Arizona is having the heat this week and by the end month, mostly beginning of June we will see a pattern change, which could sneak up some moisture up out of Mexico. This cutoff system is between Hawaii and California right now. A separate cutoff low will be lifted this weekend up through Northern California and the Pacific Northwest where it will produce widespread thunderstorms there. National Weather Force networks will take care of that area (click here to hit FB page).
As for Arizona Weather Force’s forecast area of responsibility, there is still great uncertainty surrounding the beginning of June. Physics tells me that with the upper low this weekend swinging up, the Fujiwara effect will dance with an upper system west of it and swing southwest of California, which will put it low enough in latitude to scoop up moisture out of Mexico. The Fujiwhara effect, sometimes referred to as the Fujiwara effect, Fujiw(h)ara interaction or binary interaction, is a phenomenon that occurs when two nearby cyclonic vortices orbit each other and close the distance between the circulations of their corresponding low-pressure areas. The effect is named after Sakuhei Fujiwhara, the Japanese meteorologist who initially described the effect. Binary interaction of smaller circulations can cause the development of a larger cyclone, or cause two cyclones to merge into one.
Given the moisture from thunderstorms in Mexico will be generated by Caribbean moisture plumes westward, this leakage is possible in Arizona for the beginning of June and the scattered shower/thunderstorm probabilities will be on the rise.
Monsoon season officially goes from June 15th through September 15th. I still believe this season will have a start sometime late June into early July, centering Independence Day. The official final monsoon forecast will be released at National Weather Force via Arizona Weather Force on June 1st.