WEATHER: Monsoon Delay Brings Desert Flood... And Heat!
Illustration (Image Credit: Wix)
Sixty four millimeters of rain last Wednesday morning in the western Negev! And, as if they needed another "natural" disaster, the city of Sederot was severely flooded, with cars floating through the streets. The picture to the right shows a radar facsimile derived from our lightning network Wednesday morning. This storm lingered for almost an hour in nearly the same location! There was also a quick, but heavy rain in Jerusalem Wednesday that caused a quick ponding of water on roads or what we might call old-fashioned puddles.
So, what's going on? By this time of year the weather in the eastern Mediterranean is usually under the influence of the Indian monsoon. Winds circulating around the monsoon warm the air in the middle atmosphere, which prevents clouds from growing high enough to bring summer rains. However, this year there is an area of lower pressure in western Siberia, which appears to be preventing the Monsoon from reaching here. Moreover, the monsoon itself seems to have had a delayed strengthening. The lack of the monsoon air combined with weak storms arriving from southern Europe means that the air remains unstable to cloud formation, while the relatively warm Mediterranean sea provides plenty of moisture to these growing storms. The Times of Israel notes that the last time it rained so much in the Negev was 26 years ago, when there was 50 millimeters. This would have been 1992, which I believe followed a severe winter of 1991-92. Looking ahead at our forecast, there appears to be a quick warm-up in time for Shabbat as high pressure builds eastward from Africa. Yet, the forecast shows relatively cool temperatures prior to and to following the warm-up. Amazingly enough, there may be more rain in about a week's time as another storm moves by, possibly just to our north. Will the rainy weather continue even beyond next week? The note on the Indian monsoon doesn't forecast appreciable strengthening in the monsoon for at least a couple of weeks. Regardless, I tend to lean towards something more going on than just changes to the Indian monsoon. I remember years when it rained (once) somewhere in the country during the month of May, and even August, but this year we've had consistent periods where rain has affected more than just a single localized area. One positive outcome of all this strange weather is that the weatherman (or woman) has remained immensely popular — at a time when most people are usually at the beach sipping watermelon juice or just staying home complaining about the heat. I can't go anywhere without people stopping me to comment on the weather. I've even been solicited for TV (internet) interviews. All I can say is that it's fortunate that I've been extra busy — and even my kids are taking an extra moment to speak with me and wonder "What's going on with our weather!?"
Image credit: The Jerusalem Herald
Dr. Lynn is a lecturer at The Hebrew University of Jerusalem, Earth Sciences Department. He is also CEO of Weather It Is, LTD, a company that specializes in reducing weather risk.
