Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 280051
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
851 PM EDT Wed May 27 2015
Updated 845 PM EDT Wed May 27 2015
Last of the convection has exited the Bluegrass. To our north and
west, isolated to scattered storms along the cold front in central
Indiana are not organizing and do not appear able to push any
boundaries south. Therefore have continued the trend of backing off
overnight POPs. Most of the area will remain dry, with south central
and east central Kentucky having the best chance for a stray shower
Updated 615 PM EDT Wed May 27 2015
Complex of storms that formed this afternoon, and produced isolated
strong to severe winds, has pushed south and east. Trailing
stratiform rain still lingers across the Bluegrass. Models had
advertised convection developing along the cold front but between
the front hanging farther north than expected, and the atmosphere
being worked over, that has not happened. Updating the forecast to
cut back on POPs for tonight. Believe most of the night will be dry,
but with the juicy air mass still in place it`s hard to rule out a
stray shower. Will also include patchy fog after midnight, mainly
east of I-65, given wet ground and small T/Td spreads.
.SHORT TERM (Now through Thursday Night)...
Issued at 245 PM EDT Wed May 27 2015
Have line of storms along the I-65 corridor this hour. The northern
part of the line has been the strongest at this point, with the
southern more widespread and less organized. Thinking at this point,
after collaboration with SPC, is that most of the storms the rest of
the afternoon will be below severe limits, so holding off on issuing
a watch at this time. DCAPE`s are not as impressive over the eastern
part of the area.
The next round of storms for the day will depend on how quickly we
recover from this first round. Areas along and north of the I-64
corridor will have the best chance to fire again before sunset, but
looking upstream there is a dearth of low clouds over southern
Illinois. Will limit late afternoon chances to under 40% for now.
Should these late storms fire up, we could additionally see some fog
form overnight, thanks to lighter winds and the extra influx of
For Thursday, there will be a little less moisture in place across
the region, but more importantly there should be less of a trigger.
Thus storms that develop should not become organized, though an
isolated wind/hail threat isn`t out of the question. Have gone with
40% or less coverage mainly across south central KY, in the area
with best moisture and isolated coverage in the north. Highs
Thursday should be a touch warmer than today, given the less
coverage of storms. For lows, went pretty much with persistence.
.LONG TERM (Friday through Wednesday)...
Issued at 248 PM EDT Wed May 27 2015
An unsettled pattern will continue through the long term period with
rounds of showers and storms expected through the forecast period.
Friday will be quite warm with highs in the mid 80s. The region
should become unstable by afternoon with scattered storms
developing. These should continue into the overnight period.
A stronger shortwave will approach from the west on Saturday. In
addition, a cold front will begin to move in from the northwest by
late in the day. With better forcing aloft and moisture pooling
ahead of the front, storm coverage will increase with a 60-70%
chance for most of the region.
The front will move through most of the region by Sunday night, but
then looks to stall out near the KY/TN border. It will then move
back north as a warm front early next week. Given daytime heating
and multiple boundaries in the vicinity, storm chances will continue
into the first half of the work week. These look to be scattered in
nature with potential lulls in the activity during the overnight
periods. There will be a slight cool down in the wake of the front
with highs reaching into the mid 70s to around 80 on Sunday and
Monday. Temps will warm a bit back into the low 80s by Tuesday.
.AVIATION (00Z TAF Update)...
Updated 735 PM EDT Wed May 27 2015
Complex of storms just pulling out of LEX at the moment, leaving
behind mid-level and cirrus debris. Expect a VFR evening with light
south winds, but the main concern overnight will be fog potential.
In this pattern we`ve had a hard time getting the winds to
completely decouple at night, but with the proximity of the front
there is a better chance tonight. Add in wet ground from the rain
this afternoon, as well as the already tight T/Td spreads, and we
have multiple factors coming together for restricted visibility.
Some discrepancy in model guidance with the GFS MOS suggesting dense
fog while the usually pessimistic NAM MOS shows stratus. For now
will go with MVFR visibilities developing after midnight, and TEMPO
groups for a brief IFR restriction around daybreak. High confidence
that LEX will go IFR at least briefly, but moderate at best for SDF
Once we start to mix out late Thursday morning, VFR conditions will
return with sct-bkn diurnal cu and light southerly winds.