Saaroni, Hadas (Department of Geography, Tel-Aviv University, Israel)
Ziv, Baruch (Department of Geophysics and Planetary Sciences, Tel-Aviv University, Israel)
Alpert, Pinhas (same affiliation)
Bitan, Arieh (Department of Geography, Tel-Aviv University, Israel)
Continental easterly windstorms have a major economical and environmental implications, such as agricultural damages, damages from strong winds, coastal floods, air pollution potential, foest fires and dust stroms, for Israel and the levant region. Continental windstorms are common around the Mediterranean coasts. Along the northern coasts the winds are generally cold, like the bora or the mistral, and along the southern coasts they are generally warm, like the ghibli or the sirocco. At the eastern Mediterranean basin and in the Levant region, these storms are intermittently warm and cold during the same season and often even the same event.
Quasi-stationary systems as well as moving disturbances cause such windstorms. For this reason, the resulting weather conditions may be extremely variable, depending on the characteristics of the advected air mass and may appera as an advected frost on the one hand and severe heat waves on the other hand. Specific regions in Israel that are sensitive to easterly storms, such as the westerly slopes of the mountains and valleys with west-east orientation, are influenced by these windstorms for about 10% of the year. However, widspread storms that cover the entire region occur only about 1.8% of the year. These windstorms are, therefore, classified in the present study according to their climatological and synoptic characteristics. The dominant synoptic situation found in the Red-Sea trough, with associated warm advections. These storms appear only between October-May and are most frequent during the cold season. The diurnal course is characterized by a strengthening in the morning hours, and weakening during noon to afternoon hours, because of the opposing effect of the westerly sea breeze, which suppresses the easterly winds. Nevertheless, synoptic conditions may contribute to this tendency as well. A significant increase in the frequency of easterly storms occuring at a distance from the seashore has been identified. Preliminary and accurate forecasting of the occurrences of these storms and their spatial distribution is a most important tool for defense against them.