textproduct: NWS Flagstaff

SYNOPSIS

Monsoon moisture will return to the area through the coming week bringing better storm chances, especially for areas along and south of the Mogollon Rim. With the added moisture, hot temperatures begin to trend downward Monday ending up towards seasonal averages later in the week.

DISCUSSION

A strong high pressure system aloft was in the process of building over the north-central United States. The position of the high will place much of Arizona in a favorable position for increasing monsoon moisture over the coming week.

For today...Thunderstorm complexes over southern Arizona and northwest Mexico last night collapsed pushing moisture northward across portions of south and central Arizona. The result, deep moisture is in place from about the Mogollon Rim southward. Model sounding CAPE values range from around 200 J/kg across the Mogollon Rim to 400-600 J/kg at lower elevation south of the Rim. As storms build over the higher terrain of the Mogollon Rim, White Mountains and San Francisco Peaks with daytime heating storm motion to the west and southwest is expected (a combination of steering flow aloft and downslope moving outflow). The strongest storms are expected to be toward the southern edge of the Mogollon Rim southward across Yavapai and Gila counties where the highest CAPE values will be found. With hot temperatures continuing at the lower elevations any thunderstorm downpours will be capable of producing 45-60 mph winds gusts, the result of evaporational cooling. As usual, localized downpours in excess of 1.0 inch in less than an hour are likely. Values of CAPE south of the Rim are such that an isolated storm or two will be capable of producing nickle size hail. Elsewhere, further north and east weaker and more isolated storms are expected as moisture is laking further north.

For the remainder of the week...The high aloft will remain over the north-central United States into Wednesday before an inverted trough moving from east to west (south of the high center) dominates the weather across the southwest United States through next weekend. The net result is the door will remain open to the continued intrusion of moisture from over the Gulf of California and northwest Mexico, gradually working it's way further north. Look for active monsoon weather to continue with the chances for daily showers and thunderstorms continuing through into next weekend.

AVIATION...Monday 13/00Z through Tuesday 14/00Z

VFR overnight, VFR with MVFR possible near heaviest storms. A few isolated showers or thunderstorms are possible overnight. Scattered showers and thunderstorms will redevelop over the higher terrain around 18Z Mon and move out westwards over the lower deserts as the afternoon progresses. Winds light and variable or terrain driven overnight, becoming S-SW 5-15kts after 18Z Monday. Gusty and erratic winds up to 30-40kts possible near thunderstorms.

OUTLOOK...Tuesday 14/00Z through Thursday 16/00Z...VFR with MVFR possible near heaviest storms. Scattered showers/storms each afternoon mainly between 18Z-04Z throughout most of the area. Winds SW-SE 5-15kts daytime, light and variable or terrain driven overnight. Gusty and erratic winds up to 30-40kts possible near thunderstorms.

FIRE WEATHER...Monday and Tuesday

Temperatures trending back towards normal as monsoon moisture increases across the area. Showers and thunderstorms likely each afternoon along the higher elevations with a 10-30% chance of showers or thunderstorms in the high desert regions. Winds S-SE 5-15 mph Monday, S-W 5-15 mph Tuesday. Min RH's 15% deserts to 35% mountains Monday, 15% deserts to 40% mountains Tuesday.

Wednesday through Friday...Afternoon and evening showers and thunderstorms likely across most of the region each day with the best chances over the higher elevations. Temperatures near seasonal averages. Winds S-SW 5-15 mph. Min RH's 15-30% deserts to 50-60% mountains.

FGZ WATCHES/WARNINGS/ADVISORIES

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