Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 201403
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1003 AM EDT Wed Sep 20 2017

...Forecast Update...
Issued at 958 AM EDT Wed Sep 20 2017

Fog has mostly dissipated across central Kentucky, except for the
deeper river valleys. Over southern Indiana, coverage is still
limited, but fog is most pronounced along the I-65 corridor where it
remains banked up against the Knobs to the west. Expect the
dissipating trend to continue, and should be able to update to clean
up the morning fog wording in forecasts within the next hour.

Issued at 643 AM EDT Wed Sep 20 2017

Observations have recently improved in many spots and most of the
dense fog seems to be confined to the river valleys. Will consider
cancelling the Dense Fog Advisory and leaning on a Special Weather
Statement.

.Short Term (Now through Thursday)...
Issued at 315 AM EDT Wed Sep 20 2017

Today...

GOES 16 satellite imagery is showing fog beginning to show up nicely
over much of the CWA, especially in and around the river valleys.
Plan on issuing a Dense Fog Advisory for most of the CWA minus a
tier or two of counties in our far west. Fog should burn off a
couple hours after sunrise.

An elongated upper ridge axis will become more prominent from the
southern Plains up through the Great Lakes today. Meanwhile,
lingering moisture associated with a weak upper low over central OH
will only very slowly push east. Models suggest that a stray shower
or two could occur, but coverage and confidence in this occurring in
any one spot is too low to warrant any mentionable precip chances.
Under plenty of sunshine, highs should be able to warm to the mid
and upper 80s today, along and west of I-65. Depending on cloud
cover and fog in the east, high will be more confined to the mid 80s.

Tonight - Thursday...

Expect it to be another foggy night tonight given mostly clear skies
and calm winds. One limiting factor will be upper sky cover that
could spoil the best radiational cooling conditions. Will mainly
mention patchy fog for this reason.

Upper ridge strengthens and becomes a bit more established over the
area tonight into Thursday. There has been a consistent signal in
the model data for an isolated shower or storm on Thursday.
Reluctant to mention any pops given the pattern recognition with a
strengthening upper ridge, but there will be some instability.
Either way, most folks will be continued dry and well above normal
for temps. Look for mid and upper 80s with a few western spots
possibly touching 90.

.Long Term (Thursday night through Tuesday)...
Issued at 315 AM EDT Wed Sep 20 2017

Strong upper ridging will hold over the area through the weekend and
into early next week, keeping our conditions mostly dry and temps
above normal. Models continue to show some hints of isolated shower
or storm activity at times during this stretch, however the overall
pattern suggest quite a bit of subsidence and the lack of any
noticeable triggering mechanisms. Also, a look at forecast soundings
shows more of a subsidence inversion than it did yesterday. So, will
continue the idea of keeping any precip chances silent.

Highs are expected to be mostly in the upper 80s as we end the work
week and head into the weekend. A few spots could touch 90, most
likely in our western CWA. As we end the weekend and start the new
work week, the upper ridge isn`t quite as strong so temps are
expected to be more in the mid to upper 80s. These values are around
10 degrees above normal for this time of year.

Lows will range in the mid to upper 60s as we move toward the
weekend, however will drop into the low to mid 60s through the
weekend and into early next week.

&&

.Aviation (12Z TAF Update)...
Issued at 650 AM EDT Wed Sep 20 2017

Main concern this morning will mainly deal with fog at the TAF
sites. Things have recently improved, so will start the TAFs out
more optimistic and mostly in the MVFR range. After fog burns off,
it should be a pretty quiet day with a Few-Sct cu and light and
variable winds. Some fog development is possible again tonight.

&&

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

$$

Update.........RAS
Short Term.....BJS
Long Term......BJS
Aviation.......BJS



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