JKL issues Area Forecast Discussion (AFD) at May 3, 11:00 AM EDT003
FXUS63 KJKL 031500
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1100 AM EDT Sat May 3 2025
.KEY MESSAGES...
- The periodic potential for showers and thunderstorms continues
through the next week.
- Near normal to below normal temperatures will envelop eastern
Kentucky through most of the next week.
&&
.UPDATE...
Issued at 1100 AM EDT SAT MAY 3 2025
A lull in the shower activity now evident over much of
southcentral Kentucky/Middle Tennessee and is expected to slowly
work northeast across the remainder of the forecast area through
early afternoon ahead a stronger line of showers and possible
thunderstorms with the incoming cold frontal boundary. Though
rainfall will diminish over the next few hours, relatively thick
upstream cloud cover observed in satellite imagery casts doubt on
how much surface heating will be realized. High temperatures for
this afternoon were lowered a few degrees -- now expect readings
in the mid 60s for most locations, except a few upper 60s to near
70 in the deeper river valleys well east of the Pottsville
Escarpment. The PoPs were refined based on latest guidance to show
the frontal precipitation line reaching the Lake Cumberland/I-64
corridor areas around 2 PM and slowly move eastward to the US-23
corridor by 7 PM.
UPDATE Issued at 757 AM EDT SAT MAY 3 2025
Only very minor changes were made to adjust timing of showers
advancing into the area from the west.
&&
.SHORT TERM...(Today through Sunday)
Issued at 531 AM EDT SAT MAY 3 2025
Early this morning a positively tilted upper trough extends from
OK northeast over the upper Great Lakes, while an associated
cold front is over the Ohio Valley. The front is nearly parallel
to the upper level flow and is moving only very slowly
southeastward. The upper trough will move slowly southeast today
while it closes off as an upper low over the mid Mississippi
Valley. Meanwhile, this will support development of a modest
surface low over KY. The whole regime then shifts ever so slowly
eastward tonight and Sunday as the upper low becomes larger/more
closed.
Large scale southwest flow aloft ahead of the trough/low will
result in deep moisture over our area today, bringing showers.
Even though clouds and precip will be extensive, limited heating
of the the warm and moist air mass on the warm side of the frontal
boundary may result in enough instability for some thunder, with
the greatest potential over the eastern portion of the forecast
area where diurnal heating should be greatest.
The surface low will shift eastward tonight and send the boundary
through as a cold front. At the same time, a dry slot will wrap
around the mid/upper level low and spread into the JKL forecast
area from the southwest. The loss of deep moisture and loss of
instability will bring an end to thunderstorms and most showers
tonight.
The entire regime will continue slowly shifting eastward on
Sunday, with the closed upper low nearby in the afternoon. What
heating can occur beneath the cold upper low will result in
destabilization during the day, and showers and possibly
thunderstorms should increase in coverage, but the extent of
coverage is still uncertain. Based on a model blend, a mid range
POP around 50% was used at this point.
.LONG TERM...(Sunday night through Friday)
Issued at 509 AM EDT Sat May 3 2025
In the field of meteorology, there is a colloquial saying that
applies to the atmospheric set-up that we will experience here in
Eastern Kentucky throughout the long term forecast period. It goes
like this, "Upper level low, weatherman's woe." When the period
opens on Sunday evening, the mid/upper level trough responsible for
the past weekend's active weather is forecast to become cut off from
the northern stream upper-atmospheric flow. The resultant closed low
will wobble over the Greater Ohio River Valley through Tuesday as a
blocking pattern sets up over the contiguous United States. Sensible
weather specifics in this time frame will be largely dependent on
the exact positioning of the low, hence the aforementioned saying's
prevalence. Models generally agree that the forecast area will
remain on the more active southeastern side of this low pressure
system before the block breaks and ridging temporarily builds in on
Wednesday. Guidance begins to diverge after that, but it is
plausible that a second upper level low and atmospheric block sets
up to the west of the forecast area late next week. Thus, forecast
uncertainty is relatively higher than usual due to the volatile
nature of these upper level low set-ups. That being said, the latest
forecast model solutions generally favor active weather in our part
of the Commonwealth next week.
