Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Louisville Kentucky
639 PM EDT Tuesday Sep 1 2015
..updated aviation discussion...
issued at 535 PM EDT Tuesday Sep 1 2015
Quick update to account for the showers that have developed over
Bowling Green, plus the small chance of an isolated shower eastward
through the Glasgow area and up to around Campbellsville over the
next couple of hours. Radar showing some small areas of increased
reflectivities aloft in that region.
Short term (now through Wednesday night)...
issued at 312 PM EDT Tuesday Sep 1 2015
Overall pattern features an upper ridge centered over the southeast conus,
meanwhile a weak upper low is spinning over central Indiana. This
feature will gradually round the apex of the ridge, sliding just
northeast and then east of the County Warning Area through the short term.
Very isolated showers and storms have developed over southern
Indiana this afternoon. Most spots will stay dry, however very
localized spots could see brief heavy rainfall, cloud to ground
lightning and gusty winds up to 40 miles per hour. Upper feature will gradually
slide east overnght and then southeast toward dawn. Will go dry
through the overnight with the loss of daytime heating/instability
however will begin to reintroduce slight chance probability of precipitation across our far
NE during the afternoon hours on Wednesday, lingering into Wednesday
night as the upper low begins to push east of the area.
For tonight, am a bit concerned about the potential for some patchy
dense fog, especially in the river valleys. Overall conditions will
be favorable for radiational cooling. Think the most likely areas
will be west of I-65 and across southern Kentucky. Our NE should see a bit
more cloud cover influence from near the upper low so more optimisic
that dense fog will not form there. Will mention in the zones and in
the hwo, but will hold off any any additional headlines at this time.
Most lows will be in the middle and upper 60s tonight with a few
locations staying around 70. Wednesday highs should be a degree or
two warmer than today, so will go with and 88 to 93 range. Areas
west have the best shot at the 92s and 93s. Wednesday night lows
will be slightly milder in the 68 to 73 range.
Long term (thursday through tuesday)...
issued at 305 PM EDT Tuesday Sep 1 2015
Only subtle changes in the long term with mostly a persistent
forecast day to day. Ridging aloft is the reason for this
persistence...however latest GFS/Euro now hinting at a weak inverted
trough meandering across the region at various times. This boundary
may be enough to focus isolated diurnal convection. Coverage will be
limited by precipitable waters only in the 1.3-1.5 inch range.
Superblend came up with a couple of periods in the scattered
range...but in keeping with a persistence forecast and that dry air
in place decided to limit to isolated coverage.
Otherwise our temperature forecast remains a little above normal
each day. Backed off for day 7 closer to normal...as thicknesses are
forecast to come down some.
Aviation (00z taf update)...
issued at 639 PM EDT Tuesday Sep 1 2015
With little change in the overall meteorological set-up, will go
with a largely persistence forecast for this taf package. So...will
have to contend with the possibility of morning fog once again,
especially at bwg. Lex and even sdf may briefly drop below 7sm
around dawn (br at Lex, urban haze at sdf).
Outside of that, this taf period should be largely free of problems