Yesterday's West saw the highest rainfall intensity in which locations?
New Precipitation Alert Service Warns of Rare and Extreme Weather Events
A new service, the "R-Cat Extreme Precipitation Alert," is now available to help citizens in the western United States stay informed about rare and intense rainfall events. Developed by the Center for Western Weather and Water Extremes (CW3E) at the University of California San Diego, this service provides real-time alerts for extreme precipitation levels during storms.
The R-Cat scale, created by CW3E Director Marty Ralph and U.S. Geological Survey scientist Mike Dettinger, categorizes extreme precipitation events based on three-day observed precipitation totals (rain and/or the liquid equivalent of snow that fell). R-Cat 1 represents precipitation between 200-299 mm (roughly 8-12 inches) over 3 days, R-Cat 2 represents precipitation between 300-399 mm (roughly 12-16 inches), R-Cat 3 represents precipitation between 400-499 mm (roughly 16-20 inches), and R-Cat 4 represents precipitation exceeding 500 mm (more than roughly 20 inches) over 3 days.
Recent research has highlighted the connection between extreme 3-day precipitation events in the western U.S. and intense storms, particularly those caused by atmospheric rivers (ARs). AR storms, narrow corridors of concentrated moisture transport in the atmosphere, are key contributors to these extreme precipitation events. They have been linked to a warming-induced increase in moisture content and consequently the frequency of AR events by approximately 0.6–0.8% per decade. This increase in AR events corresponds to a rise in extreme precipitation occurrences in the western U.S.
The event at Strawberry Valley, located on the western slopes of the Sierra Nevada Mountains, was an "R-Cat 4" extreme precipitation event, with a maximum three-day precipitation of 521 mm (20.51 inches). This new tool developed by Scripps climate scientist David Pierce and Ralph was able to identify and report the event in real time.
R-Cat 3 and R-Cat 4 events are rare, with specific multi-decadal datasets (2002–2021) analyzing their occurrence, but exact frequencies vary spatially and temporally. R-Cat 4 events are less frequent than R-Cat 3. To subscribe to the alert via email, send an email with subject "subscribe" to a specified address. The service is free and is intended to provide information to interested individuals in a timely manner.
In summary, the R-Cat Extreme Precipitation Alert service offers valuable information about rare and intense rainfall events in the western U.S. By providing real-time alerts for these extreme precipitation events, citizens can better prepare for potential flood hazards and landscape changes caused by AR storms.
The R-Cat Extreme Precipitation Alert service, based on environmental-science findings, provides real-time alerts for rare and extreme rainfall events in the western U.S., helping citizens predict weather-forecasting matters, particularly climate-change-induced atmospheric river events causing severe weather.
