Weather It Is (7:23 AM Update: Certainty/Uncertainty)

Quick Update at 7:23 AM:

My favorite words: "Abba it's snowing."  It is snowing in Gush Etzion.

Temperatures have dropped to near freezing and will continue downwards during the day (provided the sun doesn't peak through the clouds).

The last snow event produced about 15 cm here in Efrat, although almost 65 ml of precipitation was measured.  That is, we converted less than a quarter of the precipitation amounts to actual snow that was measurable.  Much of the accumulating snow fell in thunderstorms (or as "thundersnow").

Today, the temperatures at 850 mb and 700 mb will trending downwards, and will be 1 or 2 C cooler than in the last storm.  Hence, we are likely to convert a higher percentage of precipitation totals into accumulating snowfall.  On the other hand, since this snow will be mostly produced from altostratus and nimbostratus clouds (rather than cumulonimbus) -- as the atmosphere is not as unstable and the moisture source is less than in the previous storm.  As the precipitation rates will be lower than in the last storm,  the snow may "find" it harder to stick (or accumulate).  It all depends on the precipitation rate and surface temperatures.  The rate should be less than with part 1 of this storm, but the temperatures should be cooler.  So, the potential is there, but not easy to predict whether it will be realised -- other than that the roads may become treacherously dangerous.

As the coldest air arrives this afternoon at 500 mb, there will be the possibility for enhanced snowfall rates.

Barry Lynn


Good Morning:

We're certain that temperatures will continue their inexorable fall downwards today.  We're certain that it is going to get very cold -- downright cold.

We know that generally the storm forming in this extremely cold influx of air has some moisture associated with it.  We see patches of light to moderate precipitation on the radar. We know that generally 5-10 cm might fall in Jerusalem, and we know that 10-15 cm might fall in the area of Gush Etzion. However, we are far from certain that the precipitation will fall heavily enough to accumulate or exactly when it will change to snow.

We can only speak about potential, and of course -- we all live our lives according to what we hope is our potential.

Because it will be getting colder, and we see that the coldest air will arrive by early afternoon aloft -- travel is not advised today in the higher elevations of Jerusalem and Gush Etzion.

Travel south is also not advised as there may be flooding of rivers and stream beds.

Shabbat will start to see a warm up, and rain, or possibly snow changing to rain is expected Saturday night into Sunday.

Otherwise, possibly rain mid-week, and then not much of winter (nor spring) is seen afterwards -- just a break in the inclement weather.

Shabbat Shalom,

Barry Lynn