7AM Day 1 Convective Outlook for Monday, August 25. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN ARIZONA
SUMMARY
Isolated severe wind gusts are possible over parts of south-central Arizona this afternoon through early evening. Otherwise, the potential for severe storms is low across the remainder of the continental U.S.
..Synopsis
A large upper-level trough will continue to amplify across the eastern CONUS today. High pressure, currently analyzed across the northern Plains early this morning will expand slowly southward through the day which will push the polar front off the Atlantic coast and perhaps into the Gulf. A persistent upper-level ridge will exist across the Southwest and into the Great Basin/Rocky Mountains. Beneath this ridge, a continued monsoon push will result in widespread thunderstorm activity this afternoon/evening.
Southern Arizona
Thunderstorms are forecast to develop this afternoon/evening across much of the Southwest amid weak to moderate instability (1000-1500 J/kg MLCAPE) as temperatures cool aloft. A belt of stronger mid-level southeasterly flow (20-25 kt) is forecast to overspread the region and provide ample shear for some multicell storm clusters. Initial storms which are expected to form across the higher terrain in southeast Arizona may result in congealing outflow with a damaging wind threat as storms move generally west-northwestward through the evening.