By SHARON UDASIN
02/04/2014

Dry winter is caused by a phenomenon called “blocking,” in which most rain systems are “stuck” in Western Europe, expert says.

Although the northeastern US may have spent January pummeled by snowstorms and frigid temperatures, Israel last month was troublingly dry, experts from the Water Authority and Israel Meteorological Services said on Monday.

Throughout the month, Lake Kinneret’s water level only rose 11 cm., while that of the Dead Sea dropped eight cm., according to the Water Authority’s Hydrological Services.

Nationwide the country has received only about 64 percent of its average annual precipitation since the beginning of the rainy season, the Water Authority said.

In many areas – particularly in the Jerusalem region, the West Bank, the country’s center and its northern tip – January was the driest to date, the Israel Meteorological Services (IMS) said.

“The month of January ended aridly in an extreme manner,” a statement from the Water Authority said. “In some places it was the driest ever since Meteorological Services began taking measurements.”

Only about 25% of the average amount of rain for January fell over the Kinneret basin, with even smaller percentages falling in Western Galilee and the Yarkon and Taninim basins.

By February 1, Lake Kinneret reached only 211.28 m. below sea level, reflecting the “abnormal cessation in rains” that persisted from the middle of December through nearly all of January, the Water Authority said.

The available volume of water in Lake Kinneret in January amounted to about 18 million cu.m., significantly lower than the average volume for January, as well as for last January.

In the 88 years since Hydrological Services has been measuring the Kinneret’s available water volume, it was only this low in January of 2009, the authority said.

Following a decline of three cm. in December, the Dead Sea dropped an additional eight cm. in January, the data said. Since the beginning of the 2013-2014 hydrological year, the Dead Sea has dropped 33 cm., compared to 26 cm. in the same season last year.

The amounts of rain that fell in January represent “a negative record in the Center and parts of the North of the country,” the IMS said.

While for most stations the IMS has data accumulated over the past 70 years, there are some areas with more than 90 years of records.

This was the driest January for Jerusalem, for which the IMS has data ranging back to the mid-19th century.

Particularly uncharacteristic of the month was the complete lack of rainfall in the Jordan Valley and the Beit She’an Valley, the IMS said.

Such a condition, in which a northern or central monitoring station did not record any rain in January, previously occurred only in 1955, the organization added.

Although less than average amounts of precipitation fell over the coastal plain, the reservoirs along the plain did rise over the month of January – 12 cm. in the South, five cm. in the Center and eight cm. in the North – for the third year in a row, the Water Authority reported.

All in all, the northern coastal plain received between 15 and 40 mm. in January, compared to the annual average of approximately 130-160 mm. for this month, according to Israel Meteorological Services.

The central coastal plain and most of the south received between five and 15 mm., compared to the usual 120-150 mm.

The largest amounts of rainfall fell in the central Galilee, with about 35-55 mm. of precipitation wetting the region.

These quantities, however, represent less than 30% of the region’s January average, IMS data said.

Other parts of the Galilee and the Golan only received between 20 and 30 mm., in comparison to the usual 150-200 mm.

The minimal amount of rainfall over the Western Galilee and increased resource exploitation there contributed to sharp declines in the water level of the basins in the region, the Water Authority said.

The springs of the Western Galilee also featured sharp drops in their flow rates for the month of January.

The flow rates of the Dan and Banias springs also declined, due to the decreased amount of rain falling over Lake Kinneret, the Water Authority said.

In addition to the abnormally dry conditions that characterized January, temperatures were also higher than usual, reaching more than four degrees Celsius above the period’s average for the second half of January, according to the IMS.

Although this January may have been the driest for many areas of the country, it is too short of a period to speak of climate change trends, Amos Porat, director of the IMS Climate Department, told The Jerusalem Post on Monday.

This dry winter, he said, has been caused by a phenomenon called “blocking,” in which most of the rainfall systems were “stuck” in Western Europe, Porat said.

While Israel received fair and dry weather, countries like the United Kingdom and France experienced a lot of rainfall and stormy weather.

This has been the prevailing situation since the beginning of winter, aside from the two-week stormy period in mid-December, Porat added.

“After a dry January, February doesn’t look good either,” he said.

“We don’t see a significant weather system in the coming week. However, these systems might come later.”

http://www.jpost.com/National-News/January-driest-month-in-ages-for-many-regions-in-Israel-340267