JKL issues Area Forecast Discussion (AFD) at Sep 23, 1:50 AM EDT209
FXUS63 KJKL 230550
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
150 AM EDT Tue Sep 23 2025
.KEY MESSAGES...
- Multiple rounds of showers and thunderstorms are expected
through the week.
- While this rain will largely be beneficial in alleviating dry
conditions, it could also lead to isolated flash flooding,
especially on Wednesday.
- Another potential for thunderstorms with strong winds exists on
Wednesday.
&&
.UPDATE...
Issued at 1150 PM EDT MON SEP 22 2025
Grids were freshened up based on recent radar and observation
trends. Showers and some embedded storms should continue moving
across the region overnight in advance of an approaching
shortwave trough. Temperatures should move little from current
values overnight with the rainfall and cloud cover.
UPDATE Issued at 815 PM EDT MON SEP 22 2025
Initial stronger convection has moved off into WV with a linger
outflow boundary moving into the far southeastern portions of the
CWA. Additional areas of showers with some embedded thunder
linger back to the west. Where the outflow boundary and convection
has passed temperatures have dropped off into the 60s. Pops as
well as hourly temperatures and dewpoints have been updated based
on recent observation, radar, and convective allowing model
trends.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 500 PM EDT MON SEP 22 2025
A large, elongated, positively tilted upper level trough
stretches from Quebec southwest across the north central CONUS
late today. On the southern side of this trough there is a
shortwave trough traveling eastward through the mid Mississippi
and lower Ohio valleys. It is promoting convective development as
it approaches, especially with daytime heating/destabilization
which has occurred. The combination of modest shear (near 40 kts
of flow at mid levels in our northern counties) and pockets of
decent instability (1500-2000 J/KG) is resulting in some strong
storms organizing over central KY late today. These pose a risk of
localized damaging winds as they move into the JKL forecast area
this evening. The severe wx threat should lessen as
heat/instability eventually wanes this evening. A resurgence of
non-severe thunderstorms is possible overnight into Tuesday
morning as the shortwave trough continues to approach. There is
also a potential for multiple occurrences of storms to bring
locally heavy rainfall. While recent dry weather should mitigate
the overall flooding threat, won't rule out some hydro issues
where the heaviest rainfall totals occur.
It's unclear how things will play out on Tuesday. While any
morning activity would tend to inhibit destabilization, there is
potential for enough recovery for a diurnal increase. This again
should be on the decline in the evening. The upper trough is
expected to deepen and become somewhat more longitudinal on
Tuesday night. Models show this supporting deepening of a surface
low just west of KY. This would increase our lower level
warm/moist advection, with an increase in POP resulting overnight.
.LONG TERM...(Wednesday through Monday)
Issued at 755 PM EDT Mon Sep 22 2025
Active, wet weather is expected to continue for the first half the
long term forecast period across Eastern Kentucky. The forecast
guidance suite collectively resolves longwave troughing over the
Eastern CONUS through Friday before the pattern shifts and model
solutions begins to diverge. As various disturbances rotate around
this parent troughing feature, multiple rounds of showers and
thunderstorms appear likely to impact the region. That activity is
poised to give the Greater Ohio River Valley some highly beneficial
rainfall, although some of these storms could be on the stronger
side. Likewise, the cumulative nature of the rainfall could lead to
some hydrological concerns by the end of the work week. Headed into
the weekend, guidance generally points towards synoptics that would
advect a cooler and drier continental airmass into the area. As the
early-period pattern breaks down, a cutoff/closed upper level low is
expected to emerge over the Gulf Coast. The latest deterministic
model runs have moved closer to a consensus regarding the
positioning of said low on Saturday, but continue to struggle to
resolve the amount of moisture wrapping around this feature early
next week. Thus, confidence in the forecast is much lower for Sunday
and beyond.
When the period opens on Wednesday morning, the aforementioned
troughing is expected to be in a deepening phase. The forecast area
will be positioned to the east of this positively-tilted trough
axis, and this set-up favors cyclogenesis in the Ohio River Valley.
A surface low pressure system is expected to develop and then move
northeast as the day progresses. The system's warm front is expected
to lift north that morning, producing an initial round of rainfall.
Likely PoPs continue into Wednesday afternoon/evening, and some of
this rain is likely to be accompanied by thunder as temperatures
warm into at least the upper 70s. Questions linger regarding the
amount of available instability for storms in this time frame, as it
is uncertain whether or not temperatures will warm further into the
80s behind that warm front. Antecedent cloud coverage from the
morning activity could mitigate the thermodynamic environment for
stronger storms, although shear parameters look more favorable. The
LREF joint probabilities for favorable MUCAPE/bulk shear parameters
are currently in the 30-45% range on Wednesday afternoon/evening
across northern/western portions of the forecast area. Mean bulk
shear values of 30-35 knots would support a damaging wind gust
threat if enough instability is realized and frontal forcing could
allow for the development of multicellular clusters or a QLCS. With
a warm front nearby, we will also need to monitor the potential for
localized low-level shear enhancement. The Storm Prediction Center
has outlined most of the forecast area in a Marginal (Level 1/5)
Risk for severe thunderstorms on Wednesday, but noted that the risk
appears conditional due to these mesoscale uncertainties. As higher-
resolution models begin to provide more detailed insight into this
set up, confidence in details related to timing/coverage/hazard
types will increase. Interests are accordingly encouraged to stay
tuned to future forecast updates, especially because the evolution
of Wednesday's event will play a role in Thursday's forecast.
