Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 201044

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

.Forecast Update...
Issued at 643 AM EDT Tue Sep 19 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


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


...Dense Fog Advisory This Morning...

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...(06Z TAF Issuance)
Issued at 121 AM EDT Wed Sep 20 2017

Forecast challenge overnight will be dense fog...particularly in
southern and east-central KY.  Widespread rainfall from early
yesterday, combined with clear skies and light winds should favor
fog formation overnight.  Hardest hit areas will likely be HNB/BWG
and LEX.  SDF will probably go down as well...but am not sure that
it will go down below a mile at the moment.  Cigs/Vsby improvement
will take place right after sunrise as the fog and low stratus mix
out.  The outlook for later today is for VFR at all the terminals.


IN...Dense Fog Advisory until 10 AM EDT /9 AM CDT/ this morning for

KY...Dense Fog Advisory until 10 AM EDT /9 AM CDT/ this morning for



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