Wednesday, June 26, 2013

500 mb Anticyclone Shifting North


Satellite image above shows several smoke plumes from wildfires in the Southwest, as well as deep convection in northern Mexico yesterday at 2340 UTC. The storms are lined up along and east of the Continental Divide, with the anvils blowing off toward the east to southeast. As the 500 mb anticyclone moves northward, the mid-level winds at Chihuahua shifted to the east and picked up in speed during the night. The 1200 UTC sounding from Chihuahua is shown below, with nice steering flow from the east toward Sonora. This was needed to get storms and outflows to move westward. So this is a positive sign for increasing MCS activity to the south of Arizona.


This morning's NAM forecast for 500 mb valid at 1200 UTC on Saturday morning is shown below. Very ugly anticyclone is forecast to centered over northwest Arizona. The circulation around the high will try to advect some middle-level moisture from the Northwest toward New Mexico and Arizona. However, for a pattern such as this to become very active requires a significant push of low-level moisture into southern Arizona. If low-levels remain dry, we'll mainly see high-based, mountain storms with gusty winds and a threat of dry lightning.


No comments:

Post a Comment