Lillian Mendes sent in a very cool shot of a “Hole Punch Cloud” from Palomino Valley. These are created when a jet flies through a thick cirrus layer of clouds, usually when taking off (likely this particular jet took off from the Reno/Tahoe Airport). As it “punches through,” particulates from the jet’s exhaust cause some of the supersaturated moisture in the cirrus layer to condense and drop out as light precipitation up there, only to evaporate within a couple of thousand feet on the way down. It leaves behind this eerie, almost otherworldly looking cloud formation. It’s very cool!

Temperatures will continue to rise into the weekend as a ridge of high pressure builds into the region. Friday’s high in the upper 70s will be followed by a real shot at 80 degrees on Saturday with sunny skies both days. A trough of low pressure approaches the coast by the end of the weekend which will spell the end of the autumn heat, dropping Sunday back into the 70s, Monday into the 60s and bottoming out in the upper 50s on Tuesday. Apart from the cooler temperatures (and variable amounts of cloudiness), the trough will also bring some dusty winds Late Sunday into Monday, which will increase the fire danger. A Fire Weather Watch goes into effect Sunday afternoon and evening as a result.

The first widespread killing freeze of the season will occur Monday morning after a cool northerly flow left a cold airmass across western Nevada. Skies will remain sunny across the region for the next week, with a slow but steady warming trend occurring for the rest of the work week. Low temperatures will range from the upper 20s at the Reno airport to as low as the upper teens in some of the coldest outlying microclimates. High temperatures will start in the low 60s Monday and will warm into the low 70s by the latter half of the week.

The question that is always asked at this time is should I shut off my sprinklers. It really depends on how “freeze-proof” your irrigation system is. Most modern systems can withstand a few sub-freezing nights without any damage (I’ll leave it up to you to decide how freeze resistant your system is.) And with an extended forecast that looks very dry, if yours can survive a few nights in the 20s, I’d keep it active. But is certainly is time to cut back on the amount of water you are using, and do remember to disconnect your hoses from the bibs so that the faucets drain completely.

As our skies clear off, look for some areas to get down into the “hard freeze” territory over the next several days. Morning lows at the airport will likely dip into the upper 30s through Sunday morning (with low 30s and even upper 20s in the colder outlying valleys), while daytime highs will warm into the upper 60s Friday and then to the mid-70s on Saturday. The flow turns back to the north on Sunday, dropping our highs back into the 60s, and dropping Monday morning’s lows to below the freezing mark across the entire region, with several places likely to fall into the mid and even lower 20s. A Freeze Watch has been posted for Sunday night through Monday morning for the entire region as a result. Temperatures will gradually rebound to the low 70s by the middle of next week.

Some cooler weather will work its way into the region over the next couple of days, dropping our high temperatures back into the 60s. A couple of weak “inside slider” systems will drop down out of the north, bringing in some clouds and giving us a slight chance of a shower or two, although it is not expected to be a particularly wet pattern. Temperatures rebound back to near 70 degrees as we head into the weekend with clearing skies. Clear overnight conditions will likely cause some regional frosts and freezes over the weekend.