Oregon’s grape harvest was completed, for all practical purposes, by October 18. There may have been some White Riesling lurking out there, in search of botrytis cineria, but not much. Reports say that the same is true for Oregon’s southern wine areas (Rogue and Umpqua River Valleys) and the Columbia River Gorge, as well as the State’s bellweather Willamette Valley.
The consensus among winemakers is that 2012 was a very good harvest. Full flavors and good balance are the theme of the day, especially for Pinot Noir in the Willamette Valley. The climate was good enough that vineyards did not have to thin the crop to achieve ripeness, but the good ones did some of that anyway.
2012 was a crop year that started late, gained on normalcy during the summer, then finished with a fairly normal Pinot Noir harvest during the second week of October. Just how does this year stack up against the many outstanding vintages since 2002? And, can we imply something about vintage quality from 2012’s climate conditions?
For this task, we turn to the U.S. Bureau of Reclamation’s Agrimet weather stations near Forest Grove (FOGO) and Aurora (ARAO). These sources have been cited before. The Agrimet stations collect data on such parameters as air temperature, evapotranspiration, precipitation, wind direct and speed, solar radiation, and soil temperature. The data is automatically uploaded to satellite every 45 minutes, then downloaded to a central computer in Boise, Idaho. All of these processes occur without human intervention, eliminating adjustments and errors. The data is available on the internet.
The only shortcomings of these data sources are: the limited number of Agrimet sites; elevation differences from vineyard sites; intervening topography; and the short length of time each station has been in service. For the Forest Grove station (FOGO), installation was done in 1991 (21 years). The equipment is situated in a farm field near Verboort, away from highway and other urban heat island effects. It is on the valley floor at 180 feet MSL, whereas area vineyard sites are 300-600 feet MSL. Adjustments are easy for vineyard locations around Forest Grove, but Dundee Hills vineyards are 25-30 miles to the south, with an intervening range of hills defining a different watershed and vulnerability to a significant gap in the Coast Range which admits cooler off-ocean winds at both ends of the growing season. Vineyards around Forest Grove, on Chehalem Mountain (Carlton-Yamhill AVA) and the east flank of the Eola Hills are protected from these intrusions by the Coast Range. Vineyards sited on the Dundee Hills and the west slope of Eola Hills receive the full force of these seasonal maritime intrusions, resulting in greater rainfall and cloud cover in spring and fall.
Another consideration is the rain shadow effect in the Tualatin Valley. There is a well-documented history to this pattern. Prevailing winter weather comes from the southwest, heavily laden with moisture from the Pacific Ocean. As this air passes over the Coast Range, it is compressed, reducing its water-holding capacity. Rainfall increases to 120 inches by the crest. On the east slope of the Coast Range, the air expands, increasing its water-holding capacity. By Forest Grove, annual precipitation decreases to approximately 42 inches per year.
As the air passes over Portland’s West Hills, rainfall increases again, averaging 48 in/yr. The rain shadow is defined by a triangle with points approximately at Forest Grove, Beaverton and Tigard. Inside the triangle and its perimeter zone, cloud cover is diminished and sunlight reaching the vineyards is increased.
Aurora Agrimet Station is 18-20 miles to the east of Dundee. It was installed in 1998, fourteen years ago. It, too, is on the valley floor compared to Dundee Hills vineyard elevations similar to the Forest Grove area.
First, let’s review the total degree-days logged between April 1 and October 31. The degree-days for each day are calculated by subtracting 50 from the day’s mean temperature in °F. The cumulative degree-days for 2012 are compared with the 1992-2012 average in Figure 1.
2012 exceeded the 21-year average during mid-April through Mid-June, and after the first week of August. Coupled with lower-than-normal soil temperatures in March, largely due to extensive cloud cover, bud break was delayed 2-3 weeks later than the normal mid-April timing.
How did 2012 stack up against the “best” Pinot Noir vintages since 2000? “Best” is defined as wide consensus among prominent wine critics as outstanding, or better than 90 points on the 100-point scale.
