textproduct: Eureka

KEY MESSAGES

* An early season storm is on track to bring moderate to heavy rainfall, slick roads, and strong southerly winds today into early Thursday.

* Another low will bring additional light rainfall and colder temperatures late in the week, with a chance for interior frost.

SYNOPSIS

A strong area of low pressure will move in today. Strong southerly winds will develop with this storm system, along with moderate to locally heavy rainfall. A disturbance ahead of it will still have slight chances for isolated thunderstorms very early this morning for Trinity County and potentially some areas closer to the coast.

DISCUSSION

A deeper upper low will move into Northwest California today. Southerly winds aloft will be strong for an early season storm, with 44 to 55 kts down to 925 mb (around 2000 ft). Wind Advisories have been issued for elevations above 1000 ft for Humboldt and Del Norte counties for gusts of 40 to 50 mph. Stronger gusts up to 60 mph will be likely for interior ridges of Del Norte. Despite the strong southerly flow aloft, little to no instability and a persistent low level inversion should inhibit mixing near the coast and in sheltered valleys. As a result, the strongest gusts are expected to remain elevation dependent, mainly above 1000 to 1500 ft, with lower elevations likely underperforming. NBM still holds moderate chances (40 to 55%) for wind gusts over 35 mph for the lower elevation coastal areas. However, there are high probabilities of (up to 60%) for gusts greater than 35 mph along the Del Norte Coast.

Expected rainfall totals continue to trend higher with this atmospheric river type storm system. Rates will be moderate to locally heavy, up to 1/2 inch per hour for select ridges. The King Range and ridges of Humboldt and Del Norte, with a south to southwest orientation, have moderate to high chances (50 to 70%) of seeing over 2.5 inches. A broad area of Northern CA will see 0.5 to 1.5 inches of total rain.

As the first significant storm system of the season, a few early- season hazards are worth noting. Strong southerly winds may bring down weakened limbs and branches at a more than typical rate, particularly those stressed during the dry summer months. Additionally, accumulated oil and other roadway residue will result in slick driving conditions as rain initially develops.

A much colder and unstable area of low pressure looks to then dive down from the north from Thursday through Friday. There will be a shot for thunderstorms, overnight interior frost, and additional light rainfall.

AVIATION...(06Z TAFs)

A strong early season storm will move through Northwest California today. IFR to MVFR ceilings will persist for terminals as the low moves onshore. Strong southerly winds are expected for coastal terminals and near coastal ridges of Humboldt and Del Norte counties with gusts from 30 to 45 knots likely. Also, period of LLWS are expected mid morning. Ceilings are expected to lower to IFR/LIFR by late this evening for coastal terminals.

MARINE

An early season, strong storm system will move through the waters today, bringing strong southerly winds starting early this morning. Areas of sustained gale strength winds to 34 kts can be expected to sweep through the northern waters this morning through the afternoon. Winds will quickly ease tonight. A mid period northwest swell will then fill in Thursday, potentially creating advisory level 10 ft seas.

FIRE WEATHER

Another area of low pressure will bring widespread wetting rainfall and areas of moderate to locally heavy rainfall today. Southerly winds will quickly increase starting this morning with the low, and will become strong through the evening. Gusts of 40 to 50 mph are forecast for the ridges from Cape Mendocino and northward, with higher gusts over the interior Del Norte ridges. Additional light rainfall and chances for thunderstorms are likely Thursday, while temperatures turn much cooler.

EKA WATCHES/WARNINGS/ADVISORIES

CA... Wind Advisory from 5 AM early this morning to 8 PM PDT this evening for CAZ101-102.

Wind Advisory from 7 AM this morning to 8 PM PDT this evening for CAZ104>106.

NORTHWEST CALIFORNIA COASTAL WATERS... Gale Warning from 9 AM this morning to 6 PM PDT this evening for PZZ450.

Small Craft Advisory from 2 PM this afternoon to 10 PM PDT this evening for PZZ455.

Gale Warning from 6 AM this morning to 6 PM PDT this evening for PZZ470.

Small Craft Advisory from 9 AM this morning to 10 PM PDT this evening for PZZ475.