Plaincast — the National Weather Service forecast, decoded into plain English

Plaincast decodes the National Weather Service's Area Forecast Discussion — the real forecast, written 3 to 4 times a day by the meteorologist on shift — into plain English. The discussion is where a forecaster explains their reasoning: which models disagree, what they are watching, and how confident they are. Below is the current edition for Las Vegas, with its shorthand expanded. The full experience — an AI plain-English summary beside the annotated original — loads with JavaScript, and every one of the 68 forecast offices has its own edition.

Area Forecast Discussion · National Weather Service Las Vegas (VEF) · issued Saturday, October 24 at 4:48 AM PDT.

Messages

Gusty north winds today with lingering shower and storm chances in northwestern Arizona.

Quiet and seasonable conditions through at least Wednesday, with signs of a more active pattern returning late in the week.

Discussion

Water vapor imagery shows a trough overhead with a vort max over southern CA in the process of pinching off into a closed low. Behind the shortwave, gusty north winds are currently pushing through the southern Great Basin and into the northern Mojave Desert. These will continue advance southward, encompassing most of the forecast area by sunrise. Strongest winds anticipated in Death Valley and the southern Owens Valley where gusts of 40-50 mph are possible through the morning hours. Elsewhere, expecting gusts generally 20-35 mph, weakening during the 2nd half of the day. The formation of the closed low will cause the system to slowly exit the region, lingering over northwestern AZ this afternoon. The cold air aloft, residual moisture, and daytime heating should drive isolated to scattered showers and maybe even a few storms over eastern Mohave County (20- 40%), with lower chances (10-20%) over southeastern NV and the Colorado River Valley. Can't completely rule out an isolated instance of flash flooding in eastern Mohave County, but odds are 5% at best.

Our low finally exits on Sunday, leaving us in a zonal pattern for a few days before transitioning to southwesterly flow later in the week. From Sunday - Thursday, the forecast calls for seasonable temperatures, light breezes, and dry conditions. Late in the week, ensemble guidance shows an energized subtropical jet trying to push moisture into the southwestern US. Cluster analysis shows several variations of offshore troughing during this time, so there remains a fair amount of uncertainty, but there appears to be a good signal for the existence of an offshore trough and southwesterly flow over us. Should this come to fruition, we should see an increase in southwest winds and low to moderate (10-50%) precipitation chances around Halloween weekend.

This is the plain-text edition, decoded without AI so it loads anywhere. Read the whole Las Vegas discussion at /o/VEF/, see what changed since the last one, or open The National Desk for where the weather is today.