SEATTLE – A “bomb” cyclone spinning offshore in the Pacific Northwest has ushered in a pattern of heavy rain and gusty winds this week, resulting in unusually active weather for this time of year.
“We’re getting closer to the rainy season, but we’re not there just quite yet,” FOX Weather meteorologist Britta Merwin said. “But Seattle, you wouldn’t be able to guess it.”
Sloppy conditions spread across the Emerald City on Sunday and Monday with periods of heavy rain and even some rare lightning, ranking as two of their wettest days of the year.
The rain was even heavier in the mountains, with another 2 to 4 inches expected to soak the windward sides that face the onslaught of the storm track by the end of the week. This water may overwhelm areas recently burned by wildfires, and debris flows will be a concern.
BOMB CYCLONE SLAMS PACIFIC NORTHWEST WITH HEAVY RAIN, RAISING THREAT OF DEBRIS FLOWS
According to the FOX Forecast Center, the recent storm system qualified as a “bomb cyclone.” This is because the area of low pressure underwent “bombogenesis,” which happens when the central pressure of a storm system drops by at least 24 millibars within 24 hours. In this instance, the pressure dropped from 996 millibars on Saturday evening to 960 millibars on Sunday evening, resulting in a decrease of 36 millibars.
“It was interesting because a storm that we were tracking over this past weekend ended up outperforming what we’ve seen in the past,” Merwin said. “Now, we’re seeing a lot of moisture push into the Northwest.”
Seattle saw 0.82 inches of rain Monday — its wettest day of the year so far, coming on the heels of 0.61 inches Sunday which now ranks as the fourth-wettest day. The two-day rain total now represents nearly 10% of Seattle’s annual rainfall total so far. It was more rain in a day in a half than the city had received through the entire summer.
WHEN STORMS ‘BOMB OUT’: EXPLAINING HOW A BOMB CYCLONE FORMS
According to NOAA’s storm reports, a home reported shingles damage and tree branches down during strong winds from a passing thunderstorm Monday in Astoria, located on the northwestern Oregon coast.
A second round of rain and scattered thunderstorms will push through the region later Tuesday into Wednesday morning. The storm’s arrival have potential to bring bursts of wind that could trigger a few power outages with the still-leafy trees in place.
The weather calms later Wednesday but the large and strong area of low pressure spinning offshore will continue pushing rain onshore through the week. After a dry weekend to wring out, a generally cool and unsettled weather remains in the forecast into next week.
The wet weather is a welcome change since the region has endured unusually dry conditions and hot temperatures since late June.
This will be some of the most active weather and intense rain the area has received in months, the FOX Forecast Center said.
“The forecast for Seattle … rain all the way through Thursday,” Merwin said. “So grab your rain gear and take it in stride.”
The Coast Guard and other state and local agencies are searching for a missing woman, who was reportedly swept by currents off Rialto Beach along Washington‘s North Coast on Monday.
Watchstanders at Coast Guard Sector Puget Sound received a report at 10:50 a.m. of a 26-year-old woman who was swept from the beach. The missing person was described to be wearing a pink sweater and black pants.
The Coast Guard directed the launch of two helicopter aircrews and one land search party to search for the missing person.