Fire weather worstens; hurricanes Pacific and Atlantic

The Zaca Fire continues to menace Santa Barbara County as temperatures have risen and humidities dropped in the area. Fire weather will continue to be unfavorable for suppression or control efforts until at least midweek. This week, there will be some northward seepage of monsoonal moisture, but the effect will probably be limited to isolated thunderstorms over the SoCal mountains and the Sierras. Synoptically, there will be some rather interesting features to discuss over the coming 2 weeks, though the impacts of these developments on the sensible weather could remain, unfortunately, limited. The most immediate item of interest is the developing deep and rather strong retrogressive trough that will form over the far eastern Pacific off of WA and OR over the next few days. This type of system is extremely rare this time of year, especially given that it will deepen below 980 mb. The most recent runs of the GFS are rather insistent that deep southerly flow will set up ahead of this very sluggish trough over CA (50+ knots at 700 mb) . The model is also indicating the development of a tropical system in the Eastern Tropical Pacific during this same time frame, which should be within 500 miles of the Baja Peninsula. This may be close enough for some moisture to be drawn northwards by this trough up and over the state of CA. It’s not particularly likely at this point, but it does bear watching. Another unlikely but interesting prospect is the possibility that remnant moisture from an Atlantic tropical system could eventually result in a moist easterly wave over the SW U.S. The development and eventual track of this Atlantic hurricane is very unceratin at this point, but upper-level flow will be favorable to advect moisture over mainland  Mexico and over the Pacific near CA if the system makes landfall on the western Gulf of Mexico shores. Again, this is rather unlikely, but it does happen here about every 3-6 years. In short…no really significant changes are likely in the immediate future, but the potential is out there.