Are those snowflakes?

The first thing “they” teach an aspiring meteorologist is: “look out the window.”  Is there “somewhere over [that] rainbow” a snowstorm brewing?  To be honest with you, I forgot that first lesson and would have missed taking a picture of that rainbow if not for my son telling me to come take a look. The rain soon let up and the rainbow is only now a picture on this blog.  Hopefully, though, it won’t be long before one can soon sit by the window with a hot chocolate and watch the snowflakes fall.

In my last blog, I pointed out that there is a general feeling among the members of my “Israeli Winter Weather” Group that enough words eventually transform themselves into something tangible, something one can say, like “wow: it’s snowing.”

The next week will put this theory or these hopes to their severest test.  Since our previous snow bust, the weather has turned mostly dry — not too warm, but there have been many sunny days.  But, not to be deterred,  Jonathan Hoffman and Yaakov Cantor have been hard at work studying and better understanding which synoptic scale set-ups give us our biggest snows.  All of them involve the building of a West European Ridge, while a third includes an extension of this ridge into eastern Europe. The building of this ridge is not a trivial matter and it too depends on upstream weather phenomena over the north Atlantic. In all of these scenarios, there has to be a really good source of cold air, and this often arrives via a trough of very cold air over Scandinavia and northwest Russia (the Siberian Express).

Based on the composites described below, it looks like we’re headed for scenario #1, where the situation is forecast to evolve to a cutoff low pressure area drifting north to south through Turkey and into the eastern Mediterranean.  If the western European ridge strengthens, sufficiently, we’ll see our first snow since January 2022.  This scenario is showing up on the Machine Learning forecast based models and as some fraction of the dynamically based weather forecasts.

Since learning from past mistakes is often the best teacher,  my guess (based on the fact that Machine learning forecasts actually do learn from past history) is that our end of the week snow chances will increase as the week progresses.

If not, it does look like a very prolonged period of rain is on the way, and that is itself a blessing too.

Below is a summary of our different composites, prepared by Yaakov Cantor.

“Here are the composites for Day -7.

1. The W. Russia ridge pattern already has a significant positive anomaly from Scandinavia to far W. Russia along with significant negative anomaly just S of Greenland. The trough downstream of the W. Russia ridge is all the way over central Asia. It has also the strongest positive anomaly near Alaska of all three composites.

2) The W. Europe ridge, no cutoff low pattern has a significant -NAO with ridging bridging from AK to Greenland and w. Europe. The trough/negative anomalies downstream is focused much further west than in the W. Russia ridge pattern – from e. Scandinavia to e. Europe.

3) The W Europe ridge, cutoff low pattern has a fairly zonal flow with magnitude of anomalies much less than other patterns. There is a weak ridge over sw Europe, weaker and further south than in the no cutoff low pattern.  This weak ridge/positive anomaly extends to south of Greenland.”