A slow-moving low-pressure system is the culprit of unsettled weather as we close out the weekend. Storm chances will increase again starting late Saturday night through Sunday.
Sunday will feature periods of heavy rainfall and thunderstorms. Flooding will be the biggest concern; some storms will likely produce a lot of rainfall within a short period of time. Training storms, or storms moving over the same areas in a short amount of time, will likely lead to flooding. Rainfall totals near 0.50" are forecast, with locally one to two inches of rain possible. It only takes one strong storm to drastically enhance rainfall amounts.
In addition to flooding, damaging wind gusts and some hail could accompany stronger storms on Sunday. Once the low-pressure system moves into New Mexico, rain and storm chances will diminish later in the day on Monday.
After a lull in the monsoon on Tuesday, the next system will make a move in our direction toward the middle of the week. A trough that will move in from the northwest will stall out over the region. This trough will return rain and storm chances Wednesday through Friday. While not as much moisture will be present, this system will likely bring cooler temperatures. It's likely that Mother Nature will treat the valley to highs in the 80's and 90's next week. The Phoenix Metro typically sees high temperatures near 97 degrees this time of year. As the system tracks closer to the region next week, we will have a much better handle on forecast specifics.