textproduct: NWS Phoenix

KEY MESSAGES

- Building high pressure will result in above normal temperatures through the remainder of the workweek

- The pattern changes going into the weekend as a weather system approached the region, leading to breezy conditions, cooler temperatures, and increasing rain chances.

SHORT TERM /Today through Thursday/

Current objective analysis reveals a tranquil setup over much of the Great Basin as an upper-level area of high pressure sits over the region while the shortwave that brought considerable cloudiness and some isolated showers yesterday moves toward the Southern Plains. With much more insolation and a warmer atmospheric profile compared to Monday, temperatures across our forecast area for this afternoon will see noticeable jump as readings for the lower deserts reach into the lower to middle 90s. Thankfully, that is a good 10 degrees or so away from record territory, but is, nontheless, decently warmer (coincidentally, by about 10 degrees) than where we typically are this time of year.

The ridge will the mainstay of the regional forecast through the middle portion of the week, keeping us warm and dry at least for a few more days. The axis of this feature will be alligned with Desert Southwest on Wednesday, which looks to be the day when temperatures will peak across the region. Afternoon highs will bump up a few degrees into the middle and upper 90s. The good news is, chances of reaching the triple digits again are quite low for most of the lower deserts, but we can not completely rule out a few spots around the Lower Colorado River Valley and Salton Sea seeing the century mark. Thursday will be close to the same, albiet a few degrees "cooler" as the axis of the high shifts to the east.

LONG TERM /Friday through Monday/

By the end of the week, ensembles continue to point towards a pattern change for our region. Ensembles show a closed low pressure system moving onshore in central CA on Friday, which will result in heights starting to lower across AZ. Ensembles show H5 heights going from 576-579 dm on Thursday to 573-576 dm on Friday. With lowering heights, temperatures will also start to cool with afternoon high temperatures falling into the upper 80s to low 90s (low to mid 80s) across the lower deserts (higher terrain). The low pressure system looks to weaken as it moves onshore this weekend and eventually get wrapped up into a trough digging out of the Pacific NW and eventually slowly progress eastward into our region by the end of the weekend.

However, there remains a decent amount of uncertainty within the ensemble members in the exact track and strength of this system as it moves onshore. If the system is stronger and deeper then precipitation chances will increase across the region as the system will bring in more moisture. However, if the system is weaker and shallower then precipitation chances may be confined to the higher terrain areas. Additionally this system could bring breezy conditions to the region. Either way temperatures will decrease and look to fall back into the 80s (upper 60s to mid 70s) across the lower deserts (higher terrain) this weekend. Temperatures on Sunday look to fall back to near to even slightly below normal. Ensembles point to having the trough slowly start to exit our region. As the trough moves eastward, dry north/northwest flow will move in drier air to our region. As a result this will put an end to any precipitation chances for our region. With the trough and associated lower heights aloft still influencing our region on Monday temperatures are currently forecasted to be very similar to those on Sunday. With afternoon highs in the upper 70s to lower 80s (70s) across the lower deserts (higher terrain), which is near to slightly below normal for this time of year.

AVIATION

Updated at 1700Z.

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 afternoon under clear skies. Wind behavior will follow the typical diurnal/nocturnal variations with usual timing of wind shifts and speeds under 12kt.

FIRE WEATHER

Dry weather and above normal temperatures will persist through the workweek. MinRHs will be in the 10-20% with overnight recoveries of 25-60%. Winds will generally be light, with some occasional afternoon gustiness through the workweek. This weekend a weather system will move into the region bringing breezy conditions, chances for precipitation, and cooler temperatures to the region.

PSR WATCHES/WARNINGS/ADVISORIES

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