Weather It Is (Winter Storm Update)

Good Afternoon:

The forecast remains as was previously stated for Har Harmon, the Golan, and coastal area  Warnings are repeated here.

Winter Storm Warning for the Hermon and Golan.

Winter Storm Warning for higher mountains outside of Sefad for 5 to 10 cm of snow/ice beginning Tuesday afternoon and lasting into Wednesday morning.

Gale Warning for coastal and mountain areas from Tuesday afternoon into Wednesday Morning.

Potential for flooding from Netanya to Haifa, and eastward toward Sefad, including the Jordan Valley on Tuesday and Tuesday night.

Jerusalem:  Rain mixing with ice pellets and wet snow towards midnight, but temperatures should remain above freezing. Little or no accumulation of snow expected.

Gush Etzion and Higher Elevations Around Jerusalem: Potential for 5 to 10 cm of ice and snow, depending on elevation. Rain, ice, and snow in the evening hours, changing to ice and wet snow towards mid-night (rain in the lowest elevations).  After a lessening of precipitation, the morning hours should see a period of ice and snow return to Gush Etzion.

The latest forecasts are in, and they leave much uncertain.  However, the upper level temperatures are forecast to be around -25 C, which are warmer than temperatures typically associated with snow in Jerusalem.  With warmer temperatures aloft, any cooling in lower levels must occur do to mechanical mixing or evaporative cooling, and there isn't enough forecast cooling to change the rain to an accumulating snow in Jerusalem.

However, at higher elevations, temperatures are cooler than in Jerusalem itself (about 1 degree Celsius for each 100 m).  Moreover, precipitation is forecast to be heavier south of Jerusalem towards morning, which should add to the potential for snow in Gush Etzion.

Forecasters would much prefer a "clear-cut" situation. The key is mixing from the 850 mb level. Such mixing is not forecast in high enough magnitude to bring snow to Jerusalem, while there is greater "hope" that there will be enough cold air seeping to the surface in Gush Etzion to bring a covering of snow.  On the other hand, 1 degree can make all the difference, and we won't know which way that one degree goes (up or down) until the morning.

I'd much rather be able to make this forecast in hindsight.

Barry Lynn