textproduct: NWS Flagstaff

SYNOPSIS

Overall dry and seasonably warm conditions will continue through at least Friday, with a slight chance for showers and thunderstorms mainly over the higher terrain through Thursday. Looking toward the weekend or early next week, cooler and wetter conditions are possible as a system moves through the West Coast.

DISCUSSION

A weak shortwave trough, currently clipping the northwestern edge of the state, is leading an increase in mid-level clouds in northern AZ and will help support a slight chance of showers and thunderstorms, mainly over the higher terrain through through Thursday before moving off to east. The ridge of high pressure extending across southwestern AZ, continue to support the overall dry and seasonably warm conditions through Friday, and is helping to limit activity from the shortwave trough. The pressure gradient between the two features is supporting easterly to southeasterly winds during the daytime, around 5 to 10 mph.

The ridge begins to break down quickly over the weekend, with southwesterly winds developing. Ensemble model forecasts show the potential for a deepening trough over the interior Pacific Northwest around Friday or early Saturday and then dives southward around Sunday and into early next week. Depending on the timing of when this trough develops and deepens, it could pull moisture from Hurricane Rachel, which is currently moving west further into the Pacific Ocean and will weaken over the next several days.

While model ensembles have trended toward tropical moisture being captured by the trough and pushed into Arizona this weekend or early next week, potentially creating some impactful weather, there is still roughly a 20-30 percent chance that the timing of when the trough and Hurricane Rachel interact could limit the amount to tropical moisture captured and pulled into the region. For now continue to monitor the forecast and any future communication about the weather for this weekend or early next week.

AVIATION...Tuesday 06/18Z through Wednesday 07/18Z

VFR conditions, no precipitation expected. Winds variable 5-15kts daytime, light and variable or terrain driven overnight.

OUTLOOK...Wednesday 07/18Z through Friday 09/18Z...VFR conditions, isolated showers or thunderstorms possible over the White Mountains and Chuska Mountains between 18Z-03Z over the next two days. Winds NE-E 5-10kts daytime, light and variable or terrain driven overnight.

FIRE WEATHER...Wednesday and Thursday

Expect mainly dry conditions and continued seasonably warm temperatures. A slight chance of high-based showers and thunderstorms remains possible for Wednesday and Thursday afternoons, but primarily for the eastern zones. Chances for wetting rains are near zero. Daytime winds NE-E 5- 10 mph each afternoon, light and variable or terrain driven overnight.

Friday through Sunday...Dry and warm conditions Friday give way to shower and thunderstorms chances for Saturday and Sunday. The chances for wetting rain increases on Saturday and Sunday as tropical moisture is drawn into the region. Winds S 5-10 mph Friday, S-SW 10-20 mph on Saturday, picking up significantly to SW 15-25 mph on Sunday.

FGZ WATCHES/WARNINGS/ADVISORIES

None.