textproduct: NWS Flagstaff

SYNOPSIS

High pressure will continue to dominate the Southwest through the forecast period. This pattern will allow for above normal temperatures and daily chances for showers/storms. Greatest coverage will be across the higher terrain each afternoon/evening.

DISCUSSION

Isolated showers and thunderstorms have tapered off early this morning over the Navajo nation with minimal heavy rain impacts seen there. For this weekend a strong ridge will continue to build across the Four Corners before slightly wobbling eastward. Even with a slight shift in the general placement of this pressure system, above normal afternoon high temperatures and daily thunderstorm chances will remain through the entire forecast period. We are also expecting an influx of additional moisture from the southeast starting Sunday and lasting through the first half of next week at least. An Extreme Heat Warning remains in effect for elevations below 4000' at the Grand Canyon and for Marble/Glen Canyons through Sunday evening. Given a major heat risk and highs near 110 for the low elevations of Yavapai county, the Extreme Heat Warning for today was expanded there. Although these are the only areas where we have a heat product in effect, all lower elevation locations will be experiencing hot daytime highs through the next several days, so avoid strenuous activity during the middle of the day and stay hydrated! As for precipitation, greatest chances will be across the higher terrain each afternoon/early evening. Flash flooding will likely be the main concern with all the recent rainfall across much of our area.

AVIATION...Saturday 25/18Z through Sunday 26/18Z

Mainly VFR conditions expected, but brief MVFR conditions possible in heavier -SHRA/-TSRA this afternoon primarily across the higher terrain. Gusty/erratic winds possible from storm driven outflows, with variable winds 10 kts or less expected otherwise. Light/variable winds return overnight.

OUTLOOK...Sunday 26/18Z through Tuesday 28/18Z...Daily chances for -SHRA/-TSRA possible each day between 18Z-03Z. Greatest coverage expected over the higher terrain. VFR conditions mainly forecast, but brief MVFR conditions possible in heavier storms/showers. Outside of gusty/erratic winds from outflows, look for westerly winds 5-15 kts each afternoon, becoming light and variable overnight.

FIRE WEATHER...Today and Sunday

Very hot at lower elevations that do not receive rain or outflow boundaries. Otherwise, expect scattered showers and thunderstorms both days. Storms will be most common over the higher terrain, due to weak steering flow. Moisture values remain high, so any storms that do develop are capable of producing localized flooding. Outside of storm activity, expect generally light winds.

Monday through Wednesday...Expect active Monsoon conditions, but still hot at lower elevations that do not receive rain or outflow boundaries. Steering flow does improve during this period, from the south, so expect greater coverage as storms move off of terrain each afternoon and evening. Outside of thunderstorm activity, expect generally light winds.

FGZ WATCHES/WARNINGS/ADVISORIES

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

Extreme Heat Warning until 9 PM MST this evening for AZZ037.