textproduct: NWS Flagstaff

SYNOPSIS

Warm temperatures and isolated to scatted showers and thunderstorms will continue through the weekend. Monsoonal moisture then increases each day through much of next week, with daily chances for showers and thunderstorms. Cooler temperatures will also set in next week.

DISCUSSION...Today

Lingering cloud cover this morning has delayed the initial start of convection this morning. However, another round of storms looks to develop around 1 PM MST over the higher terrain. Storms will then move southwest through the afternoon off the higher terrain, as development becomes outflow driven. Thus, the greatest chances will largely be from Grand Canyon to Flagstaff to the White Mountains, and areas southwest. Some additional isolated activity looks possible along Black Mesa.

Instability and shear, while still weak, look to be the greatest across Yavapai and Gila counties. So a few strong to severe thunderstorms will be possible this afternoon in these areas. Otherwise, flash flooding will be the primary hazard.

Saturday and Sunday...Isolated to scattered coverage remains into the weekend as the high gradually begins to weaken and wobble around the Four Corners. Moisture remains largely focused across western and central Arizona, thus the greatest coverage over the weekend will largely be from the Mogollon Rim, south and west. A strong to severe storm can not be totally ruled out, but flash flooding will remain the primary hazard into the weekend.

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 08/00Z through Sunday 09/00Z

Expect VFR conditions outside of thunderstorms. SCT SHRA/TSRA generally along and west of the Mogollon Rim/White Mtns through 02Z-04Z, dissipating overnight. Mainly ISOLD cells north and northeast of these areas. Heavier storms will produce brief MVFR/IFR and wind gusts to 40kts. Expect similar coverage on Saturday, mainly AFT 19Z. Sfc winds generally light outside of thunderstorms and outflows.

OUTLOOK...Sunday 09/00Z through Tuesday 11/00Z...Expect mainly VFR conditions outside of thunderstorms. SCT-NMRS SHRA/TSRA from 18Z-03Z each day, but especially for Monday and especially along and near the Mogollon Rim and White Mtns. Heavier storms will produce brief MVFR/IFR and wind gusts to 40kts. Sfc winds generally light outside of thunderstorms and outflows.

FIRE WEATHER...Saturday and Sunday

Temperatures still 5-10 degrees above average. Expect showers and thunderstorms to develop over the higher terrain each day around midday and move to the south and west during the afternoon and evening hours before dissipating early nighttime hours. Gusty and erratic winds possible ahead of and near storms. Outside of storms, expect variable winds around 5-15 mph. Minimum RH values 5-15% NE Arizona deserts to 20-35% elsewhere.

Monday through Wednesday...Temperatures cooling back down to near seasonal averages. Uptick in monsoon for the first half of the week with scattered to numerous showers/thunderstorms expected area wide each day. Gusty and erratic winds near and ahead of storms. Outside of storms, expect variable winds around 5-15 mph. Minimum RH values 15-25% NE Arizona deserts to 30-50% in the higher terrain.

FGZ WATCHES/WARNINGS/ADVISORIES

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