Michigan growers and winemakers have good reason for cautious optimism about the grapes currently ripening on their vines. An early spring followed by an unusually warm summer have vineyardists across the state reporting bumper crops that are maturing between one and three weeks ahead of usual.
In other words, visions of a potential top vintage, like 2007 or 2005, are starting to dance in their heads.
The numbers at MSU's Enviro-weather -- the go-to website for obscure state weather data -- tell the story. On Monday, August 16, their Benton Harbor station, smack in the Lake Michigan Shore wine appellation, showed 2296 degree-days since March 1. The comparable numbers were 2238 in 2007, and 2232 in 2005.
In contrast, last year's unusually cold summer coughed up just 1831 degree-days by the same date.
You don't need to be a meteorologist or plant scientist to get this
stuff. Degree-days approximate the amount of usable heat during a growing season -- assuming your metabolism functions like the average plant's, that is.
Data from up-north is even more striking. MSU's Traverse City station records 1944
degree days so far this year, compared to 1844 in 2007, 1894 in 2005 --
and a lowly 1336 at this time last year.
In other words, the summer of 2010 is running slightly warmer than Michigan's two best vintages from the last decade. Depending on where you are, that's also a full 25% to 40% above the seasonal heat accumulation that gifted us with last year's seriously under-ripe crop.
Customary cautions apply: in Michigan, it ain't over 'til the late harvest
Riesling is in the tank. Too many things could still turn 2010
into just another mighta-been year: an intense heat wave, high humidity,
too much rain as harvest approaches, a freakish early frost. And total heat isn't the sole criterion for top vintages; a gentle, lengthy growing season yields grapes with better flavor profiles and more balanced acidity than a late-summer heat wave.
But one thing is certain: if Michigan's grapes don't receive enough heat to fully ripen -- a not-infrequent occurrence -- it's hard for anyone to make first-class wine.
And by coincidence, that's just the problem our California friends face -- most unusually -- in 2010.
One reminder of this flip-flop between the states arrived a couple of days ago as the lead story in a newsletter from Tablas Creek Vineyard, one of my favorite California wineries, located just off the Pacific in Paso Robles. Their litany of woe is reminiscent of many Michigan vintages:
"We got our last rain and last frost remarkably late this year (both in May)... We started the year a couple of weeks behind because of the cool spring, and this weather isn't allowing us to catch up... we do not see any veraison in the vineyard at the end of July..."
But wait -- there's more. This may also sound familiar to folks in Michigan, especially the LMS crowd:
The relative lack of heat and the relative availability of moisture -- by Paso Robles standards, at least -- have meant that we've had to struggle against mildew this year more than any year in our history... with the more frequent fog cover... and the abundance of moisture in the ground from the 140% of normal rainfall.
[We've] been going after it with sulfur, copper and the other organic products we have available to us. It's under control, but not gone..."
Those with long memories may recall the Michigan / California flip-flop of 1998, when Michigan vineyards set ripeness records and El Nino kept most of California's grapes from fully maturing. It's too early to call 2010 a replay, but so far the vineyards of Team Michigan are holding up their end of the bargain.