LMK issues Area Forecast Discussion (AFD) at Nov 27, 3:39 AM EST870
FXUS63 KLMK 270839
AFDLMK
Area Forecast Discussion
National Weather Service Louisville KY
339 AM EST Wed Nov 27 2024
.KEY MESSAGES...
* Rain arrives late this afternoon, continuing through the
nighttime hours into Thursday morning. Rainfall amounts between
0.25-0.50" possible.
* A cool and dreary Thanksgiving Day is expected, with patchy
drizzle and low clouds.
* Unseasonably cold temperatures are likely this weekend into the
first few days of December. There is a chance for minor snow
accumulations Saturday night.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 338 AM EST Wed Nov 27 2024
Sfc high pressure and upper level zonal flow directly over our area
this morning will be swiftly departing to our east through the rest
of the morning, making way for a sfc low to bring our next rain
chances later today. This sfc low is being supported by a
strengthening disturbance currently over the Northern Plains, which
will take a southeastward track throughout the day across the
central US. When doing so, the sfc low will move across Oklahoma by
this afternoon, and should be over central Arkansas by 00z tonight.
Inverted sfc troughing will extend across the lower Ohio Valley,
with a band of frontogenesis setting up to our north this afternoon
helping to enhance our low-level forcing ahead of the sfc low's
arrival.
Dry conditions are expected for most of the day as the sfc high
provides dry air subsidence, though gradual top-down saturation will
take place, resulting in a deepening cloud layer. Strengthening low-
level jetting will begin to nose up into our area this afternoon,
resulting in an increase in WAA and moisture transport. As the upper
shortwave tracks across the Plains, a narrow band of PVA will
support an axis of frontogenesis along the I-70 corridor this
afternoon. The hi-res CAMs display this well, with good model
agreement on seeing a southwest to northeast oriented band of precip
stretching across I-70 from Missouri to Ohio by this evening. Low-
end PoPs will be spreading from northwest to southeast beginning
this afternoon, though there will be some considerable dry air to
get through at first.
PoPs significantly ramp up after 00z this evening, as the
frontogenesis band sags south of I-70 and the sfc low looms closer.
This sfc low is expected to cross south-central Kentucky between 03-
09z, which will support additional rain coverage across central
Kentucky and south of the frontogenetical band. However, our
greatest chances, and QPF, will be generally covering our northern
half of the forecast area through tonight.
With sounding profiles not indicating any instability, thunder
chances will be low with this event. Most will see light rain,
though frontogenetical enhancements will aid in higher rainfall
amounts, which are expected to be along and north of the I-64
corridor for our area. HREF probs give a 90% chance of exceeding
0.25" of rain north of I-64 by 12z Thursday, though our entire area
carries between a 50-80% chance of exceedance. Probs for QPF over
0.5" decrease for our area, with the greatest chances focused
between Indianapolis and Cincinnati. Total QPF is generally between
0.25-0.50", which is aligned with the latest probs.
Temperatures for today will range from upper 40s across southern
Indiana, to the mid to upper 50s across south-central Kentucky. For
tonight, we'll remain above freezing across the entire area, with
most locations getting down to the upper 30s, though some lower 40s
across our south are possible too.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 338 AM EST Wed Nov 27 2024
Initially quasi-zonal upper pattern on Thursday will become more
amplified as broad eastern CONUS trofiness around a strong closed
low centered over James Bay.
Could see a wet start to Thanksgiving as an upper shortwave swings
eastward across Kentucky on Thursday morning, shunting the moisture
feed to our south and east. Trapped moisture in a post-frontal
boundary layer and cyclonic flow aloft will allow for lingering
drizzle and a chilly, dreary Thanksgiving Day.
Dry weather will follow Thursday night through Saturday as cold high
pressure builds from the NW. A fairly mixy boundary-layer will keep
temps from bottoming out Thu night, but most locations will dip into
the 20s. Friday night appears to the the colder night with a 1028mb
sfc high settling into Kentucky, and more favorable radiational
cooling to allow Sat morning lows in the teens to lower 20s. Daytime
temps will struggle into the 30s.
Next chance for precip will be late Saturday and Saturday night as a
Clipper shortwave moves through. Not much moisture available, but
thermal profiles support all snow and dynamics will be able to
squeeze out a few hundredths of an inch of QPF. Unless we see better
available moisture or stronger lift, we should keep snow totals
under 1 inch. Given the nocturnal timing and forecast in the upper
20s, we'll have to watch this system for at least minor road impacts
as the time draws closer.
Snow quickly exits on Sunday morning, but the unseasonably cold air
sticks around well into next week, and will make the start to
meteorological winter feel like, well... winter.
&&
.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 1255 AM EST Wed Nov 27 2024
VFR flight conditions will continue this morning despite increasing
cloud cover ahead of our next system. Cloud levels will gradually
lower below 10k ft later this morning, with light winds from the
south. Light rain will enter the region by this evening as a sfc low
moves into the TN Valley. Ceilings will gradually lower to MVFR by
the end of the period, with some vis restriction possible with any
heavier rain. In the extended SDF TAF, cigs are forecast to drop to
IFR after 28/06z.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
SHORT TERM...CJP
LONG TERM...RAS
AVIATION...CJP
Source:
LMK issues Area Forecast Discussion (AFD) at Nov 27, 3:39 AM EST---------------
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