textproduct: Eureka

SYNOPSIS

Moderate to locally heavy rain into Wednesday morning for mostly Del Norte, Humboldt, Trinity and northern Mendocino Counties. Lingering showers expected Wednesday and Thursday. Moderate to heavy rain and breezy southerly winds arrive again Thursday through Friday. More rain and strong gusty winds will be possible this weekend.

KEY MESSAGES

- Moderate to locally heavy rainfall into Wednesday morning with a 5% chance for minor urban and small stream flooding for Del Norte, Humboldt, Trinity and northern Mendocino Counties.

- A 15% chance for minor flooding late Thursday night through Friday with another round of moderate to locally heavy rain.

- More rain with a 5% chance for minor flooding over the weekend.

- Stronger wind gusts from 45 to 60 mph expected Thursday night and Friday morning for coastal headlands and mountains of Del Norte and northern Humbodlt.

- Snow levels falling to 3500 to 4500 feet Wednesday with very little or no snow accumulations expected.

- Another powerful storm possible this weekend.

DISCUSSION

Moderate to heavy rainfall has been observed as an IVT plume passes through the region, particularly over windward facing terrain. Sharp rises in some rivers, creeks, and streams are also observed early Wednesday morning.

Chances for wind gusts from 45-50 mph for the Del Norte coast increases Thu night into Fri morning as a 925mb speed max around 45-55kt develops in advance of the next front Thu. Lacking instability will prevent these stronger winds from reaching the surface, but the ridges of Del Norte, Crescent City area, and the King Range are expected to see 40 to 50 mph wind gusts. A wind advisory has been hoisted.

Above average warmth will keep snow snow levels quite high in general through Fri. Snow levels will drop to 3500-4500 feet on Wed but precip amounts will fall off and any accumulations will be very light. Snow level rapidly increase again Thu night in advance of the next IVT plume.

Frontal boundary on Friday will eventually sag south into srn Mendo and srn Lake by Sat morning and precip will wind down in the north. Precip may continue for southern zones. Models diverge on development of a new frontal wave and northward surge of IVT this weekend later in the weekend. We could be in store for more heavy rain and strong winds this weekend or early next week. Looking at the chance of IVT > 250 kg/m/s the following week Dec 22-26, confidence is moderate to high in wet weather continuing for the latter portion of Dec. IVT diagrams do show a southward shift in IVT but this may shift back northward. Stay tuned.

AVIATION

Showers continue to bring MVFR to LIFR conditions to the airports across the area. Breezy southerly winds continue, but are expected to switch to northwest and diminish towards morning. Conditions are expected to improve around 11 to 14Z this morning from north to south as the showers move out of the area. Confidence is fairly high that conditions will be VFR through the day with light northwesterly winds. Tonight offshore flow is expected to keep the coast VFR through much of the night, although interior valleys will likely see fog. MVFR conditions are briefly possible at the coast early Thursday. MKK

MARINE

Southerly winds of 15 to 25 kt continue across the waters early this morning. These are expected to switch to the northwest towards morning. These winds north to northwest winds will diminish to 5 to 15 kt by midday. Wednesday afternoon the northwest swell is expected to increase once again to around 10 to 13 feet. For the northern waters have expected to small craft advisory right through the start of the gale watch. The swell is expected to briefly reach 10 feet in the southern outer waters and the small craft advisory remains in effect for that.

Wednesday night into Thursday the winds are expected to become southerly again. These are expected to increase to 15 to 30 kt midday Thursday through early Friday morning. Some gusts to gale force are likely in the northern waters. The gale watch in the northern outer waters remains on track and have added a gale watch to the northern inner waters.

Friday and Saturday the winds are expected to diminish and generally be less than 20 kt. Another weather system is expected on Saturday, but there is wide variability in the model solutions on that. There is certainly the potential for gales, but there are also a lot of solutions with lower winds. MKK

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 7 PM PST Thursday for PZZ450.

Gale Watch from Thursday evening through Friday morning for PZZ450.

Small Craft Advisory until 6 AM PST Thursday for PZZ470.

Gale Watch from Thursday morning through Friday morning for PZZ470.

Small Craft Advisory from 6 PM Wednesday to 6 AM PST Thursday for PZZ475.