Weather: Tuesday’s blue Santa Cruz skies the ‘calm before the storm’
SANTA CRUZ >> As blue skies turned to gray Tuesday afternoon, the National Weather Service was describing the early break as merely “the calm before the storm.”
The lack of dramatic storm conditions may have played a factor in the approximately 261 of about 2,800 households within the Santa Cruz County evacuation zones the Santa Cruz County Sheriff’s Office said that outright refused to leave ahead of Tuesday night’s predicted intense rainfall. Sheriff’s Office spokeswoman Ashley Keehn said that number of evacuation refusals may actually be on the low end, as some people say they plan to leave and do not follow through.
“When people do that they run the risk of being trapped and of needing help and not being able to get a hold of help because the power’s out and phone lines are down and they can’t get a hold of emergency personnel when they need them,” Keehn said. “If they do get a hold of us but there is an active debris flow in an area, that could physically block our rescue crews from getting in to them.”
In a weather forecast update posted online by the National Weather Service’s Bay Area region, meteorologists predicted the oncoming atmospheric river would arrive first in the North Bay Area in time for the evening commute hours, before moving south toward Santa Cruz County. Of highest concern for the county is the “burn scar,” areas left ravaged by the summer’s CZU August Lightning Complex fires.
Atmospheric rivers are defined by the National Oceanic and Atmospheric Administration as “columns of vapor” that move with the weather, “carrying an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River.”
“Short-term rain rates approaching 0.75 (inches) will be possible as the coldfrontal boundary passes through,” according to the National Weather Service. “The daylight hours of today will be your last chance to make potentially life-saving decisions. The heavy rain occurring during the darkness of night along with winds likely to produce power outages in the Santa Cruz mtns will only add to the confusion of the upcoming night.”
Keehn said that public officials have spent weeks alerting those living in areas impacted by the CZU August Lightning Complex fires that when heavy, intense rain flow was predicted, they would be a risk of life-threatening debris flow risk and would be asked to evacuate ahead of time for their own safety.
In addition to sending sheriff’s deputies doorto-door in the evacuation zones, Keehn said personnel also have been trying to locate people staying in evacuation areas who may not have access to phone service and emergency notifications. Those residents who refused to evacuate were asked by deputies to sign a refusal waiver, Keehn said.
Brian Kawzenuk, a meteorologist with the Center for Western Weather and Water Extremes at Scripps Institution of Oceanography, said Tuesday afternoon that this week’s storm was the area’s first major precipitation event of the year. During what is otherwise a drought for the area, the rainfall alone might not be of huge safety concern. However, for the more vulnerable fire-swept areas, the high-intensity storm is likely to have an outsized impact, he said.
“Overall large-scale flooding doesn’t seem to be as much of an issue because of the dry conditions. But a lot of models are pointing to that this might be able to produce what’s called a narrow cold frontal rainband,” Kawzenuk said. “It’s really a sort of thin band of really strong precipitation with very high rain rates.”
Meteorologists fore- cast the atmospheric river would continue south before stalling over Monterey County and that the weather’s impact to Santa Cruz County may be slightly lessened from earlier predictions, though general rainfall is forecast to continue throughout the week.
“The one bit of good news with the latest model trends is the boundary should pass through Santa Cruz county fairly quickly with the heaviest rain ending by around sunrise Weds for the CZU burn area,” according to the National Weather Service. “Daylight will reveal what massive logs, debris and mud do when encountered by heavy rainrates.”
The region is only recently recovered from last week’s widespread and multiday power outages resulting from a Jan. 19 windstorm. Cal Fire San Mateo-Santa Cruz Unit has issued preemptive evacuation warnings for areas in and around Boulder Creek, Ben Lomond, Felton, near Swanton Road on the North Coast and other regions ahead of the evening’s storm for areas believed to be at risk of debris flows.
Agencies such as the Scotts Valley Fire Protection District, Central and Aptos/La Selva fire protection districts, Boulder Creek Volunteer Fire Department and the City of Santa Cruz Fire Department are offering residents within their jurisdictions opportunities to pick up sandbags ahead of potential rainstormcaused flash floods.