Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 261932

Area Forecast Discussion
National Weather Service Louisville KY
332 PM EDT TUE JUL 26 2016

.SHORT TERM (Now through Wednesday Night)...
Issued at 315 PM EDT Tue Jul 26 2016

Nearly stationary boundary near the Ohio River is only triggering
isolated convection as yet. Still it remains a moist and boundary-
rich environment, so still expecting scattered showers and storms
through sunset. Main threat with any storms that develop would be
locally heavy rainfall, but still can`t rule out a wet microburst
due to precip loading. However either of these threats remain fairly
marginal, and convection will diminish quickly after sunset.

Very much a persistence pattern as we head into Wednesday with
scattered diurnal T-storms. Flow remains weak, so heavy rainfall is
the main threat yet again.  Afternoon heat indices will approach 100
degrees, but not on a widespread basis to warrant a SPS. Warm and
muggy nights will continue, with most locations staying solidly in
the 70s.

.LONG TERM (Thursday through Tuesday)...
Issued at 325 PM EDT Tue Jul 26 2016

Thursday will provide the most widespread precip chances of the week
as a weak but slow moving upper wave swings through the Ohio Valley.
Will carry likely POPs during the day on Thursday, with copious
rainfall amounts expected. Still looking for fairly widespread 1-2
inch totals, with locally higher amounts likely. Localized flash
flooding is a possibility, but in the absence of widespread heavy
rain today, will hold off on issuing any Flash Flood Watch. Clouds
and precip will limit diurnal temp ranges Thu-Fri.

The operational GFS shows the upper troffing persisting into the
weekend with ridging surging back in early next week, and is in good
agreement with the model`s ensemble mean. The last few runs of the
op GFS have shown a slight trend towards a more progressive movement
as well. The operational ECMWF is slower to advance the trof
eastward, but the ensemble mean is a bit quicker, leaning more
toward the GFS solution. So, will put some trust in the ridge
building back in Monday-Tuesday.

At the surface a weak, broad trof will oscillate across the region
through at least Sunday before losing much of its identity in the
new work week. Scattered thunderstorm activity can be expected in
conjunction with the surface and upper trofs and the summertime
warmth and moisture. Precipitable water values will be slightly
above normal through the period. While we can expect some heavy
rainers, the best chances for severe weather will remain over the
Great Plains and Midwest, with gusty pulsers our best bet for strong
storms locally. PoPs will be highest through the weekend, then trend
downward early next week with the increasing ridging aloft and
possible dissipation of the surface trof.

Temperatures will be near normal.


.AVIATION (18Z TAF Update)...
Issued at 1245 PM EDT Tue Jul 26 2016

Largely a persistence forecast, as we remain in a similar air mass
and pattern to yesterday, and confidence is lacking in the
specifics. Convection is not as active today, but the first couple
of storms have recently popped over southern Indiana. Will be a
close call on whether to initialize SDF and/or LEX with VCTS, but
for the sake of brevity we will do just that since there should be
convection in the vicinity by 19Z. BWG is far enough south that it
should stay dry through at least mid-afternoon.

Best rain chances will again be in SDF and LEX later in the
afternoon, and will take visibilities down solidly into MVFR, with
some brief IFR even possible. For the TEMPO group, will carry
borderline MVFR/IFR.

Storms should die down around sunset, with fog potential as the main
overnight concern. For now have included several hours of MVFR vis
in LEX, but keeping BWG unrestricted based on recent performance.
However, this will likely need to be adjusted based on how much rain
falls this afternoon, and where it falls.

Once mixing commences mid/late Wed morning, expect VFR conditions
and light SW winds.


.LMK Watches/Warnings/Advisories...


Short Term........RAS
Long Term.........13/RAS
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