Weather It Is (Nice Weather, Then Uncertainty

Good Afternoon:

The weather is really nice.  It's warm, the skies are a pretty blue, and the winds are light.

A few intrepid folks have actually switched out their wardrobes to spring.

One must ask, though, is this wise?

A ridge of high pressure will remain fully in control of our weather until Friday when it should give way to an approaching cool front.  Hence, Shabbat will be noticeably cooler and there will be a chance of showers. Temperatures will rebound a bit on Sunday but then a stronger front and storm should arrive for Monday and Tuesday.

Looking beyond mid-next week shows no clear signal.

In fact, you may remember that a short time ago we trumpeted the latest CFS forecast that indicated that March would be cooler, wetter, and stormier than normal. I did this without my usual warning about model uncertainty.

Why?  Because the time series of CFS forecasts should take into account model uncertainty (they probably do).

Yet, what is apparent from these links:

http://www.tropicaltidbits.com/analysis/models/cfs-mon/2016020900/cfs-mon_01_apcpna_month_me_1.png

http://www.tropicaltidbits.com/analysis/models/cfs-mon/2016021500/cfs-mon_01_apcpna_month_me_1.png

http://www.tropicaltidbits.com/analysis/models/cfs-mon/2016020900/cfs-mon_01_T2ma_me_1.png

http://www.tropicaltidbits.com/analysis/models/cfs-mon/2016021300/cfs-mon_01_T2ma_me_1.png

http://www.tropicaltidbits.com/analysis/models/cfs-mon/2016020900/cfs-mon_01_z500a_me_1.png

http://www.tropicaltidbits.com/analysis/models/cfs-mon/2016021500/cfs-mon_01_z500a_me_1.png

for example, just six days apart that the Climate Forecast Systems Model cannot predict the possible slow-mode changes in ocean temperatures, currents, snow melt, etc, that can affect next months weather.  So, the issue here is model physical integrity on top of model uncertainty -- a very bad combination for weather (or seasonal) prediction models.

So, even if we could possible look beyond next week's uncertainty (attributable to initial GFS model  uncertainty), we certainly cannot say anything meaningful about next month's weather (at least not those who rely on dynamical forecast models).

There are those who claim success at seasonal forecasting using statistical relationships Well, they didn't do so well this year even in the presence of a very strong El-Nino.  My strong feeling is that dynamical forecasts taking into initial condition uncertainty is the way to go (towards more accurate seasonal forecasts), but we'd also like to go to Mars and then the stars, and we're not there yet.

So, is there any economic value in these longer range forecasts?  The question should really be asked and answered.

Barry Lynn