Saturday Morning

A quick look at the morning model runs continues the trends noted yesterday.  The HIRES NAM model doesn’t even produce ANY rain for the Louisville area – keeping the heavy rain/storm threat from northern IN to SW Ohio, eastern KY (east of I-75) and West Virginia.

The NAM continues yesterday’s trend, but in a much weaker fashion.  It now pushes a line of showers/t-storms through the region after midnight with the majority of rain (on the light side) ending before Noon.

The GFS as usual is the slowest.  It is also a weakened version of yesterday.  It holds off the rain/storm cluster until well after Midnight with all rain wrapping up shortly after Noon. Again the rain totals predicted are much lower than yesterday’s prediction.

So, here’s my latest forecast:

Afternoon:  partly cloudy, hot and humid…high 90ish (a highly technical term

Tonight:  20% chance for thunderstorms until midnight.  After Midnight, showers and thunderstorms are likely.  Gusty winds possible.  Rain chance 60%.  Low…72.

Tomorrow:  Showers end during the morning, then sunny and breezy in the afternoon…high…87.

Severe Storm Threat

Most, if not all, of the severe weather will occur over eastern Indiana and SW Ohio (and southeast from there).  An isolated severe thunderstorm is possible,  but not likely, within 35 miles of Louisville.

There is also talk of a second chance for severe storms tomorrow afternoon or evening.  To me, this seems like someone’s idea of a bad joke.

Friday afternoon

I’m not much of a fan of extended outlooks and/or long range forecasting.  Nevertheless, I do check a model that portends to go out weeks and months.  That model is known as CFSv2.  I like to see the slow, usually subtle, forecast changes the model picks up.  But today I noticed a big shock – a dramatic one week change in August’s outlook.

Below is the forecast from July 17.  The top left image is the raw computer output.  The upper right is a statistically “normalized” version of the raw data.  The bottom images are probabilities of occurrence.  Notice the eastern U.S.  Forecast for an above normal surface temperature (2 meters) is quite evident.

That was July 17.  Here’s the same image from today’s run…

An amazing flip-flop!  If correct, we’re looking at a very nice August.  But, if it flips once, it can flip again.  This is a perfect example why I don’t like forecasting beyond 3 days.

Almost five years into retirement, I find I can’t keep my mouth shut concerning our local weather, some climate matters (and other stuff).  But, now its a hobby, not a job.  So, I won’t post every day.  However, on days when the weather gets “interesting”, I plan to get my two cents in along with everyone else.  After 40 years of forecasting our local weather and watching it closely for another five, I feel I’ve learned a few things to add to weather discussions.  I’ll finish this re-introduction with one of my favorite quotes.  It’s attributed to Neils Bohr, Nobel Prize winning developer of quantum physics and probably, along with Einstein, one of two best physicists of the first half of the 20th century.

“Prediction is very difficult, especially about the future.”