Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 142326
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
726 PM EDT Thu Sep 14 2017

...Updated Aviation Discussion...

.Short Term (Now through Friday Night)...
Issued at 215 PM EDT Thu Sep 14 2017

Main concern tonight continues to be fog potential. This morning, we
had widespread dense fog across Illinois and eastern Missouri. We
have seen a few breaks in the clouds west of I-65 so far this
afternoon, but they have been filling in with any little bit of
heating coming from those breaks. Would expect those areas west of I-
65 to clear out more this evening...though time-height sections do
promote some periods of low-stratus development, which would lower
the potential for dense fog. Will continue to beef up fog wording
for overnight, and will add in to our Hazardous Weather Outlook,
given increasing confidence.

Once that fog burns off, Friday should turn into a great day, for
most of the region. Our east still stands the best chance for any
cloud cover to linger/redevelop into the afternoon, but west of I-65
should earily warm into the 80s. Fog may once again creep into the
picture Sat. morning, but do not expect that day to be as dense as
Friday`s.

.Long Term (Saturday through Thursday)...
Issued at 215 PM EDT Thu Sep 14 2017

The rest of the weekend continues to look warm and dry, as strong
ridging builds aloft up from the northwest Gulf of Mexico. For Sun.
night/Monday, model consensus continues to show a break in the ridge
just enough for some rain chances to move into our southern Indiana
counties. Points south and east of that area should be dry, as the
ridge aloft gets strengthened by Hurricane Jose, forecast to be off
the Mid-Atlantic coast. The next break in the ridge may come late
Wednesday into Thursday, as Jose moves farther away from our area
and another trough moves into the Midwest.

The rain chances in this forecast have lower confidence, but with
the ridge aloft, there is pretty good confidence that we will flip
from the below-normal temperatures we have seen so far in September
to above-normal temps. Our hot spots should see the upper 80s.
Hopefully the green-ness of the area with our antecedent rainfall
will keep those spots from touching 90.

&&

.Aviation (00Z TAF Update)...
Issued at 726 PM EDT Thu Sep 14 2017

Surface high pressure building over the central Appalachians will
bring light winds to the region tonight. Much of the cloudiness that
we experienced over the last few days has broken up this evening.
These partially clearing skies and light winds atop wet ground will
lead to fog and low cloud formation tonight. Guidance hits LEX the
hardest as it will be closest to the high. However, HNB and BWG, due
at least in part to local conditions, are expected to fog in as
well. Urban SDF will be somewhere in the middle.

There is still some question as to how much of the expected sub-VFR
weather Friday morning will come from low stratus and how much will
come from fog. At this time it looks like the clearest skies will be
at the western TAF sites, leading to fog as being the likeliest
candidate for LIFR (maybe even VLIFR) conditions at HNB and BWG. At
LEX there may be more of a combination of stratus and fog, but at
any rate LIFR conditions are expected there too -- possibly VLIFR
around dawn. Crossover temperatures are in the 60-65 degree range
and those readings should be met or exceeded at all of the TAF sites
late tonight.

There won`t be much wind on Friday however temperatures will rise
quickly enouogh that the fog should be able to burn off in a
reasonable amount of time. LEX will probably take the longest to
improve to VFR.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&

$$

Short Term........RJS
Long Term.........RJS
Aviation..........13



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