones. Showers have persisted across that area.
Otherwise, low stratus and fog has been showing signs of breaking
up and lifting out. Visibilities remained or have come back up at
several of our area reporting stations across the east. Believe
this is due in part to radiative feedback from some of the
thicker stratus. Further west, where at least partial clearing
occurred overnight, visibilities have remained low at some
reporting sites due to the fog. Have a Special Weather Statement
out to cover the lower visibilities. Otherwise the forecast
remains on track.
&&
.SHORT TERM...(Today through Saturday)
Issued at 532 AM EDT FRI MAY 24 2024
Remnants of last night's MCS is gradually pulling out of eastern
Kentucky this morning. With ample boundary layer moisture, low
stratus and fog have been developing in the wake of this system
as it moves out of the area. Areas most impacted by the low
stratus and fog have been our western most zones, especially our
Bluegrass counties where at least some partial clearing has taken
place. Cloud cover has tended to keep any fog development at bay
across our eastern zones, though some patchy fog is dropping
visibilities at times, in places. Have issued a statement
highlighting the potential of lower visibilities across our west
where the fog is more substantial. Will continue to monitor the
remainder of the area for a possible expansion of the statement
further east if necessary.
A fairly progressive pattern is in place during the short term.
Relatively zonal flow aloft will carry embedded short wave
disturbances through the area during the short term, with two main
windows, or peaks of convective activity to deal with. The first
will be a round of showers and thunderstorms this afternoon into
early this evening, then a reemergence of convection for Saturday
afternoon and evening. In between some isolated shower and
thunderstorm activity can not be ruled out.
At this time the potential of severe weather during the period is
limited. There is ample instability to deal with this afternoon,
with MLCAPEs climbing to between 1000-2000 J/kg. However, there is
very little environmental effective shear to draw upon, which is
expected to limit any organized and/or stronger convection today
and this evening. The first round of convection will overspread
eastern Kentucky from the southwest this afternoon continue to
move northeast into the early evening. CAMs show a line of
convection forming to our southwest over the MidSouth this
morning. This activity will lift northeast as the day progresses,
reaching our far southwest by late this afternoon. However, timing
of the convection into our area (late this afternoon and evening)
will not be favorable. With the loss of diurnal heating, and the
necessary ingredients for sustained convection, the activity will
gradually wane and dissipate through the late afternoon and
evening as it moves into eastern Kentucky.
Convection is expected to be a bit more widespread for Saturday
afternoon with the approach of a surface cold front. This front
will drop as far as the Ohio River Valley before stalling just to
our north. However, the boundary will be close enough to provide a
focus for additional showers and thunderstorms through the
afternoon and early evening Saturday. Instability will be a tad
higher Saturday, with MLCAPEs peaking out around or just above
2000 J/kg. Effective shear will be marginal, around 20-25 kts with
the surface boundary in the area. This should be enough that a
few thunderstorms could become strong. As a result the Storm
Prediction Center has added portions of eastern Kentucky in a
marginal risk for severe weather. At this time the threat of
severe weather is quite low and would be limited to gusty winds
and hail. As with any thunderstorms, rain could become heavy at
times, possibly leading to some localized flooding problems. All
of this is adequately handled in our HWO products.
.LONG TERM...(Saturday night through Thursday)
Issued at 444 AM EDT FRI MAY 24 2024
The extended starts off fairly active across the CONUS, with a
couple of short waves exiting our area and the southeastern CONUS to
start things off. The short wave in our vicinity will allow
scattered showers and storms to linger across our area for a bit,
before they exit the area around dawn Sunday, as the upper level
system moves off to our east. Another much more potent weather
system will be taking shape to our west over the central Plains, in
the form of a vigorous short wave. The shortwave will develop on the
southern periphery of a larger upper level system that will be
moving slowly across southern Canada to finish out the weekend. As
the short wave moves across the central Mississippi Valley and
across the Great Lakes on Sunday, it will strengthen. As this
happens, a steady fetch of warm, moist air from the Gulf of Mexico
will stream into the Tennessee and Ohio Valleys. This influx of air
will create moist and unstable conditions ahead of the approaching
short wave. A surface based area of low pressure will also form over
the Plains on Sunday, and will strengthen and move east in response
to the eastward progression of the upper level system mentioned
earlier.
What this all amounts to, is conditions will be primed for shower
and thunderstorm development across our entire area, especially
Sunday night and Monday, as the cold front moves through. The latest
model soundings indicate plenty of instability will be in place
Sunday night into Monday, with a weak low level capping inversion
also evident. There will also be fairly strong flow aloft Sunday
night and Monday, particularly at the 850 and 500 mb levels. All
these components will favor not only general shower and thunderstorm
development across the area heading into Memorial Day, but will also
provide the necessary ingredients for strong to severe storms. The
latest day 3 outlook from the Storm Prediction Center has a marginal
to slight risk of severe weather in place for our area from Sunday
morning through Monday morning, so we will need to monitor the
situation closely over the next couple of days for severe weather
potential.
The best chances for showers and storms for us will be from Sunday
afternoon through Monday, as the initial short wave moves through,
followed by the surface front. Once the cold front has moved through
Monday, the models suggest that another upper level disturbance will
break off from the back side of the eastward moving southern Canada
system and then dive southward through the Great Lakes and into the
Ohio and Tennessee Valleys Monday night and Tuesday. With some
moisture still in place, showers and storms will likely linger
around the area Tuesday night and Wednesday, before finally moving
off to our east with the departing upper low late Wednesday
afternoon. After that, a ridge of high pressure should settle over
the region to finish out the week, with decreasing clouds and dry
weather taking over the end the week.
Based on current model data trends, temperatures should be generally
above normal during the period. We will probably see slightly below
normal readings Wednesday and Thursday, after the second upper level
system moves through, but overall, daytime highs should range from
the upper 70s to mid 80s around the area, as persistent southerly
and southwesterly flow will be in place in association with the
passage of the late weekend system. As of now, it appears that the
primary forecast concern will be the potential for severe weather
Sunday through Monday, which we will keep a close eye on in the days
leading up to the event. If severe weather were to occur, the
primary threats would be damaging wind gusts and large hail, with
isolated tornadoes also possible.
&&
.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 239 PM EDT FRI MAY 24 2024
Mainly VFR conditions are expected through the period. The only
exceptions would be localized IFR or worse conditions in valley
fog overnight and early Saturday (which is not forecast to affect
TAF sites) and a small potential for localized sub-VFR conditions
in convective precip at times.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...HAL
SHORT TERM...RAY
LONG TERM...AR
AVIATION...HAL
Source:
JKL issues Area Forecast Discussion (AFD) at May 24, 2:39 PM EDT---------------
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