textproduct: NWS Flagstaff

SYNOPSIS

Hot temperatures will remain this weekend. On Sunday, monsoon moisture begins to return to the area bringing better storm chances and more extensive coverage of storms across the state through next week. With the added moisture, temperatures begin to trend downward Monday towards seasonal averages.

DISCUSSION

Area of high pressure continues to move off towards the northeast setting up in a position more favorable for monsoon moisture to make its way into the southern half of Arizona on Sunday. Moisture continues to push north Monday before covering most of the state by Tuesday and lasting throughout the week. Above average hot temperatures will last at least one more day before the added humidity and cloud cover moderates the heat with a trend towards normal temperatures by midweek and potentially a few degrees below normal by next weekend. An Extreme Heat Warning remains in effect for lower elevations of the Grand Canyons and Marble Canyon until Sunday evening.

For Sunday storms form along the Mogollon Rim and White Mountains and push out westward towards the mid elevation deserts. With low level layers still being on the dry side, downburst winds towards severe levels are a possibility. Currently Storm Prediction Center has most of Yavapai County and the southwestern half of Gila County in a Marginal Risk for severe storms to account for the downburst wind potential. A marginal risk for flash flooding is also possible generally in areas south of I-40, but the drier low levels of the atmosphere may come into play on limiting rainfall amounts with this initial push.

Depending on how much cloud cover and overturning of the atmosphere occurs Sunday a similar setup looks to occur on Monday, storms firing over the higher terrain and moving west to northwestward. The main difference on Monday will be the lower levels of the atmosphere being moistened up and a bit more conducive to higher rainfall amounts. A marginal risk of flash flooding continues for southern and western halves of Arizona. By Tuesday into Wednesday the marginal risk of flash flooding overspreads most of the state with numerous showers/storms expected each day. This trend continues for the rest of the week as monsoon moisture continued to remain over the state.

AVIATION...Sunday 12/00Z through Monday 13/00Z

Mainly VFR conditions. ISO -SHRA/-TSRA possible mainly near a KSEZ-KPAN line through 03Z. SCT SHRA/TSRA expected again after 19Z, mainly south and west of a KGCN-KFLG-KJTC line. Brief periods of MVFR conditions and gusty outflow winds possible in and around TS. Winds SW-SE 5-15 kts.

OUTLOOK...Monday 13/00Z through Wednesday 15/00Z...Mainly VFR. SCT SHRA/TSRA each day, with the greatest likelihood south and west of a KGCN-KFLG-KJTC line. Brief periods of MVFR conditions and gusty outflow winds possible in and around TS. Winds SW-SE 5-15 kts each day, becoming light and variable overnight.

FIRE WEATHER...Sunday and Monday

Remaining hot. Increasing chances for showers and thunderstorms with activity spreading further north and west each day. Strong storms with gusty winds will be possible each afternoon and evening, mainly across Yavapai and Gila counties. Outside of storms, winds 5-15 mph south through west on Sunday shifting to south through southeast on Monday.

Tuesday through Thursday...Shower and thunderstorm activity increasing across the region, best chances from the Mogollon Rim and White Mountains southward where wetting rains are likely. Otherwise, turning a bit cooler with winds mainly southwest 5-15 mph.

FGZ WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning until 8 PM MST /9 PM MDT/ Sunday for AZZ005- 006.