Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 172348

Area Forecast Discussion
National Weather Service Louisville KY
748 PM EDT Tue Apr 17 2018

...Updated Aviation Discussion...

.Short Term...(This evening through Wednesday night)
Issued at 315 PM EDT Tue Apr 17 2018

Surface and upper ridging building into the Ohio Valley today, with
a warm advection regime now well established. Expect seasonable
temperatures tonight with some mid-level clouds and winds staying up
just enough to slow the diurnal drop in temps.

Wednesday will be warm and increasingly breezy as a deepening low
ejects out of the Rockies and heads toward the Great Lakes. High
temps will climb into the lower/mid 70s even in the face of
considerable cloud cover.

Precip chances don`t start to ramp up until late afternoon, by which
time the trailing cold front will be moving into the area. Will
carry chance POPs, but this system is moving fast enough that QPF
will be quite light due to limited moisture.

The real wild card will be wind given the tight pressure gradient,
and even behind the cold front. GFS is more bullish with winds than
the NAM, especially ahead of the front. Clouds and their impact on
mixing will be the limiting factor in the afternoon, and at this
point we will go with sustained winds around 20 mph with 30-35 mph
gusts, but if the GFS solution works out we could be near advisory
criteria. Breezy conditions will continue into the night in the cold
advection, with gusts over 30 mph in southern Indiana and north
central Kentucky.

.Long Term...(Thursday through Tuesday)
Issued at 245 PM EDT Tue Apr 17 2018

Mainly dry and roughly seasonable weather in the long term.
Initially we`ll be solidly below normal, with widespread frost and a
freeze in some areas Thursday night with Canadian high pressure
overhead. Will be a few degrees warmer Friday night into Saturday
morning, but will still see some frost concerns in the Bluegrass

Once the cold start is out of the way, expect pleasant but otherwise
cool weather for outdoor activities on Saturday, with increasing
mid/high cloud cover and high temps reaching the 60s.

Closed upper low over the Plains is expected to dive into the Deep
South, leaving the Ohio Valley high and dry except for a slight rain
chance late Sunday. Latest Euro remains even more suppressed than
the GFS, so even that slight chance POP could prove generous.

Slow warming trend continues into early next week, with at best a
slight chance POP on Tuesday. Next cold front to bring any
substantial precip coverage or amounts holds off until at least


.Aviation...(00Z TAF Issuance)
Issued at 748 PM EDT Tue Apr 17 2018

Primary aviation impact this TAF period will be shifting winds
tonight into tomorrow, with strong gusts likely on Wednesday.
Largely VFR ceilings are forecast.

SCT to BKN mid-level clouds are still forecast to develop overnight
as a warm front sets up over the area. The terminals should stay dry
tonight. Surface low pressure is forecast to move to northern
Missouri by 12z Wed, then on to Ohio by 00z Thu. Still expecting
southerly flow to get established over southern KY first through the
rest of the evening hours. Toward 06z, winds at HNB/SDF/LEX are
expected to veer easterly. They`ll continue to take on more of
southerly component with time after sunrise. From mid-morning on,
the rest of the period will feature gusty southwest winds due to a
tightening pressure gradient. Gusts of 25-30 kts will be common,
with peak gusts of 30-35 kts.




Short Term...RAS
Long Term...RAS
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