Marine Weather and Tide Forecast for Westhaven-Moonstone, CA

DISCUSSION

KEY MESSAGES:

-Hot and dry weather building across the interior through Thursday with highs in the mid 80s.

-Regular, shallow diurnal marine layer right along shore.

-Very slight chance (15%) of isolated thunderstorms over Lake County late Wednesday afternoon.

-Cooler weather and light rain for the northern half of the area this Wednesday.

WEATHER PATTERN OVERVIEW: An upper level ridge and high pressure will gradually continue to build across the area over the next few days. For the interior this will allow for gradually clearing, warming, and drying conditions. Temperatures will most likely peak around Thursday wither interior valleys seeing highs peak in the mid 80s. There is, however, little chance (< 15%) of an highs of 90 in populated areas. For the coast, a regular diurnal cycle of marine stratus and fog is likely. High pressure will most likely compress the marine layer, forcing fog and stratus closer to the surface overnight.

The only chance of precipitation in the short term would be isolated showers and Thunderstorms Wednesday afternoon. While most areas will remain dry, there is a slight chance (15%) of isolated showers over the higher terrain of Lake County late Wednesday afternoon.

A narrow trough and surface low will skate down the coast during the day Saturday. At the very least, this low will bring thick cloud cover and much cooler and more moist conditions with highs in the mid 50s. There is potential for wetting rain across the area though any rain will be light. Most likely rainfall for the northern half of the area will be 0.1 to 0.25 inches over 24 hours with just a trace amount of rain further south.

The vast majority of model ensemble members show weak ridging and high pressure returning Sunday through mid next week with another trough setting up for later in the week. Gusty north wind will return along shore particularly Sunday afternoon.

FORECAST CONFIDENCE AND DEVIATIONS: There is relatively little uncertainty in the overall forecast. In the short term, the greatest uncertainty is regarding the potential for isolated thunderstorms Wednesday afternoon in Lake County. There is high confidence in the CAMs regarding robust instability, the most uncertain variable will be moisture. There is a very wide range in moisture potential, but about 20% of models (particularly the convective models) show enough moisture to generate isolated thunderstorms over high terrain. Any storms that for would likely be mostly dry.

In the mid term forecast, precipitation this weekend is the area of greatest uncertainty. The vast majority of models show only very light precipitation, though a small contingent (10%) shows some potential for rainfall over 0.3 inches along the North Coast. /JHW



AVIATION
Mainly VFR conditions are in place across the area. An area of stratus moved into KCEC, this looks like it will quickly move through the area, but confidence is low on this. This may impact KACV as well, but confidence is low on this as well. There are also some higher level clouds moving by to the north of the area. There are gusty winds along the coast this afternoon and up the river valleys. Winds are expected to diminish tonight. Stratus is expected to return along the coast at least in some areas.
There is some offshore flow behind the system moving by the area and this may limit the coverage of stratus. Any stratus that does form should clear fairly quickly in the morning on Wednesday. MKK



MARINE
Northerly winds continue this afternoon, although they are running a bit lighter than was previously expected. The small craft advisories remain on track and have extended them into Thursday.
Wednesday night and Thursday winds diminish more significantly and wind driven waves follow. A cold front may bring a brief period of southerly winds on Friday. This will be shortlived and stronger winds are expected to build back in Friday night and Saturday. These are expected to peak on Sunday with gale force winds. Models have come into better agreement on these gales so have trended the forecast towards the GFS and above the NBM. Waves will remain mainly wind driven. MKK



EKA WATCHES/WARNINGS/ADVISORIES
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory until 11 AM PDT Thursday for PZZ450- 455.

Small Craft Advisory until 9 PM PDT Thursday for PZZ470.

Small Craft Advisory until 4 AM PDT Friday for PZZ475.