022 
FXUS63 KLMK 242300
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
700 PM EDT Mon May 24 2021

...Updated Aviation Discussion...

.Short Term...(This evening through Tuesday)
Issued at 222 PM EDT Mon May 24 2021

Above normal temperatures are the main story for the short term, but 
there are some subtle shifts in the pattern that are encouraging for 
what is to come. During the overnight hours and into tomorrow, we'll 
see a slight decrease in mid-level geopotential heights over our 
region as our stubborn ridge of high pressure begins to slowly break 
down and shift eastward. The effects of this really won't be 
noticeable until tomorrow afternoon, where mid-level lapse rates 
will steepen just enough to allow for some CAPE to develop. Most 
high-res models allow for little to no convective development, while 
coarse models tend to be more generous with storm potential. Given 
the lack of appreciable lifting mechanisms and potential for mid 
level dry air entrainment inhibiting convective growth, forecast is 
leaning toward the CAMs verifying vs other guidance. Because there 
is little to no CIN, though, will at least introduce a slight PoP 
(20%) in the forecast despite some of the unfavorable factors for 
convective development. Regardless of whether or not storms form, 
temperatures will be quite warm and similar to today, with highs in 
the upper 80s to right around 90.

.Long Term...(Tuesday night through Monday)
Issued at 257 PM EDT Mon May 24 2021

Tuesday Night through Friday Night...

The upper level ridge axis that has been providing the dry and warm 
weather will continue to break down at the beginning of the period. 
As this occurs, a mid-level trough axis is forecast to swing through 
the region along with a weak frontal boundary.  The front will be in 
the area on Wednesday and will serve as a focus for convective 
development.  Capping looks a bit weaker on the model runs and we 
should have an unstable atmosphere in place.  Afternoon MLCAPE 
values will be up in the 1000-1500 J/kg range.  However, background 
wind fields are still pretty weak with less than 30kts of shear 
expected.  Freezing levels are pretty high and low-mid level lapse 
rates are pretty marginal.  Given the instability showers and 
thunderstorms are a good bet and some could be potentially strong. I 
suspect that a marginal risk of severe will likely be forthcoming in 
future outlooks. 

We'll be in between systems on Thursday, but enough instability will 
be around for at least isolated-scattered storms to be possible in 
the afternoon.  A better chance of showers and storms will occur 
late Thursday night as a large convective complex is expected to 
develop across the Midwest Thursday afternoon.  This feature should 
spread east/southeast late Thursday night and impact our region 
early Friday morning.  The outflow from these storms may provide a 
focus for renewed convective develop across our eastern sections 
(east of I-65) on Friday.  Overall threat for Thursday night looks 
marginal once again because the storms are expected to arrive in the 
overnight when we will be devoid of substantial instability. 
However, some stronger storms are possible Friday afternoon across 
the east as we get some heating in the afternoon.  

Highs Wednesday will be in the mid 80s with overnight lows in the 
low to middle 60s.  Highs Thursday again should top out in the mid 
80s with overnight lows in the mid-upper 60s.  Friday should feature 
cooler temps with highs in the upper 70s to the lower 80s and 
overnight lows dropping into the middle 50s.

Saturday through Monday...

Starting to see a bit more agreement within the models for the 
upcoming holiday weekend.  Saturday will feature an upper level 
trough over the region which could keep a bit of cloud cover and 
possibly some scattered showers ongoing across the region.  Overall, 
it doesn't look like a washout at this point.  Temps will be cooler 
with highs in the upper 60s to the lower 70s.  Sunday looks to be 
dry at this point with a bit of rebound in temperatures.  Probably 
will see highs warm back into the mid-upper 70s with some spots 
hitting 80 once again.  The upper level ridge looks to build back 
into the region for Monday with mainly dry conditions for Memorial 
Day and highs in the lower 80s.

&&

.Aviation...(00Z TAF Issuance)
Issued at 655 PM EDT Mon May 24 2021

VFR conditions will persist through the valid TAF period with light 
SW winds around a strong dome of high pressure. Could start to see 
more diurnal cu, but bases will be at least 5-6K feet and coverage 
won't be enough for a ceiling.

&&

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

$$

Short Term...DM
Long Term...MJ
Aviation...RAS