Catalina rains still showing up in model runs

This was pretty neat, this forecast map from yesterday’s  11 AM AST WRF-“GOOFUS” (GFS) run.  Look at all the rain barging into Arizona and Catalina!

Plenty of rain here in southern California AND Arizona!  Valid at 11 AM November 20th.
Plenty of rain here in southern California AND Arizona! Valid at 11 AM November 20th.

What’s remarkable is that the ensemble runs made yesterday’s prediction of rain, one discussed here,  quite the “outlier” of the rest of the “members” of the spaghetti plots,  so one wouldn’t be expecting to see any rain for Catalina again!

But, here was that rain again, and this whole storm complex along the California coast falling mostly within that time period where over the decades there has been a tendency for storms to strike the more southerly locations between the 10 and 20th of November, something that was mentioned yesterday as a bit of a conundrum.  Rain, though not as much, was shown again in the next run based on 5 PM AST global data, and due to that prediction of less rain, I am not showing it.

Below is a comparison of how the ensemble outputs (shown as “spaghetti” plots of a couple of key contours at 500 mb (around 18,000 feet above sea level) have changed since yesterday.  To this observer, its been  an unusually large change in where the grouping of those key contours are in just 24 h (they always change some, of course).

Notice how the blue (contours of flow pretty much in the heart of the jet stream) and red lines (periphery of it)  have been shifted 10 degrees latitude and more southward from the first plot to the second, latest spaghetti plot, indicating that we’re going to be more in the storm track at that time, and the likelihood of a rain threat on the 19th-20th is more credible, less subjectively based as was yesterday’s take.   Maybe subjectivity in forecasting isn’t that bad afterall…

Valid at 5 PM, Wednesday November 19th.
Valid at 5 PM, Wednesday November 19th.  Note how the red and blue lines bulge northward along the West Coast, suggesting a fair weather pattern.


Also valid at 5 PM AST, Wednesday November 19th.
Also valid at 5 PM AST, Wednesday November 19th.  Blue lines (contours along which the wind blows from left to right) are now much farther south, and the red lines are now so far south they’re almost not in the map domain.  Also, those red lines now do not bulge northward anymore, but rather are suggesting a broad trough along the West Coast at lower latitudes, completely different than the plots just 24 h earlier.

The End

(unless I think of something later.)