Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 260126
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
926 PM EDT MON APR 25 2016

...Updated Aviation Discussion...

...Forecast Update...
Issued at 922 PM EDT Mon Apr 25 2016

Overall, no major changes to the forecast for the remainder of
this evening and overnight. Continue to expect a dry overnight
with a weak impulse traveling across central IL/IN to keep bulk
of showers/storms north of the area. This feature will act to drop
a frontal boundary toward the area, which may bring a few light
showers toward dawn but most likely just an increase in cloud
cover. Mild night with lows holding up in the 60s.

For tomorrow, latest guidance continues to suggest the combination
of a passing mid-level wave and daytime instability will spark a
round of showers and storms by mid-afternoon. Consensus of the hi-
res data shows this to initiate across southern Indiana, then
track into north central or central Kentucky. In coordination
with neighboring offices, bumped up chances into the 50 to 70
percent range for parts of the area for mid/late afternoon into
early evening. Severe threat is still on the table with some
loosely organized multi-cell clusters producing damaging winds.

.SHORT TERM (Now through Wednesday Night)...
Issued at 309 PM EDT Mon Apr 25 2016

Now - Tonight...

Dry weather will continue this afternoon and through the much
overnight under influence of high pressure. For the remainder of the
afternoon, highs will max out in the 80 to 85 range with scattered
diurnally driven clouds. SW winds between 10 and 15 mph will gust up
around 25 to 30 mph at times.

Expect lows in the lower 60s tonight with increasing cloud cover
toward dawn. A few rain showers may be possible toward sunrise but
most spots should remain dry.

...Rounds of Showers and Storms through Midweek, Some Strong
Possible...

Tuesday - Wednesday Night...

By Tuesday, surface low will travel into New England with a trailing
cold front stretching across southern IL/IN/OH toward the Ohio
River. With destabilization in the form of low level moisture
convergence and heating ahead of the front, expect scattered showers
and storms to develop by mid to late afternoon. Additionally, a
subtle mid level perturbation will slide through the flow aloft,
helping to enhance deep shear a bit during this time. This could
promote some storm organization in the form of a few line segments
with a damaging wind threat. Heavy rain, lightning and some hail
will also be secondary threats. Highs should reach into the low 80s
on Tuesday.

Think we`ll see a drop off in coverage on Tuesday Night with the
passage of the wave and loss of heating. However, with the front
still in the area will keep lower coverage in the grids. Expect mild
lows in the low 60s.

Strong and negatively tilted shortwave ejects out of the Plains to
the upper Midwest during the day Wednesday through Wednesday night.
As this occurs, low level response will help to drag the stalled
frontal boundary back to the north as a warm front. This will allow
for scattered to numerous showers and storms along the warm front in
the morning. Then, another round of showers and storms is expected
once the better forcing arrives in the afternoon and evening.
Destabilization will be in question, but should be able to at least
realize some instability in the warm sector by afternoon/evening.
This combined with the forcing and enough deep layer shear for
organization a few strong storms will again be possible. Main
threats for severe would be damaging winds. Additionally, heavy
rainfall, cloud to ground lightning, and some hail will also be
possible with any stronger storm.

Coverage of storms should be diminishing by dawn on Thursday with
temperatures falling into the low 60s by this time.

.LONG TERM (Thursday through Tuesday)...
Issued at 355 PM EDT Mon Apr 24 2016

The active, progressive upper level flow with periodic impulses
moving through the lower Ohio Valley will continue late in the work
week, this weekend and into early next week. Overall, an unsettled
pattern for the area.

On Thursday, one round of showers and thunderstorms will likely be
exiting during the early morning hours as a PV anomaly passes
through the region. The surface low remains back to our northwest,
so with daytime heating and modest lapse rates, MUCAPE around 1000
J/kg develops during the afternoon. Shear profiles aren`t
impressive, so storm mode likely to be pulse or loosely organized
multicells.  Likely some residual boundaries around so scattered
afternoon and early evening showers/storms will be possible. Look
for highs right around 80.

Friday continues to look like our driest day of the week as we`re in
between weather systems. High pressure originating out of the lower
Great Lakes will provide drier, slightly cooler air. Look for partly
to mostly sunny skies and highs in the low 70s to near 80, warmest
near the TN border.

The western trough will reload and eject another surface low out
into the central Plains and mid-Mississippi valley this weekend.
Still plenty of uncertainty in the strength and position of the
surface low and warm front Saturday morning, but overall the chances
of showers/storms will be on the increase during the day. Higher
confidence that we`ll see additional rounds of storms Saturday night
into Sunday, and likely into the first part of next week. The
environment will favor stronger to potentially severe storms as well
with a more favorable shear environment. Latest 7 day rainfall
outlook shows the potential for 2 to 4 inches of rain through early
next week so depending on how storms play this week, we may have to
monitor the hydrologic side of things more closely.

&&

.AVIATION (00Z TAF Update)...
Updated at 702 PM EDT Mon Apr 25 2016

Plan on breezy southwest winds to settle down a couple hours after
sunset this evening with mostly clear skies outside of a few high
base cumulus clouds around. A surface front will slowly approach the
area tomorrow morning, which might spark a few showers across north
central Kentucky, however, the better chances for a couple rounds of
showers and storms comes starting in the mid afternoon hours, most
likely to impact SDF/LEX. Still many questions on storm coverage and
intensity but a few hours of storms looks possible, from around 21z
to 02z. There is a lesser threat at BWG at this point. Will let
future shifts provide more detailed timing specifics of greatest
thunder chances. Otherwise, outside of any storms plan on VFR
conditions through the period.

&&

.LMK Watches/Warnings/Advisories...
KY...NONE.
IN...NONE.
&&

$$

Update.........ZT
Short Term.....BJS
Long Term......ZT
Aviation.......ZT



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