textproduct: NWS Flagstaff

SYNOPSIS

Mostly dry and warm conditions will continue today with a slight chance for an isolated shower or thunderstorm across the higher terrain this afternoon. Cold, windy, and wet conditions return over the weekend as tropical moisture moves into the region, with the potential for a significant rainfall event.

DISCUSSION

A ridge of high pressure will try to build into the area today but it remains weak as it tries to build into the area. As a result, it will be short lived across the region as a trough/low pressure starts to develop over the eastern Pacific. A few lingering showers or thunderstorms may develop through this afternoon across the higher terrain but expect most areas to remain dry with warm temperatures continuing.

The weather shifts over the weekend as we see tropical moisture and a couple of troughs/lows move into the region. The low over the eastern Pacific is cut off and starts to interact with what will eventually become the remnants of TS Rachel. This system will be slow to move on Saturday, but as a trough digs down from the Pacific Northwest, it will begins it push to the northeast and towards the Desert Southwest. The latest model runs take Rachel and start bringing the moisture inland on Saturday in the deepening south- southwest flow, with the bulk of moisture arriving late Saturday and Sunday. This moisture will hang around through the weekend and into next week, with periods of rain, some of which may be heavy, especially over western Arizona. The tropical remnants look to push to the northeast and out of the area by late Sunday, but the deepening PacNW trough will dive southward along the California coast, and move through the area early in the week, possibly not exiting fully until Wednesday. Certainly a pretty unsettled period for our region.

QPF ranges remain fairly widespread but the potential for 1-3" with locally higher amounts are possible. Current projections based on the path for Rachel put the highest amounts across Yavapai and western Coconino counties with higher amounts to the west in Mohave County. There remains some uncertainty as to whether we will see prolonged periods of light to moderate rain or more robust heavy rainfall along with thunderstorms through the event, the latter of which could lead to flash flood concerns. As Rachel pushes to the northeast, we should be able to get a better picture of where the best moisture advection will take place. With that in mind we will hold off on any flood watches at this time.

Another thing to keep an eye on will be the increasing south to southwest winds as the gradient really tightens up with Rachel pushing towards the SoCal coast and the deepening PacNW trough. Winds look to be strongest in the Sunday through Tuesday time frame. Winds will start to increase on Saturday but become stronger on Sunday, where we will see south to southwest winds 15-25 mph with gusts 35-45 mph. Winds look to remain strong on Monday but then start to taper off on Tuesday. Wind Advisories may be needed so stay tuned for updates. Keep any eye on the forecast as we get more refined over the next day or two.

Beyond midweek, a ridge looks to build into the region, bringing back dry conditions, lighter winds, and warmer temperatures.

AVIATION...Friday 09/06Z through Saturday 10/06Z

VFR conditions. Increasing clouds Friday afternoon, with isolated -SHRA/-TSRA developing. S-SW winds mostly 10-15 kts Friday afternoon, except gusts up to 30 kts near showers.

OUTLOOK...Saturday 10/06Z through Monday 12/06Z...Mainly VFR through 18Z Saturday, with periods of MVFR possible thereafter. Isolated -SHRA/-TSRA through 12Z Saturday, then scattered coverage of SHRA/TSRA after 12Z Saturday. SHRA/TSRA becoming widespread after 00Z-06Z Sunday. Periods of MVFR/IFR possible Saturday night into Sunday in +RA. S-SW Winds increasing to 10-20 kts with gusts 25-30 kts on Saturday, then 20-30 kts with gusts 35-45 kts Sunday.

FIRE WEATHER...Today and Saturday

Mainly dry conditions through today, outside of an isolated high-based shower or thunderstorm over the higher terrain. Cooler and wetter conditions move in on Saturday, and especially through Saturday night. Expect south winds around 5-15 mph today, increasing to 10-20 mph on Saturday.

Sunday through Tuesday...Cool conditions with numerous to widespread showers and thunderstorms on Sunday, becoming scattered Monday and Tuesday. South winds 15-25 mph with gusts 35-45 mph on Sunday, subsiding to 10-20 mph with gusts 30-40 mph on Monday. Winds become south to southwest 10-15 mph with gusts 20-30 mph on Tuesday.

FGZ WATCHES/WARNINGS/ADVISORIES

None.