Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 190726

Area Forecast Discussion
National Weather Service Louisville KY
326 AM EDT Thu Oct 19 2017

.Short Term...(Today through Friday)
Issued at 300 AM EDT Thu Oct 19 2017

The surface high was centered over Virginia early this morning, with
satellite imagery showing mostly clear conditions. A patch of cirrus
was spreading southeast over southern Kentucky. As seen on the GOES-
16 fog product, river valley fog development has been very limited
thus far. This is due to quite a bit more wind in the boundary
layer, and a number of surface observations around the area still
feature a light southerly wind. Patchy dense fog could still develop
over the next few hours, particularly near Lake Cumberland.

The upper level jet is well off to our north across Canada, and this
will continue to be the case through the short term. Upper level
ridging will build east across the region today through tomorrow,
while the surface high will remain anchored over VA/WV.

This will allow our spectacular stretch of Fall weather to continue,
with afternoon highs warming a few degrees each day. Highs today
will reach the low to mid 70s, with everyone solidly into the mid
70s Friday. Lows tonight will dip back down into the 40s.


.Long Term...(Friday night through Wednesday)
Issued at 320 AM EDT Thu Oct 19 2017

We`ll have another dry, warm day on Saturday as a deep upper trough
moves into the Plains. We`ll likely see quite a bit more high level
cloud cover streaming east from the advancing trough and surface
cold front. Rain chances increase on Sunday, but the most likely
time frame for showers and some storms looks to be Sunday night
through Monday night.

Still some notable timing and synoptic pattern evolution differences
heading into early next week, but the 00z runs of both the GFS and
ECMWF feature a closed upper low developing over the South Sunday
night and splitting from the northern ribbon of shortwave energy.
The surface cyclone then responds by deepening and tracking NNE to
the Great Lakes by Tuesday. In wrapping up the system, the ECMWF
slows it down more and features a more westward track in the new
surface low. Both solutions do, however, suggest a rainy and breezy
period to begin the work week.

As the system continues to strengthen toward the Canadian border on
Tuesday, we`ll see cold air advection ramp up on the backside as a
deep upper trough settles over the Midwest. It continues to look
quite chilly by the middle of next week, with highs only in the 50s
on Wednesday.


.Aviation...(06Z TAF Issuance)
Issued at 105 AM EDT Thu Oct 19 2017

High pressure to our south and east will remain in control through
the valid TAF period. Main challenge will be fog potential at BWG,
which finally truly decoupled within the last hour. Should be able
to cross over Wed afternoon dewpoints, so will include at least a
TEMPO for IFR vis around daybreak. Farther away from the surface
ridge, the remaining sites still have larger temp/dewpoint spreads,
and flags on taller flagpoles suggest there is still some boundary-
layer mixing, so we`ll stay VFR.

SW winds during the day will remain near 10 kt, with little or no
cloud cover. Winds decouple again around sunset, and the next
issuance may need to address fog potential toward daybreak Fri.




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