textproduct: Eureka

KEY MESSAGES

* Breezy afternoon winds will elevate fire weather concerns for the interior this afternoon.

* Dry, generally mild, seasonable weather continues this weekend.

* Isolated thunderstorms are possible Tuesday afternoon and evening.

* Fall-like conditions possible next week with multiple chances of precipitation and cooler temperatures.

SYNOPSIS

Generally mild, seasonable weather continues across the area with slightly below normal interior temperatures and coastal areas seeing overnight stratus. A troughing pattern returns next week bringing multiple chances of precipitation.

DISCUSSION

A sunny Sunday is likely across the area as a weak marine inversion and breezy northwesterly winds clear quickly scatters any stratus that forms overnight. Interior temperatures will nudge higher today as mid level heights briefly increase ahead of the next trough, which is expected Tuesday.

The stratus will deepen again and persist longer along the coastal areas Monday ahead of a potent midlevel disturbance. Instability has trended down with this disturbance. Chances for MUCAPE over 100 J/kg have been reduced to around 10%, primarily in Trinity County and over the coastal waters. The inconsistency in global models arises from questions in potential 500-700 mb relative humidity. NBM maintains 10% chances for thunderstorms mainly for Trinity County, but perhaps into Del Norte and Humboldt as well. That solution sounds reasonable at this time, but there are still large discrepancies and a growing shot for no activity at all. Regarding fire weather concerns, models do precipitate moisture to the surface with any potential shower or thunderstorm, but soundings do look on the drier side for the described interior areas. The higher instability may progress through with the forcing associated with the passage of the dynamic shortwave Tuesday night. Guidance has been trending wetter Wednesday and less unstable Tuesday however. Regardless, a much wetter environment will immediately follow the trough.

Confidence is growing on a second colder, wetter system moving into the Pacific Northwest Wednesday, with additional disturbances to follow in a well established troughing pattern. The main uncertainty is how far south this will be positioned, but precipitation estimates continue to grow, with much of the North Coast at over 50% chances to receive at least a half inch of rain. Wetting rain (>0.1") chances are around or above 80% for the North Coast and around 40-60% for much of the interior outside Lake County. There are also moderate to high chances for southerly winds to gusts over 25 mph Wednesday with the storm system. This is a ways out, so there is still plenty of time for this pattern to change, but right now signs are pointing to fall-like conditions. Regardless of precipitation, temperatures are likely to fall well below normal. Chilly morning lows in the 30s and 40s are possible for much of the interior.

AVIATION...12Z UPDATE

A weak bank of coastal stratus exists for the Humboldt Bay are this morning with MVFR conditions. This is expected to scatter out by mid morning leading to VFR with strong northerly winds. A return of more widespread cloud coverage for the coast is expected for Sunday night into Monday morning. Inland areas will experience VFR with breezy, mainly-northerly, afternoon winds funneling through the terrain before giving way to calm, variable winds.

MARINE

Apart from areas around and south of Point St George, winds in the inner waters north of Cape Mendocino remain below advisory level. Gust up to 35 kts can be expected around Cape Mendocino again this afternoon and evening. Additionally, isolated areas of gale strength gusts will expand farther into the southern outer waters. Steep wind driven seas of 7 to 10 ft will develop as a result, with locally higher amounts in the southern waters around the cape. These will combine with a long-period south swell arriving today. The northerlies will begin to quickly subside Monday as a troughing pattern returns. Seas and winds look to be quite low for much of next week from the troughing. A stronger front with a round of increased southerly winds will be possible around mid next week.

FIRE WEATHER

Somewhat lighter but continued breezy conditions will continue today with low RH in the twenties to teens. A southerly wind surge will push through the Sacramento valley Monday, and winds could be especially breezy over northeast Trinity County. Westerly winds will be gusty on Monday over much of our interior while minimum RH and overnight recoveries continue to improve.

A potent shortwave trough will bring a chance for mostly dry lightning, or a mixture of some wetter showers/storms Tuesday or Tuesday night. The available mid to lower level moisture to fuel these storms is still largely in question. There is currently around a 10 percent chance of the thunderstorm occurrence for mainly Trinity County Tuesday afternoon. The passage of the shortwave through Tuesday night may bring additional chances, including outside of Trinity County. The more moisture rich scenarios bring in higher level instability, so the situation bears watching at least. Guidance has been trending wetter Wednesday and less unstable Tuesday however.

There is second colder system forecast to follow Wednesday and bring accumulating rainfall over the area. Eastern Trinity County has a 50 to 65 percent chance of a wetting rainfall with this system. Areas farther northwest will have a good chance of meaningful accumulating rainfall. Breezy southerly winds are possible Wednesday, which could be problematic if lightning does occur on Tuesday and little rainfall follows. The overall environment will certainly moisten up however. Additional shots of at least light rainfall continue through late in the week and potentially into next weekend with a continued troughing pattern.

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 PM PDT this evening for PZZ450.

Small Craft Advisory until 9 AM PDT Monday for PZZ455-470.

Small Craft Advisory until 3 PM PDT Monday for PZZ475.