Katherine, AZ 86429 Weather

Key messages

* Precipitation chances and cooler temperatures return today and continue through the weekend.

* Cool and dry conditions for early next week.

Discussion

through Thursday.

Moisture from former TS Vance will continue to stream north overnight, with dewpoints currently in the 50s over the lower Colorado River Valley and generally mid-40s to around 50 south of I- 15. This plume will push further inland through the day along with increasing shower and thunderstorm chances. Light radar returns have been observed overnight across southern Nevada, likely associated with a weak vort max riding up along the moisture boundary. A slight chance of light showers and an isolated thunderstorm remains before sunrise across southern Nevada, eastern San Bernardino, and western Mohave counties; however, recent HRRR runs have backed off on this potential.

Shower and thunderstorm chances will ramp up this afternoon, especially across Mohave County where the greatest instability resides. Convection here is expected to be more widespread, and with PWATs around 1.00" to 1.25", localized flash flooding will be possible. Storms may also develop further west into Clark and Lincoln counties, though coverage will be more scattered with localized downpours. Areas further west should remain dry through the day.

Conditions dry out Friday night with only isolated showers possible Saturday. As the primary trough off the California coast pushes inland late Saturday night into Sunday, more widespread precipitation will overspread the region. Forecast impacts and rain totals remain somewhat uncertain given sensitivity to the system's exact track: a more progressive, aggressive wave spreads precipitation across the entire forecast area, whereas a slower track shunts moisture east and keeps activity largely confined to Arizona. Current guidance suggests the lower valleys could see between 0.25" and 0.50", with Mohave County potentially picking up around an inch. With limited cold air aloft and the core of the trough staying over northern Nevada, snow levels will remain high (generally above 9,0009,500 feet). The highest peaks of the Spring Mountains could pick up several inches of snow, but recreational areas like Lee Canyon should see little to no accumulation.

As the trough exits early next week, a tightening surface gradient along its western flank will drive breezy to gusty winds Monday, particularly across the southern Great Basin. Most gusts will subside Monday evening, though terrain-channeled winds through the Colorado River Valley could linger into Tuesday. Cooler air will settle in behind the system despite shortwave ridging building overhead, keeping highs roughly 5 degrees below seasonal normals through Tuesday under dry conditions.

Aviation

For Harry Reid: For the 18Z Forecast Package: Light south winds build into the late morning with a pause in rain chances. Breezier winds arrive in the mid-afternoon from the south- southwest with shower activity increasing across the valley. CHances for storms will be possible in the lines of showers, and could result in gustier winds and cloud bases as low as 6000 ft AGL along with chances for lightning. Storm chances decrease into the evening and winds ease into the night while turning westerly, but chances for showers linger through the night and much of Saturday morning. Showers exit late that morning with winds turning easterly. Breezy southeast winds arrive into Saturday afternoon.

For the rest of southern Nevada, northwest Arizona and southeast California: For the 18Z Forecast Package: Showers continue to move across the Las Vegas Valley and the Colorado River Valley, with some quickly-passing, non-impactful rain chances for the rest of the TAF sites. Moderate to gusty south to west winds arrive this afternoon. As winds increase, storms and better chances for showers arrive for all but KDAG and KBIH. Storm chances ease in the late afternoon and into the evening, but shower chances look to linger into the night. WInds reduce into the evening and overnight, becoming light across much of the region.

Spotter information statement

Spotters are encouraged to report any significant weather or impacts according to standard operating procedures.