Saturday, June 04, 2011

If Only We Had Some Low-Level Moisture!

A large cyclone is spinning off the California coast, as shown in the blended PW image above. While the moisture plume into the cyclone is spectacular, note that PW values of around 30 mm have crept further north and now reach nearly halfway up the Gulf of California (GoC). However, deep mT moisture remains south of 20 degrees north. The nearest moisture source that could affect areas west of Continental Divide is from the debris of convective storms in north-central Mexico - see post below.

This morning's NAM forecast for 5 pm tomorrow afternoon (Sunday June 5th) is shown above for 500 mb and 700 mb. The 500 mb winds hint that there could be some fetch from northern Mexico northward along the Arizona/New Mexico border that would bring some middle-level moisture northward from today's storms south of the border. The 700 mb forecast indicates that the winds over Arizona will be mostly from the west, keeping lower levels dry and CAPEless. The mountains along the Continental Divide generate substantial upward vertical velocities (negative omega) at 700 mb. Thus, possible high-based storms tomorrow over the highest terrain. If this pattern were occurring with low-level moisture and CAPE in place, then tomorrow would be a big storm day for southeastern Arizona.

This morning's early run of the Atmo, high-resolution, version of the WRF-GFS model forecasts light showers at 8 pm tmorrow evening across eastern Cochise County (image above is model forecasted composite radar reflectivity. The intensities in this forecast don't appear strong enough to produce lightning - however, tomorrow's details will depend upon how the middle-level flow fields evolve tonight and tomorrow morning.

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