Saturday, June 27, 2009


The most widespread storm activity of the season occurred over northwest Mexico last evening. See IR image from 0300 GMT above. This is an encouraging sign and the activity may have played a role in triggering at least a shallow GoC surge at Yuma early this morning. Note that Td jumped 8F between 6 and 7 am and was still at 69F at 9 am this morning.

Precipitable water continues to increase slowly over south half of state and influx of low level moisture at Yuma will help continue this trend. CAPE at low elevations remains very limited and more boundary layer moisture would help, particularly as 500 mb temps are increasing.

Yesterday there were no reports of measurable rain from the Pima County Alert network of 90+ gauges.

Last weekend the ECMWF and GFS were at odds concerning the large middle level anticyclone that was over the Plains states, with the GFS indicating a westward shift toward the Four Corners. The anticyclone remains over northeastern Oklahoma this morning and the ECMWF clearly was better on that feature. It was however too wet over much of the Southwest.

This morning all three models (NAM, GFS, and ECMWF) are in agreement that the strong, shortwave trough, currently over southern Canada southward to Colorado, will dig southeastward over the Great Lakes and push the anticyclone westward to the Four Corners region by 72 hours. So, a considerable readjustment of the large-scale pattern will be occurring during next couple of days.

There may be some afternoon storms today at lower elevations, given the low-level moisture trends, but CAPE will be highest over the mountains. Chance of rain remains close to zilch here at our house.


No comments:

Post a Comment