969 
FXUS63 KLMK 161717
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
117 PM EDT Thu May 16 2024

.KEY MESSAGES...

*   Widespread showers and storms Friday into Saturday, with gusty 
    winds and heavy rain possible in the stronger storms Friday 
    afternoon and Friday night. 

*   Drier and warm Sunday and Monday. 

*   Showers and storms return Tuesday and Wednesday.

&&

...Updated Aviation Discussion... 

.UPDATE...
Issued at 1022 AM EDT Thu May 16 2024

Low stratus continues to hang on a little longer than expected 
across southern and central KY but current visible satellite imagery 
shows clouds beginning to break and mix out. As the low stratus 
clears high clouds associated with the next approaching system will 
increase high clouds over the are start around midday into the 
afternoon. Only updated the sky grids to reflect the current cloud 
cover and the increase of clouds later this afternoon. The rest of 
the forecast remains on track. Product updates coming shortly.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 305 AM EDT Thu May 16 2024

Synopsis...Split flow pattern will continue during the next 24 to 36 
hours with weak mid-level ridge transitioning through the lower Ohio 
Valley today ahead of a southern-stream shortwave trough over Texas. 
At the surface, subtle high pressure will stretch from the lower MS 
Valley to the Southeast while a tenuous stalled boundary dissipates 
along the OH river.   

This morning...As expected, satellite and surface observations show 
fog/stratus developing across most of the forecast area. As of this 
moment, lowest visibilities are concentrated across southern Indiana 
and north-central Kentucky where clearing was evident earlier 
tonight. Further south, visibilities are still slightly higher and 
stratus dominate over a more surface-based event. This could be 
explained, in part, by the continuous action of gravity waves 
generated from upstream convection which might be promoting boundary 
layer mixing. Overall, HREF guidance supports visibilities falling 
through sunrise leaving the possibility of issuing a Dense Fog 
Advisory for parts of the forecast area. Expect any fog/stratus to 
start lifting by 14Z as daytime mixing kicks in. 

Afternoon/Evening...The weak mid-level ridge will continue moving 
eastward and vorticity energy from the southern-stream shortwave 
trough will approach the area. As a result, anticipate a slight 
uptick from west to east in light shower activity during the late 
afternoon and evening hours. Otherwise, winds will remain light and 
shifting from the west in the early afternoon to the south-southwest 
in the evening.  

Tonight...Better rain and storm chances are forecast for the 
overnight hours as isentropic lifting and moisture advection support 
brief moderate rainfall and a few lightning strikes. GFS forecast 
soundings and CAM guidance indicate best storm chances towards 
sunrise on Friday given better lapse rates and saturated profile. 
Widespread flooding or severe weather is not expected with this 
activity.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 305 AM EDT Thu May 16 2024

A 500mb trough over the southern Plains Friday morning will advance 
to the Ohio and Tennessee Valleys by Saturday night. The main 5H 
wind energy will stay to our south from Texas to Georgia, and this 
is where CIPS analogs and CSU-ML prog the best chances of severe 
storms. GFS shows the best water vapor transport concentrated over 
the Gulf Coast states as well. Still, precipitable water values 
around 1.5" are expected in southern Indiana and central Kentucky 
Friday and Saturday as long as robust convection to our south 
doesn't steal the moisture. As a result, widespread showers and 
storms are in the forecast. Can't completely rule out a few strong 
storms, especially in southern Kentucky Friday evening, beneath the 
left exit region of the upper jet and on the nose of a LLJ coming up 
from Alabama and Tennessee, but right now it looks like instability 
will be weak and deep layer shear marginal. With deep moisture and K 
Index of 30-35, efficient rainers and locally heavy downpours and 
flooding appear to be the main threat. 

Showers may linger east of Interstate 65 Sunday as the system slowly 
pulls away, but overall it's looking drier for Sunday-Monday in our 
position between systems to our east and west. 

Confidence decreases for Tuesday-Wednesday as models grapple with a 
pattern change from split flow this week/weekend to more of a trough 
west/ridge east early next week and then more quasi-zonal by mid-
week. But, the general consensus is that our next weather-maker will 
move through the region during this time period, accompanied by more 
showers and storms. The chance for severe storms in on the table as 
surface low pressure moves from the central Plains to the Great 
Lakes, interacting with an open western Gulf. This idea is further 
supported by ECMWF CAPE-Shear EFI and CSU-ML progs, especially 
Tuesday night into Wednesday. 

Temperatures will be on a moderating trend once the rainy system 
Friday-Saturday starts to move off to the east. By Monday and 
Tuesday highs in the middle and upper 80s can be expected with dew 
points in the 60s.

&&

.AVIATION /18Z TAFS THROUGH 00Z SATURDAY/...
Issued at 117 PM EDT Thu May 16 2024

Low stratus hung on longer than expected especially from LEX-RGA-BWG 
but current visible satellite imagery shows clouds have started to 
mix and clear out. While VFR conditions will remain through the 
forecast period, increasing mid/upper clouds along with rain and 
even some storm chances are in the forecast especially overnight 
into tomorrow morning. Mid-level wave coming out of TX will work 
into the Ohio Valley overnight into tomorrow morning. Models show an 
area of showers/storms working across our area in the predawn hours. 
Bulk of the heaviest rain/storms could occur tomorrow morning before 
a lot of the shower activity with isolated storms develop tomorrow 
afternoon.

&&

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

&&

$$

UPDATE...BTN
SHORT TERM...ALL
LONG TERM...13
AVIATION...BTN