Weather It Is (Snow/Extreme Cold + Summary)

Good Afternoon:

We all hope that the little things we do can make a difference -- little storms may think similarly.

The after effects of our powerhouse of a storm linger today, and there has been intermittent snow (in the higher elevations) and rain across the country. 

Yet, tonight and tomorrow's storm -- while of relatively small scope and impact -- may have profound affects on the central Jerusalem region (somewhat spared by the mega-storm). 

The weather will change tonight and it will bring remembrances of the "The Day After Tomorrow." In the movie: "The superstorm sucks vast quantities of frigid upper atmospheric air down to the surface, flash freezing any living thing caught outside" (http://www.wunderground.com/resources/education/thedayafter.asp).  

While not physically plausible the change in our weather to sub-freezing temperatures will feel extreme in the least. In fact, this is the first time I have seen the Global Forecast Systems (GFS) model (of relatively coarse resolution) produce below freezing temperatures in Efrat (by Saturday morning). 

While we know it is going to get cold, the wrinkle in the forecast is the precipitation amounts and the changeover to snow from Jerusalem Southwards. The moisture field with this storm is suppose to be from about the mountains of northern Jerusalem southward, while the GFS indicates that the heaviest precipitation amounts will be just south of Jerusalem.  

The temperatures at 850 mb should be about freezing early this evening and then drop to minus six! by tomorrow evening. The temperatures at 700 mb should drop from about -10 to -16 C during the same period.  The 500 mb temperatures will fall below -25 C by midnight tonight (Thursday).  With the cold temperatures and moisture field, we expect a change over to all snow (certainly by morning) and then it is on to the deep freeze. 

In terms of snow amounts, we should expect less to the north and more to the south. One might estimate 5 cm in Jerusalem, 10 or 15 cm in Gush Etzion and on the higher mountain ridges in the south. It all depends on the this relatively small scale storm and its moisture field translates into a precipitation pattern that affects real people. 

Other weather highlights: flooding in the Arava is a strong possibility. 

The storm predicted for Saturday night/Sunday is not well resolved yet by the forecast models.

I can infer that our snow predictions were quite good in the city of Sefad, the Galilee peaks, and the Golan (where 25-50 cm or more fell).

In Jerusalem, the failure of the models to correctly predict the late onset of the precipitation made a big difference in snow amounts: Jerusalem had 5 cm while out here in Gush Etzion there was 15 cm (about a third of what was predicted, but travel came to a stand still nevertheless).  Ironically, the forecasts prediction of light snow ahead of the big-push of moisture (delayed, of course) was quite good and made for a feeling that this was going to be a good forecast day.

Barry Lynn

Yedioth Ahronoth says that Jerusalem was disappointed by its few centimeters of snow, compared to the northern city of Safed, whose veteran residents said they don’t recall a snowfall like Wednesday’s (the city got 68 millimeters of precipitation).

Read more: The calm after the storm | The Times of Israel http://www.timesofisrael.com/the-calm-after-the-storm/#ixzz3OEuZzJq8
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