Weather It Is (Winter Returns and Why)

 Good afternoon:

While it has been periodically and sometimes extremely rainy, my outdoor plants are not sure whether to bust out to spring or hunker down for winter. After all, we had a relatively warm fall and December, and the temperature has rarely reached the low single digits here in the Jerusalem hills. So, why not?

Also, they've heard about global warming and are skeptical that winters in our part of the world just won't be, but will be something they'll tell their kid-seedlings about. 

So, I showed them the charts and maps, and they came away -- even more confused.  Our best guess is that there will be a trend towards much cooler weather after mid-next week and that the cooler, if not colder weather should last into the third, if not the end of the third week of January.  Moreover, we could be moving into the type of weather pattern that brings Siberian cold southward, setting up our first real chance (but just a chance) of snow.  

The reason that the forecast models are confused is because the atmosphere is acting contrary, in a sense, to the typical "La-Nina" Pacific Ocean forcing leads to a pattern of wet/cold and dry/warm locales. Here's a summary from one of our Israel Winter Weather group's Yaakov Consoor, who is a seasonal weather forecaster specialist.

Since late 2020, the ocean temperatures in the equatorial eastern-central Pacific have displayed a La Nina state, meaning water temperatures around 1C cooler than usual.  However, the atmosphere has not always responded in kind.  A La Nina-influenced weather pattern in winter tends to feature a weaker than usual southern (subtropical) jet stream from near Hawaii to the southern US, and from the Middle East to South Asia.  This typically leads to drier conditions across the southern US, South and Southeast Asia, and to some degree across the Middle East as well.  

Meanwhile, an El Nino-influenced weather pattern in winter is typically characterized by a stronger than usual southern jet stream from near Hawaii to the southern US, and from the Middle East to South Asia. This tends to be associated with wetter conditions across the southern US, south and Southeast Asia.  In the Middle East, including Israel, wetter conditions are also characteristic of El Ninos, especially in the past 30 years and especially in the late fall and early winter (Nov and Dec).

The weather pattern has at times between late Oct and Nov, and especially since around Dec 10, turned more El Nino like across the globe with an enhanced Southern jet stream fueling severe flooding events along the West Coast of the US, as well as in Italy, Spain and the Middle East.  Locally, here in Israel, we saw a dramatic turnaround from drought conditions in Oct and most of Nov to a wetter than usual trend that began in Dec, with the Dec 20-23 storm bringing more than 150 mm in large parts of the Sharon, Tel Aviv area, and western Shomron.  

Will the El Nino-like pattern continue the rest of the winter?  Climate models and past experience suggests this is highly unlikely.  A turn toward a more typical La Nina pattern is likely late Jan into Feb.   However, the longer range outlook beyond Jan 20 is still rather uncertain at this point. 

So while we pray the second half of the rainy season will “deliver the goods”, especially in a Shmita (sabbatical) year, the outlook remains rather murky and foggy, as is typical for long range forecasts in Israel.  ארץ אשר יהוה אלהיך דרש אתה תמיד עיני יהוה אלהיך בה מרשית השנה ועד אחרית שנה – Eretz Yisrael  is a land where the eyes of Hashem are always on the Land, from the beginning of the year until the end, so perhaps only G-d knows what we can expect through the rest of the winter.