Stagnant summer pattern

Filed in Uncategorized by on July 28, 2007 1 Comment

The weather pattern across the West that has been in place for nearly a month will continue to dominate for the forseeable future.  The anomalously strong and southerly jet that brought record rainfall to coastal WA earlier in the month has weakened and moved north a bit, but is still more active than it usually is in the dead of summer. The associated weak troughs off the West Coast are preventing any large heatwaves from developing and are also tending to keep any northerly surges of monsoonal moisture very brief as the westerlies push the moisture to the east. A very moist monsoonal pattern  has been present over AZ and NM for several days, bringing numerous intense thunderstorms and flash flooding. Unfortunately, this moisture will stay mostly in the far SW and will make only minor inroads into SoCal and NV, where some rainfall could be very beneficial right now. There is little hope for change on the horizon, as weakly zonal flow over CA and the western states will continue to advect uninteresting Pacific air over the region for the next 1-2 weeks. One note: the Zaca Fire in SoCal looked earlier this month to be quite the menace to firefighters for weeks (and possibly months) to come. As a result of rather favorable weather conditions, the fire had been nearly contained before gusty winds pushed a section of flames over an unfinished line in the San Rafael Wilderness this morning. If this spot cannot be contained (and it’s already at 300 acres, with a plume on visible satellite imagery), we will probably be hearing much more about this fire as the dry season continues…