Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 220246

Area Forecast Discussion
National Weather Service Louisville KY
946 PM EST Tue Nov 21 2017

.Forecast Update...
Issued at 940 PM EST Tue Nov 21 2017

Cold front is pushing into southern Indiana, and just within the
last hour or so has generated enough lift to show some decent radar
returns. Still fighting a lot of low-level dry air, so even where
precip does reach the ground, it`s still a fairly tall order to get
measurable precip. Update will be mostly transparent, but might
include mention of actual showers across Washington/Scott/Jefferson
Counties in Indiana, and sprinkles for at most one tier of counties
south of that.


.Short Term...(This evening through Wednesday night)
Issued at 215 PM EST Tue Nov 21 2017

It`s a breezy, sunny afternoon with temperatures near normal for
this time of year. Broken cirrus clouds are beginning to spread
overhead from western KY and southern IL ahead of an approaching
cold front. The cold front was draped from Lower Michigan through
central Illinois, where radar showed a thin band of light precip
pushing east. The front will push through between 00-06z tonight,
resulting in northwest winds and cold advection for the rest of the
overnight period. A shortwave trough will also swing through this
evening, and there will be a modest increase in mid and low-level
moisture content right at fropa. Can`t rule out brief sprinkles
across southern IN and the northern Bluegrass, but the vast majority
of any light precip will stay in Indiana and Ohio.

Temps will start dropping behind the front overnight, but some
lingering low clouds and a 5-10 kt surface wind will keep them from
dropping too far before sunrise. Lows should range from the upper
20s to mid 30s.

The upper trough axis swings through on Wednesday, and we`ll see a
north wind with surface high pressure off to the west. Clouds should
gradually clear out from west to east Wednesday morning, resulting
in a mostly sunny rest of the day. Highs will be in the low to mid
40s. High pressure will settle over the Ohio Valley Wednesday night,
which will mean a cold start to Thanksgiving. Overnight lows should
end up in the mid 20s for most, with typical cool spots possibly
reaching the low 20s.

.Long Term...(Thursday through Tuesday)
Issued at 225 PM EST Tue Nov 21 2017

Thanksgiving - Friday...

No meaningful forecast changes for Thanksgiving, Black Friday, and
weekend holiday travel. Dry weather is expected with up and down
temperatures. Surface high pressure will linger across the region on
Thanksgiving, eventually shifting off the East Coast on Friday.
After a cold start, Thanksgiving should feature partly sunny skies
with highs in the mid 40s to low 50s. Lows Thursday night should end
up near or slightly below freezing.

The active storm track will remain across the northern U.S. Friday
into the weekend. Another one of these low pressure systems will
deepen into the Upper Midwest on Friday. The surface cyclone will
remain north of the Canadian border, but southwesterly WAA ahead of
it should boost highs into the mid 50s to around 60. Just a wind
shift and increase in cloud cover is expected Friday night with the
frontal passage.

Saturday - Tuesday...

Saturday should feature near normal temps, as colder air lags the
wind shift. We`ll then see temps drop back down to around freezing
Saturday night, and Sunday will be another chilly day in the 40s. As
surface ridging builds across the region, Sunday night will likely
be quite cold with lows back into the 20s. Dry weather will continue
through Tuesday, with temperatures likely to moderate once again
heading into the middle of next week.


.Aviation...(00Z TAF Issuance)
Issued at 550 PM EST Tue Nov 21 2017

VFR ceiling and vis expected through the valid TAF period. Winds
have slacked off as the cold front moves closer, and that boundary
is not too far NW of HNB. Expect the front to push through this
evening, and while there is a fairly substantial mid-level and/or
high-based strato-cu deck behind the front, that will likely stay to
our north. Will keep the mid-level clouds scattered with a cirrus
ceiling. Could see a decent NNW surge keeping winds around 12 kt
overnight at HNB, and can`t rule out some gusts in the teens.
Otherwise speeds will remain just under 10 kt.




Short Term...EBW
Long Term...EBW
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