textproduct: NWS Flagstaff

SYNOPSIS

Daily afternoon and evening thunderstorm chances will occur throughout this week. Temperatures will be close to mid September averages with occasional southwesterly breezes in the afternoon hours.

DISCUSSION

The main story this week will be the passage of multiple shortwaves interacting with monsoon moisture that remains across the state. The first will arrive this afternoon as an upper level Low traveling along the northern Tier trails a wave across the state. Expect thunderstorm coverage to increase today with individual storm motion moving off to the northeast. The highest POPs favor the western zones today, with the best POPs moving into the eastern zones on Monday as the wave pushes east.

Starting on Tuesday a trough deepens off the West Coast. Another wave off this trough approaches Tuesday night through Wednesday morning. This will be followed by another wave Thursday into Friday. Each of these waves will keep the daily shower and thunderstorm chances going. This last wave moving out on Saturday morning may potentially bring some drier air into the area which could confine precipitation chances to the far eastern part of the state or push the precipitation all the way into the New Mexico but we'll have to keep monitoring to see if that's the case.

AVIATION...Sunday 13/12Z through Monday 14/12Z

Mainly VFR conditions, brief MVFR conditions possible near stronger storms. Expect scattered showers and thunderstorms to develop between 18Z-03Z, best chances generally west of a KPGA-KPAN line. Daytime winds S-SW 10-20kts, light and variable or terrain driven overnight. Gusty and erratic winds possible near thunderstorms.

OUTLOOK...Monday 14/12Z through Wednesday 16/12Z...Mainly VFR, brief MVFR possible near stronger storms. Scattered to numerous showers and thunderstorms likely during the afternoon and evening hours, with some nighttime showers and storms possible Monday night into Tuesday morning and Tuesday night into Wednesday morning. Highest coverage of storms will favor areas east of I-17 and US-89. Winds S-SW 10-20kts daytime, light and variable or terrain driven overnight. Gusty and erratic winds possible near thunderstorms.

FIRE WEATHER...Today through Monday

Scattered showers/storms coverage more widespread over the next couple days. Storms will be capable of producing heavy rain, hail, frequent lightning, and gusty/erratic winds. Daytime winds S-SW 10-20 mph gusting up to 25 mph. Minimum RH values generally between 30-55% each afternoon.

Tuesday through Thursday...Daily chances for showers/thunderstorms will continue each afternoon/evening. Coverage of storms may vary each day depending on previous day's activity. Storms will be capable of producing heavy rain, hail, frequent lightning, and gusty/erratic winds. Daytime winds S-SW 10-20 mph. Minimum RH values generally between 30-60% each afternoon.

FGZ WATCHES/WARNINGS/ADVISORIES

None.