textproduct: NWS Phoenix

KEY MESSAGES

- Elevated flows will continue on the Salt and Gila rivers through at least the middle of the week due to recent releases from upstream dams.

- Dry weather with occasional breeziness and slightly above normal temperatures are expected through at least midweek. - Unsettled weather with increased chances of showers may return to the region over the weekend into next week.

SHORT TERM /TODAY THROUGH THURSDAY/

Split upper level flow continues across the CONUS with the southern stream remaining quite weak and well south of the Desert Southwest. Eastern Pacific upper level ridging has also spread eastward into our region with models heavily favoring this ridge to maintain its position into the middle part of the week before a much more amplified upper level pattern develops. This pattern will keep dry and tranquil weather conditions for our area for several more days with clear skies through midweek. The stable heights aloft will also result in very little variation in temperatures with lower desert highs staying between 80-85 degrees and overnight lows in the 50s.

LONG TERM /FRIDAY THROUGH SUNDAY/

The amplifying upper level pattern late week suggests a Pacific trough will develop off the West Coast by around Thursday with a small majority of latest runs' ensemble members forming a closed low just off the coast of southern/central California by Friday. Other members have more of a faster and less amplified disturbance which could still occur, but is a bit less likely to happen. For now with the majority of the members, including the deterministic members, calling for a closed low to approach the region on Friday, higher level clouds will be the first feature to move in from the southwest.

The latest model trends however lean more toward the low tracking across northern Baja into Sonora Mexico Friday night and Saturday. If this track holds, we are not likely to get much lower level moisture to advect northward, along with the bulk of the system energy missing us to the south. The latest NBM/WPC PoPs have been scaled back due to the potential more southerly track leaving mostly 10-20% chances over the lower deserts and up to 30% over Arizona higher terrain areas Friday night-Saturday night. Any further weakening of the system or farther track to the south would decrease rain chances. Despite the uncertainty in rain chances, there is higher confidence in a cooler air mass moving into our region for next weekend. Current NBM forecast temperatures show highs dropping into the mid to upper 70s starting Saturday. Even if this first system ends up not providing any meaningful rainfall, guidance is hinting at one or even two additional weather systems for next week.

AVIATION

Updated at 0945Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major weather issues will exist through Tuesday morning under clear skies. An easterly component will be predominant the majority of the period, however variability will be common both around sunrise, then again after sunset when directions may attempt to become westerly before reverting back to east.

Southeast California/Southwest Arizona including KIPL and KBLH: No weather issues will exist through Tuesday morning under clear skies. Winds trends will be similar to the past 24 hours favoring a west component at KIPL and north directions at KBLH, albeit with prolonged periods of nearly calm conditions.

FIRE WEATHER

Dry conditions and slightly above normal temperatures will prevail for the bulk of the coming week. Minimum humidity values will hover near 25-40% across eastern districts and 20-30% in western districts. This follows fair to good overnight recovery near 30-60% in western areas and good to excellent levels 50-80% in eastern areas. Marginally breezy easterly winds will be observed across ridge tops and terrain gaps of eastern districts during the morning hours today and again later in the week, otherwise expect light winds.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...None. CA...None.