textproduct: NWS Flagstaff

SYNOPSIS

Deep monsoon moisture will remain over the area into the coming weekend and well into next week. With this moisture comes the daily threat of thunderstorms, along with the risk for locally heavy rainfall and flooding. With the added moisture and cloud cover, daytime temperatures will largely remain below normal.

DISCUSSION

Another active monsoon day is underway as Arizona remains entrenched in a moisture-rich airmass. Mid level high pressure remains anchored to our north over Utah, Colorado and Wyoming, resulting in an east to northeasterly steering flow across the state. Scattered thunderstorms have initiated over the greater Flagstaff and Prescott areas as well as high terrain across eastern Arizona. The easterly steering flow and best moisture/instability will focus activity across western portions of the area today, including Yavapai and Coconino counties. Precipitable water values across western Arizona range from 1.5" to nearly 2.0" and are anomalously high (near and above the 99 percentile) for this time of year. Additionally, the Bellemont sounding PW value of 1.22" is the daily max for this date. With the abundance of moisture, slow storm motion, and modest instability, flash flooding will continue to be the primary concern. A few stronger cells that manage to capitalize on pockets of higher instability will be capable of localized hail or gusty winds. Similar to the last few days, a second round of showers/storms from the northeast is possible later this evening and tonight.

A similar day is in store for Saturday with convective initiation over the Rim and higher terrain, with light steering flow moving things to the west/southwest through the afternoon. Heavy rain leading to flash flooding will continue to be the primary concern through the weekend.

Late in the weekend and into early next week, the easterly wave that's been over Texas and New Mexico looks to make it's way into Arizona. This will help keep us in an active monsoon pattern with daily showers/storms. Steering flow looks to remain from east to west through at least midweek next week. The second half of the week could begin to see a shift in the pattern to more of a southerly flow. There are no indications of any major pattern shifts or moisture changes through the foreseeable future.

AVIATION...Saturday 18/06Z through Sunday 19/06Z

ISO SHRA possible through 14Z, with SCT-NMRS TSRA/SHRA expected after 18Z/19Z. Brief MVFR/IFR conditions and gusty winds within ISO +TSRA. Winds light and VRB, becoming S-W 5-15 kts after 18Z.

OUTLOOK...Sunday 19/06Z through Tuesday 21/06Z...Daily chances for SCT-NMRS SHRA/TSRA, with the best chances during the afternoon and evening hours. Brief MVFR/IFR conditions and gusty winds within ISO +TSRA. Winds primarily VRB 5-10 kts each day, tending S-W during the afternoon.

FIRE WEATHER...Saturday and Sunday

Expect a medium to high grade monsoon environment to continue, with generally light winds outside of outflow and thunderstorm activity. Most storms will produce a wetting rain with stronger storms producing localized Flash Flooding. Cooler than normal daytime temperatures with the cloudiness.

Monday through Wednesday...Daily chances for showers and thunderstorms, with generally light winds outside of outflow and thunderstorm activity. Most storms will produce a wetting rain with stronger storms producing localized Flash Flooding.

FGZ WATCHES/WARNINGS/ADVISORIES

None.