textproduct: NWS Flagstaff

SYNOPSIS

Active monsoon pattern will continue through Monday night, with flash flooding being a primary concern. Calmer conditions forecast to return for the middle of the week. Unsettled weather looks to return by the end of the week/next weekend.

DISCUSSION

Isolated to scattered activity remains mostly east of I-17 and south of I-40, and hi-res guidance suggests this southeastern portion of our CWA to be the center of attention for showers/storms through the rest of the overnight period. The severe threat appears to have dwindled, but there's plenty of lightning and brief heavy showers still out there. A Flash Flood Watch continues through 5 AM MST for Yavapai County, northern Gila County, and Oak Creek and Sycamore Canyons.

An additional Flash Flood Watch is in place starting at 2 PM MST today (Sunday) for all of central/northern AZ and continues through late Monday night. Monsoonal moisture hangs on tight today and much of Monday. This is reflected in our PWAT values ranging from an inch towards the AZ/UT border and near 1.5 inches across the Mogollon Rim southward. Taking a look at the recent U of A WRF run, activity this afternoon could be slightly delayed from early morning debris clouds, so expect showers/storms to pick up closer to noon-1PM. Initially, we'll see activity fire up along the Rim and northward, but then the potential for a MCS to form south of our CWA later in the evening will lead to widespread showers/storms Sunday night into Monday.

By Tuesday, we'll see a quick decline in PWATs as a shortwave trough glides across the Great Basin region and pushes moisture further south. There is still potential for isolated activity primarily across the Kaibab Plateau and White Mountains Tuesday through Thursday, but overall should be much quieter in terms of active weather for the middle of the week. Not to mention the westward trajectory of Tropical Storm Karina will not help bring in any additional moisture during this timeframe.

Friday onward we could return to an active monsoon pattern. Model guidance suggests high pressure strengthening across the central US and another tropical system funneling up the western California Baja Coast. There's still uncertainty on how everything will pan out, but for now know we could see a quick return of active weather Friday and over the upcoming weekend.

AVIATION...Sunday 30/12Z through Monday 31/12Z

VFR conditions expected through at least 18Z, with decreasing ceilings/visibilities likely afterwards due to increasing chances for SHRA/TSRA. Showers/storms will continue through the end of the period after 18Z. Gusty/erratic winds likely near storms, with W-SW winds 10-20 kts otherwise.

OUTLOOK...Monday 31/12Z through Wednesday 02/12Z...MVFR/IFR conditions may continue through 06Z Tuesday, due to persistent SHRA/TSRA. Afterwards, expect quickly improving conditions. Gusty/erratic winds likely near storms, with SW winds 10-20 kts during the afternoon hours and becoming light and variable overnight.

FIRE WEATHER...Sunday and Monday

Active monsoon weather continues each day, as well as into the overnight hours. Storms will be capable of producing hail, heavy rain, frequent lightning, and gusty/erratic winds. As a result of the heavy rain threat, a Flash Flood Watch is in place for all of central/northern AZ Sunday afternoon through Monday night. A cooling trend is expected, leaving daytime highs 5-10 degrees below normal by Monday. Outside of storm driven outflows, look for southwest winds 5-15 mph Sunday, becoming lighter out of the south on Monday.

Tuesday through Thursday...Precipitation chances will quickly decline through the middle of the week, but an isolated shower/storm across the higher terrain is not completely out of the question. Daytime highs will slowly warm each day, bringing temperatures closer to seasonal norms. Look for southwest winds 10-20 mph each afternoon, becoming light and variable overnight.

FGZ WATCHES/WARNINGS/ADVISORIES

Flood Watch from 2 PM MST /3 PM MDT/ this afternoon through Monday evening for AZZ004>018-037>040.

Flood Watch until 5 AM MST early this morning for AZZ008-018-037- 038.