Thursday, January 12, 2017

Weather It Is (Nice Weather)

Good Evening:

A ridge of high pressure is building over the eastern Mediterranean.

Contrast our beautiful weather with that in England (which some here would like,
and some like the gentlemen in front of me would not), where an arctic blast/trough
has barreled through with thunder snow.

http://www.telegraph.co.uk/news/2017/01/12/severe-snow-weather-warnings-across-uk-will-reach-london/

After a rainy, chilly December, it looks like January should be pretty much "bone-dry" and relatively mild.  This is because the ridge of high pressure looks to be a somewhat persistent feature for the next week or so.

Contrast this with the near misses we had when it came to possible big snows the past few weeks. However,  the storm track was just to our north, and that was enough to leave us out of the real cold and snowy weather.

So, if you like mild, sunny, Jerusalem winter weather, you should be happy for the next couple of weeks (with the exception of Sunday when it might shower).

As for February: nothing yet to report (but its 28 days should be enough to give us another chance or two for winter).

Barry Lynn

Sunday, January 8, 2017

Weather It Is (Winter Cold, Stormy Weather)

Good Afternoon:

A very strong storm is approaching from the northwest and it will bring the coldest weather of the year.  In fact, tomorrow morning should be the coldest weather of the year so far.

However, the storm will swing around back to the north, thus limiting the precipitation to the coastal and northern areas, where 25 to 50 mm should fall just to the north of Tel-Aviv and perhaps > 50 mm along the northern coast.  Snow in the Hermon will continue to add to their snowy winter totals.

The storm will bring strong, if not gale-force winds into Monday, and dust will be prevalent -- especially in southern areas.

I noted in the NWS forecast for New York City yesterday that their winter storm took an unexpected jog to the northwest, blanketing most of southeastern NY with half a foot of snow (and especially Long Island and southeastern Connecticut with even heavier snow). The forecast models picked up on this the Friday afternoon before the snow on Saturday (Shabbat).

Might a "jog" to the southeast happen here.  It could, but it isn't likely.  If it does, though, it would bring wet snow to the higher elevations of the central mountains.

Looking further ahead: we still see lots of instability in the circulation pattern: heavier rain may fall generally across the country early next week, but this mid-week could first bring another bout of cold and showers.

Barry Lynn

Friday, January 6, 2017

Weather It Is (Very Cold, Dust, Some Precipitation)

Good Afternoon:

Highlights:

i) Much Colder

ii) Snow in the north, rain along the central and northern coasts.

iii) Lots of dust arriving until the storm brings cleansing rains Sunday night.

It may not feel much like winter today, but winter doesn't care.

Temperatures will fall tonight into Monday morning as a very strong storm approaches from the Northwest.

Right now, it appears that the heaviest precipitation will be from Tel-Aviv northward into the Hermon (where heavy snow will fall) from Sunday night into Monday.

The storm will bring strong to gale force winds.

The central mountainous area may get by with light precipitation as the storm is forecast to swing out just before causing a severe impact to the central areas.  Still, there may be a period of wet snow or snow Sunday night into Monday. If the storm swings away as forecast, though, it won't accumulate or make much of an impact.

Looking at the global forecast, we don't see much variability among forecasts so the likelihood that the storm will indeed move further south is not high.

The instability in the weather pattern should persist for the next couple of weeks.

For a more in depth look at the coming storm pattern, go here:

https://www.facebook.com/JerusalemWF/posts/1802855426634883

Wednesday, January 4, 2017

Weather It Is (Winter Storm Watch Cancelled)

Good Morning:

Last week both the European and American global forecast models suggested that a storm would arrive from the west, and then receive a reinforcing blast of cold air from the north.

A couple of days ago, the GEFS (American model) suggested that the storm arriving from the west would only give us a glancing blow, while the European model held on for a more snowy situation.

Now, both models forecast that the storm will miss us (to the north), bringing us only light rain along with chilly winter temperatures from the beginning to the middle of next week.

Temperatures will rise to mild winter levels from today to Friday, but will fall through Shabbat to quite chilly levels by Sunday morning, and remain there until Wednesday.

The GEFS is still showing the possibility of a period of snow within this period, but it might also just be light rain.

Until the forecasts from the ensemble converge, there isn't much more to add -- except that winds could be quite strong through the period, even gale force.

Barry Lynn

Monday, January 2, 2017

Weather It Is (Winter Storm Watch)

Good Evening:

Ynet is reporting that December was one of the coldest and wettest in many years.

http://www.ynetnews.com/articles/0,7340,L-4901825,00.html

This is good news.

We've been writing for the last few weeks about the waviness in the atmospheric circulation, and how changes to the very large scale from November to December provide an extra reason to "expect" snow this year.

The problem with expecting snow is that snowstorm happen in Israel once or twice a year even when global circulation patterns or not on average favorable, and sometimes not at all.  Folks report that the winter of 1991/92 actually brought an unusually high number of snow storms, but this was followed by a period of time in which the general knowledge was that it rarely snowed in Jerusalem.

Yet, anyone born since 2011 would have a different opinion, and remember snow in more years than less, and even snow twice a year in some.

Theoretically, if the global ensemble shows a snow storm 30% of the time (where time here is the period of one week), it should snow at least one of those times during a month.  Up to now, I have been wondering if the ensemble is a bit progressive (over-predicting the possibility of extreme cold/snow).  We've seen the possibility of snow appear on the week plus forecast and then disappear as the future blends into the present.

However, the storm on the horizon (for early next week) may just restore our faith in the GEFS (if not your weather forecaster). Perhaps, even more encouraging is the agreement between the EURO and GFS deterministic models, and their ensemble for a negatively tilted trough to move in (early next week).  When troughs are oriented NW to SE, it means that the circulation around the trough will encourage divergence aloft and the spin up of a surface low pressure (bringing strong vertical motion and plenty of moisture).

In the meantime, we'll continue to have chilly weather and light rain from time to time through Wednesday. before a bit of a warm up before the next storm.

Stay tuned.

Barry Lynn

Saturday, December 31, 2016

Weather It Is (Winter Sticks Around)

Good Evening:

There is much "action" on the horizon.  Most encouraging is the waviness of the upper level (500 mb) pattern, where two waves will pass by on Monday and Tuesday night. The second will be colder than the first, and it might lead to some snow showers Tuesday night.

Looking at the lower atmospheric levels, there is some humidity, but temperatures should stay above freezing, so any snow showers should just melt.

The cold temperatures should moderate on Wednesday into the end of the week, but we see indications that early next week might turn quite cold, bringing back a chance of snow.  This storm (the third in our series) shows possible phasing between the lower and upper levels, which would bring lots of precipitation, wind, and snow.

We seem to be seeing a lot "opportunities" (~30% chances) for snow this year on the forecast maps.  If the global model has predictability beyond five days, then one of these weeks it will snow.

It was noted by a fellow blogger at "Jerusalem Snow" that the Climate Forecast Systems Model shows a cold January in store for us.  This is a change from what it showed in its three month outlook prior.

Barry Lynn

Friday, December 30, 2016

Weather It Is (Cold, But Not Much Else)

Good Afternoon:

Some light rain is expected from late tonight into late afternoon/evening Shabbat.

The rain will arrive with a strong chill, and there could be some wet snowflakes mixed in with the rain.

The cold should continue into Wednesday, with another chance of rain Monday Night/Tuesday.

Otherwise, the cold and the rain should take a break until the end of the week after next.

Shabbat Shalom/Chanukah Samaech,

Barry Lynn