Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 291713
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
113 PM EDT Mon Jun 29 2015
...Updated Aviation Discussion...
.SHORT TERM (Now through Tuesday)...
Issued at 308 AM EDT Mon Jun 29 2015
...Isolated Hail and Wind Threat with Afternoon/Evening Storms...
The eastern CONUS remains under a NW flow aloft pattern through the
short term, with individual disturbances bringing chances for severe
weather each afternoon/evening.
Currently, a batch of numerous showers is working into areas west of
I-65, ahead of an upper PV anomaly that will rotate across the lower
Wabash River Valley, then up toward central IN this morning. With
the best forcing lifting off to the NE, will keep numerous to
categorical wording across the far north CWA, tapering to scattered
coverage across southern KY. A few rumbles of thunder may still be
possible so will leave iso T mention in.
The main batch of showers should exit to the east by mid to late
morning, with variable cloudiness lingering behind this first system
into early afternoon.
Focus will then shift to a second round of convection that is
expected to fire by early to mid afternoon. A second vort max is
noted on water vapor imagery up around the Quad Cities area and will
drop SE through the upper flow into central IN through the day. As
this occurs, surface low that is currently over central IL will move
into central IN/OH with a trailing cold front sliding into our CWA.
Do expect that some heating may occur ahead of this front, along
with dew points pooling in the upper 60s. The combination of
increasing instability, moisture convergence along the front, and
some influence from the vort max across our north should lead to
scattered to numerous storms developing roughly along a line from
Madison, IN to Louisville, to Greenville, KY between 1 and 3 PM EDT.
These storms will then push east through the afternoon/early
evening. Given the moderate instability characterized by CAPE values
in the 1500-2500 J/KG range and slightly better than marginal bulk
shear values around 30-35 knots, a conditional severe risk will
exist for isolated instances of damaging winds and large hail across
our NE. Can`t rule out a severe storm anywhere east of the line
mentioned above, however best ingredients will be where SPC has
slight risk drawn, closest to the the vort anomaly and associated
surface low. Can`t rule out an isolated tornado given any localized
boundary, however vertical wind profile is mostly SW at the surface,
gradually veering to W in the mid levels. Not overly excited about
the 5% tornado probability without the presence of more backed
surface winds, nevertheless a few brief supercell stuctures may
develop which help to support the higher risk.
Highs today will be dependent on cloud cover, but generally expect
79-84. SW winds will gust up around 25 mph at times.
Storms will push east of the area in the early evening, with a
relatively quiet overnight. Did leave small chances for lingering
showers across the far south and far NE.
As we move toward dawn on Tuesday, another mid level disturbance
swings through the east CONUS trough, bringing another round of
scattered to numerous showers and t-storms spreading SE across the
CWA through the day. With similar ingredients with respect to
instability/shear a conditional severe threat will once again be
possible. Expect similar high temperatures in the low to mid 80s.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 305 AM EDT Mon Jun 29 2015
Period will begin with a trough axis right across our region, with
residual storms from afternoon convection starting to wind down. Our
next waves of rain will come down on northwesterly flow aloft, not
always timed to peak heating either. Given cloud cover and
difficulty timing these features, will maintain high temperatures
Flow aloft begins to transition by the end of the work week. Another
trough will dig into the Midwest. This could be bring a warm up, as
we move more into a warm sector ahead of this system, but confidence
too low to go back up to climo for readings. Moisture in the region
combined with heating each day should provide the spark for at least
.AVIATION (18Z TAF Update)...
Issued at 112 PM EDT Mon Jun 29 2015
The TAF period will be characterized by generally VFR conditions,
with brief restrictions possible in thunderstorms this afternoon.
Thunderstorms have already begun to form near the Ohio River, with
coverage expected to increase this afternoon across southern and
east-central KY, mainly affecting KLEX and KBWG. Brief restrictions
are possible in any storm with gusty winds.
Otherwise, skies will go partly cloudy overnight. Some light fog
will be possible at KBWG where winds will be the lightest, but
confidence in fog occurrence is not very high. Confidence will
increase if KBWG receives rain this afternoon/evening. Tuesday will
begin as VFR with additional scattered storms possible, but
most will be after this valid TAF period and into the SDF planning