Total degree-days accumulated from April 1 through October 31 for the 21-year average, several best vintages, and 2012 were:
Total degree-days for 2012 exceeded the 21-year average by 2.0%. By the end of October, 2012 was close to 2002, less than 2006, and greater than 2008, the last being hailed as Oregon’s greatest Pinot Noir vintage ever.
Forest Grove and Dundee amounts are adjusted to reflect the difference between the FOGO Station and typical vineyard elevations.
Degree-days accumulated in each month are plotted in Figure 2. Degree-Days for March are shown because they affect the timing of budbreak. Soil temperature controls the timing when roots begin to push their new shoots and sap builds pressure to force the buds to expand, before any green tissue is showing above ground. 2002, 2008 and 2012 experienced about fifty degree-days in March. 2006, 2010 and the 21-year average logged around 100 March degree-days which would have been consistent with long-term behavior of budbreak at mid-April. 2012 budbreak was 2-3 weeks later than that.
2012 had above-normal April temperatures, normal temperatures in May, then below normal heat in June. After a normal July, 2012 ran above-normal in degree-days from August through October. 2012 finished the year with more thermal input than 2008.
In general, 2012 was cooler than 2008 during April through July, but warmer than 2008 and the long-term average for the balance of the crop year.
Another general observation regarding all of the years plotted, is that the variation in degree-days was sizeable and inconsistent for April through June, then began to focus on a common pattern thereafter.
Heat is only one part of the total energy that drives photosynthesis. The other is light, or solar radiation. Agrimet provides data in langleys. We find the measure, WH/m2 (watt-hours/square meter), easier to work with.
Solar radiation received at FOGO during the 7-month season, as well as estimates for Forest Grove area vineyards and Dundee Hills, are presented as follow:
These totals are expressed as Kilowatt-Hours per square meter (KWH/m2). The estimates for Dundee Hills are adjusted for distance from the FOGO station, intervening topography and the spring and fall weather conditions already discussed.
In 2012, solar radiation received at Dundee Hills was slightly less than for 2002 and 2006, but significantly greater than 2006 and 2008. 2012’s solar radiation was 4.2% more than the 21-year average.
Monthly solar energy patterns for the five years and the 21-year average are plotted in Figure 3.
The growing year started with 2012 racking up very close to the average WH/m2/day (watt-hours per square meter) in April as 2008, 2010 and the 21-year average. 2012 had more radiation than all of the others, but lost ground with a June drop. But still, June 2012 was equal to 2008 and 2010.
In July, 2012, solar radiation was significantly less than all of the others. To this point, 2012 had the lowest cumulative radiation of all of the years analyzed. Progress of the vines was behind all of them. From that point on, August through October, 2012 had more solar input than was incurred in any of the other years. Thus, the vines caught up with a “normal” year, and were harvested in a period that was consistent with long-term experience, first week of October in the Forest Grove area, almost one week later in the Dundee Hills.
[box]Heat summation and solar radiation compared[/box]
The picture becomes more complete when we review heat summation and solar radiation side-by-side, or rather over-and-under. Figure 4 does that.
The first apparent characteristic of the curves in this juxtaposition is how the heat summation values lag behind those of solar radiation. It’s just a little proof that all energy on earth is initiated by energy from our sun.
Wet and cloudy weather in June nullified the otherwise early start of vine growth in April and May when both heat and light were above the 21-year averages. After July, above-normal solar radiation pulled the vine processes along, driving photosynthesis to biological ripeness. Whereas heat summation led in carrying the 2008 vintage through to ripeness in October, it was solar radiation that did most of the work during the same period of 2012.
