textproduct: NWS Flagstaff

SYNOPSIS

Isolated showers and thunderstorms are expected today across the area, with scattered activity in northwest Arizona and the White Mountains. Storm activity will be confined to far eastern Arizona Monday before spreading back westward through next week. Temperatures will be close to normal through Labor Day, warming above normal by mid week.

DISCUSSION...Today

Sub-tropical moisture has surged northward as a result of Hurricane Marie (~800 miles W of the tip of the Baja California peninsula). A band of showers and embedded thunderstorms has moved northward through northern Arizona at the leading edge of the moisture surge, largely driven by large-scale ascent ahead of an approaching shortwave. As the shortwave ejects off the Pacific, the band begins will stall through the remainder of the day. Much of the latest hi-res guidance shows it stalling over northwestern Arizona, largely to the west of our CWA, just brushing northwestern Coconino County. Elsewhere, mainly dry conditions are expected, outside of a few isolated showers an thunderstorms along the higher terrain. Rainfall amounts so far this morning have been fairly minimal, with only a few hundredths to a couple tenths in the steadier areas of precipitation. Therefore, the threat for any strong thunderstorms and flash flooding remains low.

Monday and Tuesday...With moisture still in place, a few isolated showers and thunderstorms will be possible again Monday. Activity looks to however be fairly minimal, as warming aloft will limit the potential for vertical motion. Drier surface conditions will also limit how much rain will actually reach the ground.

Coverage for Monday looks to be mainly focused across the eastern Mogollon Rim, White Mountains, and the Chuska Mountains. A similar trend looks to follow suit into Tuesday, through potentially expanding coverage along the remainder of the Mogollon Rim.

Wednesday through Saturday...High pressure over the central US begins to retrograde back over the southwest over the second-half of the week. Much of the EPS, GEFS, and CMCE members have PWATs remaining high enough for continued monsoonal activity through at least the end of the work week; albeit a slight downward trend. Thus, continued daily chances for afternoon showers and thunderstorms seems reasonable. Much of the activity should be fairly isolated to scattered in nature, and most numerous over the higher terrain. Temperatures also look to gradually climb each day, as heights gradually rise over Arizona.

Thereafter, there remains some uncertainty as a trough may descend through the Great Basin and suppress some of the moisture to the south. A strengthening ridge behind the trough over Nevada may also further suppress upward motion, while also ushering in drier air from the north.

AVIATION...Sunday 06/18Z through Monday 07/18Z

Mainly VFR conditions. Expect scattered showers over northwest Arizona today with KGCN and KPGA terminals potentially seeing a few showers or thunderstorms today. A few isolated afternoon thunderstorms are also possible over the White Mountain region. Rest of the state will be dry. Winds SW-W 10-20kts daytime, light and variable or terrain driven overnight.

OUTLOOK...Monday 07/18Z through Wednesday 09/18Z...Mainly VFR conditions. Isolated to scattered showers and thunderstorms possible over the White Mountains and East Rim Monday afternoon, isolated to scattered afternoon showers and thunderstorms possible over the Rim and White Mountains Tuesday afternoon. Winds SW-W 5-15kts daytime, light and variable or terrain driven overnight.

FIRE WEATHER...Monday and Tuesday

On Monday, isolated to scattered afternoon showers and thunderstorms will be confined to the higher terrain in the eastern third of Arizona. By Tuesday afternoon showers and thunderstorm chances begin to move westward along the Mogollon Rim with continued chances over the mountains of eastern Arizona. High temperatures near normal Monday warming to about 5 degrees above average Tuesday. Winds SW-W 5-15 mph with gusts to 25 mph each afternoon, light and variable or terrain driven overnight. Minimum RH's each afternoon ranging from 15% in the lower deserts to 30-40% in the mountains.

Wednesday through Friday...Afternoon showers and thunderstorms remain primarily over the higher terrain of the Rim and White Mountains each day. Temperatures warming to 5-10 degrees above normal. Winds S-SW 5-15 mph each day, light and variable or terrain driven overnight.

FGZ WATCHES/WARNINGS/ADVISORIES

None.