Don’t expect a muddy race like the mess that was the Kentucky Derby. There is a chance of rain Friday evening, but the track at Pimlico should have plenty of time to dry by Saturday afternoon.

The weather plays a big part of Preakness tradition every year, rain or shine. In 1909 a new members’ clubhouse was built with a weather vane in the shape of a horse and jockey to replace the old one, an arrow-shaped vane that is now displayed in the museum at Pimlico.

Since then, the tradition at Pimlico is to paint the jockey’s jersey in the colors of the winning stable.

In 1966 the members’ clubhouse burned to the ground, and a replica of the building’s cupola, complete with the horse-and-jockey weather vane, was constructed and moved to the infield. A handyman is sent to the top of a ladder to paint the jockey as soon as the race becomes official.

Other Preakness day weather notes: The warmest Preakness Day ever recorded was 87 degrees; the coolest was 52 degrees. There will be no extremes this year—it will be sunny and pleasant with temperatures in the 70s. The Preakness has never been rained out.

Ed Hoffman is the publisher of The Baltimore Guide and an amateur meterologist.

Ed Hoffman, Publisher of The Baltimore Guide and Amateur Meterologist.

Will it rain on Sunday? There’s a chance it will.

If you’re mowing the lawn or working outside this weekend, you should get it done on Saturday. It won’t rain the entire day Sunday, but the chances increase from 20 percent in the morning to 40 percent in the afternoon that wherever you are, there will be a shower or even a thunderstorm.

Often a forecast will read “a 30 percent chance of scattered showers.” It is an odd choice of words. The chart below, from the National Weather Service, is an attempt to standardize the POP (percent of precipitation) with expressions used in verbal forecasts.

* 0% – No mention of precipitation
* 10% – No mention of precipitation, or isolated/slight chance
* 20% – Isolated/slight chance
* 30% – (Widely) scattered/chance
* 40% or 50% – Scattered/chance
* 60% or 70% – Numerous/likely
* 80%, 90% or 100% – No additional modifiers (i.e. “Showers and thunderstorms”)

That’s right they really take this stuff seriously. Next time you hear a forecast of isolated showers, don’t panic, it only means a 10% chance. These terms only apply to convective precipitation, that is, thunderstorms and showers caused by the local heating (rising air) and cooling (descending air) of the atmosphere causing condensation and rain or snow to occur. Did you ever wonder what the difference is between partly cloudy and mostly sunny? There is one, email me or visit my blog next week.