Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 280518

Area Forecast Discussion
National Weather Service Louisville KY
118 AM EDT Fri Oct 28 2016

...Updated Aviation Discussion...

...Forecast Update...
Issued at 940 PM EDT Thu Oct 27 2016

The main forecast challenge tonight is fog development.  Some of the
high-res models from this evening are hinting that a large portion
of the area may see dense fog tonight if sky cover dissipates by
late evening.  Other high-res models aren`t so optimistic keeping
the low clouds in and only patchy light fog over much of the area.
Not confident enough to stray much from the current forecast leaving
the possibility for locally dense fog out there but more likely is
light patchy or areas of fog.  Will need to monitor closely as we go
into the overnight hours.

.Short Term (Now through Friday Night)...
Issued at 300 PM EDT Thu Oct 27 2016

Cold front continues to progress south and east through the Ohio
Valley this afternoon, with chilly NW winds behind it starting temps
on their way down already. Main short-term concern will be fog
tonight, as skies clear this evening under already narrow T/Td
spreads. Guidance points to some dense fog potential toward Fri
morning, but with the continued lack of rain it will come down to a
race between radiational cooling and dry air advection. Still not
inclined to hit the fog that hard, and will go with patchy/areas of
fog. Still think any dense fog will be localized and will mention it
in the Hazardous Weather Outlook.

Temps near climo tonight will recover quickly starting Friday as the
surface high retreats into the Appalachians and upper ridging builds
from the SW.

.Long Term (Saturday through Thursday)...
Issued at 300 PM EDT Thu Oct 27 2016

...Near Record Highs Next Week...

Large upper ridge over the southern CONUS will dominate the weather
pattern for most of the period. Very low-amplitude pattern will keep
the stronger westerlies well to our north, so while a dry front or
two could push into the Ohio Valley, they will be moisture-starved
and lack the forcing to produce any rainfall.

Main story will be unseasonably warm temperatures, with highs close
to the 80 degree mark each day. Any better push of warm air with
decent sunshine will push us more solidly into the lower 80s, which
would threaten record highs. Current forecast reflects a model
consensus, but runs a couple degrees short of some of the MOS
guidance, so we may need to bump the temp forecast even higher as
confidence increases.

Models start to diverge on Thursday with the beginning of the
breakdown of the ridge. GFS drops a vigorous low from eastern Canada
into New England, with a backdoor cold front dropping into the Ohio
Valley. The ECMWF drags a "bowling ball" upper low across the Desert
Southwest. Either of these solutions could start to turn our pattern
unsettled on Thursday, but for now will keep the forecast dry,
especially since the timing is also very much in doubt, especially
if a closed low solution works out. Temps will drop off a bit, but
continue above normal through Thursday.


.Aviation (06Z TAF Update)...
Issued at 118 AM EDT Fri Oct 28 2016

Aviation weather for the overnight is a complicated one for sure.
Cloudiness has pretty much eroded across southern IN and central KY
early this morning.  However, a batch of high clouds is quickly
pushing in from the northwest and will likely overspread the region

It appears that MVFR/IFR conditions will be possible at KBWG and
KLEX early in the period as skies remain clear and temperatures fall
toward the dewpoint.  On the other hand, KSDF looks a bit more
optimistic overnight with perhaps only a drop into the MVFR range
for a short period.  Current thinking is that fog will develop
within the clear skies between now and 28/07-08Z especially at
KBWG/KLEX. However, visibilities may improve as the high clouds come
in from the east limiting the radiational cooling later this morning.

Overall, forecast confidence for the overnight is below average in
terms of visibility and low cigs.  Will continue to closely monitor
conditions and additional amendments may be required.


.LMK Watches/Warnings/Advisories...


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