73 replies to this topic

[wxmx]

Ridingtime, on 14 February 2012 - 09:58 AM, said:

Just curious how you are seeing this? I have only been looking at the GFS and from what I am seeing, it is showing a strong low pressure system that initially brings rain to Jerusalem, and then it passes north over Israel bringing in a cold front while precipitation continues to fall eventually changing to snow.

Maybe you are seeing the Euro and it is showing something different? Or am I missing something on the GFS?

Here is what I am seeing that seems to indicate snow to me:

Surface temps are in the upper 30s when coldest...850s temps are just -1C or so.

[donsutherland1]

Ridingtime, on 14 February 2012 - 09:58 AM, said:

Just curious how you are seeing this? I have only been looking at the GFS and from what I am seeing, it is showing a strong low pressure system that initially brings rain to Jerusalem, and then it passes north over Israel bringing in a cold front while precipitation continues to fall eventually changing to snow.

Maybe you are seeing the Euro and it is showing something different? Or am I missing something on the GFS?

The forecast soundings show too much warm air at 925 mb-950 mb. Surface readings are mainly in the upper 30s or lower 40s (GFS and ECWMF).

[Ridingtime]

donsutherland1, on 14 February 2012 - 10:29 AM, said:

The forecast soundings show too much warm air at 925 mb-950 mb. Surface readings are mainly in the upper 30s or lower 40s (GFS and ECWMF).

Gotcha, I need to find the surface temp maps. This even applies with Jerusalem's elevation eh?

[donsutherland1]

Ridingtime, on 14 February 2012 - 11:09 AM, said:

This even applies with Jerusalem's elevation eh?

Right now, it applies to most or all of Jerusalem. I don't know the highest spot, but suspect that it isn't high enough. The 12z Euro might even be a bit warmer than the 0z run. Fortunately, there's still time for things to change and I hope they do.

[Ridingtime]

donsutherland1, on 14 February 2012 - 01:30 PM, said:

Right now, it applies to most or all of Jerusalem. I don't know the highest spot, but suspect that it isn't high enough. The 12z Euro might even be a bit warmer than the 0z run. Fortunately, there's still time for things to change and I hope they do.

I see. Hoping things change too. I kind of feel this is our last chance this winter, which so far has been snowless (as well as the past 3 winters here).

Mind pointing me to a link where I can evaluate model surface temps?

[wxmx]

Ridingtime, on 14 February 2012 - 02:05 PM, said:

I see. Hoping things change too. I kind of feel this is our last chance this winter, which so far has been snowless (as well as the past 3 winters here).

Mind pointing me to a link where I can evaluate model surface temps?

For the GFS
http://wxweb.meteost...shtml?text=lljr

For the Euro
http://wunderground.com/wundermap

[jconsor]

The topography of central Israel is too complex for operational models to handle surface temps well. The ECMWF is better than the GFS, however, due to its superior resolution.

Also, note that because Jerusalem's elevation is around 800 m, it is normally around the 925 mb level in winter storms, so temperatures below that level are not relevant. In this particular storm, because pressures will be low initially, Jerusalem will be around the 910-915 mb level for the first half of the storm and close to 900 mb for the second half.

Also, the GFS model has such a coarse resolution that it "thinks" Jerusalem is at a much lower elevation than it is. The elevation increases from sea level to over 800 m in about 35 miles from the coast to the central mountains of Israel.

Having researched past winter storms in Israel and spoken to those who are experts, the most important factors are the 850, 700 and 500 mb temps. Generally in order to get accumulating snow:

850 mb temps: below -1C, and ideally below -2C
700 mb temps: below -10C
500 mb temps: below -25C

Current GFS forecasts indicate 850 mb temps around -1.5C for Sat and early Sun, 700 mb temps around -11.5 to -12C the entire storm, and 500 mb temps of -24 to -25C for Sat, but rising to around -21 to -22C by Sun morning. The 500 mb temps are borderline, but the other indicators are good for snowfall.

The other factor to consider is that the GFS doesn't have the sounding completely saturated at low levels during the time when temps are cold enough for possible snow - Sat into early Sun. It has 900 mb RH around 75 to 85% during that time, implying that temps could drop significantly via evaporational cooling if heavier precip occurs.

donsutherland1, on 14 February 2012 - 10:29 AM, said:

The forecast soundings show too much warm air at 925 mb-950 mb. Surface readings are mainly in the upper 30s or lower 40s (GFS and ECWMF).

[Ridingtime]

jconsor, on 15 February 2012 - 03:19 AM, said:

The topography of central Israel is too complex for operational models to handle surface temps well. The ECMWF is better than the GFS, however, due to its superior resolution.

