Marine Weather and Tide Forecast for San Luis, AZ

DISCUSSION
Current atmospheric analysis reveals persistent quasi-zonal flow stretched out over much of the Desert Southwest, resulting in a prolonged period of little day-to-day regional condition variations.
However, it looks like this quiet flow regime will begin to break as an Eastern Pacific area of low pressure begins its advance toward the western CONUS. Before this pattern shift takes place, temperatures will continue to run near to slightly above normal for this time of year, with lower desert highs ranging generally in the upper 80s to lower 90s this afternoon.

The influence of the above-mentioned low will begin to be felt as early as Friday with cooling temperatures, mostly over the western deserts of SE California and SW Arizona, and increasing winds for portions of the region. In terms of temperatures, the initial cooldown will not be very pronounced as temperatures fall only a few degrees into the middle and upper 80s for the areas mentioned above. Elsewhere across the desert of south-central Arizona, temperatures will continue the status-quo that has been observed over the past several days with temps in the upper 80s to lower 90s. With cooler air beginning to filter in, a tightening of the regional thermal and pressure gradient will help generate breezy to locally windy conditions for parts of our forecast area, particularly the typical downsloping areas of western Imperial County, portions of the Lower Colorado River Valley, and the high terrain areas east of the Phoenix metro. Due to the high probabilities (>90% chance) of gusts reaching or exceeding 40 mph in western Imperial County, a Wind Advisory has been posted and will go into effect Friday afternoon. Elsewhere, gusts 20-30 mph will be common, with locally higher gusts at times.

The closed-low will eventually make landfall on Saturday, and some of the greatest impacts associated with will be felt, from more noticeable cooling temperatures, to a continuation of enhanced breeziness. Saturday looks to be the windiest day this weekend, with widespread 25-35 mph gusts, with the potential for higher gusts across the most wind prone areas. As of now, no wind advisories have been issued outside of the one for far western Imperial County.
However, it would not be surprising if that advisory is extended eastward to encompass the Imperial Valley, and a separate advisory is issued for the Arizona high terrain over the next day or so. On both Friday and Saturday, the enhanced breeziness, combined with a very dry air mass in place, will result in periods of elevated to locally critical fire weather conditions across portions of the region. As for temperatures, this system will funnel unseasonably cool air over the Desert Southwest (though there likely will not be too many complaints about that) dropping temperatures a good 5-10 degrees below normal, with initial cooling over the western deserts Saturday before spreading further east by Sunday. Widespread temps in the middle to upper 70s are expected by Sunday, with just a few spots making into the lower 80s. Lingering breeziness is likely on Sunday as the system weakens, but gusts should remain below the advisory level threshold.

Heading into the start of next week, models depict the weekend low splitting into two separate systems, with one ejecting toward the Plains, while the other hangs back over the Southwestern CONUS and Northern Sonora. The general consensus is that this secondary system will not be as strong as its predecessor, so little in the way of impacts are anticipated. At the most, periods of elevated winds and maybe a delay in a more noticeable warming trend will be the main impacts. Beyond that, clusters indicate the return of high pressure to the western CONUS by the middle of next week, ushering in the return of benign conditions and above-normal temperatures.

AVIATION
Updated at 1700Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH:

No major weather concerns will exist through Friday morning under periods of some passing high cirrus decks. Trends in the timing of directional wind shifts will be similar to the past 24 hours with speeds somewhat weaker and gustiness less pronounced today. However, a few late afternoon/evening gusts 20-25kt will still be possible across SE California terminals. Stronger winds will frequent gusts will be likely Friday afternoon and evening.

FIRE WEATHER
Dry conditions will persist through the next 7 days, with seasonably warm temperatures through the end of the workweek. Expect diurnally driven and generally light winds today, with typical afternoon upslope breeziness. An approaching low pressure system late week into this weekend will increase winds Friday for the western districts and areawide by Saturday, leading to locally elevated to near critical fire weather conditions for the typically prone areas, such as the Arizona high terrain east of Phoenix. Temperatures will also cool below normal this weekend as a result of the low pressure system. Afternoon minRHs will generally fall into the upper single digits to lower teens through the end of the workweek before rising slightly this weekend, in the middle to upper teens, thanks to the cooler temperatures. Overnight recoveries will be poor to fair, generally between 25-45% through Friday night, increasing to 30-50% for the eastern districts by Saturday night and slightly higher (45- 60%) for the western districts.

PSR WATCHES/WARNINGS/ADVISORIES
AZ...None.
CA...Wind Advisory from 2 PM Friday to 5 AM PDT Sunday for CAZ562.