Waiting on the southwestern US monsoon
Monday, July 3, 2017
The wave of energy discussed in the last forecast has moved east of the Steamboat Springs area, and drier air has moved in behind the departing disturbance. There may still be a chance of some afternoon or evening sprinkles later today.
Temperatures will warm further for Independence Day and the work week as a ridge of high pressure builds over the western US. Moisture to fuel any afternoon storms will be sparse for most of the work week as generally light northwest flow keeps hot and dry air over our area.
By the end of the work week and heading into next weekend, incoming Pacific energy is forecast to nudge the western U.S. ridge eastward, placing the ridge axis over the spine of the Rocky Mountains. The weak southerly to southwesterly flow on the west side of the ridge will allow the monsoonal moisture pooling around the Sonora Desert to move northward, though the northward extent of this moisture surge is uncertain.
The robustness of the moisture surge may also be moderated by the incoming Pacific energy traveling over the top of the western U.S. ridge and digging southward into the eastern third of the country. The cooler air to our east may nudge the western ridge back westward which would interrupt the fledgling monsoonal flow over Colorado.
The end result is the hot and dry conditions forecast for the work week will be followed by some increasing moisture and the chance of afternoon storms heading into weekend.
