textproduct: Eureka

SYNOPSIS

Series of atmospheric river storms will continue to bring periods of heavy rain, possible flooding, strong winds and dangerous surf through the weekend.

From previous discussion

Thursday evening the next in the parade of atmospheric rivers moves onshore. This is expected to continue to with additional rounds of rain through Sunday night. None of the individual storms look particularly strong, but there will be very little break in between them and this will increase the potential for flooding. There will likely be some 6 to 12 hour breaks, but these are too small to put in the forecast at this point. Each storm will also likely see strong winds, however at this point it is difficult to pick out a day with particularly strong winds. These systems look fairly warm for the most limiting the impacts from snow and having a higher potential for rainfall.

Monday and Tuesday are expected to see mainly dry conditions as a ride builds in. Some of the ensemble clusters some light rain moving over the top of the ridge, but some remain dry. This may be shortlived with the clusters starting to show another system possibly as early as Wednesday. MKK

AVIATION

VFR flight conditions have been maintained today; overcast skies have been due to a steady stream of "higher" low and mid cloud ceilings. Valley fog briefly dipped UKI into IFR/MVFR. At the far North Coast: a tightening pressure gradient has kept CEC gusty...and by noonday coastal Del Norte started experience light rain. Rain and lowering clouds will continue to spread across the entire region this evening ahead of an approaching frontal system. Above ground winds have intensified resulting in LLWS at the coastal TAF sites... and will last through Thursday morning. Also, possible thunderstorms due to instability could impact CEC and ACV ahead and along the frontal boundary in the morning. /TA

MARINE

An approaching warm front arriving from the NE Pacific to our area will dramatically manipulate the marine conditions today. Winds will increase substantially this afternoon. Winds will sweep into the northern outer waters first before moving inland and southerly. Gale force sustained winds in all the forecast zones with northern waters receiving possible storm force gusts (>48kts) from 3 PM this afternoon through 3 AM tomorrow morning.

As this front approaches, atmospheric instability is expected in addition to strong winds. This instability possibly resulting in the possibility of strong, pop-up thunderstorms and maybe even some waterspouts over the northern section of our waters from Humboldt Bay up to the Oregon state boarder and farther north due Cape Blanco. This hazard is possible from this afternoon until the early hours of tomorrow morning.

Another large swell (~20ft) should enter our waters this afternoon, which in addition to very steep wind waves, will create chaotic seas. These conditions will repeat several times through the remainder of the week into the weekend as additional fronts enter our area bringing pulses of large swell and locally generated hazardous wind waves due to repeated gale force winds sweeping through the coastal waters.

HYDROLOGY

Rivers, streams and creeks will rise sharply again by early Thu morning as another front/IVT plume generates a bout of moderate to heavy rain tonight. Fronts/IVT plumes have been progressive with sufficient time in between each period of heavy rain for water levels to drain. Soils remain saturated and run off responses have been quick. The next IVT plume will follow Thu evening and overnight and rivers will once again rise rapidly. Longer duration moisture flux with sustained (48 hour or more) of moderate-to-heavy rain for the northern basins raises concerns for more significant areal flooding and main stem river flooding this weekend. Ensemble hydrograph plumes indicate low probabilities, generally less than 20%, except for the Eel River at Fernbridge which has about a 45% chance of exceeding minor flood stage of 20 ft this weekend. Stay tuned. DB

BEACH HAZARDS

An incoming large, long-period westerly swell is expected Thursday morning with similar wave dimensions and resulting beach oriented surf around 20 to 23 feet, lasting well into Sunday with a brief lull late Thursday night. A high surf advisory has been issued for this initial s well before a lull in breaking waves and subsequent return of large breaking waves shore- side. Beachgoers, please be aware. These large waves can be erratic and unpredictable, and will be capable of sweeping people into the frigid and turbulent ocean water. Stay safe by remaining off jetties, rocks, wet sand )where waves have previously broken) and steep beaches. If you end up going to the beach, be on high alert and never turn your back to the ocean.

EKA WATCHES/WARNINGS/ADVISORIES

CA... High Wind Warning from 7 PM this evening to 4 AM PST Thursday for CAZ101.

High Surf Advisory from 2 AM to 11 PM PST Thursday for CAZ101-103-104-109.

Wind Advisory until 4 AM PST Thursday for CAZ102-104>106.

Wind Advisory from 10 PM this evening to 4 AM PST Thursday for CAZ103.

Winter Weather Advisory until 8 AM PST Thursday for CAZ107.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 PM PST this afternoon for PZZ450.

Storm Warning until 3 AM PST Thursday for PZZ450.

Small Craft Advisory until 6 PM PST this evening for PZZ455- 475.

Gale Warning from 6 PM this evening to 3 AM PST Thursday for PZZ455-475.

Storm Warning until 3 AM PST Thursday for PZZ470.