Also, note that because Jerusalem's elevation is around 800 m, it is normally around the 925 mb level in winter storms, so temperatures below that level are not relevant. In this particular storm, because pressures will be low initially, Jerusalem will be around the 910-915 mb level for the first half of the storm and close to 900 mb for the second half.

Also, the GFS model has such a coarse resolution that it "thinks" Jerusalem is at a much lower elevation than it is. The elevation increases from sea level to over 800 m in about 35 miles from the coast to the central mountains of Israel.

Having researched past winter storms in Israel and spoken to those who are experts, the most important factors are the 850, 700 and 500 mb temps. Generally in order to get accumulating snow:

850 mb temps: below -1C, and ideally below -2C
700 mb temps: below -10C
500 mb temps: below -25C

Current GFS forecasts indicate 850 mb temps around -1.5C for Sat and early Sun, 700 mb temps around -11.5 to -12C the entire storm, and 500 mb temps of -24 to -25C for Sat, but rising to around -21 to -22C by Sun morning. The 500 mb temps are borderline, but the other indicators are good for snowfall.

The other factor to consider is that the GFS doesn't have the sounding completely saturated at low levels during the time when temps are cold enough for possible snow - Sat into early Sun. It has 900 mb RH around 75 to 85% during that time, implying that temps could drop significantly via evaporational cooling if heavier precip occurs.

Awesome, thanks for this post. Very educational, and good data for helping me understand tracking weather here in Jerusalem. I guess we can then certainly call this a good threat for snow. Obviously things can change, but I have a little more hope now I'll be seeing snowflakes on Shabbos

[Sock Puppet]

Hey Riding, have you checked this site out? http://www.02ws.com/...ion.php?&lang=0

[yl715]

jconsor, on 15 February 2012 - 03:19 AM, said:

The topography of central Israel is too complex for operational models to handle surface temps well. The ECMWF is better than the GFS, however, due to its superior resolution.

Also, note that because Jerusalem's elevation is around 800 m, it is normally around the 925 mb level in winter storms, so temperatures below that level are not relevant. In this particular storm, because pressures will be low initially, Jerusalem will be around the 910-915 mb level for the first half of the storm and close to 900 mb for the second half.

Also, the GFS model has such a coarse resolution that it "thinks" Jerusalem is at a much lower elevation than it is. The elevation increases from sea level to over 800 m in about 35 miles from the coast to the central mountains of Israel.

Having researched past winter storms in Israel and spoken to those who are experts, the most important factors are the 850, 700 and 500 mb temps. Generally in order to get accumulating snow:

850 mb temps: below -1C, and ideally below -2C
700 mb temps: below -10C
500 mb temps: below -25C

Current GFS forecasts indicate 850 mb temps around -1.5C for Sat and early Sun, 700 mb temps around -11.5 to -12C the entire storm, and 500 mb temps of -24 to -25C for Sat, but rising to around -21 to -22C by Sun morning. The 500 mb temps are borderline, but the other indicators are good for snowfall.

The other factor to consider is that the GFS doesn't have the sounding completely saturated at low levels during the time when temps are cold enough for possible snow - Sat into early Sun. It has 900 mb RH around 75 to 85% during that time, implying that temps could drop significantly via evaporational cooling if heavier precip occurs.

Very interesting. I resided in the Gush Etzion region for a year or so in 2009. Some of the higher hilltops (Neve Daniel) recorded a decent amount of snowfall- some of the others (Alon Shvut, Elazar) recorded almost next to nothing. Topography and elevation are really tricky elements in the Judean Hills.

[Ridingtime]

Sock Puppet, on 16 February 2012 - 10:04 PM, said:

Hey Riding, have you checked this site out? http://www.02ws.com/...ion.php?&lang=0

Yah I check out that site everyday. Incidentally, the head moderator/meteorologist checked out on vacation or something before this upcoming potential snow fall. Bad timing if you ask me. But overall a decent site

[Ridingtime]

So this storm ended up being a bust, at least for snow in Jerusalem. What was upsetting was that it really was not just the temperatures that were the issue, but rather, the forecasted precipitation did not seem to really come or at least stay consistent.

The storm blew in Friday afternoon, and tons of rain fell accompanied by a lot of wind. The rain ceded Friday night and the temps started to drop. Saturday was when more precipitation was expected to come which was supposed to be snow. But it ended up just getting sunny a lot of the morning with passing showers of rain mixed with sleet. In the afternoon more spotty icy showers came, but essentially that was it before everything turned back to rain at night. Since then it has been raining pretty hard off and on.

I think in a sense, the GFS forecasted surface temps were correct. It never felt cold enough for there to be a consistent snow on Saturday. But the GFS, and I am assuming the Euro also, was wrong with how much precip was supposed to fall. During the coldest temps on Saturday, not that much really fell, in spite of the forecast showing precip all day.

