Marine Weather and Tide Forecast for Picture Rocks, AZ

DISCUSSION
The upper pattern this morning is defined by an upper-low centered off the central California coastline, and a high amplitude ridge extending along the Rockies down into the Rio Grande Valley. Look for that upper-low to continue to drive south today with strong northerly flow on the backside of this feature, making its way off the southern California coast by 07/00Z this afternoon then slowing down around the tip of the Baja Spur by 08/00 Saturday afternoon. A decent moisture plume (0.85-1.00 inch PWAT) seen on the GOES satellite imagery this morning across the southern Baja into southern Sonora Mexico should get wrapped up ahead of this upper-low into far southeast Arizona as early as Saturday afternoon, and then NW/W across the rest of Southeast Arizona Saturday night into Sunday. The majority of this moisture will reside in the mid-to-upper levels.

Expect a significant amount of virga beginning Saturday afternoon as the atmosphere tries to moisten up from the top down into Sunday morning. The best lift in the lower-to-middle levels will wait until 08/21Z Sunday afternoon thru 09/12Z Sunday morning when a marginally strong diffluence/deformation axis moves across Southeast Arizona from the south (along the N/NE periphery of the upper low moving through Southern Sonora Mexico Sunday). I would expect scattered coverage of mainly light showers showers from Tucson south and southeast Sunday and Sunday night. At this time, I don't reckon there is enough lower-level moisture for impactful rainfall totals. The 06/00Z NBM indicates up to a tenth in the valleys from Tucson south and southeast, with a quarter inch in the higher terrain...and this fits the scenario well. Given the southern track of this upper-low, I would expect high snow levels with this system, with only a mix of rain and snow in the highest elevations.

This upper-low quickly ejects east across northern Mexico Monday with another impulse trying to carve out a mean trough in the Eastern Pacific. This will essentially leave Southeast Arizona along the western edge of a broad trough across the southern states next week. Although there are timing issues between the 06/00Z operational GFS and ECMWF, they both have the same idea of another, stronger trough ejecting into the Desert Southwest next Friday/weekend. This general pattern is more favorable for an upper-low to grab hold of deeper subtropical moisture in the Pacific and push it towards our neck of the woods. The Climate Prediction Center posted their 6-10 day Precipitation Outlook with likely above (50-60%) normal precipitation. Given the orientation of the upper pattern, this system is more likely to be impactful than the system we are expecting this weekend.

AVIATION
Valid through 07/12Z. SCT-BKN high clouds AOA 20k ft AGL thru 06/21Z then SCT-BKN 12-15k ft AGL and BKN 20k ft AGL thru the end of the valid period. ELY/SELY SFC wind less than 10 kts thru 06/20Z, then SLY/SWLY 10-13 kts into the early evening.
Aviation discussion not updated for TAF amendments.

FIRE WEATHER
An upper-level storm system tracking across Sonora Mexico this weekend will result in scattered wetting rains across Southeast Arizona as early as Saturday, but more likely Sunday and Sunday night. This rainfall is expected to remain light, generally below a tenth in the valleys and a quarter inch in the higher terrain from Tucson south and southeast. Otherwise, afternoon high temperatures will remain 6-10 degrees above normal.
Min RH levels at all elevation will be in the 15-25 percent in the valley and 25-35 percent in the mountains today, increasing 5 percent both Saturday and Sunday, decreasing again by the middle of next week.

TWC WATCHES/WARNINGS/ADVISORIES
None.