Grand Junction (GJT) — the National Weather Service forecast in plain English · Plaincast

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Flooding is ongoing across portions of southeast Utah and southwest Colorado, and is expected to continue through Saturday.

While some rivers have crested, some rivers will experience their crest Saturday.

Isolated to scattered showers and storms are expected Saturday. They will be capable of producing moderate to heavy rainfall that could result in additional flooding.

A few storms may be capable of producing strong winds and large hail Saturday afternoon.

Discussion

ONGOING FLOODING WITH MORE RAINFALL THIS WEEKEND:

The low pressure system responsible for pulling in the tropical moisture that resulted in the abundant rainfall the last couple days is sitting over southern California and Nevada. This low pressure system is expected to move into Arizona by Saturday afternoon and lift northeast across Utah and western Colorado during the day on Sunday and exiting to the northeast by Monday morning. As this happens, the low pressure system will pull another round of moisture around the low from the southeast on Saturday. The latest hi-res CAMs indicate convection developing across southeast Utah and southwest Colorado overnight into Saturday morning with more scattered to widespread showers and storms spreading further north Saturday afternoon and evening, favoring areas along and south of I-70. While the deep tropical moisture has vacated the region, precipitable water anomalies with this push of moisture are projected to be around 200 percent of normal, which while not as high as a few days ago, is still enough to cause issues and heavy rainfall. The main concern is that many areas are already saturated from previous rainfall and there is ongoing flooding with many rivers and creeks running high. So any additional rainfall, especially where stronger convection occurs could result in more flooding and continuation of ongoing flooding. The rainfall amounts through Sunday are expected to range from 0.5-1.0 inches along the highway 160 corridor with slightly higher amounts in the mountains and lower amounts outside of southwest Colorado. While we could see gusty winds and hail with a few storms, the main concern is heavy rainfall. high-resolution CAMs appear to show convection winding down Saturday night with some isolated showers lingering. Showers become more isolated to scattered on Sunday as the low pressure lifts overhead, but these showers are expected to be lighter than previous few days. Conditions begin to dry out Monday as this low lifts northeast over the Plains.

As we move towards next week, models are also in fairly good agreement that dry zonal flow will begin to propagate through the region by Monday. Because of this, we will be seeing cooler than normal temperatures, with the potential for overnight lows to drop below freezing for a couple hours at a time. Meanwhile, a low pressure system looks to enter the Pacific Northwest with a few shortwaves moving across the Northern Rockies through the week potentially bringing light showers to the north but overall, conditions appear to dry out until late next week when showers potentially return as a shortwave trough moves through the Desert SW and 4 Corners region pulling in some Pacific moisture. Keep in mind, this is still relatively far out, so confidence remains low on this matter as model solutions are varied.