On Sunday night, most of the available forecast guidance resolves
the parent low near Louisville. This would place our forecast area
in a regime of southerly wind components and favorable cyclonic
vorticity advection. Plentiful cloud coverage is likely to keep
temperatures seasonably mild, with overnight lows in the upper
40s/near 50. On Monday, the low is likely to wobble eastward, which
will introduce more of a westerly wind component to locations near
the I-75 corridor. Combined with persistent cloud coverage, this
could yield in a notable temperature gradient across the forecast
area. Highs near 60 are likely in our western counties, but could
reach 70 further to the east, where SW flow will persist for longer.
As lobes of vorticity rotate around the low, precipitation chances
will increase. Plain rain is more likely in the cooler locations,
although a rumble of thunder cannot be ruled out across far Eastern
Kentucky. If the low wobbles further east than what is currently
resolved in the forecast guidance, Monday could be cooler area-wide,
with a more stratiform cloud deck and drizzly light rain chances.
Thus, the potential for temperatures to under-perform on Monday will
need to be monitored closely.
By Tuesday, most guidance depicts the low shifting slightly further
north and east towards Lake Erie, which would place the area in a
regime of westerly flow. This shift should allow drier continental
air to wrap around the back side of the low, leading to less
widespread cloud coverage and relatively lower rain chances.
Temperatures should remain in the mid/upper 60s due to neutral
thermal advection, but the continued presence of cyclonic vorticity
lobes and the potential for some orographic lifting brings yet
another day of shower chances to the northeastern half of the
forecast area. However, guidance can sometimes be too progressive
with these cutoff lows, and the forecast for Tuesday could change if
it lingers around for longer. Under-achieving temperatures and
cloudier/wetter conditions would be possible if the low remains in a
similar position as it was on Monday, so stay tuned to future
forecast updates.
Guidance re-connects the low with the upper atmospheric flow by
early Wednesday morning, allowing it to eject off to the Northeast.
In its wake, weak ridging and a surface high pressure will
temporarily build into the commonwealth, leading to clearer
overnight skies. Mild ridge-valley temperature splits are possible
in this time frame, which also looks to be the driest part of the
forecast period. However, the flow aloft is expected to back towards
the SW on Wednesday in response to the proximity of a second upper
low in the Ozarks. The resultant moisture return favors increasing
cloud cover and perhaps increasing rain chances on Wednesday, but
the simultaneous midlevel height rises favor relatively warmer
afternoon highs in the lower 70s. As previously mentioned, the
blended forecast guidance used to populate the long term forecast
grids is sometimes too progressive with the evolution of these
features, and Wednesday's moisture return/rain chances are marked
with heightened uncertainty as a result. It is possible that
Wednesday could trend drier, but rain chances are still poised to
return late next week. That being said, the forecast for Thursday
and Friday will be highly dependent upon the evolution of both a Rex
Block over the Great Plains and a trough digging into New England.
It is difficult to discern any one particular solution at this
temporal range given the spread in the forecast model suite, but the
NBM averages out to continued highs in the lower 70s, lows near 50,
and continued rain chances through the end of the period.
In short, much of the long term forecast period is shrouded in
greater than usual uncertainty due to the intricacies of these upper
level low set-ups. Interests with outdoor plans next week are
therefore encouraged to pay attention to higher-confidence, near-
term forecast updates to assist with decision making.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 757 AM EDT SAT MAY 3 2025
Conditions were largely VFR, with pockets of MVFR at TAF issuance.
Rain was occurring along and west of a line running through KLOZ
and KSYM. As time goes by, the MVFR ceilings are forecast to
become dominant across the area today (last in the far east), with
showers also spreading eastward and persisting much of the time
through the day. Can't rule out a few thunderstorms as well, but
predictability is too low for inclusion in TAFs. Precipitation
will largely taper off from west to east tonight, but conditions
may actually get worse after precipitation wanes, with mostly IFR
ceilings forecast to overtake the area tonight.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...GEERTSON
SHORT TERM...HAL
LONG TERM...MARCUS
AVIATION...HAL
Source:
JKL issues Area Forecast Discussion (AFD) at May 3, 11:00 AM EDT---------------
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