Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 020505
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
105 AM EDT Tue Sep 2 2014
...Updated Aviation Discussion...
Issued at 948 PM EDT Mon Sep 1 2014
Had a secondary batch of convection that developed a few hours ago
down around the E-town and Bardstown area. This convection moved
northeast along the BG Parkway and is now passing east of the I-75
corridor. A residual outflow boundary exists from near McLean
county eastward to near Madison county. Expect some additional
convection to pop along this boundary this evening and into the
overnight hours. Coverage looks to be isolated-scattered at
best...mainly south of the BG/WK Parkways and north of the
Cumberland/Nunn Parkway. Will be keeping in a chance showers/storms
in this area through the evening and into the early overnight
Otherwise, we expect partly cloudy skies to continue across the
region into the overnight hours. Convection out across Missouri is
expected to continue eastward and then push into our NW/W counties
very late night...perhaps around dawn Tuesday. Thus, will continue
with the current forecast of low chance PoPs this evening and then
let them ramp up from west to east late tonight and Tues morning.
Overnight lows will remain mild with lower 70s expected.
.SHORT TERM (Now through Tuesday Night)...
Issued at 303 PM EDT Mon Sep 1 2014
A cold front stretching from the Great Lakes to the Red River Valley
will sag southeastward this evening. Tonight a strengthening low
level jet will impinge on the front as a shortwave trof slides in
from the northwest. With plenty of moisture available, showers and
thunderstorms will develop from Oklahoma to Indiana overnight. This
activity will push into the Ohio Valley by morning. Timing of this
rainfall is difficult to nail down, but right now it looks like wet
weather will become widespread across southern Indiana after
midnight, into the Louisville metro and Ohio River counties a few
hours either side of dawn, and into the rest of central Kentucky
during the day Tuesday.
Over the course of the day Tuesday showers and thunderstorms will
remain a good bet. The initiating cold front will be dissipating,
but enough boundaries and instability will be in the area to
continue chances of convection. Locally gusty winds will be the
main threat from any stronger cells.
Tuesday night any remaining storms in the Lake Cumberland region
will gradually taper off and/or exit to the southeast. Patchy fog
looks like a good bet after midnight, though lingering cloud cover
may put a monkey wrench in that.
Tonight will be very warm and muggy with lows only in the lower and
middle 70s. There will be a slight breeze from the south around 5
to 10 mph, but it will still be uncomfortable for folks without air
High temperatures on Tuesday are challenging given the clouds and
rain in the area, but lower to middle 80s sound about right.
Tuesday night will be a little cooler behind the front, with
temperatures dropping into the middle and upper 60s.
.LONG TERM (Wednesday through Monday)...
Issued at 303 PM EDT Mon Sep 1 2014
Wednesday through Thursday...
In the wake of a progressive yet shallow 500mb trough exiting New
England, ridging will build northwards over the Tennessee and Ohio
Valleys from Wednesday through late Friday. As upper heights build,
expect a warm and humid period that will feel a lot like mid summer.
With the storm track well north across the upper Midwest, rain
chances will stay sparse with just isolated afternoon and evening
convection at best. Despite recent ample rains, highs will still
approach or just exceed 90 degrees. Expect warm muggy nights with
lows near or just above 70.
Friday through Monday...
A shallow progressive upper trough will move across the northern
Great Lakes Saturday into early Sunday. In the wake of this system
surface high pressure of Canadian origin will sink southwards across
the upper Midwest and eventually the northern Ohio Valley. Ahead of
this though, an elongated cold front will slowly sag southwards
through Illinois and Indiana late Friday, possibly crossing the
Commonwealth by early Sunday. This boundary, which will run roughly
parallel to the mid-level flow will be slow moving. One or more
rounds of convection will accompany this boundary due to pre-frontal
convergence and moist air. Friday night and Saturday will provide
the best chance for storms based on a compromise on the speed of
this front. Some showers may linger Sunday morning across our
southern counties, however, by afternoon cooler and distinctly drier
air will arrive from the north. Friday`s highs will approach 90,
with highs only in the mid-80s for an expected mostly cloudy
Saturday. Sunday will become much less humid with clearing and a
high only in the upper 70s to around 80.
High pressure will become centered over the Great Lakes on Monday,
with northeast winds expected across the Commonwealth. With mostly
clear skies expected after morning lows possibly in the 50s, highs
will reach the upper 70s to around 80.
.AVIATION (06Z TAF Update)...
Issued at 105 AM EDT Tue Sep 2 2014
VFR conditions will prevail at the TAF sites through the majority of
the remaining overnight hours, with a steady SSW wind between 5
and 10 mph. Upper level clouds will overspread the area ahead of an
approaching convective complex, along with a few lower level clouds.
A convective complex has developed across central IL southwestward
through southern Missouri ahead of several mid level disturbances.
Meanwhile, a weakly defined warm front was draped across central KY
between BWG and SDF. This feature will lift northward toward dawn
with isolated to scattered showers developing along it after 4 AM
EDT. Included VCSH mention at SDF/LEX through mid morning, with
potential to briefly go MVFR in a rain shower. There should be a
lull after the initial morning precipitation chances, then
convection is expected to fire in the early afternoon along the
remnant outflow/differential heating. This is expected to be between
SDF/LEX, although some thunderstorms could be around all terminals
through the afternoon and early evening. Expect convection to die
around sunset with some lingering clouds.
Winds will gradually veer to SW and then WSW through the day,
staying up around 10 mph. Once winds slacken late this evening, they
will return to SSW.