Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 261659
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1259 PM EDT THU MAY 26 2016

...Updated Aviation Discussion...

...Forecast Update...
Issued at 939 AM EDT Thu May 26 2016

Lingering showers and isolated storms across the Bluegrass have
slowly dissipated as LLJ begins to weaken and push to the east. A
nice clear slot resides behind it across central Kentucky and
southern Indiana, with southerly flow and dewpoints in the mid 60s.
Further to the west across central Illinois, a line of storms is
steadily moving east.

Extrapolating this line will put it into southern Indiana and
northern Kentucky by early afternoon. Our air mass should be able to
destabilize with dewpoints in the mid 60s and temps in the 80s. The
past few runs of the HRRR have finally latched onto this line and
brings it across southern Indiana and northern Kentucky. Some of the
other hi-res models have this ideas as well. As a result, increased
POPs quite a bit for parts of the area through the late afternoon.
Will likely need to fine tune or increase POPs further east across
the Bluegrass if this complex holds together across the entire area.

The very weak shear environment will limit severe storms, but
lightning, heavy rain and gusty winds will be a threat.

Issued at 555 AM EDT Thu May 26 2016

MCV loitering about south-central Kentucky has triggered showers and
a few isolated T-storms extending north into the Bluegrass region in
the last 2 hrs or so. The bulk of this precip is sliding into
eastern Kentucky already, but we`re continuing to see a smattering
of showers re-develop behind it. Also saw a few lighter showers over
southwest Indiana, but those are not holding together well at all.

Grids have been tweaked to better capture hourly trends, and hi-res
products will be updated shortly. No update to the zones as the
overall trend for the next 12 hrs is still pretty much unchanged.

.SHORT TERM (Now through Thursday)...
Issued at 300 AM EDT Thu May 26 2016

Summertime air mass is now established over the Ohio Valley with
dewpoints into the 60s and precipitable water pushing 1.5 inches.
Upper trof has settled in over the High Plains, with an amplifying
ridge along the East Coast.

This pattern figures to remain fairly stagnant for the next couple
of days, resulting in a continuation of the warm and fairly muggy
conditions that took hold on Wednesday. Even with abundant low-level
moisture, the greatest instability and the favored track for most of
the synoptic-scale upper disturbances will be to our north and west.
Convective potential will be driven largely by whatever
destabilization can occur diurnally, and low-level boundaries that
manage to push in with decaying MCSs from the Plains. Will carry a
20-30 POP with a slight diurnal signal through tonight.

Confidence in model guidance is fairly low, but signs do point to a
dry day on Friday as deep southerly flow may better focus storms
over the Mississippi Valley, leaving us in a relative minimum for
moisture and instability. Will go with a dry forecast for now, but
proceed cautiously. With the dry forecast, would expect Friday to be
the warmer day in the short-term, with upper 80s quite likely
anywhere that sees enough insolation.

.LONG TERM (Thursday night through Tuesday)...
Issued at 300 AM EDT Thu May 26 2016

Unsettled pattern will continue through the Memorial Day weekend,
with warm and muggy conditions and isolated to scattered showers/
storms almost on a daily basis.

Will start out Saturday with the most amplified pattern, but the
upper trof over the Plains tries to lift out, with a fair bit of
bagginess in the flow translating NNE through the Ohio Valley. This
will likely be the most unsettled day of the period, and we`ll carry
the highest POPs but still limit to a 50 percent chance given low
confidence in the timing of any impulses.

As we head into Memorial Day and early next week, the pattern
flattens out a bit. The wild card is the warm core system that is
progged to develop off the Carolina coast. If it gets close and/or
strong enough, subsidence could keep a lid on convection here,
allowing us a dry day but pushing temps close to 90. Otherwise will
see a continuation of the summer pattern, resulting in isolated/
scattered POPs, with the best chances in the afternoon, and temps
running several degrees above normal, especially by night.

&&

.AVIATION (18Z TAF Update)...
Issued at 1245 PM EDT Thu May 26 2016

Well...line of storms from HNB to along the Western KY Parkway
pushing eastward and is the main story of first 12 hours of the
forecast. This moving eastward at 30 to 35 mph.  Mesoscale processes
during the afternoon sunshine will allow the storms to maintain
themselves into the SDF area by 1830z.

Scattered storms have developed along old outflow boundaries across
the BWG area, and will have VCTS this afternoon with better
instability in the warm sector.

The HRR takes the precip eastward into the Bluegrass Region around
22z, if in fact it maintains itself. Will be nowcasting LEX TAF.
Surface winds today will be south to southwest around 10 kts with
gusts 10-20 except in storms where gust up to 35 mph are possible.
HNB just had a gust to 36 mph.

Any storms should weaken later this evening with VFR conditions.
However, there could be some light fog developing at BWG and
LEX around daybreak.

Forecast is much drier for Friday with only very isolated
convection around the CWA.

&&

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

$$

Update.........ZT
Short Term.....RAS
Long Term......RAS
Aviation.......JDG



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