Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 182235

Area Forecast Discussion
National Weather Service Louisville KY
635 PM EDT Fri Aug 18 2017

...Updated Aviation Discussion...

.Short Term (Now through Saturday Night)...
Issued at 330 PM EDT Fri Aug 18 2017

The weather will stay fairly quiet this weekend. Fair weather cu
field will diminish this evening, along with the westerly breeze.
Drier air has advected into the region, with afternoon dewpoints in
the low to mid 60s. Skies will be mostly clear this evening and for
the first half of the overnight period. Mid-level cloud cover is
expected to increase early Saturday as an upper trough swings in.
Lows tonight will be in the mid/upper 60s. Patchy fog will be
possible Saturday morning, especially near rivers.

Low pressure over Iowa this afternoon is forecast to track east
across IL/IN tonight, dragging a weak boundary with it. Moisture
isn`t very deep and will be confined mostly to the mid-levels.
Still, a few showers are possible Saturday morning, mainly north of
I-64. Saturday will feature a mix of sun and clouds, with highs in
the mid/upper 80s. Ridging Saturday night will bring continued fair
weather with lows in the mid 60s.

.Long Term (Sunday through Friday)...
Issued at 345 PM EDT Fri Aug 18 2017

Sunday and Sunday Night...

Ridging will build in at the surface and aloft over the southeast
United States, resulting in dry weather and typically warm
summertime temperatures.

Eclipse Day...

Upper ridging will remain in place as the surface high shifts off to
the east. While southerly return flow does develop, it should remain
light. The 12z versions of the GFS/ECMWF/GEFS continue to feature
quite a bit of dry air in the low and mid-levels. Scattered high
clouds are still a possibility, so am featuring a 25% sky cover
forecast around the time of the eclipse. Convection will likely be
ongoing across parts of the Midwest, like Iowa and northern
Illinois. As long as it`s not overly thick, thin cirrus may not mess
with eclipse viewing too much. And the brief cooling from the
eclipse itself may help to limit diurnal cu formation.

The day is likely to be dry and hot, with max temps around 90
degrees. Folks planning to be outside for an extended period should
dress for the weather and stay hydrated, as heat indices will likely
reach the mid 90s just before and after the eclipse.


A cold front will sweep through the region from northwest to
southeast Tuesday and Wednesday, accompanied by showers and
thunderstorms. Pacific high pressure will then come in with dry
conditions Wednesday night and Thursday. Heat index values should
again climb into at least the middle and possibly upper 90s Tuesday
afternoon, but then cooler conditions can be expected Wednesday and
especially Thursday.


.Aviation (00Z TAF Update)...
Issued at 635 PM EDT Fri Aug 18 2017

Expect mainly VFR conditions through the valid TAF period. West
winds are losing the gustiness from earlier this afternoon and will
continue to diminish after sunset. However, enough dry air advected
in that we do not expect to cross over afternoon dewpoints.
Therefore, even with light winds, any Saturday morning fog will be
limited to MVFR vis in BWG and LEX.  SDF will be a close call with
any showers that develop in response to the upper trof, but expect
that activity to remain to the north and impact limited to a VFR
strato-cu ceiling.




Short Term........EBW
Long Term.........EBW
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