textproduct: NWS Flagstaff

SYNOPSIS

Warm temperatures continue with isolated to scattered showers and thunderstorms through the weekend. Cooler temperatures and more widespread showers and thunderstorms are expected next week.

DISCUSSION...Today

Another round of scattered showers and thunderstorms is expected this afternoon into the early evening hours. PWATs remain around 0.80-1.00 inches across western and central Arizona, but sharply fall off north of the Mogollon Rim to around 0.50 inches in the Four Corners region. Thus, the greatest chances of storms this afternoon will remain mainly along, and southwest of the Mogollon Rim. A few isolated storms over Black Mesa and the Chuska Mountains are not totally out of the question.

Given the pool of moisture over central Arizona, flash flooding will be the primary concern this afternoon. However, latest RAP guidance forecasts 800-1200 J/Kg of surface CAPE, along with around 20 kts of 0-6 km shear just south of the Mogollon Rim this afternoon. Therefore, a one or two strong to severe thunderstorms can not be totally ruled out across Yavapai or Gila counties. Large hail will be the primary threat from any severe storm that does develop.

Sunday...As the high begins to shift, flow and moisture begins to be more supportive of storm coverage shifting to the Mogollon Rim and north. Coverage looks to still remain mainly isolated to scattered, with the best chances still remaining over the higher terrain. Flash flooding will remain the primary concern, however a strong to severe storm can not be totally ruled out.

Monday through Thursday...The high begins to weaken into the start of next week, and moves into the Four Corners region. Sub-tropical moisture increases further across northern Arizona, resulting in near daily chances for scattered to widespread showers and thunderstorms. Given the increased moisture, flash flooding will be primary hazard for the coming week. Daily coverage however remains uncertain, and will largely be determined by any lingering debris clouds. Otherwise, cooler temperatures and light winds prevail into next week.

AVIATION...Saturday 08/18Z through Sunday 09/18Z

Expect mainly VFR conditions outside of thunderstorms. ISO-SCT SHRA/TSRA between 19Z-03Z, mainly along and west of a KGCN-KFLG-KSJN line. Some storms will produce brief MVFR/IFR and wind gusts to 40 kts. Outside of storms, expect SW-W winds 5-15 kts.

OUTLOOK...Sunday 09/18Z through Tuesday 11/18Z...Expect mainly VFR conditions outside of thunderstorms. ISOLD-SCT SHRA/TSRA Sunday afternoon/evening, then SCT-NMRS coverage on Monday. Highest coverage along and near the Mogollon Rim and White Mtns, moving west/southwest into Yavapai/Gila counties later in the afternoon and evening. Some storms will produce brief MVFR/IFR and wind gusts to 40 kts. Outside of storms, expect SW-W winds 5-15 kts.

FIRE WEATHER...This afternoon through Monday

Above normal temperatures with isolated to scattered thunderstorms through Sunday. Storm coverage increases Monday along with slightly lower temperatures. Greatest coverage across higher terrain and areas to the south and west each afternoon/evening. Stronger storms may contain heavy rain, small hail, frequent lightning, and gusty/erratic winds. Outside of storms, expect variable winds around 5-15 mph. Minimum RH values 10-20% across NE Arizona, 20-40% elsewhere.

Tuesday through Thursday...Near to slightly below normal temperatures with scattered to widespread thunderstorms each day. Outside of storms, expect variable winds around 5-15 mph. Minimum RH values 20-40% across NE Arizona, 30-60% elsewhere.

FGZ WATCHES/WARNINGS/ADVISORIES

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