LMK issues Area Forecast Discussion (AFD) at Dec 25, 12:32 AM EST ...Updated Aviation Discussion...434
FXUS63 KLMK 250532
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
1232 AM EST Wed Dec 25 2024
...Updated Aviation Discussion...
.KEY MESSAGES...
* Another round of light rain showers late tonight and early
Wednesday. Christmas Day will feature above normal temperatures.
* Above normal temperatures Thursday through the end of the week.
Multiple disturbances to bring rain chances most days.
&&
.UPDATE...
Issued at 931 PM EST Tue Dec 24 2024
Weakly defined warm front is currently best analyzed across southern
Indiana where notably higher dew points have pooled. This feature is
expected to move a whole lot, but do expect it could lift northward
a bit overnight and more into central Indiana by tomorrow morning.
As this occurs, focus for light rainfall should mostly stay along
and north of the Ohio River thanks to a weak isentropic lift
component. This is where we have the highest precipitation chances,
however QPF should total much more than a tenth of an inch or less
through the overnight. South of the Ohio River, pops taper pretty
dramatically with dry conditions expected across southern KY.
Overnight lows won't budge a whole lot given the cloud cover, and
most lows should stay in the low to mid 40s.
&&
.SHORT TERM /THROUGH THURSDAY/...
Issued at 243 PM EST Tue Dec 24 2024
Mid-afternoon satellite imagery shows an extensive amount of mid-
high level cloud cover across the region. Starting to see a few
breaks in the clouds from the I-65 corridor and points west. Where
we've had some breaks, temperatures have warmed into the upper 40s
in many spots, with a few areas hitting 50-51. The cooler spots in
our area were out near the I-75 corridor where temps were still
running in the mid 40s. Earlier rain showers have pretty much
abated for the time being. For the remainder of the afternoon
hours, dry conditions are expected. Afternoon highs will top out in
the 44-50 degree range before falling into the lower 40s by sunset.
For this evening, dry conditions are expected across the region. We
may see some light rain showers get into the far western CWA by late
evening with temperatures averaging between 40-44 degrees. Later
tonight, the next upper level shortwave trough axis will move
eastward toward the MS Valley. Another round of weak isentropic
ascent aided by a warm advection scheme will generate an arcing band
of precipitation from western KY northeastward into southern IN and
in KY along the Ohio River. Rainfall amounts will be light here and
it will not be a complete wash out. Overnight lows look to cool
into the 37-42 degree range.
For Christmas Day, cloudy skies are expected with a continuation of
light rain showers from western KY into southern IN. These rain
showers look to diminish through the day as forcing moves away from
the region. Ill-defined frontal boundary is forecast to lift
northward during the day offering a warmer round of weather. Highs
will range from the upper 40s to lower 50s across southern IN and
the northern half of Kentucky. South of the WK/BG Parkways,
temperatures are expected to warm into the mid-upper 50s.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 243 PM EST Tue Dec 24 2024
Wednesday Night-Thursday...
Upper trough currently over the Red River Valley, per latest GOES
imagery, is progged to weaken as it heads to the lower MS Valley by
Wed. night. 12Z deterministic GFS holds onto some light QPF along
the Ohio River that night, but most other guidance keeps this light
precip over southern IN. Will show a tighter pop gradient SE to NW
than what current NBM is giving, keeping many of our southern KY and
Lake Cumberland counties dry. Cloud cover is more likely to linger.
Despite this, high pressure slowly pushing to the northeast U.S.
will mean more of a southerly return flow bringing warmer conditions
Thursday.
Thursday Night Through the Weekend...
Expect this to be a wet period, with a series of disturbances
rotating around broad troughing over the north central U.S. Ensemble
and deterministic guidance both indicate two short waves impacting
our region to close out the work week. Onset timing for precip with
the first wave suggests it getting perhaps to our far western
counties at some point during the morning commute Friday, then to
the I-65 corridor by lunchtime, then most likely areawide by
evening.
Persistent southwest flow aloft along with quick-moving disturbances
riding through that flow will mean waves of rain chances through the
weekend. Timing of those breaks is not possible this far out, but we
can give estimates on rainfall amounts over this extended wet
period. Grand ensemble (CMCE/GEFS/EPS) shows over an inch totals as
likely (60-70%), with only a few members getting over 2 inches
(~20%). Airmass will be fairly juicy through the period, especially
for late December, with precipitable waters above an inch, above the
90th percentile for this time of year.
Severe weather chances look very low...at this point. Best chance
(again very low) could come early Sunday, depending on the location
of a surface low riding along a cold front trying to push this
series of waves east of us. GFS soundings show some helicity ahead
of this feature, but no low-level instability to work with. Will
keep watch on this, cause this time of year it doesn't take much
instability to allow for some severe weather to occur. European
Extreme Forecast Index (EFI) also not too excited about the CAPE
shear profile here.
Cloud cover and moisture as well as persistent southerly flow will
keep temperatures well above normal for late December.
Monday and Tuesday...
Brief zonal flow behind the Sunday system will mean a brief break in
precip chances...but we get to them again early Tuesday and through
the day as yet another wave moves through here. Temperatures really
won't chill down much, as we remain well above normal. Deterministic
GFS, Canadian, and Euro all show the next system coming in...though
exact confidence in timing always has to be a question with a
shortwave on Day 7. That too will have an impact on surface low
development. The 12Z Euro is interesting with a fairly deep surface
low moving up the Ohio Valley. Still way too early to deal with
specifics here, but as in the case of Sunday's low, something worth
watching.
&&
.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 1231 AM EST Wed Dec 25 2024
A weak frontal boundary near the area will continue to provide light
rain chances and cloud cover this morning. The boundary will
gradually shift to the north throughout today, which will lead to
improving conditions later on this Christmas Day. Still, will likely
hang onto cigs in the low VFR range (3500-5000 feet). BWG is
expected to have prevailing VFR conditions, and no notable rain
chances. Look for light E to ESE winds through this entire TAF cycle.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...BJS
SHORT TERM...MJ
LONG TERM...RJS
AVIATION...CJP
Source:
LMK issues Area Forecast Discussion (AFD) at Dec 25, 12:32 AM EST ...Updated Aviation Discussion...---------------
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