Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 261933
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
333 PM EDT Tue May 26 2015
.SHORT TERM (Now through Wednesday Night)...
Issued at 311 PM EDT Tue May 26 2015
Widespread showers and scattered thunderstorms have developed this
afternoon ahead of a negatively tilted shortwave rotating up through
the mid Mississippi River Valley. Atmosphere is moderately unstable,
however mid level inversion evident on NAM soundings and verified by
AMDAR is limiting updrafts above 15-20 K feet. Mid level lapse rates
are expected to remain weak through the afternoon/evening.
Showers and storms will continue to lift NNE as the entire focus
shifts slowly east through the evening. Storms are already shutting
off from the west as a subtle front moves through the region and
subsidence behind the wave takes over. So, will hold onto
categorical pops east of I-65 through around sunset.
Expecting a pretty quiet overnight, although an isolated shower or
storm may scoot along and north of the I-64 corridor around and just
after Midnight. This would associated with another weaker PV anomaly
scooting through the flow. Expect lows in the mid and upper 60s as
SW winds stay up just a bit. There is some concern for fog potential
given the moist low level airmass and lighter winds. However,
stratocu deck has potential to develop which would be another
limitng factor. Overall, confidence is too low to include mention at
Wednesday morning should start out mostly dry with any isolated to
widely scattered showers (iso-storm) confinded to our far south and
east. Our NW half of the CWA should stay dry through the morning and
most of the afternoon, with partly cloudy skies and a steady SW
wind. With decent heating, expect temps to rise into the low and mid
By Wednesday afternoon, another disturbance passes through the SW
flow and should be able to initiate scattered to numerous storms
across our NW. Actually more impressed with isolated severe chances
across southern IN tomorrow afternoon as atmposphere should be more
unstable than today. Flow will still be weak, although just marginal
enough for perhaps some organization. This wouldn`t be a widespread
threat, but a few instances of gusty winds or hail seem possible.
Scattered showers and storms should hang around mainly across the
northern CWA through the Wednesday evening hours with lows in the
low and mid 60s.
.LONG TERM (Thursday through Tuesday)...
Issued at 310 PM EDT Tue May 26 2015
Wet. That`s all you need to know about the extended forecast. OK, if
not wet, then at least the chance of wet...for every 12-hour period
through day 7. I will concede that for Thursday night the precip
chances will only be down in the southeast part of our area (near
Lake Cumberland), but otherwise, the forecast is a broken record.
On the plus side, despite the persistent chance for rain, the chance
for excessive rain, and severe weather, for that matter, do not look
impressive. The overall upper air pattern through the period keeps
an elongated positively tilted trof to our west, but close enough
for the Ohio and Tennessee Valleys to receive showers or low-end
thunderstorms as short waves ride through to the north. There are
hints by the second half of the weekend into early next week of a
trof digging down into the southern Mississippi Valley. This could
give the area the best chance for significant convection, but this
far out, it is only worthy of mention.
Despite the persistent rain chances, the overall rainfall totals
expected for the entire week are only on the order of 1.5 to 2.5
inches, so no widespread river or flooding issues are anticipated.
Of course, the usual caveat of any individual storm being capable of
producing isolated heavy rains still applies. Probability-wise,
chances are only in the 30-50% range...not because it won`t occur,
but because when it rains, coverage will be spotty.
As far as temperature go, highs will be in the 80s through Saturday,
then in the upper 70s to lower 80s for the remainder of the period.
Lows will be in the 60s.
.AVIATION (18Z TAF Update)...
Updated 122 PM EDT Tue May 26 2015
Focus continues to be on thunderstorm coverage through the
afternoon. Sct-Num coverage has developed in an unstable environment
ahead of an upper disturbance. Expect on and off rounds through the
afternoon. Ceilings will stay just above the VFR/MVFR threshold
(outside of any t-storms) with a strong south wind between 15 and 20
mph, gusting up around 30 mph.
Timing at SDF: Rounds of showers/T-storms between 2-7 PM. Brief MVFR
or IFR Vis. Another round of VCTS around midnight possible.
Timing at LEX: Rounds of showers/T-storms between 2-8 PM. Brief MVFR
or IFR vis. Another round of VCTS after midnight possible.
Timing at BWG: Rounds of showers/T-storms bewteen 2-5 PM EDT. Brief
MVFR or IFR vis.
Winds will subside toward sunset and models are suggesting that MVFR
ceilings will be possible. Depending on how showers/storms evolve
today, patchy fog could develop as well tonight if winds are calm.