Shelbyville, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

422
FXUS63 KLMK 292014
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
314 PM EST Wed Jan 29 2025

.KEY MESSAGES...

*  Widespread soaking rains arrive Thursday afternoon and continue
   into Friday. Rainfall amounts up to 2 inches expected, with
   locally heavier amounts possible.

*  Widespread flash or river flooding is not expected with just
   minor, localized concerns in low-lying or poorly-drained areas.

*  Dry and mild conditions for this weekend into early next week.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 313 PM EST Wed Jan 29 2025

Seasonably chilly night in store tonight as a building sfc ridge
passes overhead. Winds should decouple, allowing temps to drop to
just below freezing in most areas, with an opportunity for the
sheltered valleys to drop well into the 20s.

On Thursday morning the sfc high should be retreating from the
southern Appalachians toward the Hampton Roads area, with return
flow developing in the Ohio Valley as the negatively tilted upper
ridge passes overhead. Mid-level clouds will quickly increase, with
precip spreading into south-central Kentucky by early afternoon as
isentropic lift develops.

The precip shield should spread north and east through the
afternoon, with rain becoming moderate to occasionally heavy by
sunset in areas west of Interstate 65, and at least a steady soaking
rain underway across most of the area. Not expecting severe wx or
even thunder as instability is lacking. Temps will rise quickly in
the morning, then level off in the 50s with the afternoon clouds and
precip.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 313 PM EST Wed Jan 29 2025

Synopsis...Southern-stream cut off low will lift across the Central
Plains and eventually reach the Ohio Valley late this week as a
weak, positively-tilted shortwave trough. At lower levels, attendant
occluded low will track across the Upper Ohio Valley with triple
point moving roughly along the Ohio River Thursday night into
Friday, supporting great moisture influx into the region as potent
low-level jet extends from the Southeast US. For the weekend,  mid-
level ridge will fill in behind the ejecting shortwave trough with a
stronger anomalous high off the Baja Coast and shortwave energy
moving into the Pacific Northwest/Northern Plains. This pattern
change will promote stable conditions under quasi-zonal flow aloft.
Such regime will probably be reinforced heading into next week as
the anomalous Baja high merges with the weaker mid-level ridge over
the Central US and wave energy becomes confined to the northern half
of the CONUS.

Model Evaluation/Confidence...There is generally good model
confidence regarding precipitation placement and amounts during
Thursday-Friday rainfall event. Overall, models converge on a wide 1-
1.5" QPF area over the Lower Ohio Valley with a some models
depicting a secondary area of 1.5-2.0" and narrow swaths of slightly
higher (2+") totals along north-central Kentucky. The latter
scenario is still possible if moderate to isolated heavy rainfall
rates combine with training/long lasting convective elements.
Forecast confidence increases this weekend and early next week as
positive upper height anomalies build and strengthen during the
period. However, uncertainty increases by the middle of next week as
global deterministic guidance struggle with position and intensity
of shortwave energy moving through the ridge in place. Aside from
timing differences, there is also a non-zero p-type chance with some
of the runs.

Thu Night - Friday...Little change from previous forecast reasoning
as widespread moderate rainfall is expected Thursday night into
Friday morning. Highly anomalous moisture transport, enhanced
convergence associated with the strong low-level jet, and decent
warm cloud depth will will allow a persistence period of moderate to
isolated heavy rainfall to spread west to east Thursday evening into
the overnight hours. HREF probabilities of 1"/hr precipitation rates
are negligible given the lack of instability amid poor mid-level
lapse rates and strong surface inversion. Therefore, rainfall totals
will be a mostly a result of moderate rates of stratiform nature
during a prolonged (6 or more hours) period of time as the warm
front lingers along the Ohio River. That being said, narrow swaths
of weak, training convective elements can yield short-lived but
efficient rates of up to 0.75"/hr. As mentioned above, storm totals
should oscillate anywhere between 1-2 inches with localized higher
amounts, which is below the current FFG thresholds even amid recent
snowmelt. No widespread flooding concerns are anticipated and only
minor flooding issues can arise in poorly-drained and low-lying
areas. As for river flooding, there are no major concerns at the
moment with the 1/29 HEFS run picking up a low chance (around 20%)
of minor flood stage at Peaks Mill (PKMK2) and Dundee (DUNK2). By
Friday, precipitation chances will quickly diminish in the morning
as the system moves to the east and dry slot overspreads the region.
GFS forecast soundings show deep mixing and steepening lapse rates
and although the LLJ core will be moving away, breezy conditions
could manifest in the morning hours and early afternoon. Isolated,
low-topped showers could move along southern Indiana and northern KY
later in the afternoon and evening as the occluded low transitions
across the area.

Weekend and Next Week...Dry weather will continue during the weekend
with a quick temperature dip on Saturday behind a cold front.
Nonetheless, warming temperatures will return on Sunday as the mid-
level ridge establishes over the Ohio Valley. A dry frontal passage
on Tuesday could bring down temperatures a few degrees again while
keeping PoPs at bay given the lack of deeper moisture.

&&

.AVIATION /12Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1151 AM EST Wed Jan 29 2025

VFR conditions and diminishing winds through tonight as high
pressure settles over the Ohio Valley. Return flow sets up early Thu
morning, with a mid-level cig coming in ahead of the next system.
MVFR conditions as precip develops, but expect that to be late
enough in the day to only impact the SDF planning period. Close call
at BWG whether rain gets in before 18Z. Winds 10 kt or less from the
SE on Thursday.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.

&&

$$

SHORT TERM...RAS
LONG TERM...ALL
AVIATION...RAS