textproduct: NWS Phoenix

UPDATE

06Z Aviation Discussion.

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 and tranquil weather with slightly above normal temperatures and some occasional breeziness are expected through middle of the week.

- A more unsettled pattern with increasing rain chances is possible over the weekend into next week.

SHORT TERM /TODAY THROUGH THURSDAY/

A benign weather pattern is expected across the Desert Southwest through the middle of the week as an overall ridge of high pressure prevails overhead. This will produce dry and tranquil conditions along with mostly clear skies. Temperatures will be in an above normal category each day with afternoon highs across the lower deserts topping out in the low to mid 80s along with overnight lows in the 50s to around 60 degrees.

LONG TERM /FRIDAY THROUGH SUNDAY/

An 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 0540Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation weather concerns are expected through the forecast period. An easterly wind will prevail through tonight and at least the first half of Tuesday. The typical westerly shift is forecast to return late Tuesday afternoon by around 20Z-22Z. Wind speeds should remain light through the period, generally 6 kts or less. Overnight into early Tuesday morning, there could be minor LLWS concerns (below TAF criteria) on the order of 10-15 kts out of the east. Skies will remain mostly clear aside from a few high clouds passing over southcentral AZ on Tuesday.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns are anticipated through the forecast period. Winds will favor a W-NW component at KIPL and N direction at KBLH, albeit with prolonged periods of nearly calm conditions at both terminals. High clouds will gradually filter into SE California late tonight.

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. Outside of some marginally breezy conditions across ridge tops and terrain gaps of eastern districts during the morning hours, fairly light winds will prevail through the middle of the week.

PSR WATCHES/WARNINGS/ADVISORIES

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