Monday, July 07, 2014

Complicated Day Today

The morning sounding from TUS is shown above, with plot and diagnostics from SPC. The thermodynamics are quite good for storms today, with substantial CAPE and moisture available. However, the vertical wind profile is bizarre, with light speeds (except at high levels) and directions from all over the place. So, it is tough to know if there will be a steering wind for storms and, if so, from what direction. The current NAM forecast indicates that steering would be from north-to-south well into the night tonight. Morning showers have seemed to be stationary or moving toward the south. Where will storm anvils spread to? Winds at 200 mb are west to east, but winds at 150 mb are north- to south. With the CAPE available, I would guess that anvils would spread to the south. Not a good situation if storms are trying to move to south.

I have done my own 500 mb analysis this morning and it is below. The 500 mb pattern is also quite a mess. There are at least three separate anticyclone centers ("A") and two weak cyclones ("C"). Weak troughs weave all through the broad anticyclone. There are very weak vorticity maxima with the two cyclones, as per the 12 UTC NAM analyses - second below.

The latest NAM forecast for 500 mb (below, valid at 00 UTC this evening) amplifies the vorticity center that is southeast of Tucson and moves it southward across Sonora. The NAM forecasts maximum storm activity and rainfall to be associated with this feature and to be heaviest south of the border.

I will hope that storms drift into this part of town from the Catalinas - last time I tried for this I was way off.

Finally, this morning's weather story from the NWS Office is below, and it highlights one of my pet peeves with NWS forecast discussions. The statement, "Energy pushing in from New Mexico..." is meaningless technical jargon (unless the writer defines what kind of energy he/she is referring to). I assume that this statement actually refers to the vorticity maximum that the NAM is currently forecasting to move southward. 

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