000
FXUS63 KLMK 171729
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
129 PM EDT Sun Sep 17 2017

...Updated Aviation Discussion...

.Forecast Update...
Issued at 907 AM EDT Sun Sep 17 2017

Fog that developed this morning is once again quickly dissipating.
GOES-16 imagery shows just a bit left in a few river valleys and
this should be gone soon. The forecast was updated to remove the
mention of fog and update cloud cover grids. Otherwise, no changes
were made.

&&

.Short Term...(Today through Monday)
Issued at 320 AM EDT Sun Sep 17 2017

High pressure continues to remain in control of the weather over the
Ohio Valley this morning.  Clear skies and light winds have led to
valley and river fog development once again.  This should continue
through the pre-dawn hours and then mix out after sunrise.

For today, we expect another repeat performance.  Partly cloudy
skies are expected this afternoon.  Most high resolution models show
some very isolated showers or storms developing.  We saw this
yesterday afternoon, but not much of anything hit the ground.  For
now, have continued to go with a dry forecast.  Highs will warm into
the 82 to 87 degree range.  The coolest readings will be found in
the east (Bluegrass/I-75 corridor) and the warmest will be west of I-
65.

For tonight, clouds will be on the increase from the northwest to
the southeast as a frontal boundary pushes toward the region.  The
front looks to remain north of the region tonight which should keep
any measurable precipitation to our north and northwest.  Lows will
be a little milder with readings in the low to mid 60s.

Clouds will continue to increase on Monday as the frontal boundary
pushes in from the northwest and the upper level ridging over the
region flattens out.  The best chance of showers and storms looks to
be over southern Indiana and the far northern portion of KY during
the afternoon hours. High temps look to warm into the 80-85 degree
range.

.Long Term...(Monday night through Saturday)
Issued at 335 AM EDT Sun Sep 17 2017

As we move into early next week, the model consensus really has not
changed all that much in regards to the current forecast.  A ridge
that has been providing us with dry conditions will continue to be
flattened out across the area with some weak disturbances moving
through in the mean flow aloft.  This will generally lead to on and
off showers/storms from Monday night through Wednesday.  The
guidance suggests the best chances for precipitation will be in the
Tuesday to Wednesday time frame.  Highs during the period will top
out in the lower to middle 80s with overnight lows in the 60s.

As we head into the second half of the week, the models continue to
suggest that deep troughing will develop over the western US with a
corresponding downstream ridge building over the eastern US.  This
should result in a drier trend in our forecast as we close out the
week and head into next weekend.  Still think that we could see some
isolated showers and storms Thursday and Friday afternoon with
lesser chances as we head into the weekend.  Temperatures will
remain above normal with highs in the lower to middle 80s and
overnight lows in the lower to middle 60s.

As we move beyond next weekend and into week 2, the weather pattern
is expected to remain active across NOAM.  Current guidance suggests
that troughing will remain in place across the western CONUS with a
corresponding downstream ridge axis over the eastern US.  Late in
the weekend, tropical cyclone Maria is expected to pass through the
Caribbean islands and then make a trek poleward.  The extent of the
poleward track will depend on the amount of ridging over the
northeastern US.  The GFS solutions tonight suggest a poleward
motion and eventual recurve...though that is a typical bias of the
GFS.  Of more concern is that the Euro solutions are further south
and west with the system...suggestive of a tropical cyclone threat
for the southeastern US in the 9/25-27th time frame.  Locally, it
appears that drier than normal conditions along with above normal
temperatures can be expected.  Precipitation chances look to
increase by the middle of week 2 with the approach of a strong
trough from the west and the possible effects of Maria from the
south and possibly southeast.

&&

.Aviation...(18Z TAF Issuance)
Issued at 125 PM EDT Sun Sep 17 2017

Will see a slow increase in moisture from the west today. Cloud
cover may affect our ability to fog overnight, so have backed off a
little on what the short-term model consensus is giving us for
visibliities around daybreak Monday. Also, cannot a shower in the
HNB/SDF terminals late in the period, but chances are low enough to
keep out of this set of TAFs. Winds will continue to be light and
variable this period.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Update...EER
Short Term...MJ
Long Term....MJ
Aviation...RJS