A storm system stalled over south-central Utah and north-central Arizona is expected to continue to produce rain through Tuesday in Southwest Colorado.
In addition, a weak to moderate El Niño pattern is forming in the equatorial Pacific, which should increase the odds of favorable snowpack in the mountains of Southwest Colorado, said Matt Aleksa, a meteorologist with the National Weather Service in Grand Junction.
The current system had warmer air ahead of it and is being infiltrated by dry air, which is limiting the amount of snowfall in Southwest Colorado, Aleksa said.
Still, it brought the first significant snow of the season to the highest peaks in the southern San Juan Mountains this week.
"Overall, it looks like we're in an unsettled pattern where you get storm system after storm system bringing good moisture into the area," Aleksa said.
The current system, he said, is expected to move out of the area Tuesday, and clearing skies should make Tuesday night cold, with the low temperature in Durango expected to dip to 32 degrees - the first frost of the season.
"It won't be a deep freeze into the high- and mid-20s," Aleksa said.
Mountain passes saw slushy, wet conditions Saturday night and Sunday morning, and passes have a chance to be snowpacked Sunday night and early Monday morning, he said.
Rain from the current system is expected to be steady and moderate through Tuesday. Aleksa said it does not appear rainfall will come hard or fast enough to cause flooding in the 416 Fire burn scar.
"We don't anticipate it will be a problem. You should be getting light, steady rain that is measured in the tenths-of-inches in an hour as opposed to measuring rainfall at an inch an hour. It's not the kind of rain that comes all at once - to the point where the ground in the burn area can't handle it."
Another storm system is expected to move into the region Thursday and Friday, he said.
After that storm system, Aleksa said the remnants of Hurricane Sergio could enter the Southwest United States early next week.
Models differ on where Sergio will track, as the hurricane is expected to make landfall in the southern Baja California peninsula early Friday morning.
Some models show it will move through northern Mexico and miss the Four Corners, while others show it will move through Arizona and New Mexico - possibly bringing rain and snow to Southwest Colorado.
The weak to moderate El Niño pattern forming in the Pacific, Aleksa said, should favor a wet fall and a good start to winter snowpack in the southern San Juan Mountains.
"El Niño should extend to into late spring, and odds favor we'll see a better winter," he said.