Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 251720
Area Forecast Discussion
National Weather Service Louisville KY
120 PM EDT WED MAY 25 2016
...Updated Aviation Discussion...
Issued at 1255 PM EDT Wed May 25 2016
North/south loosely organized complex of showers/storms continues to
slowly drift eastward across western Kentucky. A break in the cloud
cover and an increase in surface dewpoints has allowed SBCAPE to
increase to near 1000 J/kg. Shear environment remains weak and
messy, so overall not expecting anything strong to severe but just
the chance of more typical summer-like showers/storms. Some gusty
winds, lightning and brief heavy rain is possible as this line
drifts into our western areas this afternoon. POPs were brought up
west of I-65 through the evening. Otherwise, forecast is on track so
Issued at 1025 AM EDT Wed May 25 2016
Extensive mid/high cloud deck this morning combined with slightly
drier air has kept instability axis well west of the forecast area.
A weak decaying upper level system passing through western/central
Kentucky produced light morning showers, but recent returns have
diminished. Some light sprinkles or showers are possible generally
most locations will be dry.
Convection across southern IL and far southwest KY is just slowly
drifting to the east, but wanes as it moves into the less favorable
environment. Will maintain just slight chances through the
afternoon, mainly across southern Indiana and west of I-65 where the
greater moisture resides. Highs are still on target for the low/mid
.SHORT TERM (Now through Wednesday)...
Issued at 315 AM EDT Wed May 25 2016
Mild conditions have held on through the night, with light south
breezes and slowly increasing dewpoints. Aside from a few radar
returns that suggest isolated light rain showers over south central
Kentucky, we are almost entirely precip-free as new convection
advertised by most of the models has failed to materialize over the
lower Ohio and Wabash Valleys, and an earlier MCS has almost
completely fizzled over western Tennessee.
Short-term forecast confidence is sorely limited due to this poor
model initialization. Expect an increasingly muggy low-level air
mass to evolve today, with isolated to scattered shower and
thunderstorm chances. Ongoing MCSs over Kansas and Oklahoma will
likely gust out before reaching the Mississippi, but these will bear
watch for any MCV development that could serve as a trigger here
later tonight. Again will limit POPs to slight or low chance, with
the best chances over southern Indiana as the upper flow pattern
would seem to favor disturbances tracking ENE across there.
Expect more of the same on Thursday as it is becoming increasingly
difficult to pin down the upper impulses that may trigger convection
over the Ohio Valley. Precip chances will remain limited to chance,
and temps will continue to run several degrees above normal by day,
and trend warmer each night.
.LONG TERM (Wednesday Night through Monday)...
Issued at 310 AM EDT Wed May 25 2016
Upper ridging over the southeast CONUS will be the main player
through the weekend into early next week, resulting in warm and
muggy conditions. Upper trofiness will hold over the Plains, and
impulses will round this trof and head into the Great Lakes, with
scattered showers and storms possible if any of these disturbances
track close enough to the Ohio Valley.
For now will largely broadbrush POPs in the 20-30% range, but at
this point would not brand any day a washout. As disturbances become
more clear, will likely see some POPs bumped up while others could
be removed. Temps will be modulated primarily by clouds and any
convection that pops in the afternoons, with the main theme being
above normal. The real unknown, especially late in the weekend, will
hinge on the fate of a subtropical system that most of the models
show off the Carolina coast. If this system is strong and/or close
enough, we could get into the subsidence region on its western
flank. That would cut into precip chances and give temps a better
chance of cracking 90 on Monday and/or Tuesday.
.AVIATION (18Z TAF Update)...
Issued at 1245 PM EDT Wed May 25 2016
Well...this TAF cycle is all about the chances for showers and/or
storms. Cluster of storms has developed over Srn IL/Wrn KY from
larger outflow from larger cluster of storms over the Ozarks. This
activity has maintained the morning stable layer of thick mid deck
of clouds over KY. The new HRR keeps the storms moving eastward and
will at least be SHRA vcnty in SDF after 21z. BWG looks like storms
will get there around 1815-1830z.
In fact the HRR takes all the wrn TN convection and brings it into
western CWA, and this seems realistic. Will keep VCTS through
early evening at BWG.
Our confidence is less at LEX, so will keep dry for now and see how
convection evolves and moves east into lower dew point air and more
VFR ceilings and visibilities are expected through this TAF
period,(except in storms). Winds will be SSW today of 10-18 mph
today and slacken overnight to SSE.