textproduct: Eureka

SYNOPSIS

A mix of sun and clouds is expected Friday before rain showers and possibly thunderstorms return for the weekend. Mainly dry weather is expected Monday and Tuesday with more rain possible Tuesday night or Wednesday.

DISCUSSION

High pressure is over the area this morning with a vertically stacked area of low pressure approaching from the west. Dry weather is expected to continue through the day. Tonight most models show a line of showers moving through at some point on Saturday and then again on Sunday as the upper low moves overhead. The NBM shows the best in eastern Trinity county, much of Mendocino and Lake counties. However even in these areas there is only 55 to 65 percent chance of CAPE exceeding 200 j/kg. The NAM showers higher CAPE, but still the lapse rates aloft are only 6.5 to 7 c/km. This system is expected to move through fairly quickly and therefor keep precip amounts fairly low. There is a 20 to 50 percent chance of some areas exceeding a half in Humboldt, Del Norte and far northern Trinity counties. There is only a 20 percent chance of exceeding a half inch around Humboldt.

There is still a lot of uncertainty on the track of this weather system and the associated area of low pressure. A small shift in the track of the low pressure could significantly change the forecast for rainfall and thunderstorms. This uncertainty continues into Sunday and Sunday night as the upper level low moves overhead. Rainfall amounts on Sunday look lower than on Saturday with the probability over a half inch less to 30 to 40 percent across the area.

Monday the upper level low starts to pull out of the area, however this often occurs slower than expected by the models. There is a better agreement that the afternoon will see dry weather. This dry weather and clear skies may allow fog to develop Monday night in the interior valleys. More rain is expected Tuesday night into Wednesday morning. This also looks like it will be fairly light rainfall. A more persistent dry pattern is expected to start late next week. MKK

AVIATION...(6Z TAFs)

VFR conditions are likely to prevail for the next 24 hours. However, there is a chance for shallow ground fog to periodically bring brief LIFR impacts to the terminals overnight. Any low clouds or fog will lift and scatter shortly after sunrise. Winds are forecast to be light with the coastal terminals unlikely to exceed 10 kts. JB

MARINE

Winds generally remain light and northerly today, but some gusts of up to 20 kts are possible around Cape Mendocino and the far northern outer waters. Seas will build this afternoon and overnight as a long period northwest swell of around 8 ft at 15 seconds arrives. Combined seas may briefly exceed 10 ft in the outer waters overnight. Some high-res models are starting to show a tighter pressure gradient Saturday, bringing potentially stronger winds. There is currently high uncertainty of the magnitude and timing and timing of these winds. HREF is showing around a 30% chance for Gale Force gusts south of Cape Mendocino Saturday and a 50 to 60% chance for gusts over 25 kts. Regardless, winds will diminish again late Saturday and Sunday. Winds and seas are likely to remain mild through at least Tuesday of next week. JB

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 3 PM Friday to 10 AM PST Saturday for PZZ470.