Moisture returns to the US West Coast
![](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2021/10/MIMICTPW_LastTenDaysEPAC.rockanim.gif)
A sequence of two intense storms in the north Pacific Ocean, noted in the GOES-17 airmass RGB below, has drawn moisture into the northwestern United States. A MIMIC (Morphed Integrated Microwave Imagery at CIMSS) Total Precipitable Water rocking animation, above (rocking animation from this site), shows the development of a ribbon of moisture that moved into the northwestern United States.
![](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2021/10/AirMassRGBAnnotated-20211022_1000toggle.gif)
Advected Layer Precipitable Water (ALPW, from this website), differentiates the moisture into layers. At 1200 UTC, one moisture axis was right across the Bay Area of California, with 20-24 mm of moisture in the sfc-850 mb layer, 10-12 mm of moisture in the 850-700 mb layer, and 5 or 6 mm in the 700-500 mb layer.
![](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2021/10/Advect_V01_LPW_alt_112_stepVertical.gif)
Accumulated 1-hour precipitation (estimated with CMORPH-2) for the hour ending at 1200 UTC on 22 October, below, shows a ribbon of rain from just north of the Bay Area to central Oregon; largest amounts over northern California are 6-8 mm for the one hour. CMORPH-2 estimates of precipitation are available at RealEarth.
![](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2021/10/CMORPHHourlyEnding_1200UTC_22Oct.png)