textproduct: NWS Flagstaff

SYNOPSIS

High pressure continues to be the main story for the forecast period. Expect above normal daytime highs and daily chances for showers/thunderstorms. Coverage on storms will vary each day, but greatest odds will be across the higher terrain.

DISCUSSION

Once again our synoptic pattern remains the same with a strong area of high pressure dominating the Southwest. This pattern will allow high temperatures to stay several degrees above normal for this time of year, and for daily chances of showers/storms. The main adjustment since yesterday was the extension of the Extreme Heat Warning for the lower elevations of the Grand Canyon and also Marble/Glen Canyons through Friday evening. Although we do anticipate greater storm activity today and Thursday, model guidance lacks confidence on how far northward these showers/storms will reach. Regardless, temperatures will be hot, so minimize outdoor activity during the middle of the afternoon and stay hydrated!

The high will push northward today and tomorrow, allowing for convective activity to expand more westward from the eastern Rim and White Mountains. The NBM does have precipitation chances tapering off a little Friday and Saturday, before the high lands in a more favorable monsoon position for Sunday onward.

In short, expect above normal temperatures through the period, and isolated to scattered chances of showers/storms through the weekend, primarily across the higher terrain. Next week may hold greater coverage for convective activity, but we'll dive more into that in the days to come.

AVIATION...Wednesday 05/18Z through Thursday 06/18Z

VFR conditions, brief MVFR possible near heavier showers/storms. Scattered showers/storms mainly south of I-40 from 19Z-06Z. Winds SW-W 5-15kts daytime, light and variable or terrain driven overnight. Gusty and erratic winds possible near and ahead of storms.

OUTLOOK...Thursday 06/18Z through Saturday 08/18Z...VFR conditions, brief MVFR near showers/storms. Scattered showers/storms expected each day between 18Z-03Z and possibly lasting until 06Z. Winds SW-W 5-15kts daytime, light and variable or terrain overnight. Gusty and erratic winds possible near and ahead of storms.

FIRE WEATHER...Wednesday and Thursday

Above normal daytime highs will persist. Showers and thunderstorms likely each afternoon, primarily across higher terrain today, expanding westward on Thursday. Winds will generally be out of the west 5-15 mph, becoming light/terrain driven overnight. Minimum RH values between 5-15% along and north of the Little Colorado River Valley, and 20-40% elsewhere.

Friday through Sunday...Daytime highs will remain 5-15 degrees above normal through the weekend. Isolated showers/thunderstorms forecast for Friday and Saturday, becoming more widespread by Sunday/next week. Look for variable winds generally around 10 mph Friday and Saturday, becoming westerly winds 5-15 mph on Sunday. Minimum RH values between 5-20% along and north of the Little Colorado River Valley, and 20-40% elsewhere.

FGZ WATCHES/WARNINGS/ADVISORIES

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