Another Rare June Tropical Cyclone Remnant Visit

The passage of tropical cyclone (TC) remnants across the southwest U.S. is rare, but not unprecedented in June.  As illustrated by Ritchie et al. (2011),  rainfall events associated with TC remnants are most common over the southwest U.S. in September.  Action in June is more limited.  During the 1992–2005 period examined by Ritchie et al. (2011), there were only 2 rainfall events associated with TC remnants in June.

Number of eastern Pacific tropical cyclones, number of tropical cyclone remnants that brought rain to the southwest U.S., and number of tropical cyclone remnants that did not bring rain to the southwest but had other impacts.  Study period 1992–2005.  Source: Ritchie et al. (2011)

We've already had one this year associated with TC Andres, and now we'll have another associated with TC Blanca.  Blanca was a category 4 hurricane, but as of this morning had weakened to a tropical storm centered near the Isla Santa Margarita off the west coast of the Baja Peninsula.  High clouds in advance of Blanca were already streaming into southern Arizona.

As can be seen in the contours above, Blanca is accompanied by a slug of high integrated water vapor (a.k.a. precipitable water) and preceded by a surge of high integrated water vapor up the Gulf of California.  This moisture is expected to push into southern California and Arizona today and stream into southern Utah late tomorrow.  At the same time, moisture from the midlatitude Pacific also pushes into the Intermountain region from the west.

Thus, although we're in a bit of a break today and tomorrow, with just some isolated mountain showers and thunderstorms, the action should be on the increase after Tuesday with a good chance of showers and thunderstorms statewide on Wednesday and Thursday.

After nearly turning on my sprinklers in April, I still haven't run them and if we can get more rain midweek, I'll likely make it to at least the middle of the month.