Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 290536
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
136 AM EDT Mon Sep 29 2014
...Updated Aviation Discussion...
Issued 843 PM EDT Sun Sep 28 2014
Forecast is largely on track this evening. Did extend the isolated
shower mention across the northern third of the CWA for another few
hours. The best area of focus will generally be along the Ohio River
Valley through around Midnight where an inverted surface trough
continues to linger. May also get some upper level support from a
weak upper level disturbance that will roll through the region later
tonight. Most spots will remain dry outside of the weak and isolated
Issued 538 PM EDT Sun Sep 28 2014
Updated the forecast to trim pops across south central KY. Latest
mesoanalysis shows best moisture convergence and instability along
the inverted surface trough axis which generally stretches along the
lower Ohio River Valley. Additionally, latest visible satellite
shows swelling cu in this area, with less impressive development
across portions of central and southern KY. Will just keep the
showers in the forecast for the next few hours across our north and
west, and will go dry with the loss of daytime heating later this
.SHORT TERM (Now through Monday Night)...
Issued at 250 PM EDT Sun Sep 28 2014
Cumulus clouds have developed across the region this afternoon and
very isolated showers are showing up on radar. Some of these showers
are popping up in southern Indiana, so have spread pops across the
entire forecast area. Will continue to carry 20% chance through the
afternoon, but coverage will likely not even be this high. With
sunset any showers will dissipate. In addition the moisture with
this system will shift into eastern KY tonight. Dry conditions are
expected through the remainder of the forecast period.
An upper level trough will swing across the region overnight and
ridging aloft will start to build back in tomorrow into tomorrow
night. Winds will shift to northwesterly and then northerly
tomorrow. However, this is not expected to bring in cooler air as
temperatures tomorrow will be similar to today in the lower to
middle 80s. Lows tonight will be tricky and depend somewhat on how
fast clouds clear. In general they look to range from the upper 50s
to lower 60s. With clear skies tomorrow night, temperatures will be
cooler, dropping into the mid 50s to around 60.
.LONG TERM (Tuesday through Sunday)...
Issued at 300 PM EDT Sun Sep 28 2014
Brief upper level ridging will cross the area Tues/Wed resulting in
dry conditions and temps slightly above seasonal normals. Expect
mostly sunny skies both days with highs topping out in the low to
The main weather system in the long term is a strong cold front
progged to move through the area late Thurs night into Friday
morning. Models have sped up the arrival of precip a bit on the 12Z
run with most models indicating that we could indeed see scattered
showers/storms Thurs afternoon ahead of the front. Thus, trended
the precip window back into late Thurs afternoon for now. The main
episode of showers/storms associated with this system looks to be
Thurs night into Friday morning and did go ahead and increase POPs
to 60-70% during that time frame. As far as storm strength goes,
think we could see perhaps some strong cells with gusty winds on
Thurs afternoon/evening before the main convective line arrives.
Think the main threat with this system will be moderate to heavy
rains at times Thurs night as the main line moves through. PWATs
jump to 1.7-1.8 inches which is 2 standard deviations above normal
for this time of year. Antecedent ground conditions are dry but are
generally hard in nature which may combine with the heavy rains to
cause brief minor flooding issues. This weather system looks to be
fairly quick moving with rains moving out from west to east Friday
during the day.
Behind the front, cool and dry conditions will be ushered in for the
weekend. Expect high temps on Sat only in the 60s with Sunday highs
a bit warmer in the upper 60s/lower 70s. Overnight lows will take a
dip into the 40s Sun morning.
.AVIATION (00Z TAF Update)...
Issued at 115 AM EDT Mon Sep 29 2014
Main challenge overnight will be fog potential at BWG, where cirrus
shield has cleared within the last hour or two. Temps are progged to
just touch the crossover temperature, but latest MOS guidance is not
hitting the fog as hard as previous runs. High-resolution models
don`t seem to have a very good handle either. Will go with
prevailing MVFR and a TEMPO for IFR visibilities around daybreak.
SDF and LEX will not have as much time to radiate out due to the
lingering mid-level deck, and will have a harder time reaching
crossover temps. Will keep thos sites VFR.
Light W-NW winds expected late in the morning, along with scattered
diurnal cu as mixing picks up. Even better radiational cooling
conditions Monday night will open the door for significant
restrictions to visibility on Tuesday morning, especially in BWG.
Can`t rule out IFR Tuesday morning in LEX either, but that remains
beyond the scope of this TAF issuance.