[box]Other ripeness indicators[/box]
In Burgundy, a 100-day rule has been observed. The time between 50% bloom and harvest averages 100 days. The range varies from 92 days to 108 days in a bell curve type of distribution. A warmer growing season shortens the period, and vice versa. In the Forest Grove area, 2012 50% bloom occurred typically on July 4-5 and the harvest was typically October 10-15. The average gap was about 100 days, and that compares favorably with long-term experience of 50% bloom at 850 cumulative degree-days and harvest 98-100 days later. Both events occur about 4-6 days later in the Dundee Hills and further south in the Eola Hills.
Another indicator of biological ripeness is brown stems and seeds. Up to that time, they are lime green in color (see photo below):
Laboratory analysis of phenological data for the grapes is used by most winemakers in determining the picking date. Titratable acidity, pH, and residual sugar are the “big three” measures. It is possible to plot the progression of these properties on graph paper as an assist in scheduling a picking date. Although attempts have been made to develop ratios between these factors as an infallible indicator of ripeness, none of them have succeeded. The reason is that the vines adjust their march to ripeness to the climate conditions they experience. So, “hang time” really does count for something. In a cooler year, the grapes will achieve biological ripeness at lower sugar and pH, and higher acidity. The opposite happens in a warm year.
Most winemakers keep in mind that all three measures are adjustable in the winery. Most of the methods are perfectly legal.
The ultimate test of biological ripeness is the winemaker’s palate. Several consultants and wine writers report comments by winemakers that indicate the 2012 Pinot Noir crop yielded fruit with mature flavors and tannins, good acid:sugar balance, lively pH, and concentration. In general, veteran winemakers are reticent to hype the vintage this early, for fear that the news might cause serious wine collectors to put off that purchase of a few cases and wait for the new wines to be released. Further, experience teaches that what is apparent in the harvested fruit, may not successfully complete the transition into outstanding wine. Many rookie winemakers, alternatively and generally, are happy that anyone will listen to them.
The best procedure for determining the picking date is to plot the phenological data until they show the grapes are “in the ballpark” of ripeness. Then, it is time to go taste the grapes in the vineyard to finalize the harvest decision.
Even though some vineyards had to hustle to get the grapes picked before the sugar got too high, it was that kind of year. We experienced an almost total drought in July, August and September. Only 0.03 inches fell on July 19, and 0.01 inches on the following day. The vines had to perform their magic using water stored in the soil before July. That amount would be 7.2-12.0 inches of water for 3-5 feet of soil depth to bedrock. When the soil moisture was depleted, the vines began to pull water out of the grapes for photosynthesis and so the leaves could transpire for cooling.
The result was some shriveling, but it occurred over a long period of time, as compared with some past years when Oregon had 95+ temperatures for several days in September. When high temperatures drive up the sugars, high sugar occurs too quickly for full development of flavor constituents. When final ripening is permitted to happen over a longer period, at lower temperatures, real complexity and concentration of flavors follow.
What can we conclude?
The climate conditions of August, September and October will be what defines the 2012 vintage. Solar radiation was higher in all three months than 2008 and the 21-year average. Heat was greatest in both comparisons during August and September, before deteriorating slightly in October. These features are consistent with greater flavor concentration and complexity than in the 2008 vintage.
Tasting the grapes at a couple of vineyards also indicated a terrific vintage. The sugar was so high, at 23-24°Brix, it probably masked the other flavors to some degree. Nonetheless, the important flavors were detectable in sufficient amount to indicate a great vintage.
By chewing on some seeds, one can get an idea of the tannins that will be in the wine. In this year’s harvest, fine tannins were present (rather than the sharper gross tannins) in sufficient amount to give the wines backbone.
From this point on, the fate of the wines is in the hands of the winemaker. Will he/she successfully translate the potential into the finished product?
The color of the wines will be darker than usual. Pinot Noir should have ample pigments to make inky black wines. The Pinot Gris at harvest was the darkest I’ve seen, with a medium gray-purple color all over that is typically only on the south side of the grapes. No doubt, this characteristic has its origin in the string of 90+°F temperatures during August 13-18, at the beginning of veraison when the grapes change color. August 16 and 17 reached 99.3 and 100.1°F, respectively.