Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 250459
Area Forecast Discussion
National Weather Service Louisville KY
1259 AM EDT WED MAY 25 2016
...Updated Aviation Discussion...
Issued at 1010 PM EDT Tue May 24 2016
Have updated the grids this evening to account for the latest
observational/guidance trends. MCS over eastern AR has quickly
shown signs of decay over the past hour, with the convection and
stratiform precip shield shrinking. Guidance has not handled this
convection well, so there is some uncertainty in the forecast for
tonight. Latest thinking is that with the main effective boundary
staying well off to the southwest, we will struggle to see much in
the way of development through the first part of the overnight
hours. As a weak wave lifts through the area early Wednesday
morning, just enough isentropic ascent will develop to perhaps
squeeze out a few convective showers. While an isolated storm can`t
be ruled out, don`t think coverage will be enough to even warrant
mention in the forecast overnight so have removed thunder wording
through 12Z. Otherwise, forecast looks on track.
.SHORT TERM (Now through Wednesday Night)...
Issued at 248 PM EDT Tue May 24 2016
As of mid afternoon, a surface analysis showed high pressure
centered across the mid-Atlantic coast, while latest visible
satellite had mostly clear skies minus a few cumulus west of I-65.
The upper levels are characterized by an anomalous cut off low off
the New England coast while weak ridging to southwesterly flow was
across the central Plains. Temperatures locally were in the upper
70s to low 80s with a rather dry air mass in place. Dewpoints have
mixed out into the upper 30s to mid/upper 40s.
For this evening and tonight, look for a gradual increase in
moisture as the upper disturbance to our west begins to slowly drift
toward the area. Overall it will be a dry evening as the instability
axis remains to our west, however late this evening and overnight,
we`ll see increasing 850 mb moisture transport. This may fuel some
elevated showers or storms, mainly north of the KY parkways into
southern Indiana. However, coverage isn`t expected to be high so
POPs were confined to the 20 to 30 percent range. Plan on lows in
the low 60s.
For Wednesday, look for a slightly more humid/muggy day as dewpoints
creep up into the low 60s, especially west of I-65. This increased
moisture, combined with a passing upper level shortwave, will help
spark a bit more coverage of showers/storms in the afternoon. The
highest chances, still capped at about 30 percent, will be across
southern Indiana and portions of west-central Kentucky. Plan on
highs in the low/mid 80s. A muggy evening/night will then be on tap
with lows staying up in the 60s.
.LONG TERM (Thursday through Tuesday)...
Issued at 253 PM EDT Tue May 24 2016
The long term period will be characterized by an upper level ridge
anchored off the southeast US while passing shortwave troughs will
work to dig through the central Plains into the lower Great Lakes.
Our area will be on the periphery of this ridge, at least Thursday
into the weekend.
This upper level ridging will work to limit precipitation chances to
mainly diurnal showers/storms with more organized convection likely
staying to our west/northwest. We`ll have to watch to see if the
ridge breaks down any further and allow these systems to pass more
closely, but for the most part, look for a more summer-like pattern
with above normal temperatures in the mid/upper 80s and mild/muggy
overnights in the mid/upper 60s. The model consensus precipitation
chances were capped in the 20-30 percent range for most periods in
the forecast, and it`s possible as the forecast becomes clearer,
POPs during a few of these periods may be able to be completely
.AVIATION (06Z TAF Update)...
Issued at 1258 AM EDT Wed May 25 2016
Mainly VFR conditions will be carried in the TAFs for this forecast
period. The challenge, however, is the potential for showers and
storms. The storms over west central TN have been weakening.
However, most short term guidance shows showers developing north of
this area early this morning and pushing east across central
Kentucky. The models do seem to be overdoing the ongoing
precipitation somewhat, however, so confidence on coverage is low.
Therefore, will include VCSH this morning into the afternoon hours
based on a consensus of the guidance. Thunderstorms are not out of
the question today, but given the uncertainty in coverage, will hold
off on mentioning TS in the TAFs at this time.
Ceiling are expected to remain mainly VFR unless a thunderstorms
moves over the terminals. Winds will be out of the south to
southeast and could be a bit gusty this afternoon at SDF and BWG.