textproduct: NWS Flagstaff

SYNOPSIS

Moderate monsoon activity will continue through Monday, mainly along the higher terrain during the afternoon and evening hours. Then, as high pressure builds over Arizona, hot and mainly dry conditions are expected to develop as the flow of moisture northward into the region diminishes.

DISCUSSION

High pressure aloft was centered over New Mexico Sunday morning. It is expected that the high center will slowly drift southward through about Tuesday then westward becoming centered over southeast Arizona by Friday/Saturday. Look for daily chances for showers/thunderstorms across northern Arizona through Tuesday, with diminished chances later in the week as a drier and more stable air mass develops over northern Arizona.

For Today...Monsoon moisture will remain in place. As a result, we're looking at another round of isolated to scattered showers and thunderstorms. Much like on Saturday, look for shower and thunderstorm development over the mountains around midday with activity then tending to move north and east with the general flow aloft. Storms during the day will likely be most numerous from the Mogollon Rim and White Mountains northward. Another aspect to keep an eye on is the possibility of a convective blowup over southern Arizona this afternoon and evening. The potential is for a strong outflow boundary to be sent northward interacting with moisture and instability across central to northern Arizona. The result would be a mid to late evening (and even overnight) uptick in showers and storms across portions of northern Arizona (especially along and west of the I-17/Highway 89A corridor). Otherwise, light winds and generally hot conditions.

For Monday and Tuesday...Monsoon moisture remains in place with daily chances for showers and thunderstorms. The flow aloft will remain southerly with the bulk of activity expected from the Mogollon Rim and White Mountains northward. Otherwise, with the high remaining over the southwest United States, light winds will continue along with above normal temperatures, turning especially hot by Tuesday as high pressure begins to strengthen over Arizona.

Looking from Wednesday onward...Models appear to be trending toward high pressure aloft becoming centered over southeast Arizona. This solution would bring in a more southwest to west flow aloft which would deliver a drier air mass as well as a capping layer under the influence of weak subsidence. In addition, daytime temperatures will be on the increase, likely rising to the upper 80 to lower 90s in the mountains to 105 to 110 degrees at elevations below 4000 feet. A reminder that we remain in the grips of summer.

AVIATION...Sunday 23/12Z through Monday 24/12Z

Mainly VFR conditions. Another round of scattered SHRA/TSRA developing after 18Z and continuing through at least 03Z. Brief MVFR conditions and gusty/erratic wind possible in heavier SHRA/TSRA. Otherwise, look for variable winds at 5-15 kts.

OUTLOOK...Monday 24/12Z through Wednesday 26/12Z...Expect mainly VFR conditions. Scattered afternoon/evening SHRA/TSRA Monday, with coverage decreasing to isolated by Tuesday. Outside of gusty/erratic outflow driven winds, look for daytime winds mainly southwest to west 5-15 kts. Light and variable winds at night.

FIRE WEATHER...Today and Monday

Expect daily chances for showers/thunderstorms, with the greatest coverage across the higher terrain. Activity will ramp up around midday then continue through the evening hours both days. Outside of gusty and erratic storm driven winds, look for variable winds generally 10 mph or less.

Tuesday through Thursday...Drier conditions will gradually return, with activity becoming limited to the White Mountains by Wednesday and Thursday. Daytime highs are forecast to become quite hot, reaching 10-15 degrees above normal. Look for southwest winds 5-15 mph each afternoon.

FGZ WATCHES/WARNINGS/ADVISORIES

None.