Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 300545
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
145 AM EDT Sat May 30 2015

...Updated Aviation Discussion...

...Forecast Update...
Updated 1042 PM EDT Fri May 29 2015

Took the evening wording out of the zones now that the diurnal
showers have dwindled significantly.  Also, eased up on PoPs east of
I-65 overnight.  No other major changes.

.SHORT TERM (Now through Saturday Night)...
Issued at 245 PM EDT Fri May 29 2015

Moist airmass is generating scattered showers across our east and
right along the western border, in general around where earlier
cloud cover kept the central CWA more stable through the morning
hours. That area may yet fill in with some scattered storms as well
later this afternoon. Coverage should decrease with sunset.

Winds will increase aloft from the south overnight as a surface low
approaches the region. We should see some gusts of 15-20 knots
tomorrow as the gradient tightens over us. We may see some showers
develop along the low-level jet toward daybreak, especially west of
I-65. Coverage should spread eastward through the day, with
thunderstorms possible as convective temperatures are reached in the
afternoon. Limited the storms to scattered as there is some question
as to how close we get to those convective temperatures with the
cloud cover in place. We may see some gusty winds come down in the
stronger storms in the afternoon, but not expecting severe winds at
this point.

The storm chances will continue Saturday night as the upper trough
swings overhead. Surface low pressure will form somewhere along the
front during the day and move into southern Indiana overnight. This
low could provide some more organization to storms during the night,
and will have to watch to see how the daytime plays out, as lots of
cloud cover/showers during the day would limit the amount of
instability available for the night.

Temperatures should continue above normal most of this period, but
with the frontal passage, we may get down to normal west of I-64 by
daybreak Sunday.

.LONG TERM (Sunday through Friday)...
Issued at 259 PM EDT Fri May 29 2015

Sunday - Sunday Night...

An upper system and its associated weak surface low will be passing
through our CWA Sunday morning into the afternoon hours. Focus for
rainfall will mainly be along and north of the I-64 corridor where
mid level deformation will occur, and in our eastern CWA as the
system moves out. Plan on holding just a slight chance of a
lingering shower across southern IN and northern KY Sunday night as
mid level frontogenesis and moisture diminish. Forecast soundings
show thermal profiles that would appear rather unsupportive of
t-storms Sunday and Sunday night, so have backed mention off to a
slight chance on Sunday.

A decent temperature gradient should setup north to south on Sunday
as the system passes, with upper 60s north to mid and upper 70s
south. A noticeable cool down occurs Sunday night with temps
dropping to the upper 50s north to lower 60s south.

Monday - Wednesday Night...

Forecast for the first part of next week has trended drier as the
29/12Z ECMWF has jumped on board with more progressive solution with
regard to the trough axis. This generally puts us in weak and dry NW
flow and then upper ridging, as deeper moisture is shunted SE. Will
still keep some very low chance pops in our far SE Monday, but the
trend  may continue to shift drier. Temps during this time will
trend warmer with Monday highs in the low and mid 70s. By Wednesday,
highs are expected to be in the low and mid 80s. Overall, raised
temperatures due to the drier trend.

Thursday - Friday...

Lower confidence for the Thursday-Friday time frame as there is a
wider range of solutions. Models are split on whether to hang a
closed upper low over the Gulf Coast states, which would allow for
some deeper moisture to work into our SW CWA. Right now, there is
some general agreement between the GFS/GEM/GFS ensemble mean in this
scenario playing out, so will mention some small chances for
showers/storms. Temps will end up depending somewhat on the
precipitation forecast, but will stick pretty close to a consensus
blend which yields low and mid 80s.

&&

.AVIATION (06Z TAF Update)...
Updated 140 AM EDT Sat May 30 2015

A cold front will approach the region today.  Ahead of it, scattered
showers/storms will fire across the area throughout the day.  The
most likely time for t-storms will be in the afternoon so will
continue to highlight in a PROB30 group.  Showers and storms will
become more likely this evening just ahead of the cold front.
Flight restrictions are likely to occur in any t-storm, however,
will hold off inserting into the last portion of the TAF until a
better handle on timing can be achieved.

Winds will continue from the south today and may get a little
gusty, to around 20 knots.

&&

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

$$

Update.........13
Short Term.....13
Long Term......BJS
Aviation.......AMS





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