Weather It Is (Winter Storm Warning)

Good Afternoon:

The latest winter storm has arrived.  It has the potential to be more severe than the last one because precipitation amounts are about two to three times more than the event of January 8-10th.  However, temperatures are a bit warmer, so expect mostly wet snow accumulations (except on the Hermon) at the higher elevations.

Here are the highlights.

1) Extremely strong winds.
a) Northern Coast: 60 km/h today with higher gusts through Wednesday.
b) Central and Southern Coasts: 50 to 60 km/h today and 60 km/h winds Wednesday with higher guests.
c) Inland areas: 50 km/h with higher gusts today and Wednesday.

2) Rain Amounts.
a) Northern Coast and north: Rain begins tonight 100 to 200 mm by 00 UTC 13 February.
b) Central Coast: Rain begins Wednesday mid-day and accumulates 50 to 100 mm by 00 UTC 13 February.
c) Inland areas: areas inland of central and northern coastal areas: 100 to 200 ml by 00 UTC 13 February.

3) Expect city and flooding in Jordan Valley.

4) Snow in the north (based on our 4 km 36 to 72 hour forecast).
a) On the Hermon snow begins around mid-night and accumulates at a rate of 4 to 8 cm/h for about 24 hours (until afternoon Wednesday).
b) Golan: snow begins around mid-night and accumulates at a rate of 2 to 4 cm/h.
c) Sefad and surroundings: snow begins late night and accumulates at a rate of 1 to 4 cm/h, depending strongly on elevation.  Late Wednesday, snow may accumulate even in Sefad at about 3 or 4 cm/h.

Total snow accumulations:
i) Hermon: 1 to 2 meters.
ii) Golan 50 cm to 100 cm.
iii) Sefad: 10 to 25 cm, with higher altitude areas of 50 cm or more.

(these numbers may update as we get within range of our 1.3 km forecast).

5) Dust: Dust storms throughout the country through tonight, confined to south of the advancing front on Wednesday (to remain south of Jerusalem).

6) Lightning: expect frequent lightning with the advancing front tonight in the north, spreading to the center on Wednesday afternoon.

7) Jerusalem:

Jerusalem is forecast to be on the southern edge of this storm. For instance, Beit-El is predicted to get 10 to 25 cm of snow with 80 mm of precipitation total. Jerusalem is predicted to get 30 mm of precipitation with no snow accumulation.  Depending on the exact path of the 500 mb trough, the heavy precipitation line could change, so this will have to be watched. Otherwise, expect 5 to 10 cm of snow in the higher areas around Jerusalem, including Gush Etzion --  Wednesday Evening and night. Again, these amounts could be subject to change depending on the storm track.

Another reinforcing shot of cold air should arrive Thursday night, Friday morning, which could bring another period of wet snow.  Rain or rain/wet snow is possible on Shabbat.

8) Potential for divergent results:

Wednesday and Wednesday night:  The surface and 850 mb temperatures are marginal for snow accumulation: hence, snow accumulations will be very highly dependent on elevation.  Also, 500 mb temperatures, while quite cold, still have a 3 degree Celsius range within the GFS ensemble Wednesday night.  Colder temperatures will bring heavier precipitation and higher snow accumulations. Also, a slight shift in storm track could raise or lower snow amounts quite substantially in the Jerusalem area.

Friday morning: temperatures are again marginal for snow in many areas.  Small differences could make a big difference in snow amounts, and the GFS ensemble does show a 1 to 2 C range of temperatures at 850, 700 mb, and 500 mb.

Rain amounts and wind: Very confident.


Barry Lynn