Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Louisville Kentucky
106 PM EDT Friday Sep 4 2015
..updated aviation discussion...
issued at 1115 am EDT Friday Sep 4 2015
Need to tape a Coin to the phonograph needle as this forecast is
starting to resemble a broken record. This afternoon looks like a
repeat of the last couple afternoons, and the only update has been
to remove the mention of morning fog.
Short term (now through saturday)...
issued at 305 am EDT Friday Sep 4 2015
Mostly clear skies were noted across the region this morning. A mix
of light fog and haze was reported at several stations. Expect the
fog and haze to continue through the remainder of the overnight
hours with temperatures cooling into the upper 60s to the lower 70s.
For today/tonight, rather stagnant upper level pattern will continue
across the region. Under mostly sunny skies, temperatures will warm
into the upper 80s to the lower 90s across the region. Some
isolated showers and storms will be possible during the afternoon.
Still hard to pin down which area would be favored. Some of the
high resolution models suggest that some slightly lower heights to
our northeast may result in the Bluegrass region seeing the highest
risk of storms. Skies will clear out in the evening and mostly clear
skies with patchy fog is expected once again. Lows tonight will
drop into the upper 60s to the lower 70s.
Saturday does not look to be all that different in terms of sensible
weather across the region. Mostly sunny, hazy and muggy conditions
are expected with highs in the upper 80s to the lower 90s with a
risk of an isolated shower/storm in the afternoon.
Long term (saturday night through thursday)...
issued at 250 am EDT Friday Sep 4 2015
The synoptic pattern at the start of the long term period will
feature broad upper-level ridging across the eastern Continental U.S.. this
regime will persist through much of the long term period before
breaking down by the middle/end of next week as a surface cold front
approaches the region.
The main story through the end of the weekend into early next week
will continue to be the heat. Low-level thicknesses continue to
suggest temperatures running in the upper 80s to lower 90s through
at least Tuesday of next week...with middle 90s likely in the typically
warm spots. A broad and very weak upper-level low along the
southeast coast will allow subtle disturbances to rotate westward
mainly across southern Kentucky Sunday into Monday...which may bring a few
showers/storms to the region. However...forcing is very weak and
surface convergence looks minimal...so think most end up staying dry
A cold front will approach the region Wednesday into Thursday of
next week as the upper level ridge begins to break down. As
expected...guidance has trended slower with the frontal passage. The European model (ecmwf)
continues to be the fast outlier...with the GFS solution being
rather stable over the past few runs. Given the known model bias of
breaking ridges down too quickly and the consistency of the GFS
solution...will continue to favor the slower frontal passage. This keeps only
slight to low-end chances of precipitation on Wednesday...with the best
chances mainly coming Wednesday night into early Thursday as the
front passes through. It appears there may be a few waves of low
pressure riding along this front as it passes through...which may
help bring some much needed widespread rainfall to the area.
Aviation (18z taf update)...
issued at 105 PM EDT Friday Sep 4 2015
Surface and upper pattern remains stagnant, resulting in a
persistence forecast. Isolated convection is possible again this
afternoon, but probabilities too low to mention in any of the tafs.
Otherwise light/variable winds and diurnal cumulus.
Fog/haze will again be a factor heading into Sat morning. Greatest
chance for restrictions will be in bwg, where we will carry
MVFR/tempo IFR similar to this morning. Sdf will be most persistent,
hanging on until late morning while bwg/Lex improve to VFR by 13-