Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 121908

Area Forecast Discussion
National Weather Service Louisville KY
308 PM EDT Thu Oct 12 2017

.Short Term (Now through Friday Night)...
Issued at 305 PM EDT Thu Oct 12 2017

Pesky stratus deck has dominated the weather today in the absence of
any strong surface pressure gradient to help scour out the low
levels. Expect the low clouds to hang on well into the evening, with
just partial clearing in southern Indiana and north-central
Kentucky, but a build-down or even some fog in south-central
Kentucky where the 925mb moisture is more solid.

By Friday morning the cold advection will shut off, giving way to a
light southerly flow which will finally scour out the boundary
layer. Still have a strong inversion between 900-850mb to limit the
depth of mixing, so Friday max temps will top out in the lower/mid
70s, which is actually just slightly above climo and splits the
difference between the bullish GFS MOS temps and the pessimistic NAM
MOS. Fri night will be fairly mild under light return flow.

.Long Term (Saturday through Thursday)...
Issued at 307 PM EDT Thu Oct 12 2017

Unseasonably warm Sat and Sat night as a vigorous upper-level wave
pushes east from the northern Rockies into the Upper Midwest, with
temps close to 15 degrees above climo both day and night ahead of a
cold front.

The front will push quickly across southern Indiana and central
Kentucky during the morning and early afternoon on Sunday, with most
of the precip behind the front. The trend from run to run has been
faster, which will limit diurnal warming and open the door for
falling temps in the afternoon.

Strong cold advection Sunday night as a strong Canadian surface high
builds into the area for the first half of next week. Temps will run
below climo through Wednesday, with highs mainly in the 60s, perhaps
just touching 70, and lows mainly in the 40s. The coldest morning
will be Tuesday, and with the high directly overhead there could be
patchy frost in the typical cold spots like Brandenburg, Cynthiana,
and Albany with lows in the mid 30s.


.Aviation (18Z TAF Update)...
Issued at 154 PM EDT Thu Oct 12 2017

An MVFR stratus deck remains blanketed over all four TAF sites early
this afternoon. The edge of this cloud deck ran from Middle
Tennessee to Eastern Kentucky. Ceilings may rise slightly more
through the mid to late afternoon, but will likely remain MVFR. We
shouldn`t get enough warming or mixing to scatter/lift to VFR.

Overnight into early Friday morning, we`ll likely see the stratus
deck build down into the low MVFR range, likely IFR at BWG. The one
wrinkle is this forecast is that drier in the cloud layer (2 kft and
below) will push north to around the KY/TN border. Any
scattering/partial clearing could result in dense fog across
southern KY early Friday morning. But the most likely scenario is a
BKN low stratus deck building down into a fog layer, also resulting
in IFR visibilities. This will be possible at the other TAF sites as
well. Winds through the TAF period will remain light. Clouds should
slowly scatter and lift during the day on Friday.




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