Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 221929
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
329 PM EDT Fri May 22 2015
.SHORT TERM (Now through Saturday Night)...
Issued at 328 PM EDT Fri May 22 2015
Mostly sunny skies were noted across the forecast area this
afternoon. Afternoon temperatures have warmed into the upper 60s
and lower 70s. Expect a few high clouds to drift in this evening
with temperatures falling back into the 60s.
A weak surface trough will swing southward toward the region this
evening. This feature will washout and will not have any effects on
sensible weather, other than some passing high level cloudiness.
Lows tonight will likely drop back into the lower-middle 50s for
most areas, but some of our cooler Bluegrass areas may drop back
into the mid-upper 40s once again.
High pressure will build back into the region resulting mostly sunny
skies for Saturday and mostly clear skies for Saturday night. An
increasing southerly flow will allow slightly warmer temperatures
with highs in the upper 70s to the lower 80s for Saturday. Lows
Saturday night are expected to drop back into the mid-upper 50s.
.LONG TERM (Sunday through Friday)...
Issued at 315 PM EDT Fri May 22 2015
The upper ridge axis will move east of the area by Sunday night in
response to an ejecting shortwave over the southern Plains. This
will shift the deep southerly flow more over the Ohio River Valley,
bringing an increase in temperatures, moisture, and rounds of
scattered storm chances.
Sunday - Sunday Night...
We`ll still be under the influence of the upper ridge axis for a
good part of Sunday, bringing a dry day with partly cloudy skies and
a steady south wind. Do still have to mention a very small chance of
a shower or storm west of I-65 by late in the afternoon on Sunday as
we get on the back side of the upper ridge and just enough moisture
transport/weak isentropic lift could spark convection in the
marginally unstable environment. DO NOT let small precip chances ruin
any outdoor plans west of I-65 Sunday afternoon/evening. Continued
the trend of advertising a pretty warm day with highs solidly into
the mid 80s in most spots.
Will continue to keep Sunday night basically dry save for a very
isolated shower possible. Look for lows in the upper 60s to west of
I-65 and in the low and mid 60s east of I-65.
Monday - Friday...
An active period of weather takes shape through the remainder of the
week as we contend with the deep SW flow and disturbances it brings
through our area. Like the idea of mainly keeping scattered coverage
of showers/storms going until details of individual perturbations
work themselves out. Remembering the overall pattern last week,
coverage ended up being on the lower end of what was anticipated and
could see that scenario playing out again.
Overall pattern certainly calls for at or above normal highs
(dependent on daily convection) and above normal lows given the
steady southerly flow/higher dew points. Have kept the idea going of
suggesting milder nights than what guidance is calling for. This
worked well last week when we were in the same pattern, so in
general look for upper 60s to around 70 each night through at least
mid week. Highs will mostly be in the lower 80s, with mid 80s
possible under less convection, and upper 70s possible under the
better coverage days.
Right now, the best coverage days look to be later Monday through
Wednesday, drying out toward the end of the week. As mentioned in
the previous discussion, severe weather threat looks relatively low.
However, it does appear that 25-35 knots of 0-6 km shear (marginal)
may couple with weakly moderate instability at times to allow for a
few stronger storms. This would be completely conditional and most
likely focused west of I-65 if it were to occur.
.AVIATION (18Z TAF Update)...
Updated at 122 PM EDT Fri May 22 2015
A weak trough axis will approach the region this afternoon and
evening. This feature is expected to wash out as it pushes into the
region and is not expected to produce any sensible weather other
than some high cloudiness moving in from the west. High pressure
will build into the region tonight bringing VFR conditions.
Probability remains low for fog development due to the expected high