textproduct: NWS Flagstaff

SYNOPSIS

Hot temperatures will remain in the region through the week with most of the area remaining dry Saturday. On Sunday monsoon moisture begins to return to the area bringing better storm chances and more extensive coverage of storms across the state.

DISCUSSION

The strong area of high pressure that's been giving us the above average temperatures this week will slowly start shifting off to the northeast by early next week. We will continue to see well above average temperatures through at least Sunday. Extreme Heat Warnings are up for the lower parts of the Grand Canyon as well as Marble Canyon through Sunday evening with temperatures reaching over 110 degrees in the bottom of these canyons. A little moisture will make it in Saturday for a few isolated storms along the Rim but moisture in the low levels will be lacking a bit, which makes things favorable for less rain but potentially gusty winds under or near the storms.

Starting Sunday the area of high pressure will have shifted off to our northeast which puts the return flow over our area and allows for a surge of moisture to move into the southern half of the state. Current models show storms firing off the Rim and White Mountains and moving west and southwest with some firing of storms over the lower deserts as well. The lower level of the atmosphere will be a little wetter with this round of storms so heavier rains are a better possibility. Lower deserts could see some strong outflow boundary winds ahead of storms moving off the Rim.

Monsoon moisture will overspread the majority of the state Monday through the rest of the week. This will lead to daily storm chances throughout the state during the afternoon and evening hours. Coverage and storm initiation times will be dependent on activity and left over cloud cover from the previous days. High temperatures will gradually return to seasonal averages by the weeks end with all the added moisture and cloud cover. Flash flooding will be a concern as rain production will be more efficient as the atmospheric column moistens along with areas potentially receiving repeated downpours day after day. Be careful with any outdoor plans this week, especially if you're recreating near canyons and recent burn scars.

AVIATION...Friday 10/18Z through Saturday 11/18Z

Mainly VFR conditions, isolated to scattered showers in the White Mountain region between 18Z-03Z could cause brief MVFR. Winds SW 5-15kts, gusts 20kts daytime, light and variable or terrain driven overnight.

OUTLOOK...Saturday 11/18Z through Monday 13/18Z...Mainly VFR conditions, MVFR possible near heavy showers/storms during the afternoons throughout the time period. Isolated showers/storms possible along the Rim and White Mountains Saturday afternoon. Showers/storms become more widespread in coverage Sunday afternoon mainly Rim southward, but some storms are possible along the Chuskas as well. Winds variable 5-15kts, gusts to 20kts Saturday, S-SW 5-15kts, gusts to 20kts Sunday. Gusty and erratic winds possible in the immediate vicinity of showers/storms.

FIRE WEATHER...Saturday and Sunday

Remaining hot. Shower and thunderstorm chances primarily over the Mogollon Rim and White Mountains area on Saturday, spreading further west and north on Sunday. Winds generally light and variable at 5-15 mph.

Monday through Wednesday...Shower and thunderstorm activity pushing across the region, best chances from the Mogollon Rim southward. Wetting rains are likely. Otherwise, turning a bit cooler with winds mainly southerly at 5 to 15 mph.

FGZ WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning from 11 AM MST /noon MDT/ Saturday to 8 PM MST /9 PM MDT/ Sunday for AZZ005.

Extreme Heat Warning until 8 PM MST Sunday for AZZ006.