Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 030150
Area Forecast Discussion
National Weather Service Louisville KY
950 PM EDT MON MAY 2 2016
Issued at 950 PM EDT Mon May 2 2016
Ongoing forecast in pretty good shape. Have a vortmax ahead of an
upper trough, now over Iowa as per latest water vapor, that the
models are forecasting to travel through central Indiana overnight.
Several of them show some light precip moving into our southeast
Indiana counties by daybreak, so upped measurable pops to 20 percent
there. This change does not affect the zones, as they pick up on the
higher rest of the morning chances. Only other change was to match
with current observations.
.SHORT TERM (Now through Tuesday Night)...
Issued at 305 PM EDT Mon May 2 2016
The synoptic pattern early this afternoon features an upper-level
trough churning across the Midwest. A PV anomaly riding up in the
southwest flow ahead of this trough is helping to induce showers and
a few thunderstorms in south-central KY this afternoon and will be
the main focus of the period.
The surface front that moved through yesterday has stalled across
portions eastern KY southwest into east-central TN. Along and to
the north of this front, convection has developed in response to the
incoming forcing for ascent. The better instability has pushed off
to the east of the region, thus only expect moderate to locally
heavy showers over the next few hours. The main threat will be
locally heavy rain, as flash flood guidance remains low across the
Lake Cumberland region. Will be keeping an eye on this area over the
next few hours for potential minor localized flooding.
The PV anomaly will push off to the east this evening, allowing
things to dry out as the atmosphere becomes subsident behind it.
Can`t rule out an isolated shower or two lingering overnight in
southern KY, but think the risk is low enough to go with no pop
mention after about 03Z. Overnight lows will be chilly, with
temperatures expected to dip into the low to mid 50s.
The upper-level low will attempt to open up on Tuesday, swinging a
trough axis through the region as it does. Moisture will be very
limited with this ascent, so do not expect widespread or heavy
shower activity. However, the forcing does appear sufficient to
warrant slight chance/chance pops with the best coverage expected in
the northern Bluegrass. Highs will be cooler in the low to mid 60s.
Brief surface ridging will attempt to build in for Tuesday night as
the region lies between systems. Clouds will likely be around to
limit temperatures from dropping too much, but lows in the mid/upper
40s appear likely.
.LONG TERM (Wednesday through Monday)...
Issued at 304 PM EDT Mon May 2 2016
The synoptic pattern at the start of the long term period will
feature an anomalous trough across the eastern CONUS. This trough
will deepen even further through Thursday, before lifting out this
weekend which will allow for improving conditions.
Wednesday will feature a strong PV anomaly digging southeast into
the Ohio Valley. After some initial morning rain, lapse rates will
steepen substantially in the afternoon as the cold core of the upper-
level low pivots across the region. Seems like a favorable setup
for convective showers and even a few thunderstorms producing small
hail during the afternoon hours. Convection will wane in
coverage/intensity after sunset.
Thursday will be the worst day of the week, as deep northwesterly
flow and stratocu will make for a raw early May day. High
temperatures will likely struggle in the 50s across much of the
region through the afternoon hours under strong cold air advection,
with perhaps a few additional showers developing across the northern
Conditions will markedly improve Friday into the upcoming weekend as
the omega block begins to break down and the upper-level low begins
to shift off to the east. Dry conditions are expected Friday into
Saturday, as temperatures climb into the 70s and Friday and back
into the low 80s for Saturday and Sunday.
.AVIATION (00Z TAF Update)...
Updated at 730 PM EDT Mon May 2 2016
Still enough residual moisture left behind from today`s cool frontal
passage to create some poor flying conditions overnight. Guidance
still suggests at least low-end MVFR conditions to develop with this
moisture, and given its depth went ahead and put in the possibility
for worse conditions in this set of TAFs. Given the lower cigs also
extended the time into Tuesday morning that at least MVFR conditions
are expected. Expect the terminals to get above fuel-alternate MVFR
around lunchtime. Winds will be light and somewhat variable, though
a general northwesterly flow is forecast.