Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Louisville Kentucky
305 am EDT Wednesday Aug 24 2016

Short term (now through thursday)...
issued at 230 am EDT Wed Aug 24 2016

Our region briefly gets out of the ridge that's been keeping US dry
and we come under the influence of more of a zonal flow for a day.
Any triggers for rain in this flow though look to remain to our
north. Airmass is more moist than it has been the last few days, but
model precipitable waters are initializing too high, with the GFS
going the highest having a precipitable water greater than 2" at ohx, compared to
the 1.73 on the 00z sounding. Thus will keep going with slight
chances of rain today and a warmer day.

Tonight, the best focus for moisture will be along and north of the
Ohio River. Models try once again to provide some weak isentropic
lift in this area, to the tune of likely pops in the mav guidance
along and north of a sdf/Lex line. Another possibility here is in the
latest NSSL-WRF, with a decaying line of storms coming in late from
the northwest. Do not want to go with likely pops, but will go into
the chance rain in our northern counties to dry in the south.

Thursday may see some lingering morning showers, but then the rest
of the day, the ridge to our south will reestablish itself over the
Tennessee Valley by the end of the day. This shift should have the effect
of lowering rain chances and forcing temperatures up.

Long term (thursday night through tuesday)...
issued at 230 am EDT Wed Aug 24 2016

Friday model consensus indicates that the ridge axis will shift
slightly east, along the smokies. Heights will still be fairly high
for US. Models show some quantitative precipitation forecast in the ring around this high, and will
go with blends here, but on the low side of chances. Saturday, the
models have trended toward that ridge being farther west, near the
mid Atlantic coast. Previous runs had it more over US, and thus we
were drier. With this trend and continued good moisture field over
US, will have to bump rain chances up for the weekend. A big and
uncertain factor in what happens to this ridge the rest of the
period is the tropical disturbance now over the Leeward Islands. Do
not want to do more than trend pops at this point given this
uncertainty. A drier forecast would mean hotter temperatures, so
there's some uncertainty in that field as well.


Aviation (06z taf update)...
issued at 110 am EDT Wed Aug 24 2016

VFR conditions are expected for the most part. The only exception
will be at bwg during the pre-dawn hrs when some light br may form.
Think that upper level clouds and a slight mixey return flow should
limit fog density to MVFR. This afternoon south-southwest winds will increase
to 8-12 kts at all taf sites. Also an isld shower/T-storm is
possible. However, with chances being very slim will only increase
low-mid level cu during the afternoon hours in the tafs attm. Any
convection chances should diminish after sunset tonight. Winds will
slacken this evening as well.


Lmk watches/warnings/advisories...


Short term........rjs
long term.........Rjs

National Weather Service Glossary of Abbreviations