Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 232312
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
712 PM EDT Wed Jul 23 2014
...Updated Aviation Discussion...
Issued at 606 PM EDT Wed Jul 23 2014
Scattered to numerous storms have re-fired ahead of the cool frontal
boundary currently along a BWG/LEX line, with the aid of
differential heating from upper level clouds. These storms are
moving slowly off to the east, and have been able to produce very
heavy rainfall, a localized damaging wind gust and hail. The threat
for stronger storms will diminish over the next two hours as storms
move east of the area, and we lose daytime heating. Did update the
forecast to increase rainfall totals and increase coverage of
t-storms this evening.
.SHORT TERM (Now through Thursday Night)...
Issued at 320 PM EDT Wed Jul 23 2014
The cold front was very near the Ohio River as of 3pm. Most storms
have exited the region with thinning of clouds noted. With many
daylight hours left, some instability may rebuild and forcing from
the front could cause a few more storms/showers to redevelop late
this afternoon and evening. However, the strongest forcing along
the front will remain SW of our region and earlier showers/storms
have created a more stable moist environment. Post frontal
convection near IND is dissipating as well. Thus, think that more
showers/storms are possible but will limit POPs to 20-30% for this
evening. Also, any convection that does form is expected to remain
below severe limits due to limited forcing and instability. In
fact, it will probably be hard to even get a strong storm going with
gusty winds in this environment.
Any convective activity should cease after midnight with only some
patchy light drizzle/low clouds and maybe even some light fog late
tonight into tomorrow morning. A cooler airmass will enter the area
resulting in low temps in the 60s tonight.
With sfc high pressure and upper level troughing over the region
Thurs/Thurs night, we`ll experience unseasonably cool conditions.
Highs Thurs afternoon will drop back into the upper 70s and lower
80s with skies becoming mostly sunny during the afternoon hours.
Thurs night lows will bottom out in the upper 50s and lower 60s
under mostly clear skies.
.LONG TERM (Friday through Wednesday)...
Issued at 320 PM EDT Wed Jul 23 2014
Friday should be one more quiet day, with lower dewpoints and
temperatures still a few degrees below normal. A disturbance flowing
down within the northwest flow aloft will run into the dry air over
us, which should keep us from getting rain. This first system could
set the stage for another system to have a little more moisture to
work with late Friday night as it gets into southern Indiana. Cloud
cover with this system, similar to today, will pose a large question
mark on temperatures and rain chances in the day Saturday. MEX
guidance is calling for highs in the 90s Saturday, with the chance
for storms waiting until the evening as yet another disturbance
rolls through and takes advantage of that heating/instability. Will
not go as high as the guidance for temperatures, but still be around
90 for many locations.
The rain chances will continue Sunday and Sunday night as we get a
cool front to move from the Midwest into the Ohio Valley. That front
will bring another round of unseasonably cool temperatures to the
region for at least the first half of the work week. Once again,
records are possible with this round of cooling.
.AVIATION (00Z TAF Update)...
Issued at 710 PM EDT Wed Jul 23 2014
Convective activity just ahead of a passing cool front should remain
just south and east of the BWG/LEX terminals this evening. Latest
obs show all of the TAF sites with northwesterly surface flow,
indicating the front has passed. The main focus for the overnight
will be how low ceilings get as model time heights/soundings
indicate quite a bit of moisture in the lower levels. SDF/LEX could
drop into the MVFR range by 10-11 PM tonight, before falling close
to the low MVFR/IFR range in the pre-dawn hours to around dawn.
Ceilings will rise back into the solid MVFR range (above fuel
alternate) by mid morning, however we will likely keep a broken deck
at our just above the VFR/MVFR threshold through the afternoon. All
of this will happen a few hours later at BWG. Will also mention some
patchy drizzle at times in the pre-dawn hours as low level moisture
looks to be deep enough and a passing wave may squeeze out some very
light precipitation. One limiting factor to how low the ceilings
get, could be surface winds staying up around 5-10 mph overnight.
Surface winds during this time will generally be out of the NW
overnight, veering to NNE on Thursday.