Lexington, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

525
FXUS63 KLMK 070242
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1042 PM EDT Tue May 6 2025

.KEY MESSAGES...

* Mostly dry weather for tomorrow, with a slight chance for isolated
  showers mainly for south-central Kentucky.

* Cold front will bring another chance of showers and embedded
  thunderstorms on Thursday.

* Warmer and drier weather possible for the weekend.

&&

.UPDATE...
Issued at 1041 PM EDT Tue May 6 2025

A quiet night lies ahead. Skies have been mostly clear this evening,
but we are now seeing increasing cirrus across the southwestern half
of the forecast area. Prior to the arrival of denser cloud cover,
patchy fog will be possible (especially in the valleys). Otherwise,
just a cool night with increasing high clouds. Expect lows in the
mid 40s to near 50 in most areas.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 320 PM EDT Tue May 6 2025

The upper level low has shifted to the northeast of the area today,
resulting in drier weather and sunshine. A diurnal cu field is over
the lower Ohio Valley today, with temps mostly in the upper 60s. The
cu field will diminish as the sun lowers in the horizon this evening.

For tonight and into tomorrow, the omega block pattern will
continue, with narrow upper ridging overhead. A weak shortwave
rotating around the parent southwestern US upper low will ride up
into the region, which will introduce increasing high level cloud
cover overnight. A mid-level vort wing will pivot across the TN/OH
Valley, which will support a low-end chance for some isolated to
scattered showers for tomorrow. Precip is expected to be light, with
model soundings suggesting a notable low level dry layer that could
prevent some precip from making it to the sfc. Will still carry a 20-
30% chance mainly for south-central KY throughout the day. An
isolated rumble of thunder may be possible, but chances are even
lower.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 320 PM EDT Tue May 6 2025

===== Wednesday Night - Thursday Night =====

By Wednesday night and into Thursday, the southwestern upper closed
low will open into an elongated and positively-tilted upper trough.
This will be the primary driver for a weak sfc low to dive
southeastward through the Ohio Valley, with an associated cold front
sweeping through from north to south across the area on Thursday.
Ahead of the front, moisture transport will not be strong, so sfc
dewpoints are forecast to remain in the 50s. While some isolated
showers will be possible ahead of the front, the best rain chances
will arrive with the front pushing through in the afternoon. This
will coincide with the best timing for destabilization, which given
sfc temps warming into the mid-70s, we could end up with a few
hundred J/kg of SBCAPE. The 100-member grand ensemble LREF has a
mean output of 500 J/kg across the area Thursday afternoon, though
deterministic model soundings suggest upwards to 1000 J/kg. Precip
coverage will increase to be at least scattered across the area for
Thursday afternoon, with showers and thunderstorms possible. With
weak and disorganized low level flow, wind shear will be weak and
supportive for non-severe thunderstorms. PWATs will not be
impressively high with this system, with up to 1.1" expected. This
would be just above the daily mean of 0.9". QPF has increased
slightly since yesterday, but still expect most of the area to
receive less than a quarter of an inch of rain.

The front will slide through the region by Thursday night, leading
to a drop in sfc dewpoints by Friday morning. Drier weather is
expected after 00z Friday (Thursday evening) and into the overnight.
Temperatures for Thursday night will range from north to south, but
could be tricky as they depend on the timing of the front.


===== Friday - Monday =====

The upper trough will deepen into a close low over Ohio/Pennsylvania
on Friday, with general troughing remaining over the region. While
the mid-level forcing will swing south of the area, a low chance for
an isolated shower may be possible along the KY/TN state line.
Otherwise, expect dry conditions and increasing sunshine for Friday.
Temps will be slightly cooler thanks to NW flow, with highs in the
upper 60s and low 70s. This will be a few degrees below normal for
this time of year.

Temperatures do gradually warm up through the weekend, with temps on
Saturday in the mid-70s, and Sunday in the upper-70s and near 80.
This will be in response to broad sfc high pressure setting up over
the Midwest. The Euro and GFS have good agreement on upper level
evolution into the weekend, with both suggesting an upper low to
spin off of the upper elongated trough and sit over the lower
Mississippi River Valley. This would keep better moisture and
forcing to our south, and a drier forecast for most of the area for
the weekend. Some mid-level vort lobes could swing up into the
Tennessee Valley, which could support some low ran chances, but
confidence remains low for now.

&&

.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 810 PM EDT Tue May 6 2025

VFR is likely through much of the period. Ridging at the surface and
aloft will shift east over the region tonight, resulting in light
winds. Cirrus clouds will increase from the southwest overnight
downstream of an upper low spinning over the Texas Panhandle.

The only concern late tonight and early Thursday is possible fog
development, particularly before denser cloud cover spreads in.
Based on crossover temperatures, HNB and RGA appear to have the best
chance at seeing fog (confidence is highest at HNB). Spotty light
rain will be possible across southern KY on Wednesday, so BWG has
the best chance (still only 20-30%) at seeing brief rainfall.

&&

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

&&

$$

UPDATE...EBW
SHORT TERM...CJP
LONG TERM...CJP
AVIATION...EBW