Fair Weather

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Tomorrow kicks off the Southeast Alaska State Fair in my hometown of Haines. Some people have asked “why Haines, and not Juneau,” the largest city in the panhandle, or Ketchikan or Sitka for that matter, if we are talking size. Well, since this is a weather blog, we’re going to talk weather. I think the answer will be clear, or at least fair.

For a summer outdoor event, precipitation is the main threat. Wind is a close second. Sure, it is nice to have warmth and sun, but those usually go along with dry weather: if it is dry it will almost certainly be warmer than if it is wet.

Here’s a graph from the Western Regional Climate Center (actually two graphs merged on my computer):

The graph shows the statistical probability for a tenth of an inch of rain (2.5 mm)–more than can be successfully ignored– to fall during a four day period based on the time of year. Juneau is in red, Haines in blue. Sitka is a bit wetter than Juneau and Ketchikan way wetter, so I’ll sticking with Haines vs. Juneau. Even though the two towns are only 75 miles apart, there is a big difference in the likelihood of significant rain during the summer. In late July, when the fair tends to be held these days, its a pretty even split for having a tenth of an inch of rain in a given four days in Haines, while in Juneau it’s 70+ percent likely. Of course the fair is not open 24/7 as is the weather station, so the probability of the rain actually falling during open hours will be somewhat less, but the comparison is what we’re after.

This graph downplays the difference if anything: Looking at the raw monthly averages, Juneau gets three times the rain of Haines in an average July and twice as much in August. There’s the climatological case for having the fair in Haines vs. anyplace else in SE AK except somewhat drier Skagway. And when you look Skagway’s winds (~20% stronger at that time of year) you might agree that Haines is still the better choice, weather-wise.

Side note: Haines and Skagway have been the agriculture hot spots of Southeast for a over a century, and the climate is a big part of that. The SE Fair used to be much later, at the end of summer, to allow crops to be ready to show. Another look at the graph reveals a strong weather case for the move to an earlier date. Hard for the gardeners, but it seems our fair, and many others I suspect, have, in the words of my neighbor, become more music festivals than traditional fairs.

What about the weather for this year’s SE AK State Fair?

After such a cold, wet 1st half of the summer, things have taken a welcome turn for the better. And our expectations have been lowered as well, so the next four days of fun and festivities is looking pretty decent. Opening day should be stellar, and Friday probably hanging on pretty well too. After that, an upper level low that’s been rotating in place off the coast will likely throw more clouds our way, making it a little cooler and setting up for the possibility of some light rain. How likely? I’ll say pretty likely that some rain will fall during the four days, but I’d say less than the 50/50 chance that climatology says for 0.10 inches or more. And remember, any rain that does fall might come  at night!

What about the other fairs in Alaska?

Fairbanks hosts the Tanana Valley State Fair in early August (3-12 this year).

“The” Alaska State Fair is held in Palmer (40 minute drive north of Anchorage) in the end of August/1st of September (August 23-Sep 3 for 2012).

Here’s some graphs for them:

A little different graph, but the same basic idea, how the precipitation varies by time of year. You can see that the Interior fair is during about the wettest time of the year for average daily precipitation. There is a marked drop off right at the start of September. Should they consider moving their fair to the 1st week of September? Keep in mind that cumuliform (showery) precipitation is more likely earlier in the summer and stratiform (steady) rain more likely in September. Showers drop more rain in a shorter time period and are usually preceded and followed by some sun, so averages in showery months look worse than a person might perceive, whereas the steady precipitation is more gloomy and gray and long lasting, if gentler. A look at the threshold probabilities (such as the graph above) might tease out that distinction. I’ll let you play around with that. Days are longer and usually warmer earlier in the summer, too. In all honesty it is so much drier in the interior than the coast, that it does not matter so much. Personally, I think Fairbanks and the interior have an incredibly nice climate from May through September compared to just about anywhere in or out of Alaska. The rest of the year? No comment at this time.

Here’s the same graph for Palmer:

In Palmer the precip does not vary too much from mid-July through September. They’re pretty much stuck with the somewhat deserved reputation of, “if it’s fair time it will be rainy.” But with a two week fair there will surely be nice days in there somewhere, if you are flexible enough to take advantage of them. At leas the crops can be ready.

I’d love to hear your thoughts, questions or experiences on this topic via the comments link.

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