Weather It Is (Crying Wolf!)

Good Evening:

Snow wise, there has been a lot of disappointment this year for those of us living in the area of the central mountains.  The phrase: "crying wolf" is one that might be ascribed to us meteorological folks.   Even if the storm did pretty much what it was predicted (closer to its arrival) -- there was a lot of hype with this storm.   Moreover, grazing the Jerusalem area with some snow showers while dumping a lot of slush in the Galilee mountains was quite disappointing for those who dream of a snow like that of December 2013.

Yet, when I saw the dancing of raindrops on the roof windows and the streets below, I felt a moment of satisfaction.  For, its not enough to just talk the walk, or walk the talk, one has to bring the merchandise, and so we did -- the rain to wash away dirt from the stones of Jerusalem.  Having one good forecast under my covers, I slept the sleep of the tired, the sleep of the spent, the sleep of the weatherman who has had a hard week!  One who knows that every word he says will be parsed twice -- and a third time if things don't work out as hoped.  It's a very hard life, but the thrill of catching the big one makes it all worthwhile (as well as providing a little helpful advice from time to time).

Before I get to the important stuff, here is a quick primer on predicting snow.

1) Identify from the global forecasts possible conditions for snow in the higher elevations of Jerusalem, etc.   It's not enough to be wet, it must also be unusually cold.  Or, it's not enough to be unusually cold, it must be wet (as I keep telling my son).

2) Use the global forecast ensembles to assess the probability of the storm occurring -- so far this winter, we're doing great in this regard.

3) Once we get within three days, use our high resolution forecasts to see just how wet and just how cold, and to see just how much snow is predicted to accumulate.  These models have been excellent.

4) Within a day, use our highest resolution forecasts to refine our snow even more.

5) Use our high resolution ensemble to asses the probability that snow amounts might exceed certain values.

An example:  In the last storm, we saw from the global models that it would generally be very wet, but not quite cold enough for a good snow.  As we got closer, we saw that the storm's heavy precipitation would skip Jerusalem, bring slush to the Galilee mountains, and that indeed it would be too warm for heavy snow, except in the Golan.  The day of, we saw that the Jerusalem area would get some snow (it did snow briefly out here), but the chance of any accumulation of was only 50% -- and even this was just an indication of the potential for heavier shower of snow (that didn't  happen).

Another example: in the previous January  storm, we relied too much on the general picture, and didn't really put enough credence in the fact that our high resolution models showed the night before and day of the storm that temperatures would be cold enough for snow, but not for a really high accumulation.

Lastly, in the December 2013  storm, we could see the cold and the wet well in advance.  Then a day or so before, we used our high resolution model to confirm that indeed there would be a heavy snow accumulation.

Which leaves us with the mid-week storm that looks like it could be more like the December storm of of 2013 than the snow/non-snow storms of January/Feb 2015. Right now, the forecasts have a split personality: about 1/3 to half of them show a very intense storm impacting us mid-week, while the other half do not.  The ones that do show snow predict a phasing of the northern and southern streams and the arrival of the storm from almost due north.  This will maximize the impact of the storm's cold air on us.

By the way, the European model is also "crying wolf."  It also shows a good possibility of a major snow storm for our area.   This just in from a serious weather hobbyist in Jerusalem: "From my eye: the Euro has a trough that develops first over the next couple of days thanks to the current high that moves over Europe. This trough isn't deep enough at the beginning of the week, but then another surge of cold air fills it in directly from Russia and a storm develops at the bottoms of the trough. This storm then plunges downward toward Israel and gets cut off but still retains some of the incredible cold. As a result, from Thursday to Saturday, the Euro brings in 500's that get below -30 and 850's [mb temperatures]  that get close to -5 c all coupled with a slow moving storm that could potentially bring a lot of snow to Jerusalem."

Before we cry too loudly, though, let's take a look at the forecast tomorrow morning.

Barry Lynn