textproduct: Eureka

SYNOPSIS

Breezy to strong north and northeast winds are expected through Thursday night. Dry conditions with above normal high temperatures are expected for the interior through the weekend. Potential for significant precipitation will return next week.

DISCUSSION

Northerlies have been increasing through the day with shallow moisture along the coast slowly scouring out this afternoon. Low cloud cover and perhaps drizzle-like showers continued over the western and northern slopes of Humboldt and Del Norte this afternoon thanks to these blustery upslope winds. Visible satellite imagery showed trailing rope clouds in the cooler air offshore over the waters behind the front. Mesoscale models have these shallow drizzle-type showers eroding and completely dissipating before reaching the coast.

Colder weather conditions are expected tonight into early Thursday under a slightly cooler air mass and drying offshore flow. Frost advisories have been issued for the valleys of Mendocino County and to a lesser extent (areal coverage wise) northern Lake. Coastal areas are not as certain with low cloud cover and gusty winds hindering the longwave cooling through the night. Offshore winds and increasing subsidence should result in lower dewpoints through the night and pockets for frost will be possible (50% chance). Interior portions of Humboldt and Del Norte are 6 days from the start of the growing season (Apr 1) while Trinity County is 21 days away (Apr 15). That is why frost/freeze products have not been issued for these Counties. Now looking at apparent temperatures for SW Humboldt, it does look to satisfy criteria for a cold weather advisory with wind chills less than 30F and strong northerly winds (gusts > 40 mph) over mostly the higher terrain.

Otherwise, dry and stable weather is expected for the remainder of this week and into the weekend. Generally above normal high temperatures and areas of minor heat risk are forecast for mostly the interior as a broad flat ridge aloft dominates. The warmest locations will continue to be in Lake, Trinity and interior Mendocino Counties where max temps are projected to peak into the upper 70s to mid 80s Thu and Fri. This is still 10-15F above late March averages. Overnight lows will remain seasonably chilly with perhaps some valley sites cooling into the lower to mid 30's. Overnight temperatures will remain elevated in the 50s and 60s in the thermal belts and over the high ridges where breezy E-NE winds persist through the night. No huge changes are anticipated at this time this weekend with above normal daytime highs likely continuing Sat and Sun. Coastal stratus may return this weekend and increase as the offshore wind abate.

Longer range models and national blend of models continue to trend wetter and colder next week, Monday March 30 to Friday, April 3rd. Higher end scenario (90th percentile) suggests multiple inches of rain (> 2 to 5 inches) spread out over 3-days while a lower end scenario (10th percentile) would yield an inch or less over the same 3-days. There are many unknowns like how much rain over what time interval and the duration. This far out it is hard to pin point, but there are signs in the model data. Snow levels will eventually fall by mid week too. How quickly and how low remains to be seen as well. If the cold core aloft dips far enough south we could definitely see some low top thunderstorms and small hail. March is usually the max on average for small hail. This is the first promising sign for significantly cooler and wetter weather I have seen in quite sometime and we will continue to message these hazards via weather story posts to give folks as much heads up as possible. You may think summer has arrived early this year considering how warm and dry it has been lately. The wet season is not over just yet. Stay tuned for more details.

AVIATION

Low clouds and drizzle this morning has quickly given way to widespread VFR conditions this afternoon. Gusty north winds has built along shore this afternoon with gusts in excess of 20 kts. Winds will persist into the evening and slowly ease overnight. Despite fresh moisture, north wind will most likely keep conditions too mixed to form low fog or clouds with a less than 20% chance of any IFR conditions. /JHW

MARINE

North winds have steadily increased through the day in the wake of a passing cold front. Wind gusts around 20 kts have built around shore by late Wednesday afternoon. Winds will continue to increase though the evening with gale force conditions in the outer waters by early Thursday morning. Slightly weaker, near gale conditions are most likely int he inner waters. Similarly strong winds will continue until early Friday with gradually weakening north winds into the weekend.

Short period seas will rapidly build alongside the winds with steep waves over 15 feet in the outer waters during the day on Thursday. Despite mostly sub-gale winds in the inner waters, still strong winds combined with wave energy from the outer waters will still create steep, hazardous short period seas over 10 feet. Steep seas will begin to fall alongside weakening winds Friday. /JHW

EKA WATCHES/WARNINGS/ADVISORIES

CA... Frost Advisory from 4 AM to 8 AM PDT Thursday for CAZ101- 103.

Cold Weather Advisory from 11 PM this evening to 9 AM PDT Thursday for CAZ104.

Frost Advisory from 2 AM to 9 AM PDT Thursday for CAZ109>115.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 5 PM this afternoon to 11 PM PDT this evening for PZZ450.

Hazardous Seas Warning from 11 PM this evening to 6 AM PDT Friday for PZZ450.

Small Craft Advisory until 5 PM PDT this afternoon for PZZ455-475.

Hazardous Seas Warning from 5 PM this afternoon to 6 AM PDT Friday for PZZ455.

Small Craft Advisory until 11 PM PDT this evening for PZZ470.

Gale Warning from 11 PM this evening to 6 AM PDT Friday for PZZ470.

Gale Warning from 5 PM this afternoon to 6 AM PDT Friday for PZZ475.