Hopes for a cool, wet winter were all but dashed yesterday as weathermen forecasted a drier than average season.
The Israel Meteorological Service yesterday published its forecast for the main winter months - December through February - predicting precipitation to fall below the 30-year average.
Don't put away your galoshes yet, though. Based on statistical probability and an analysis of October's climate conditions, the forecast is only 65 percent accurate.
The IMS forecast is based on calculating rain amounts in the past 30 years at 21 stations around the country. The average amount of rain during these years was above 300 millimeters and this winter it is expected to fall below that.
"We use the term 'a little below average,' but it could be more than 20 percent below average," said Dr. Henia Berkovich, Director of the Israeli Meteorological Service.
World meteorological services have also released forecasts for the east of the Mediterranean Sea but have not provided a clear indication about the amounts of rain due to fall in the winter months.
A British weather service forecasts a relatively rainy season in our region, while an American one predicts a dry winter.
Berkovich said these forecasts' accuracy is high regarding tropical regions but seen as not very reliable in other regions.
The IMS was not party to the Water Authority forecasts of a very dry winter, based on other meteorological stations in the world, she said.
The IMS is expected to improve its forecasting abilities in the near future, following the cooperation agreement Transportation Minister Yisrael Katz signed in Britain last week with the European Center for Medium-Range Weather Forecasts.
The ECMWF's capabilities will enable high resolution forecasting of up to two weeks ahead. However, it cannot provide accurate forecasts for a period of several months, Berkovich said.
The amounts of rainfall in Israel have been lower than the perennial average in five of the past six years, resulting in an acute crisis in the country's water supply system. The latest data published by the Water Authority's Hydrological Service shows a 20 centimeters drop in the Kinneret last month.
Groundwater levels have descended even further. The water in the Western Mountain aquifer, the source of Israel's highest quality groundwater, has reached a record low and water in the central aquifer has receded to below the red line.
The water sources of the Taninim Stream, formerly a source of the aquifer's groundwater, have reached their lowest ebb ever.
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