textproduct: NWS Phoenix

UPDATE

Updated Aviation

KEY MESSAGES

- A weak weather disturbance will move across northern Arizona today bringing additional chances for light showers.

- Sunday and Monday will be warm and dry before another weather system brings rain chances and cooling temperatures back to the Desert Southwest Tuesday.

- Another weather system could move through the region at the end of next week that will help keep temperatures below normal.

SHORT TERM /TODAY THROUGH MONDAY/

Today, a secondary shortwave will move through the region quickly moving eastward traversing through northern AZ. This shortwave will be weaker compared to yesterday's and as mentioned, positioned further north. As a result, isolated to scattered rain chances will be confined to the higher terrain and foothills north and east of Phoenix. Best chances will be the early morning hours today before upper level ridging begins to fill in behind, bringing warmer and drier conditions by tonight. PWATs will be around 0.6-0.8" and there will be little to no instability. Therefore, rainfall accumulations will be light and generally around 0.10" or less. Some wind gusts of 20-30 mph are expected through the early morning hours today, gradually weakening over the course of the day as the shortwave moves into the Four Corners region and continues eastwards.

This secondary shortwave will keep ample cloud cover overhead today, leading temperatures to cool even more. Highs today in the mid to upper 70s across SE CA and SW AZ, in the low 70s across south- central AZ, and in the 50s to mid 60s across the higher terrain areas. Behind this secondary shortwave upper level ridging will build over the Desert SW, leading to warmer and drier conditions starting Sunday. H5 heights will climb back to between 579-582 dam resulting in temperatures to climb back into the upper 70s Sunday, and even back into the low 80s by Monday. By late Monday night another system will be on the doorstep of the lower deserts, bringing another wave of cooler temperatures and better rain chances.

LONG TERM /TUESDAY THROUGH FRIDAY/

Models remain in good agreement that the next low pressure system will reach the California coast early Monday and move into the lower deserts by Tuesday morning. Tuesday rain chances will return to the forecast with NBM PoPs peaking between 50-80% in south- central AZ and the higher terrain areas, while SW AZ PoPs will be 20-40%. Rain totals Tuesday are expected to be between 0.25"-0.50" to locally higher (up to an inch) in the higher terrain. By Wednesday models are pointing towards yet again another low pressure system moving inland from the Pacific NW, however discrepancies between models are evident for how this system will track throughout the rest of the workweek. Due to this confidence remains low for PoPs by mid to late next week as things are too inconsistent at this time.

Despite how the mid-week system tracks, a more significant cooling trend can be counted on by the middle of the week as these series of weather systems move in from the northwest. They will likely usher in a cooler air mass with afternoon highs trending more towards the upper 60s to low 70s by late next week, with how much the temperatures cool being dependent on the depth and position of the systems.

AVIATION

Updated at 1105Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Occasional cigs in a 4-6K ft AGL will be the primary weather issue through Sunday morning. Confidence is good that light east winds will rapidly switch to W/SW late morning/early afternoon, then revert back to east shortly after sunset. The most likely time frame for lower cigs will be with initial sfc heating mid morning through mid afternoon, including a few SHRA north and east of terminal locations. Some breaks in coverage may occur through the day, and confidence in specific timing of cigs blo 060 is low. Another periods of decks filling in around 6K ft AGL may occur again tonight, though will only advertise a SCT deck given the lower forecast confidence.

Southeast California/Southwest Arizona including KIPL and KBLH: No major weather issues will exist through Sunday morning under brief periods of cloud decks 5-7K ft AGL, and more persistent high cirrus cigs. Confidence in wind direction forecasts are only moderate with variability common. In general, W/SW directions will be favored at KIPL, while a S/SW component will be more common at KBLH. Speeds should be much weaker than the past 24 hours.

FIRE WEATHER

Multiple weather systems are expected to move through the region over the next week bringing multiple chances for showers and a few storms to the area. A secondary weather system will pass through Northern Arizona today bringing rain chances mostly to the foothills and higher terrain areas north and east of Phoenix. In addition to the rain chances, these systems will cool temperatures off below normal. Dry conditions and warmer temperatures are then expected Sunday and Monday before another weather system moves through the region on Tuesday. A fourth weather system is then possible by the end of next week. These systems will bring additional rain chances to the region and cool temperatures back below normal. MinRHs will be around 30-60% through next week, with excellent overnight recovery. Occasional wind gusts of 20-30 mph will continue through this morning, with winds returning to their light and diurnal patterns by this afternoon. Another period of gusty winds expected with the weather system on Tuesday.

HYDROLOGY

Gila: A Flood Warning remains in effect from Painted Rock Dam through the Dateland area through at least early next week due to water released from the dam. Water release levels have now risen to 3000 cfs and are expected to remain at this release level through the next several days. This will have the potential to flood farm fields and low-water crossings along the river downstream from the dam.

PSR WATCHES/WARNINGS/ADVISORIES

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