Pattern through July 1; Monsoon Season Preview

Tomer’s Take: The pattern is transitioning across the West. The abnormally wet pattern is moving out while more normal, warmer weather is moving in. This will introduce a drier period for the West until Monsoon Season kicks in. My opinion is that Monsoon Season will start about 1-2 weeks behind schedule. Normal Monsoon Season runs July-August.

PNW Snow

Mount Rainier has seen off/on snow the last few days. Notice the reduced visibility this morning at Camp Schurman and the team of climbers ascending in the distance – summit temps are in the single digits:

Mount Rainier Forecast:

6/20: Cloudy, PM 1-2 inches, AM 20mph, PM 30mph, 3/8F.

6/21: AM dry, sun, PM 1 inch, 15-20mph, 8/14F.

6/22: AM dry, sun, PM 1-2 inches, AM 15mph, PM 20mph, 14/17F.

6/23: AM dry, sun, PM 2-3 inches, AM 15mph, PM 25mph, 17/19F.

New Pattern

Higher pressures are gradually building in across the West replacing a persistent trough of low pressure and strong Subtropical Jet Stream. It’s a dramatic shift underway!

Here’s a forecast contrast. It shows the mid-atmospheric pressure anomalies from June 18 versus forecast valid July 1.

Valid: June 18 vs. July 1

Moisture Forecast

Precipitation anomalies return to normal end of June and early July.

Valid: July 1

Monsoon Preview

I believe the Monsoon will run about 1-2 weeks behind schedule. The flow turns southerly and starts adding moisture around July 10. The Climate Forecast System suggests small moisture anomalies between July 9-July 19, 2023. This would represent the start of the Seasonal Monsoon. It adds extra moisture across NM, AZ, UT, CO, WY, ID, MT fueling afternoon rain and thunderstorms with extra lightning, hail, and flash flooding.

Valid: July 9-19.