Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 282327
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
727 PM EDT Thu May 28 2015

...Updated Aviation Discussion...

...Forecast Update...
Updated 610 PM EDT Thu May 28 2015

Have adjusted the forecast to reflect the latest radar trends.  A
few showers and isolated thunderstorms continue across the region,
having been forced by a differential heating/convergence boundary
from an MCV across southern KY.  Trends over the past hour have been
for this activity to weaken as it loses what little instability it
had to work with due to the low-level clouds we had through much of
the day.  Therefore, will adjust pops to where precip is currently,
but quickly trend the forecast dry by later this evening.  The rest
of the forecast looks in good shape.

.SHORT TERM (Now through Friday Night)...
Issued at 245 PM EDT Thu May 28 2015

Cloud cover from this morning, and lingering into the afternoon, has
helped squelch development of precip so far today, despite
pronounced vortmax crossing the Lake Cumberland region this hour.
Still, have some breaks in the clouds now forming, and with that
temperatures are starting to rise. Still have the best chance for
measurable precip close to the vortmax, but would not be surprised
to see an isolated storm pop up anywhere with the heating.

We should get a break from the rain this evening, but low-level
moisture likely will bring another round of at least patchy fog
overnight. Deeper southerly flow late tonight through Friday will
mean continued cloud cover and additional showers/storms, with the
latter starting anytime during the day. Given the uncapped
environment and higher moisture content, still not worried about
severe threats at this point.

.LONG TERM (Saturday through Thursday)...
Issued at 243 PM EDT Thu May 28 2015

The latest model guidance continues to be in generally good
agreement with the pattern through the long term period. An upper
level trough over the Plains will slowly work its way eastward and
become a cutoff low by early next week. It will work its way very
slowly across the deep south through mid week. Chances for showers
and storms will continue off and on through the forecast period.

The most widespread precipitation is expected through the weekend. A
cold front will approach from the northwest on Saturday. A secondary
low will form along this front and move northwest across central
Kentucky Saturday night. The front will continue to sag southward on
Sunday, but looks to stall out somewhere near the KY/TN border.
Showers and storms will develop Saturday in the very moist and
unstable environment. A few of the storms could become strong to
marginally severe. Very heavy rainfall is likely with these storms
given moisture will be pooling south of the frontal boundary. Storms
will continue to be likely into the overnight period and Sunday as
the front moves through.

Monday through the middle of the next work week we will see more of
a diurnal pattern to the storms. Storms look to initiate in the
afternoon with daytime heating and diminish in the evening as the
sun sets. These storms will be more scattered in nature, so it will
not rain everywhere every day despite precipitation in the forecast
every day.

After a brief cooldown on Sunday in the wake of the front,
temperatures will rise back into the mid 80s by the middle of the
week with lows in the mid 60s.

&&

.AVIATION (00Z TAF Update)...
Updated 725 PM EDT Thu May 28 2015

Another complex overnight TAF period is in store as lingering
low-level moisture will combine with weak low-level moisture
transport to potentially cause flight restrictions.  All sites
should remain VFR and precipitation-free through at least 06Z
tonight.  After 06Z, light fog and/or low stratus will be possible.
There will be more of a gradient wind tonight (around 5 knots by
12Z) which should help limit any dense fog.  Also, the breaks in the
clouds this afternoon allowed all sites to mix dewpoints into the
mid 60s, which is below the crossover temperatures.  However,
guidance continues to hint at an MVFR deck developing just before
sunrise as low-level moisture transport commences ahead of a
disturbance passing to the northwest.  It appears the lowest
restrictions will likely be at KBWG where fuel-alternate or even
high-end IFR conditions may be possible, with KLEX and KSDF expected
to see high-end MVFR cigs/vsbys.  Admittedly, this is not a high
confidence scenario.

For tomorrow, the low cloud deck may once again hang on into the
late morning or early afternoon hours, which may once again limit
afternoon instability.  Therefore, will continue with VCSH wording
and not include any VCTS mention until trends in cloud cover and
resultant instability are better ascertained.  Winds will be out of
the SSW around 10 knots tomorrow afternoon.

&&

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

$$

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




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