WEATHER: Better Warnings For Flash Floods

April 28, 2018

Wadi Flood by Pato12seg~commonswiki assumed (based on copyright claims) Own work assumed (based on copyright claims), CC BY-SA 3.0

 

 

I have never seen severe storms like the ones that hit the Jerusalem area this week. There were winds of 50 km/h (30 mph), hail greater than 1 cm in size, constant lightning/thunder, and about 20 mm of rain in only 10 minutes (or so).  

 

You might remember that in our last forecast we wrote that a sharav storm would move eastward and then up the coast, becoming absorbed in a winter-type trough dropping down from the north.  The results was a storm that brought floods on Wednesday and Thursday’s terrible tragedy in the south, as the storm stalled over our area, spinning counter-clockwise.

Because the storm was located over the land, it picked up huge amounts of dust, which was absorbed into its convective clouds. Dust has been shown to invigorate convective clouds, and one might be bold enough to say that Thursday proved the theory — and then some.

There should be a break early next week ahead of the next weather system: another sharav. It too should bring a warm-up before it arrives. This one is supposed to move inland and merge with a Red Sea Trough, which would bring more convective showers to the southern and central areas during the mid-week period.

 

Jerusalem forecast (click here for updated national forecasts):

Image credit: The Jerusalem Herald


The Education Ministry was quick to deny that they gave permission to the Bnei Zion Pre-Military Academy that sent its students on a ‘bonding trip’ hike to the Tzafit riverbed in the southern Dead Sea area. It should be pointed out that the Israel Water Authority and the Israel Meteorological Service had both issued advisories for flooding in many locations for that day.

 

Yet, I would argue that there is a disconnect between the issuing of advisories — which are done at fixed time intervals — and the public’s receipt of same. I believe this is because real-time warnings, i.e., just prior to the event, are not generally issued; and if they are they are not disseminated over cell-phones, for example.

 

This is for two reasons: these ministries don't have access to a real-time warning alert system/application and they don't have the broad view, such as can be obtained from our system, the Israel Total Lightning Network, part of the Earth Networks Total Lightning Network; this system does both these tasks.

 Screenshot Israel Total Lightning Network, courtesy Dr Barry Lynn

 

As an example, one can clearly see the imprint of the storm on the map showing high radar reflectivity and lightning within (cloud-to-ground and intra-cloud) in the screenshot from the Israel Total Lightning Network, taken during the severe storm that hit our area Thursday after 6 pm (1800 IDT).

 

This system is available to government ministries — they need only ask.  It would supplement very well the current efforts to improve forecasts and provide better warnings to the public. 

 

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.

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בס"ד

...הָרִימִי בַכֹּחַ קוֹלֵךְ מְבַשֶּׂרֶת יְרוּשָׁלִָם הָרִימִי אַל תִּירָאִי אִמְרִי לְעָרֵי יְהוּדָה הִנֵּה אֱלֹקֵיכֶם! (ישעיה  מ:ט)

...Raise your voice with strength, herald of Jerusalem; raise it, do not be afraid; say to the cities of Judah, "Here is your G-d!"

(Isaiah 40:9)

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