Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 200522

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

...Updated Aviation Discussion...

.Short Term...(This evening through Wednesday night)
Issued at 310 PM EDT Tue Sep 19 2017

The main complex of showers/storms associated with a nearby upper
level shortwave has moved east and south of our region as of mid
afternoon.  While most of the area is stable, the approaching
shortwave could still kick off a few isld cells in pockets of
instability before sunset.  After sunset, we`ll lose instability and
the shortwave will push through resulting in dry conditions.

The main challenge for tonight becomes fog development/density.
Subsidence from upper level ridging moving into the region combined
with plentiful low level moisture, light winds, and mostly clear
skies should result in an environment prime for fog development.
Think most places should see at least some fog tonight.  Patches of
dense fog are certainly possible as well and some areas may be
considered for a dense fog advisory in later forecasts.  Low temps
tonight should reach the mid 60s.

After morning fog, skies should become mostly sunny for Wed allowing
instability to build.  However, we won`t have a strong trigger to
kick off widespread convection on Wed.  Some of the high-res models
indicate a weak shortwave may be enough to trigger isld
showers/storm mainly along and east of I-65 Wed afternoon.  Wed
night looks dry with at least patchy fog possible.  Temperatures on
Wed should warm into the 80s with a few location west of I-65
reaching touching 90.  Lows Wed night should again be in the mid 60s.

.Long Term...(Thursday through Tuesday)
Issued at 320 PM EDT Tue Sep 19 2017

Strong upper level ridging will move into the region and remain
there through early next week.  Thursday will feature a small chance
for isld convection, but other than that the long term forecast is

Temperatures will likely be above normal under strong ridging.  Will
continue high temps in the mid to upper 80s with some days coming
close to 90 degrees in spots.  Lows will be in the 60s.

The upper ridging over our region may begin to break down by mid to
late week next week but lots of uncertainty remain that far out.


.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.




Short Term...AMS
Long Term....AMS
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