The Israeli forecasters here were also taken for a surprise it seems. The entire city of Jerusalem prepped itself for some snow, getting their small number of salt trucks ready. It was making it in the news too, and most of the city was expecting there to be a snowy Saturday.

So from all this I have learned that:
1) Forecasting weather here is really tricky. The elevation factor probably contributes to that.
2) It is probable that the current weather models don't receive a lot of data to accurately forecast the weather here that well. I am assuming this is the case because most of the times, the weather here is pretty mundane, especially over the summer. I can't imagine that the amount of data collected here for the weather models is the same "quality" as the data collected for places like the East Coast US, for example, where weather is much more of an issue.
3) This whole city loves snow, and people hype it up at any possible chance it will come, including some of the weatherman here.

[Ed Lizard]

^^ About the bust. On the internet, Ha'aretz:

Quote

The Golan Heights, Mount Meron and Safed were covered in white this weekend as Israelis flocked to the northern part of the country to witness the heavy snowfall. But snow was generally a no-show in rainy Jerusalem, where white flakes failed to accumulate despite predictions of a winter wonderland in the capital.

http://www.haaretz.c...parade-1.413397

[Nic]

I had no idea Israel got snow, I though it was a dry desert.

[Ridingtime]

Nic, on 19 February 2012 - 07:32 PM, said:

I had no idea Israel got snow, I though it was a dry desert.

Israel actually seems to have every climate type available. You do indeed have desert in the south on the Negev. But then go north to the Judean hills and you have an alternation of rainy and dry seasons, the land is a bit more green. Go even further north to the Golan mountains and you have typical mountainous terrain, with snow during the winter. Then finally, go to the west and you have coastal climates with all the cities along the medeterranian. It's quite a fascinating small piece of land climate-wise.

[yl715]

18z GFS showing quite a storm a week or so out.

[Ridingtime]

yl715, on 23 February 2012 - 08:13 PM, said:

18z GFS showing quite a storm a week or so out.

Yah wow, I just gave up on this winter and then saw your post. Crazy!

The 00Z is not as juiced up and cold it appears as the 18Z was but there's still something there and definitely now something to track until then.

It seems as if the cold is coming thanks to a massive ridge out east over Europe which sends a trough west down into Israel/Middle east territory. Is there a block causing this? Either way I hope that means the cold is coming directly north to south from Russia as opposed to having to pass over the Medeterranian which I think was the problem with this last storm. Also there maybe surface temp issues again, although I noticed the 500 mb and above temps are definitely cold enough, which could bode fine for Jerusalem.

[Ridingtime]

Storm this coming Wed-Thurs is looking less juicy and cold on the GFS. Anyone mind telling me what the Euro says or giving me a link to where I can see it? Thanks

[wxmx]

Ridingtime, on 25 February 2012 - 03:44 PM, said:

Storm this coming Wed-Thurs is looking less juicy and cold on the GFS. Anyone mind telling me what the Euro says or giving me a link to where I can see it? Thanks

http://www.wunderground.com/wundermap/

Similar to GFS, nothing for most of Israel, other than rain...maybe only the Golan Heights. But GFS and Euro agree about feet of snow for parts of inland Lebanon.

[Arctic_Blast]

Ridingtime, on 25 February 2012 - 03:44 PM, said:

Storm this coming Wed-Thurs is looking less juicy and cold on the GFS. Anyone mind telling me what the Euro says or giving me a link to where I can see it? Thanks

[Ridingtime]

I am reading reports that the Euro is looking better for snow. Anyone mind confirming?

[Ridingtime]

Looks like snow is still a decent possibility here in Jerusalem. First round tomorrow night and then a bigger round on Friday morning and afternoon. The media here is hyping it up too. Hope it does not end up like the last bust two weeks ago. Will keep this updated.

[donsutherland1]

Ridingtime, on 28 February 2012 - 04:28 PM, said:

Looks like snow is still a decent possibility here in Jerusalem. First round tomorrow night and then a bigger round on Friday morning and afternoon. The media here is hyping it up too. Hope it does not end up like the last bust two weeks ago. Will keep this updated.

Good luck with the storm. Hopefully, Jerusalem will pick up a decent snowfall.

[Sock Puppet]

Please take pics. Jerusalem in snow is simply magical

Ridingtime, on 28 February 2012 - 04:28 PM, said:

Looks like snow is still a decent possibility here in Jerusalem. First round tomorrow night and then a bigger round on Friday morning and afternoon. The media here is hyping it up too. Hope it does not end up like the last bust two weeks ago. Will keep this updated.

