Good radiational cooling
led to a low of 38F last night, with clouds not arriving until almost sunrise.
The clouds have since cleared out, with sunshine leading to a deep boundary
layer and a warmup to 60F with some instability cumulus clouds developing. The maximum
wind was 12 kt. Mostly clear skies and light winds will initially lead to good
radiational cooling again tonight, but then increasing mid-level clouds will
hamper or stop the cool down after 06z, leading to a warmer night compared to
last night. Winds will shift to southerly tomorrow, leading to warm advection,
but winds will be weak, and there will also be thickening clouds that will
limit the daytime heating, leading to a similar high to today. Exactly when the
clouds move in will be critical to determining the high temperature, as every additional
hour of sun will lead to a few degrees more of warming, so there is a rather
high uncertainty in the high temperature. HRRR and NAM 3-km are ~8F apart, and
I favor an in-between solution. NAM 3-km has a cold bias in general, whereas
HRRR tends to warm it up too much when there is relatively thick and/or extensive
cloud cover.
A diffuse warm front
will also likely lead to some showers tomorrow evening, though it will not be a
steady rainfall, and the initially dry low-level air will limit rainfall
amounts. Models suggest most of the rain stays to the north and west before the
end of the period (Friday 06z), except the HRRR which tends to be unreliable
beyond 18-24 hours. The strongest winds could occur near the end (Friday 06z)
as a broad low-pressure system and its associated warm front slowly approach Louisville
from the west, but they could also occur with any convective showers that generate
cold pools and brief stronger winds, though the lack of deep convection should
limit any convective winds to <20 kt.
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| Source: PivotalWeather |
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| Source: PivotalWeather |
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