Kerria Week

More data on the unusually rapid unfolding of spring in 2009: a German news agency report on 2009-04-23 (midway through week 2009/17) recalls how a sudden upward surge of temperatures back in Week 15 put a lot of blossoming into "fast forward" this year, meaning plants that are normally successive are blooming at the same time, with Malus and Syringa coming into bloom before the blossoms are off the early Prunus varieties including P. armeniaca. Some regions even report Taraxacum in full flower in Week 17, though I have yet to see this on my travels. The overdrive is "very, very unusual," said Gerhard Lux of the state-funded DWD German Weather Service at its office in Offenbach near Frankfurt. The development has surprised phenologists. In Week 14, the progress of spring in Germany had been about two weeks behind average but now spring's progress is ahead of average. With one week of April still to go, the average April temperature so far in Germany has been 4 degrees Celsius above the mean for the period 1961-1990, DWD data showed. That explains why apple trees have been coming into bloom before the early cherry blossoms have fallen. In the Rheingau, the wine-growing region west of Frankfurt on the bank of the Rhine, the difference from the mean has been 5 degrees. Rheingau Malus trees normally blossom 75 days after the flowers of Corylus appear, but this year the delay has been only 50 days, a DWD farm-weather expert said. (I have no data for Hamburg, but would estimate the discrepancy here as far less, since Corylus was not notably delayed in the north, and we are now only about half a week ahead of other years.) A DWD climatologist explained that the overdrive period began with an upsurge in temperatures in Week 15. A week later, many parts of Germany were experiencing daytime highs of 25 degrees, which is summer warmth in German terms, and the weather has stayed warm in Week 17 too. In addition there has been two thirds less rain than usual in April, DWD averages show. The drought has been pronounced in the north and east of the country, though Hamburg escaped the drought on April 22, with a good soaking greening up its gardens.