Saturday, February 20, 2016

Weather It Is (Severe Flooding Possible)

Good Evening:

Another winter rain storm is upon us -- with some snow possible on the Hermon.

A very warm layer in the middle atmosphere (at 700 mb -- reminiscent of the summertime inversion) will be replaced by winter cold and plenty of moisture.  In addition, temperatures will be dropping off at both 500 mb and 850 mb to help support cooling and convective thunderstorms.

Showers will develop tomorrow and heavy rain as well by evening.  We're expecting 10 to 25 mm in the north and  25 to 50 mm of rain generally from the central-north to the south by Monday afternoon.  This will lead to flooding in the Jordanian and Dead Sea Valleys.

In addition,  a moist streamer of air is forecast to impact the area south of Askelon southeastward to between Beer-Sheva and Mitzpe Ramon.  Forecast rain amounts should be between 50 to 100 mb, which will cause severe flooding.  Heavy rains extending to the mountains east of route 90 and southward into the Arava will also cause flooding in these areas.

Strong winds are expected Sunday afternoon and evening, with the possibility of gale-force winds with higher gusts.

The forecasting of these "streamers" of moisture is not a straightforward matter, although our last forecast of heavy rain from a streamer during the last real cold spell was right on the money.

Showers may persist until Tuesday, but the week should end on a warm note.

Beyond the end of the week, there is a 60% chance temperatures will continue their upward climb.

No major storms are definitely seen at this time, but the chance persists for winter to return.

Barry Lynn
P.S. For those who still hope for a late season snowfall: I was told that three of the last four March snow storms occurred before the 1900s, with only one March storm since then in 1980.

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