textproduct: NWS Flagstaff

SYNOPSIS

Gradually warming temperatures and a slight downturn in monsoon activity is expected for Friday into next week. Monsoon activity may start to pick up again around the middle of next week.

DISCUSSION

High pressure remains centered well to the east of the region this afternoon with a trough digging down to our west. The trough will dig down and then move into Arizona tonight. The high blocks the forward progression of the trough and we remain situated in between the two features through the weekend. As we head into next week, the high starts to reestablish itself and shifts westward, eventually settling over the desert southwest by midweek. Now that we have the pattern established, let's talk about the details.

Tonight through Friday...scattered showers and thunderstorms will continue through this afternoon and into this evening, mainly along a line from the Kaibab Plateau down through the Mogollon Rim to the White Mountains. Plenty of moisture is across the region and storms have been a pretty efficient rain producers. Flash flooding remains the greatest threat through today. Even though storm motions have been faster (10-15 mph) we continue to see training/backbuilding of storms, which only increases the potential for flash flooding as heavy rain becomes prolonged over one area. Shear is pretty weak at the surface but strengthens quite a bit as you move aloft (as seen on out 18Z sounding). Best instability and lift is over western Arizona, closer to the trough axis, where the potential for strong to severe storms will remain possible. Expect a similar set up for Friday, with another round of scattered showers and thunderstorms and the potential for flash flooding.

Saturday through Sunday...the pull between the ridge to the east and the trough to the west will place us in more of a southwesterly flow, bringing in some drier air and warmer temperatures. Moisture doesn't fully scour out and we may continue to see some isolated activity, mainly confined to the White Mountains and the higher elevations.

Monday and onward...The high starts to really make push back to the west which may help to increase moisture across the region once again. If the high is able to settle in a more favorable position, we should start to see storm activity increase little by little each day.

Another day of scattered storms, then a downturn in activity into early next week before we could see a return to a more active monsoon. Plenty to look forward to in the coming week.

AVIATION...Friday 14/06Z through Saturday 15/06Z

Fair weather and light winds are forecast overnight. The exception is in western Coconino County where a 20-30% chance for storms is forecast, potentially impacting KGCN early Friday morning. Otherwise, a round of scattered to numerous SHRA/TSRA is forecast to developing across much of the area from 18Z-03Z, with the greatest activity across northwest Arizona. Stronger storms may produce brief MVFR/IFR conditions and wind gusts as high as 35 kts. Otherwise, afternoon winds west to southwest at 10-15 kts, becoming light and variable after 03Z.

OUTLOOK...Saturday 15/06Z through Monday 17/06Z...Expect mainly VFR conditions away from thunderstorms. On Saturday, a downturn in storm activity is forecast with mainly isolated -SHRA/-TSRA over the mountains for the weekend. Stronger storms may produce brief MVFR/IFR conditions and wind gusts as high as 35 kts. Daytime winds west to southwest at 5-15 kt, light and variable at night.

FIRE WEATHER...Friday and Saturday

On Friday look for numerous showers and thunderstorms across northwest Arizona, generally isolated to scattered for the remainder of the area. Saturday will see a downturn in activity with mainly isolated storms over the Mountain areas. Daytime temperatures will remain at or near normal, with afternoon southwest winds from 10 to 15 mph, outside of any convection.

Sunday through Tuesday...Showers and thunderstorms will be few and far between for most of northern Arizona. The exception, scattered shower and thunderstorm activity is still anticipated for the eastern Mogollon Rim, White Mountains and Chuska Mountains. Temperatures will gradually warm with light south to southwest winds each day.

FGZ WATCHES/WARNINGS/ADVISORIES

None.