textproduct: NWS Phoenix

KEY MESSAGES

- A chilly morning is anticipated Saturday, with some of the coldest temperatures in well over a month likely to be observed.

- A pattern change will occur this weekend, resulting in dry weather and temperatures warming well above daily normals next week.

SHORT TERM /TODAY THROUGH SUNDAY/

The core of the troughing feature that has brought cooler temperatures and light precipitation across the Desert SW is now positioned over Southern Colorado. Today the region will continue to be under the influence from this trough with H5 heights remaining between 558-563 dam. This will keep today's afternoon high temperatures in the low to mid 60s in the lower desert areas.

The combination of clear skies and light winds will cause temperatures early Saturday morning to be coldest in over month with many of the lower desert areas bottoming out from the upper 30s to low 40s. Some of the typically colder rural areas could potentially observe temperatures near freezing. Afternoon highs, however, will begin to climb back to near normal with highs in the upper 60s and low 70s in the lower deserts, as a result of ridging beginning to build over the Desert SW. This ridge will continue to build over much of the Western CONUS by Sunday afternoon, expecting to drive temperatures even warmer, into the low 80s. This will put some of the lower elevation areas in Minor HeatRisk, which is expected to expand and become widespread heading into all of next week.

LONG TERM /MONDAY THROUGH THURSDAY/

Some amount of ridging will be maintained over the Southwest US through the upcoming workweek, though H5 heights will be maximized in the Monday-Tuesday timeframe. Ensembles continue to show the ridge being flattened during the middle of the upcoming workweek as a progressive northern stream storm track develops and sends a few systems through Canada and the northern tier states. This flattening of the ridge will allow for an IVT plume to penetrate inland either over/north of the forecast area during the middle of the week, however, the orientation of this plume and absence of any better forcing mechanism will mean that precipitation chances remain almost entirely out of the picture. Trends in the latest NBM have been for even warmer temperatures during the upcoming workweek, with forecast highs now flirting with 90F across the lower deserts as early as Wednesday. Despite the approximate 3F increase in forecast highs over the last 24 hours, NBM probabilistic guidance advertises narrow spread through Thursday, suggesting high confidence in temperatures reaching near 15F above daily normals mid-late next week.

AVIATION

Updated at 1715Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:

No aviation weather concerns under some passing mid to high level clouds can be expected throughout the TAF period. Westerly winds will prevail through early this evening before shifting out of the east during the mid to late evening hours. Overall speeds will generally be aob 10 kts, although a few gusts into the teens may linger through this afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns under some passing mid to high level clouds can be expected throughout the TAF period. The overall winds will generally be out of the west to northwest aob 10 kts with periods of light variability developing later tonight.

FIRE WEATHER

Warming and drying conditions are expected going into the weekend as a strong ridge will begin to build over the region. Afternoon minRHs today will range between 20-30% and from 30-45% in the eastern districts. This will be followed by overnight recoveries in a 45-75% range. By tomorrow MinRHs will fall into the mid teens. Lower desert highs are likely to reach 85F-90F by the middle of next week for some of the typically warmer locales. Winds will shift from a prevailing westerly direction areawide today to northerly/easterly by Saturday and becoming breezy at times across the eastern districts.

PSR WATCHES/WARNINGS/ADVISORIES

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