Illustration (Image Credit: Wix)
I really have to apologize to my wife. On Monday morning, she wore sandals, but by mid-day it was pouring rain. Her wet feet (and by extension, her) were not very happy.
I was actually away on a personal visit to New York so I wasn't yet awake to warn her that she was making a mistake by dressing for summer instead of late winter. The warning would have been provided by the Israeli Total Lightning Network, which showed relatively high intensity lightning values as a strong front moved southeastward to just off the coast. Such strong values indicate the near-possibility of severe storms.
However, I am not sure that she would have even listened to me, as the sky in Efrat certainly did not look like there would be severe lightning, hail storms, and strong winds later that morning and afternoon. Okay, that's not exactly true — she generally does not believe my forecasts and no matter how many times she gets wet (or not), I can't seem to change her mind about this.
Yet, there is one person who generally usually listens to me. She sits, and comes when called. She is also usually quite happy to see me — and unlike my kids quite expressive about it. In fact, she couldn't stop barking when I returned, jumping up and down, as well as going around and around.
Well, now that I am back I will make a better effort to my readers and my wife to convince them that I am a trustworthy source of weather information. Perhaps, I will even earn some respect.
This is especially important because we're in for some topsy-turvy weather this week as a sharav low moves across the southern Mediterranean. Like our last sharav in late April, it should bring some hot weather on Thursday and Friday and maybe some scattered thundershowers. It should then be followed by a storm dropping down from the north. However, unlike last time, we don't see that the storms should merge which would make the occurrence of flooding rains more likely.
Instead, there should be a series of weak storms that will bring showers to the northern Negev and center of the country from early to mid-next week, and heavier rain up north — as well as cool temperatures.
People have been mentioning that they don't remember a previous May with so many storms. I think that they are correct. However, the North Atlantic Oscillation (NAO) has been in — and is forecast to be in — a strong positive phase, which "helps" to build a trough (colder, more stormy weather) in the eastern Mediterranean. Also, the last several decades have seen changes in the circumpolar westerly jet (or polar vortex) which allows colder, more artic-like air to move southward more often than in the past.
Together, these changes may explain our wet and stormy spring, especially combined with elevated values of desert dust. Another interesting possibility is a late development of the beginnings of the Indian Monsoon, which causes middle and upper air temperatures to warm, suppressing cloud formation through the summer months.
It's all a bit of a mystery, and a topic worthy of further research.
Jerusalem forecast (click here for updated national forecasts):
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.