textproduct: NWS Flagstaff

SYNOPSIS

Showers and thunderstorms continue today, before most activity slowly tapers down to isolated coverage later this week and into the weekend. Once the activity slows down, expect daytime high temperatures to soar, likely reaching the warmest readings so far this year by the coming weekend.

DISCUSSION

High pressure still remains to our east and is in a slightly weakened state, due to weak troughing over the western Great Basin. Moisture levels are still on the high side, largely due to influx that arrived on Tuesday. There is also a weak MCV along the Lower Colorado River, forecast to move toward the Kaibab Plateau later this afternoon. All these things point toward at least scattered activity again today. The catch is, southerly steering flow and the MCV enhancement will favor areas along and north of the I-40 corridor, as well as the usual elevated heat source of the White Mountains.

After today, the high begins to move westward and strengthen, This slowly introduces drier, mid-level air and subsidence, activity will slow down. We don't expect a total stop, but it will be slow through the weekend. The high may return to a more favorable location by next week, with easterly steering flow returning, but much can change in a week and we will see.

Additionally, once the high relocates and strengthens, along with the Monsoon pause/slow down, temperatures will soar. We expect many areas to reach the warmest readings so far this year. The various heat products that have been issued remain appropriate.

AVIATION...Wednesday 29/12Z through Thursday 30/12Z

Expect mainly VFR conditions. SCT SHRA/TSRA from 19Z to 03Z, mainly north of a KPRC-KSEZ-KJTC line. Brief periods of MVFR conditions and gusty outflow winds in excess of 40kts possible in and around stronger storms. Sfc winds light.

OUTLOOK...Thursday 30/12Z through Saturday 01/12Z...Expect mainly VFR conditions. ISO-SCT SHRA/TSRA each afternoon/evening, especially INVOF the White Mtns. Brief periods of MVFR conditions and gusty outflow winds in excess of 40kts possible in and around stronger storms. Sfc winds light.

FIRE WEATHER...Wednesday and Thursday

Expect scattered showers and thunderstorms again today, especially north of the I-40 corridor and over the White Mountains. A downturn begins on Thursday, as high pressure strengthens overhead. Expect mainly light winds outside of thunderstorms, but trending toward westerly through southwesterly 5 to 15 mph over higher terrain in the afternoon hours. Temperatures stay around normal for more day, but then rise above normal starting on Thursday.

Friday through Sunday...A continued downturn in Monsoonal activity is expected through this period. A chance for afternoon showers and thunderstorms remains possible over higher terrain, mainly the White Mountains. Temperatures will rise significantly during this period and many areas seeing the warmest conditions so far this year. Winds will be generally light and variable at 5 to 15 mph.

FGZ WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning from 10 AM MST /11 AM MDT/ Friday to 8 PM MST /9 PM MDT/ Sunday for AZZ005-038, as well as AZZ018-037 below 4000 feet.

Extreme Heat Warning from 10 AM Thursday to 8 PM MST Sunday for AZZ006 below 4000 feet.