Weather It Is (Storm Update)

Good Morning:

There have been some small changes to the forecast.

Keep in mind that the severe winds combined with precipitation, including snow, should lower visibility, perhaps creating "white-out" conditions as the evening progresses.

However, because the lowest level cold air is moving in more from the west than north, the surface temperatures will be hard pressed to reach freezing. Snow will mostly melt in Jerusalem. The percentage chances for snow are based on our ensemble forecast.

Between 3 this afternoon and 5 this afternoon rain should arrive in Jerusalem and then mix with graupel (ice) and a bit of snow as the sky darkens.  Temperatures will drop by several degrees from about 8 or 9 degrees Celcius to about 2 or 3 degrees depending on elevation (750 m to 850 m, respectively).  Rain, graupel, and some snow should continue until about 8 P.M, when temperatures are forecast to turn colder. The chance of snow is 30%.  From 8 until 11 P.M, there are indications that a heavier downburst of precipitation combined with evaporative cooling of the surface layer will lead to the formation of an isothermal layer.  During this time, the mixture should become predominately snow and accumulate on colder surfaces (like cars and/or sidewalks).   However, if the snow briefly sticks it should quickly melt.  The chance of snow is 60%. The precipitation should taper to light rain (or a rain/snow mixture) towards midnight.

In Gush Etzion, temperatures should be a degree or two colder, and there is a greater likelihood that snow will accumulate.  The chance of snow between 5 PM and 8 PM, is 60 to 70%.  The chance of snow between 8 and 11 P.M is 100%.  However, the accumulation will be very elevation dependent; the forecast shows the snow melting in lower areas like Efrat, while accumulating in surrounding areas several centimeters.  Of course, half to 1 degree variation in temperatures will affect the accumulation, and this is within the range of model error.

Otherwise...

Gale force winds will become a "Severe Gale" late this evening and night, with winds exceeding 41 knots both along the central to southern coasts and inland to the central mountains (75 to 88 km/h). There is a chance that winds will exceed 48 knots, approaching 100 km/h (especially along the coastal areas and in the mountainous areas).

Our ensemble shows that the heaviest precipitation should fall in the central mountains, including Jerusalem from 17 IST until 23 IST, when temperatures in the lower, middle, and upper atmosphere should be at their coldest.  The heavy precipitation should be accompanied by frequent lightning and hail and smaller ice.

Be well, and stay safe.

Barry Lynn