Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 280458

Area Forecast Discussion
National Weather Service Louisville KY
1258 AM EDT SAT MAY 28 2016

...Updated Aviation Discussion...

...Forecast Update...
Issued at 1035 PM EDT Fri May 27 2016

Coverage along the I-65 corridor has ramped up again in the last
hour, riding along an instability and moisture gradient.  These
cells are moving the same direction they are oriented, however MRMS
1-hour precip totals are staying under a half inch, which matches
well with an observation from the KY mesonet at LaRue county of
0.38" in the last hour. Have updated the gridded forecast to put a
maxima in pops north/south across the middle of the CWA for the next
few hours. The focus still is expected to shift into the western CWA
after midnight, as per discussion below.

Issued at 930 PM EDT Fri May 27 2016

Have only a few more cells out there this evening, but with
boundaries moving around the area cannot rule out additional
isolated development through midnight. After that, an upper jet now
over Iowa and Missouri will strengthen towards daybreak, placing our
western zones into a more favorable area for additional development.
Combined with a plume of moisture increasing precipitable waters
into the 1.6-1.8 inch range, and we should see at least scattered
coverage west of I-65 by daybreak. The latest local WRF is handling
the current convective development along the KY/TN border well and
it favors more development west of I-65 as well. Thus have issued
a zone update out.

Issued at 500 PM EDT Fri May 27 2016

GOES-R Convective Initiation product caught on the band of showers
now around KBWG, moving north. The product did not do as well over
Lake Cumberland where a few other small cells have developed.
Adjusted the pop forecast to account for these bands of favored
areas over the near term.

.SHORT TERM (Now through Saturday Night)...
Issued at 240 PM Fri May 27 2016

The latest analysis showed high pressure at the surface and aloft
off the Carolina coast while a closed low was located in the front
range of the Colorado Rockies. Rich Gulf moisture was streaming
northward from Texas through the mid-Mississippi Valley where
convection has been firing up most of the day. Locally, southerly
winds prevailed with readings up in the mid 80s and a mix of sun and
clouds and so far dry conditions.

Despite the juicy air mass, a lack of a surface trigger or upper
level wave has kept the local area dry so far. And we`re expecting a
mainly dry evening, minus some isolated to scattered showers or
storms lifting northward off the Cumberland plateau. Additional
showers may try to develop across western KY and TN and spread east
into the area later this evening, but confidence on that happening
isn`t high.

Otherwise, plan on another muggy night with lows in the mid 60s to
near 70.

For Saturday, models continue to show an upper level impulse
swinging through the lower Ohio Valley. This should aid in a higher
coverage of showers and storms, though it certainly won`t be a
washout day. Plenty of clouds will hold temps in check, so most
locations will top out in the lower/mid 80s, but depending on timing
a few spots west of I-65 could stay in the 70s.

.LONG TERM (Sunday through Friday)...
Issued at 255 PM EDT Fri May 27 2016

By late this weekend into Memorial Day, the upper level pattern will
become more zonal. This lack of forcing aloft will limit
precipitation chances, but will still honor the moist air mass with
20 to 30 percent chances for diurnal pop-up showers/storms. Temps
will be solidly above normal, but it will be difficult to get enough
sunshine to crack the 90 degree mark in this pattern.

Heading into the middle to latter portions of next week, we`ll begin
to see amplification in the upper pattern such that a few impulses
may begin to affect the area. The 12z models don`t offer a lot of
confidence that far out, so will side with a model consensus which
advertises 20 to 40 percent chances Wednesday through Friday.
Temperatures will likely remain above seasonal normals in the 80s to
perhaps near 90 in a few spots across southern Kentucky.


.AVIATION (06Z TAF Update)...
Issued at 1258 AM EDT Sat May 28 2016

Generally VFR through the TAF period. Primarily a SCT/BKN mid deck
and southerly winds staying up around 5-10 knots today.

Though showers will be possible just about any time, the best
chances (after the first couple hours at SDF) look to be this
afternoon as an upper wave currently over the lower Mississippi
Valley drifts northeast into the region at a diurnally favorable
time. Will continue previous forecast of VCSH for this afternoon.


.LMK Watches/Warnings/Advisories...


Short Term.....ZT
Long Term......ZT
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