textproduct: NWS Flagstaff

SYNOPSIS

High pressure will continue to influence our weather through the next week. Isolated to scattered chances for showers and thunderstorms, mainly across the higher terrain each day. Hot daytime temperatures are expected, with a slight cooling towards the middle of the week and gradually increasing shower and thunderstorm activity.

DISCUSSION

Very strong high pressure remains over Arizona, with a gradual shift to the north over the next few days. Dry air aloft continues to inhibit convective development. Most of the lingering moisture remains across southern Arizona up into portions of central Arizona. As a result, expect isolated to scattered showers and thunderstorms across the higher terrain, mainly focused over eastern Arizona through Tuesday. Storm activity remains diurnally driven with showers and storms dissipating as we head into the evening each day.

Heat remains the main story through the middle of the week with near- record to record temperatures across parts of the area. Extreme Heat Warnings continue over the Grand Canyon and Glen and Marble Canyons through Wednesday and Heat Advisories remain in place through Tuesday across much of northeastern Arizona.

As the high starts to push to the north, we will see an increase in moisture and temperatures will start to cool. The placement of the high looks to remain in a more favorable position for the region to allow for the monsoon to ramp up as we head into the end of the week. Expect daily chances for isolated to scattered showers and thunderstorms each day, especially across the higher terrain. As the models have come into better alignment on the position of the high, confidence is increasing in the more active monsoon returning. With temperatures across the Grand Canyon hovering around warning criteria for the second half of the week, we may need to extend the current heat headline beyond Wednesday but that may dependent on just how quickly the moisture pushes north. For now, expect a more active pattern to return with some slightly cooler temperatures.

AVIATION...Monday 03/18Z through Tuesday 04/18Z

Mainly VFR expected. ISO SHRA/TSRA along the higher terrain through 03Z, mostly along and south of KPAN-KSJN line. W winds 10-20 kts, becoming light and variable after 02Z. Gusty/erratic winds possible near showers/storms.

OUTLOOK...Tuesday 04/18Z through Thursday 06/18Z...Mainly VFR expected. ISO-SCT SHRA/TSRA between 18Z-03Z each day. W winds 10-20 kts each afternoon, becoming light and variable overnight. Gusty/erratic winds possible near showers/storms.

FIRE WEATHER...Tuesday and Wednesday

Above normal temperatures and isolated showers and thunderstorms each day, mainly across the higher terrain. Westerly winds around 5-15 mph each afternoon, becoming light or terrain driven overnight. Minimum RH values between 10-20% along and north of the Little Colorado River Valley, with 20-40% elsewhere.

Thursday through Saturday...Above normal temperatures continue through the end of the week with daily chances for showers and thunderstorms. Greatest storm activity is expected across the higher terrain. Westerly winds around 5-15 mph each afternoon, becoming light or terrain driven overnight. Minimum RH values between 10-20% along and north of the Little Colorado River Valley, with 20-40% elsewhere.

FGZ WATCHES/WARNINGS/ADVISORIES

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

Heat Advisory until 8 PM MST /9 PM MDT/ Tuesday for AZZ009-010- 012>014-040.

Extreme Heat Warning until 8 PM MST this evening for AZZ018-037- 038.