954 
FXUS63 KLMK 201153
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
653 AM EST Thu Feb 20 2025

...Updated Aviation Discussion and General Discussion...

.KEY MESSAGES...

*  Snow showers will gradually taper off this morning, with little 
   more than a dusting of additional accumulation in the Bluegrass.

*  Another cold night tonight with lows in the single digits.

*  Mostly dry weather through the weekend into early next week. 
   Temperatures will rise above freezing Friday or Saturday, with 
   above normal temps next week.

&&

.UPDATE...
Issued at 652 AM EST Thu Feb 20 2025

Snow showers have dissipated or reduced to scattered flurries over 
southern Indiana and west central Kentucky. Traffic is flowing at 
normal speeds on primary roads and there are currently no wrecks 
showing up in the Louisville metro. So, have allowed the WSW to 
expire on time in the north and west.

Snow showers continue in the Blue Grass. Though they are light, 
they're still reducing visibilities and may be causing a dusting of 
accumulations on roads. So, have extended the WSW in the east for 
just a few more hours.

The Cold Weather Advisory continues as well. Subzero wind chills are 
being reported in several locations around the area.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 320 AM EST Thu Feb 20 2025

Scattered light snow showers will continue to be possible this 
morning, primarily over the Blue Grass, with sfc-850mb moisture 
present, the upper low still nearby over the upper Ohio Valley, and 
a little bit of help from flow off of Lake Michigan. Snow showers 
look less likely this afternoon as available moisture decreases 
slightly, the upper low moves farther away, and the component of 
flow off the lake lessens...though sct/bkn strotocu will persist 
until early evening. Northwest surface winds from very strong 
Canadian high pressure over the mid-Missouri Valley along with only 
partial sunshine will give us another cold day, with afternoon 
readings peaking around twenty degrees.

Tonight the surface high will build directly east into the Ohio 
Valley, clearing skies. With the loss of cloud cover, lessening 
winds, and continuing fresh snow pack, it will be another frigid 
night. Went below guidance with lows in the single digits.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 320 AM EST Thu Feb 20 2025

Synopsis...The active weather pattern experienced during the last 
seven days will shortly come to an end as strong surface high 
pressure builds over the region this weekend and a mid-level ridge 
establishes along the West Coast and the Central US. As a result, 
shortwave energy intrusion will remain muted with weak vorticity 
energy tracking further north. Best chance for pattern amplification 
will probably arrive by the middle of next week as a decent Pacific 
NW trough momentarily breaks the ridge and advances towards the East 
Coast where it is expected to elongate thanks to constructive 
interference from additional shortwave energy. The aforementioned 
scenario will lead to warming temperatures and increasing rain 
chances. 
  
Model Evaluation/Confidence...Forecast confidence remains high for 
the weekend and early next week given good model agreement on 
temperatures and lack of precipitation chances. On the other hand, 
deterministic guidance starts to diverge by the middle of next week 
regarding the intensity, position, and structure of the amplifying 
mid-level trough and associated surface low. This, in turn, has 
implications in the QPF signal over the Ohio Valley. So far, the 
latest GFS run (20/0Z) presents the strongest surface low and 
wettest QPF footprint while the ECMWF and especially CMC are weaker 
and drier. All in all, there is sufficient model-to-model and run-to-
run variability to argue for low confidence in the latter portion of 
the forecast.  

Friday - Sunday...After a frigid morning on Friday with single digit 
temperatures, highs in the afternoon will climb to the freezing 
point as surface high pressure provides dry weather with much needed 
solar radiation (amid a thin mid-level cloud layer). Temperatures 
will continue to warm up Saturday and Sunday as the surface high 
moves to the southeast and low-level winds shift to the southwest. 
Although a small-amplitude vort max will transition through the 
Lower Ohio Valley Saturday morning, lack of low-level moisture and 
high stability will most likely preclude precipitation reaching the 
surface with ECMWF p-type meteograms showing less than 5% of snow 
chances for Louisville or Lexington. 

Next Week...Surface high pressure will continue tracking and 
weakening across the Southeast US while a low pressure area moves in 
from the north, accompanying northern-stream shortwave troughs over 
the Great Lakes. This will lead to a slowly strengthening pressure 
gradient force and enhanced theta-e advection. Light rain chances 
will briefly return to the forecast on Tuesday as a weak cold front 
approaches from the Midwest. However, the best chances of light to 
moderate rainfall are more likely Wednesday into Thursday as a low 
pressure tracks near or over the Lower Ohio Valley. Even though 
confidence in rainfall amounts and location is low at the moment, it 
is worth monitoring the evolution of this system given the current 
state of rivers in the area.

&&

.AVIATION /12Z TAFS THROUGH 18Z FRIDAY/...
Issued at 652 AM EST Thu Feb 20 2025

Light snow showers will taper off this morning, but at least 
scattered stratocu will likely persist through much of the day 
thanks to 925-850mb RH trapped under a sharp inversion. Skies will 
finally clear this evening as a very strong dome of Canadian high 
pressure approaches from the mid-Missouri Valley.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Cold Weather Advisory until 11 AM EST /10 AM CST/ this morning 
     for KYZ023>043-045>049-053>057-061>067-070>078-081-082.
     Winter Weather Advisory until 11 AM EST /10 AM CST/ this 
     morning for KYZ033>043-045>049-053>057-064>067-077-078.
IN...Cold Weather Advisory until 11 AM EST /10 AM CST/ this morning 
     for INZ076>079-083-084-089>092.

&&

$$

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