textproduct: NWS Phoenix

KEY MESSAGES

- Dry and tranquil weather conditions with wellabove normal temperatures will prevail across the region through early next week.

- A change in the weather pattern is expected later next week with cooler temperatures and potentially increased precipitation chances.

SHORT TERM /TODAY THROUGH FRIDAY/

Unseasonably warm weather and dry, tranquil conditions continue as strong upper level ridging persists across the Desert Southwest. Early afternoon RAP analysis showed the center of the ridge of high pressure positioned west of the Baja Peninsula with 500 mb heights across the forecast area around 582-585 dm. As the upper level ridge gradually shifts eastward, heights will rise slightly for Friday, promoting a warmer afternoon to end the workweek. Afternoon highs Friday across south-central and southwest Arizona are forecast to top out 2-3 degrees warmer than today as temperatures climb into the upper 70s to around 80 degrees, with similar readings expected across southeast California. Afternoon temperatures reading around 10-15 degrees above normal will continue into the weekend.

LONG TERM /SATURDAY THROUGH LATE NEXT WEEK/

Upper-level ridging will continue to persist across the Desert Southwest throughout the weekend and early next week, continuing the dry and tranquil weather pattern. Temperatures will continue to remain unseasonably warm throughout this period with afternoon highs across the lower deserts ranging between the upper 70s to low 80s, which will be a good 10-15 degrees above normal for this time of the year. In fact, there is a high probability (>70%) of Phoenix breaking record highs, especially by Sunday and Monday, according to the latest NBM.

Model guidance continues to show a pattern change heading towards the middle and latter portion of next week as the upper-level ridge moves eastward into the southern Plains, allowing a deep Pacific trough to build off the West Coast. Examining the ensemble cluster analysis, there continues to be large spread in the overall strength and positioning of the trough. Nevertheless, the ensembles show abundant moisture spreading into the region out ahead of the troughing feature late Tuesday into Wednesday with IVT values forecast to exceed 250 kg/m/s. This increasing moisture will promote precipitation chances beginning next Wednesday, with the highest chances across the western deserts. Precipitation chances may continue through the end of next week, however, this will all be dependent on the overall strength and positioning of the trough. Given that this will be a warm weather system, all of the precipitation, even across the higher terrain, should fall as rain. With the increasing clouds and precipitation chances, along with decreasing heights aloft, temperatures mid to late next week are expected to cool down but will likely still remain above normal.

AVIATION

Updated at 2300Z.

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

No weather issues will exist through Friday evening under periods of high cirrus decks. Wind speeds will remain extremely light with only subtle diurnal/nocturnal directional shifts. Extended periods of variable directions and calm conditions will be common.

FIRE WEATHER

Persistent high pressure across the region will continue to promote dry and tranquil weather as well as unseasonably warm temperatures, 10 to 15 degrees above normal, into early next week. Winds will generally be light and follow familiar diurnal patterns. Afternoon MinRHs will range between 20-30% with good overnight recoveries of 40-70%.

PSR WATCHES/WARNINGS/ADVISORIES

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