LMK issues Area Forecast Discussion (AFD) at Dec 12, 12:48 AM EST ...Updated Aviation Discussion...560
FXUS63 KLMK 120548
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
1248 AM EST Thu Dec 12 2024
...Updated Aviation Discussion...
.KEY MESSAGES...
* A few slick spots are possible Thursday morning, particularly
where the heaviest snow showers occurred Wednesday
afternoon/evening.
* Widespread showers Saturday afternoon and Saturday night, with a
half inch to 1 inch of rainfall expected.
* Another rain event Monday and Monday night, with up to 1 inch of
rainfall possible.
&&
.UPDATE...
Issued at 951 PM EST Wed Dec 11 2024
Current nighttime microphysics satellite imagery shows most of the
lingering stratocu either scattering out or moving off to the east
of the area. While there are a few light radar returns over the KY
Bluegrass that may be producing some flurries, these shouldn't be
particularly impactful, and should wind down over the next hour as
drier air continues to filter in from the west.
Surface high pressure axis stretching from the eastern Dakotas down
into the lower Mississippi Valley will approach the region tonight
into tomorrow morning, helping winds to gradually ease overnight.
While cloud cover may start to approach our southern IN counties by
around daybreak Thursday, mostly clear skies are expected for most
of the nighttime hours. This should allow temperatures to drop into
the 20s across the area, and the current temperature forecast is on
track. While one or two slick spots cannot be ruled out tomorrow
morning in areas which received heavier snow bursts this evening,
these should be fairly isolated, and most road surfaces are already
dry. Accordingly, we'll allow the SPS mentioning impacts from slick
roads to drop off at 03Z, and monitor conditions overnight.
Issued at 724 PM EST Wed Dec 11 2024
A downward trend in snow shower activity has been observed over the
past hour to 90 minutes across the area, with a few heavier bursts
of snow still lingering along and north of the I-64 corridor. This
matches up well with where the greatest values of snow squall
parameter are on current SPC mesoanalysis, extending from the I-64
corridor northward into northern KY, southeast IN, and southwest OH.
Conditions are becoming less favorable for these convective bursts
of snowfall as low-level lapse rates have become less steep with the
loss of diurnal heating and the 850 mb thermal trough axis now
lifting to the north and east of the area. Additionally, drier air
is continuing to filter in from the west, with moisture quickly
becoming insufficient for widespread snow showers.
With that being said, a few light to moderate snow showers will
continue mainly north of I-64 and east of I-65 over the next 1-2
hours. Have added a chance for flurries farther to the southwest
through 03-04Z, by which point the sources of lift and moisture
should be pretty well out of the area. Temperatures should slowly
settle into the upper 20s and lower 30s over the next few hours.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 304 PM EST Wed Dec 11 2024
Currently, broken skies have filled in over the area, slowing
warming. Temperatures are sitting in the upper 30s and low 40s. A
band of heavy snow moved through western Kentucky, and once it got
to central Kentucky, turned to light-moderate rain/snow mix.
Observations showed temperatures wet-bulbed down to the low-mid 30s
as the band passed. This band will continue to work across central
Kentucky.
Additionally, snow showers have developed over Illinois and Indiana
as deep troughing and CVA move through the Ohio Valley. These
showers will move southeast into the region over the next few hours
and last through the evening. Model soundings show 30-50 J/kg of
SBCAPE, steep lapse rates, 30kts of 0-3km shear, marginal surface
temperatures, and plenty of moisture within the DGZ. These
conditions lead the snow squall parameter to show values between 3
and 4. Some snow showers will become heavy, however, fast
translation speeds and cellular nature of these showers will bring
brief reductions in visibilities and accumulations. Snow showers
will dissipate and exit to the east, chasing the best forcing,
around 2-3Z.
Skies will quickly clear behind the precip help temperatures to cool
into the upper teens and low-mid 20s by Thursday morning. Pressure
gradients will slowly relax overnight, keeping winds breezy through
most of the overnight period. With precip falling after sunset, wind
protected areas may see some slick spots develop. Drivers should use
caution overnight and during the Thursday morning commute. Wind-
exposed areas will likely dry out, leaving minor impacts
possible for mostly bridges and overpasses.
High pressure will build into the area Thursday, bringing continued
clear skies, light winds, and dry conditions. Temperatures are
expected to warm into the upper 30s along and north of I-64 and low-
mid 40s over central Kentucky. Light winds and sunny skies, will
help the temperatures feel a bit more pleasant.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 304 PM EST Wed Dec 11 2024
Progressive quasi-zonal upper pattern will dominate most of the long
term. Tranquil weather and moderating temps expected Thursday night
through Saturday morning as sfc high pressure over the mid-Atlantic
holds sway. As a progressive trof moves across the Plains Fri night,
deeper southerly flow allows temps to recover to above climo.
Precip breaks out Sat afternoon and peaks Sat night as a 50 kt low-
level jet cranks up, increasing PWAT values to around 1 inch. Temps
are still in the 50s and instability is nil, so expect mainly a
stratiform rain with little or no thunder potential. Rainfall
amounts will generally range from a half inch to 1 inch before
precip tapers off on Sunday.
Shortwave ridging Sunday and Sunday night will keep temps mild, with
precip chances ramping up again Monday with another progressive trof
moving through the southern Plains. Looks like another soaking rain
Monday and Monday night with little or no thunder, and temps
remaining on the high side of normal.
&&
.AVIATION /06Z TAFS THROUGH 12Z FRIDAY/...
Issued at 1247 AM EST Thu Dec 12 2024
VFR conditions are expected through the forecast period at area TAF
sites. During the daylight hours, mid-layer clouds are expected to
move east over southern Indiana and north central Kentucky. West
winds will begin to ease after 12z. By the afternoon, BWG, RGA, and
HNB winds are expected to back towards the south. During the evening
into the overnight hours, the northern sites of HNB, SDF, and LEX
will see their light winds drift towards the north, then east.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...CSG
SHORT TERM...SRM
LONG TERM...RAS
AVIATION...KDW
Source:
LMK issues Area Forecast Discussion (AFD) at Dec 12, 12:48 AM EST ...Updated Aviation Discussion...---------------
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