textproduct: NWS Flagstaff

SYNOPSIS

A downtick in monsoonal activity is expected through Monday, with only isolated storms over the higher terrain of eastern Arizona. Very hot daytime temperatures are also expected, possibly the warmest of the year so far. A cooling trend and a gradual uptick in moisture are possible towards the middle of next week.

DISCUSSION

Our downtick in monsoonal activity will continue this weekend as a strong high pressure system remains centered over Arizona. This downtick will be driven by drier air working into the region and subsidence under the ridge. Model soundings indicate that capping aloft will continue to strengthen, combined with PW dropping to the 20th-40th percentile for early August. Overall storm coverage and intensity this weekend will be suppressed. Activity will not shut off completely, still expect isolated storms over the higher terrain of eastern Arizona each day.

The primary hazard over the next few days will be heat. The decrease in moisture plus above normal heights at 500 mb will lead to the warmest temperatures of the year so far. Low elevation areas south of the Mogollon Rim, and the lower elevations of the Grand Canyon and Glen/Marble Canyon will see daytime highs approach or exceed 110 F. The Extreme Heat Warning for these areas has been extended until Monday, with the Grand Canyon heat warning extended until Tuesday. The lower elevations of northeastern Arizona will see above normal temperatures up to 100-105 F. The Heat Advisory for these areas has also been extended until Monday. Be sure to drink plenty of fluids and avoid prolonged outdoor activity this weekend if you can!

The high is forecast to weaken and elongate by the early to middle part of next week. The current forecast calls for a cooling trend and uptick in moisture beginning Tuesday-Wednesday. There is still plenty of uncertainty at this point in the forecast, and guidance varies on the strength and exact placement of the ridge. However, the overall ensemble trend is for PW to climb back towards another period of active monsoonal conditions.

AVIATION...Saturday 01/12Z through Sunday 02/12Z

VFR conditions. ISOLD -SHRA/-TSRA INVOF a KFLG-KSOW-KJTC line from 19Z to 03Z. Gusty outflow winds possible in and around TS. Otherwise, winds VRB 5-10 kts.

OUTLOOK...Sunday 02/12Z through Tuesday 04/12Z...VFR conditions. ISOLD -SHRA/-TSRA each afternoon/evening INVOF KSOW/KJTC. Gusty outflow winds possible in and around TS. Otherwise, winds VRB 5-15 kts.

FIRE WEATHER...Today and Sunday

Very hot, with the warmest temperatures of the year so far. Isolated showers and thunderstorms each afternoon/evening over the higher terrain of eastern Arizona. Winds light and variable at 5-15 mph. Minimum RH generally 10-20%, locally higher in the White Mountains.

Monday through Wednesday...Hot with a slight cooling trend and increasing moisture through the period. Isolated showers and storms over the White Mountains Monday, with coverage increasing and expanding westward on Tuesday and Wednesday. Daytime winds generally southwest through west at 5-15 mph each day.

FGZ WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning until 8 PM MST /9 PM MDT/ Monday for AZZ005- 018-037-038.

Extreme Heat Warning until 8 PM MST Tuesday for AZZ006.

Heat Advisory from 10 AM MST /11 AM MDT/ this morning to 8 PM MST /9 PM MDT/ Monday for AZZ009-010-012>014-040.