Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 211705

Area Forecast Discussion
National Weather Service Louisville KY
105 PM EDT Thu Sep 21 2017

...Updated Aviation Discussion...

...Forecast Update...
Issued at 1015 AM EDT Thu Sep 21 2017

Any fog that developed this morning has mixed out, so the forecast
has been updated to remove mention of it. The only other weather
concern for today will be isolated showers and thunderstorms this
afternoon. Made just some minor adjustments to the forecast this
afternoon to add in pops across the remainder of the forecast area
in southern IN. Otherwise the forecast is in good shape.

.Short Term (Now through Friday)...
Issued at 312 AM EDT Thu Sep 21 2017

Patchy morning fog is possible once again. A couple of spots have
gone down below a mile, however fog isn`t nearly as progressed or
widespread as it was last night at this time. So, don`t plan any
additional products unless something changes in the pre-dawn hours.

Strong upper ridging becomes a bit better established over the Ohio
River Valley today. This will lead to another hot and humid day,
with a small chance at an afternoon shower or storm. 1000-850mb
thicknesses rise ever so slightly today, so expect a degree or two
bump in many spots. This will put most areas in the upper 80s, with
a few typical warm spots likely touching 90. As far as the 20%
chance of rain goes, the lack of any notable triggering features
will make it difficult to pin down an area. So, elected to paint
most of the CWA with a slight chance from midday through the early
evening hours. Forecast soundings show a slight subsidence
inversion, but the overall thermodynamic profile is mostly uncapped
and should be able to kick off some convection with heating and
local effects.

Any diurnally driven showers/storms will quickly die off this
evening, with another quiet night in store. Other than some patchy
fog, expect mostly clear skies with lows dropping into the mid and
upper 60s.

Friday will be a dry and hot day with a touch less humidity. High
temps will still be mostly in the upper 80s, with a few spots
touching 90.

.Long Term (Friday Night through Wednesday)...
Issued at 312 AM EDT Thu Sep 21 2017

Strong upper ridging will hold over our area, with the center
shifting through the Great Lakes over the weekend and into early
next week. The ridge then begins to break down by later Tuesday into
Wednesday as a strong trough moves into the north central part of
the CONUS.

Overall, we`ll stay under the influence of the ridge, helping to
keep us mainly dry and above normal for temperatures. Highs will be
in the mid to upper 80s through the weekend, possibly touching 90 in
a few spots. Then by early next week the ridge weakens a bit and
expect temps more in the mid 80s. These values are near 10 degrees
above normal for this time of year. Lows will mostly be in the low
and mid 60s each night.

We`ve had a dry forecast going, and see no reason to change that. A
stray shower or storm could pop during and afternoon, but the lack
of any mentionable triggering and fairly weak instability/mid level
lapse rates will be a limiting factor.


.Aviation (18Z TAF Update)...
Issued at 1255 PM EDT Thu Sep 21 2017

Largely a persistence TAF set with upper ridging strongest just to
our north and west, and a weak, sloppy surface pattern. Pop-up
storms will be possible this afternoon, but coverage remains far too
isolated to warrant inclusion in any of the TAFs. Main challenge is
fog heading into Fri morning. Will primarily follow this morning`s
trends with the most significant restrictions at BWG and HNB, where
it will likely drop below field mins, at least briefly. SDF and LEX
are generally less fog-prone and will only dip into MVFR.




Short Term.....BJS
Long Term......BJS
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