Plaincast

What has changed

Fog, some dense, may form in river valley locations near and west of US-15 early Sunday morning.

Messages

(1) Gradually warming temperatures through Monday with increasing precipitation chances each day.

(2) Returning to a summer-like pattern next week.

Discussion

KEY MESSAGE 1. Gradually warming temperatures through Monday with increasing precipitation chances each day.

A weak lee surface trough near the Appalachians may still spark a shower or sprinkle this evening, but otherwise it should be dry tonight with passing clouds and lows in the 50s and 60s.

Due to onshore flow keeping low-level moisture slightly elevated, there is a chance that some fog (which could be locally dense) may form mainly in sheltered river valleys near and west of US-15. This would especially be the case where the sky goes clear late tonight into early Sunday morning.

Atmosphere becomes a bit more unstable Sunday and Monday aided by mid-level cooling and increasing warmth and instability and forcing from an approaching shortwave-trough. Should see a gradual uptick in convection each afternoon through Tuesday.

KEY MESSAGE 2. Returning to a summer-like pattern next week.

Global ensemble models agree on a highly amplified pattern across the continent. In particular, a sprawling upper ridge is likely to dominate the Desert Southwest into the Great Plains. At the same time, below average heights will persist along eastern sections of North America. While the core of lower heights stays in close proximity to Hudson Bay, an elongated longwave trough maintains its presence along the Eastern Seaboard. This configuration would support a mainly northwesterly flow regime aloft with embedded disturbances sweeping up and over the prominent central U.S. ridge.