Shower and thunderstorm chances will persist into Thursday as the
aforementioned features propagate eastward. The LREF joint
probabilities for convective parameters are slightly higher (35-50%)
on Thursday afternoon in places along/south of the KY-80/Hal Rogers
Parkway corridor relative to the previously-discussed Wednesday
probs. Damaging wind gusts would be the primary threat with any
storms that take advantage of 30-35 knots of shear and frontal
forcing, but compounding uncertainties preclude the mention of
specific severe weather outlook details at this moment in time.
Thursday generally looks cooler than Wednesday, with afternoon highs
in the low to mid 70s and plenty of cloud cover in the sky. This
will likely limit instability across the area relative to Wednesday,
but the better frontal forcing will arrive on Thursday. Furthermore,
a remnant outflow boundary or a differential heating boundary could
serve as a focal point for convective initiation on Thursday. The
currently-available model guidance is too coarse to pick up on these
finer details, and this forecast is likely to change as higher-
resolution data comes in.
Regardless of severe weather potential, this activity is poised to
bring an additional 1.5 to 2.5 inches of rain to the forecast area.
Given the recently-worsening drought across the commonwealth, that
rain should be highly beneficial. However, if any given location
sees multiple rounds of heavy rainfall multiple days in a row or
multiple times in one day, this activity could culminate in some
localized hydrological impacts. The mean values for modeled
atmospheric precipitable water content in the LREF Grand Ensemble
are between 1.75 and 1.85 inches on Wednesday, and these values
remain elevated between 1.45 and 1.55 on Thursday. Wednesday's
values are above the 90th climatological percentile, and Thursday's
are above the 75th. These PWATS, along with the long/skinny CAPE
profiles visible in model soundings in this time frame, suggest that
rainfall rates will be efficient with this mid-week convection. WPC
has outlined the entirety of Kentucky in a Slight (Level 2/4)
Excessive Rainfall Outlook for Wednesday. This means that there is a
15% chance of rainfall exceeding flash flood guidance thresholds
within 25 miles of any given location in the forecast area on
Wednesday. These probabilities decrease to 5% (Marginal, Level 1/4)
on Thursday, but if soils become saturated by Tuesday or Wednesday's
rainfall, these odds could increase in future forecast updates.
While widespread main-stem river responses are not currently
forecast, localized instances of flash flooding are possible across
the forecast area on Wednesday and Thursday. Remember - turn around,
don't drown!
As the northern stream synoptic features responsible for all of the
above activity begin to eject on Friday, a piece of southern stream
energy will get cut off near the Gulf Coast. This yields the
development of a closed low in the SE CONUS, placing the
commonwealth in a weak regime of northerly flow headed into the
weekend. As drier and cooler air advects into the forecast area
behind Thursday's cold front and the flow aloft returns to
continental origins, skies should gradually clear. A few
orographically-enhanced showers cannot be ruled out on Friday, but
cooler highs in the low/mid 70s and much lower atmospheric moisture
parameters will mitigate the potency of any showers that develop.
Saturday and Sunday look generally drier as the northerly winds
persist, leading to the return of overnight ridge/valley temperature
splits and valley fog formation. However, some guidance suggests
that flow throughout the column may turn easterly by the very end of
the forecast period. If this shift were to materialize, a deep
moisture fetch off the Atlantic could develop, and a moist conveyor
belt around the aforementioned cutoff Gulf low could bring about the
return of shower chances early next week. Model spread begins to
increase around this time frame, so confidence that far out is
fairly low. Before then, expect pleasant fall-like conditions for
the first weekend of astronomical autumn.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 150 AM EDT TUE SEP 23 2025
Rounds of showers and storms ahead of an upper level disturbance
are ongoing at TAF issuance and will continue until tapering off,
generally in the 10 to 13Z timeframe. There should be a relative
lull in coverage of activity behind this disturbance after
sunrise. However, an increase in coverage should occur once again
during the afternoon and early evening hours, warranting PROB30
mentions. Reductions to MVFR or IFR are anticipated under any
convection and several hours of prevailing MVFR are anticipated
for most terminals behind the ongoing activity. Winds will
average south to southwest at 10kt or less outside of any stronger
convection.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...JP
SHORT TERM...HAL
LONG TERM...MARCUS
AVIATION...GEERTSON/JP
Source:
JKL issues Area Forecast Discussion (AFD) at Sep 23, 1:50 AM EDT---------------
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