October 2016 to close out with rain!

Threat!  (omitted portion of the headline above)

Check this out:

Valid at 5 PM AST October 28th. 2016.
Valid at 5 PM AST October 28th. 2016 based on global data from 5 PM AST last evening.

You got yer ridgy flow on the top (“top” meaning, “Canada”, around where that yellow line humps toward the north) and yer broadly cyclonic flow on the bottom (“bottom” meaning,  “Baja Cal and Mexico”) that is, across the whole western part of North America.  This indicates that we will have a configuration that suggests a “split flow” where part of the jet stream and a trough is forced into the Southwest.  Models are showing a big trough and cutoff that brings substantial rains to Arizona!

Of course, model forecasts are pretty dicey at this range, more than 10 days, and so that’s why I am reporting it fully here with great excitement!  That’s what we do here,  go over the edge, not just up to it.

And, for that slight amount of additional credibility, the “WRF-GFS” has been spitting out big storms for Arizona over the past several runs during this late October period.  See Arizona rain below from this rendering from IPS MeteoStar:

Valid at 5 PM October 27th, 2016. The colored regions denote where the model thinks in has rain in the prior 12 h.
Valid at 5 PM October 27th, 2016. The colored regions denote where the model thinks in has rain in the prior 12 h.  The rains are foretold to just be arriving at this time, and continue for a couple of days.  Nice!

Since I ran out of anything more to say, I will post a second version of this same map as a public service for international readers who are clueless about states in the USA:

Same as above, but for international readers of this blog, and others who may be geographically challenged.
Same as above, but for international readers of this blog, and others who may be geographically challenged.

Below, the upper level configuration that goes with the pattern above:

Also valid at 5 PM AST October 27th, 2016. Notice how a lot of the flow comes down this way after extruding into Canada, but some continues on across Canada. Disclosure note: this configuration has more amplitude (and thus a bigger chance for rain in southern Arizona, than was seen in the plot from the NOAA spaghetti factory. Few readers may get this far, so that's why I am placing it here. A announcement that rain might fall in southern Arizona makes people happy, and that's why I will show those models that predict the most rain here, not ones that skimp on a future rain.
Also valid at 5 PM AST October 27th, 2016. Notice how a lot of the flow comes down this way after extruding into Canada, but some continues on across Canada. Disclosure note: this configuration has more amplitude (and thus a bigger chance for rain in southern Arizona, than was seen in the plot from the NOAA spaghetti factory. Few readers may get this far, so that’s why I am placing some element of doubt here.   A announcement that rain might fall in southern Arizona makes people happy, and that’s why I will show those models that predict the most rain here, not ones that skimp on a future rain.  Doubt about a future rain disappoints, makes people sad.  Oh, yeah, and the latest WRF-GOOFUS model run, that from the 11 PM AST global data, had none of this.  What a poop that run was!  Does that later run affect the thought of rain late in the month?  Nope.

So, there are some questions about the magnitude of this event, will it be a spring wildflower energizer with a major rain, or a just a breezy spell with a dry cold front going by?  I’m on the side that a good soaking rain will fall sometime in those last few days of October.

No clouds, so no point in going farther….

The End.

 

Author: Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.