textproduct: NWS Phoenix

KEY MESSAGES

- Dry and tranquil weather conditions are expected through the remainder of the week with slightly above normal temperatures.

- A weather system arriving late Sunday and Monday is expected to bring much cooler temperatures and chances for precipitation focused more over the Arizona high terrain.

SHORT TERM /TODAY THROUGH FRIDAY/

Upper level ridging has fully moved into the Southwestern U.S. with H5 heights rising to around 585dm later today, or into the 90th percentile of climatology. The higher heights today along with clear skies and drying conditions will help to push daytime highs well into the 70s across the lower deserts. By Thursday into Friday, the ridge will gradually weaken and shift to the east, but temperatures will stay above normal with highs staying in the mid 70s across the lower deserts. At the same time, a weakening upper level trough well to our southwest will briefly bring in some higher level clouds on Thursday before skies clear once again on Friday. Overnight lows will also rise slightly under the ridge, but the drier boundary layer conditions will generally keep lows from the mid to upper 40s across rural desert areas to 50-55 degrees for urban locations.

LONG TERM /SATURDAY THROUGH TUESDAY/

The first part of this weekend will stay quiet across the region, but we will transition into a broad troughing pattern with a fast moving disturbance first passing across northern Utah into Colorado. The lowering heights will help to bring temperatures down to fairly close to normal readings on Saturday, but conditions will stay dry and skies will remain mostly clear. As we enter a more active weather pattern once again, guidance has been trying to bring a disturbance through our region at some point Sunday into early next week.

Ensembles had initially been quite favorable for a slower and more impactful weather system, but over the past couple of days have gradually shifted toward a progressive system with a more northerly track. There are still some ensemble members (maybe 15%) calling for a slower system with more precipitation, but if the trends continue it probably will not amount much precipitation. The latest NBM only gives 10-15% PoPs for the western deserts, 20-30% for Phoenix, and 30-40% for the Arizona higher terrain. The current timing as of now brings the system through here late Sunday and early Monday with highs dropping from around normal on Sunday to a few degrees below normal for next Monday-Wednesday.

The active weather pattern should continue into the latter half of next week with guidance currently indicating a larger Pacific weather system dropping southward along the West Coast, potentially stalling out briefly to our west around next Wednesday and Thursday. If this occurs, it could result in a decent precipitation event at some point late next week for the Desert Southwest.

AVIATION

Updated at 0505Z.

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

No weather issues will exist through Wednesday night under some increasing high cirrus decks. Confidence is excellent that E/NE wind directions will prevail the majority of the time frame around Phoenix with only a brief period of light west or variable winds around sunset Wednesday. At the SE California terminals, N/NW directions will be preferred. Extended periods of nearly calm conditions will be common across the entire region.

FIRE WEATHER

Dry and tranquil weather conditions will continue into the weekend with temperatures rising to around 3 to 6 degrees above average lasting through Friday. Expect MinRHs between 25-35% through Friday and 35-45% over the weekend with overnight recoveries remaining good. Winds will be less than 10 mph and follow their normal diurnal tendencies with only marginal upslope gusts into the upper teens to low 20s. A fast moving weather system should then move through the region late Sunday and Monday providing mostly high terrain precipitation chances.

PSR WATCHES/WARNINGS/ADVISORIES

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