[Ridingtime]

So far, Jerusalem has just received tons of rain with sleet mixed in off and on, especially yesterday and yesterday night. This is the most rain I have seen from a storm while living here.

The snow is expected to come mainly tomorrow. My main concern is not the temps, as all models are forecasting enough cold now, but the precipitation. The latest GFS run showed a bit less precip than the previous one, that result in maybe 1-2 inches of snow. However, most of the Israeli forecasters here are forecasting 5-8 cm which translates into 2-3 inches. Enough to probably put this city into some havoc, simply because Israeli's supposedly don't know what to do with themselves when snow hits the roads. We'll see if it pans out. I am trying to not expect much cause I'd prefer to be surprised than disappointed. I'll do my best to take some pics if the white stuff falls!

[Sock Puppet]

You'll most likely get more than NYC has gotten all winter, lol. How much rain has already fallen?

Ridingtime, on 1 March 2012 - 09:54 AM, said:

So far, Jerusalem has just received tons of rain with sleet mixed in off and on, especially yesterday and yesterday night. This is the most rain I have seen from a storm while living here.

The snow is expected to come mainly tomorrow. My main concern is not the temps, as all models are forecasting enough cold now, but the precipitation. The latest GFS run showed a bit less precip than the previous one, that result in maybe 1-2 inches of snow. However, most of the Israeli forecasters here are forecasting 5-8 cm which translates into 2-3 inches. Enough to probably put this city into some havoc, simply because Israeli's supposedly don't know what to do with themselves when snow hits the roads. We'll see if it pans out. I am trying to not expect much cause I'd prefer to be surprised than disappointed. I'll do my best to take some pics if the white stuff falls!

[wxmx]

Not sure, looks like it wont stick because the boundary layer is warmish...it will be above freezing across most of Jerusalem. Maybe Friday morning will be the best chance to see pure snow and not a mix.

[Ridingtime]

wxmx, on 1 March 2012 - 02:52 PM, said:

Not sure, looks like it wont stick because the boundary layer is warmish...it will be above freezing across most of Jerusalem. Maybe Friday morning will be the best chance to see pure snow and not a mix.

I actually do think the models inaccurately predict surface layers here in Jerusalem for the reasons Jconsor mentioned in his post above. I also think this because unless it really is just all hype, most of the forecasters here are saying there will be accumulation and I trust their experience and expertise more than what the models are spitting out. But we'll see, I would not be too surprised if nothing sticks.

[Sock Puppet]

I was just told it's snowing in Jerusalem. Can you confirm?

[Sock Puppet]

http://english.theko...org/cameras.asp

Can't really tell if it's snowing but reports from all over the country that it is.

[Ridingtime]

Sock Puppet, on 2 March 2012 - 12:21 AM, said:

http://english.theko...org/cameras.asp

Can't really tell if it's snowing but reports from all over the country that it is.

Yup!!! I can confirm. I just woke up to it. At least 2 inches on my porch. Accumulating everywhere including the streets. It's absolutely stunning. Taking pics and will keep y'all posted

[Ridingtime]

The snow comes in waves. When I woke up there was a good 2 hours of heavy snow, and then the sun suddenly came out and melted everything. Now 2 hours after that, another wave of snow hit. I wish it could be consistent but it is definitely better than nothing.

[Ridingtime]

This second wave is also more of a mix rain and snow. Temps are definitely struggling to stay at freezing.

[Ridingtime]

So things actually look pretty done here. That second wave really didn't produce much and the sun is coming out yet again, warming the surface here too much for anything to stick if something does fall later.

It was a great early morning watching it snow quite heavy, and I'll post some pics and videos soon of that. I have some great shots of snow falling across the whole city from the top of my apartment roof.

But it was very short-lived overall, and I think yet again, the Israeli forecasters hyped this way more than they should have. The GFS and the Euro too I think consistently showed the precip dwindling after each updated model run before today. The precip on each model run looked very spotty too. But for some reason, the forecasters here predicted there would be a prolonged snow fall starting at 6 am till the night with 2-3 inch accumulations. That definitely did not come close to happening here in Jerusalem. There was indeed good initial accumulation in the morning, but after the snow ended, it quickly melted.

So lessons learned (some yet again):
-Snow here is very hyped by everyone, including most of the forecasters.
-It is challenging to get a good consistent snowfall in Jerusalem, but simply fantastic and magical when it does occur, for however long.
-Elevation helps a lot - supposedly places 800 m above sea level received around a foot of snow from Wed and Thurs. Jerusalem is 755 m above sea level.

Pics and vids to come soon!

[Ridingtime]

Here's a nice vid from the roof of my apartment building. It is much cooler seeing snow fall around a mountain range than from a place like the blocks of NYC for an example