textproduct: Eureka

SYNOPSIS

Moderate to major HeatRisk will continue across the interior through the early week, though coastal areas have seen increase marine influence and cooling. The heat wave will break down later in the week.

KEY MESSAGES

- Temperatures will continue to peak with moderate to major HeatRisk through early week.

- Shallow marine influence growing along shore will keep low clouds and fog for most of the immediate shore through Monday.

- Cooling trend for inland areas mid to late next week.

DISCUSSION

High pressure ridging continues to dominate across the area with the strongest focus shifting further north across Humboldt and Trinity Counties into Monday. High temperatures will continue to be above average, though not record breaking. These temperatures constitute a generally moderate HeatRisk with some areas of major risk for the warmest valleys. Shallow moisture remains below a strong inversion. This continues to result in areas of fog, with periods of dense fog of visibility 1/4 mile or less. The pattern also continues to favor very little breaks in these conditions throughout the day for the immediate coastal areas.

Come Tuesday, heat will continue to peak for the northern half of the area, but weakening marine influence further South will push HeatRisk back toward major in Mendocino and Lake Counties, maybe promoting heat advisories once again in some areas.

High pressure will begin to weaken late in the week with interior highs pulling back into the mid 80s. Most deterministic models show weak trough pushing onshore around Thursday. This trough will definitely cool conditions and help deepen marine influence along shore, creating a more persistent and further reaching marine layer. Most models currently suggest the trough is too weak to tap into any tropical moisture. While some showers or very weak storms could be likely, currently profiles are not favorable for widespread convection. JHW/JJW

AVIATION

The shallow and robust low level inversion that brought unyielding LIFR conditions Sunday for the coastal terminals, with period of dense fog, remains in place. That said, only brief if any windows of improvement in visibility and ceiling heights are forecast Monday. An alternate but less likely scenario is that the strong ridge of high pressure compresses the inversion to such a shallow level that the stratus dissolves better over the coast during afternoon heating. In any event, the shallow stratus and fog will continue a strong presence over the coastal terminals. It does appear that the marine layer will likely be turn shallow enough Tuesday to more fully scatter out for a period.

MARINE

Broad high pressure will allow for gentle winds and seas of 3 to 5 feet for much of Monday. A stronger ridge will nose in from the west late Monday, and the northerly winds will strengthen in response. Near gale to gale conditions will develop over portions of the waters, mainly the outers, Tuesday. The northerly winds will strengthen through Wednesday. Though winds will be lighter, short period and occasionally large seas near 10 feet will enter the inner waters around and north of Cape Mendocino Tuesday through Thursday. Thereafter, seas trend lower after the stronger northerlies likely pull farther offshore.

FIRE WEATHER

An ongoing heat wave has helped rapidly dry fuels. Interior high temperatures have been reaching near 100 with RH generally between 15 and 25 percent. Overnight RH recovery has also been poor with thermal belts with mid and upper elevation nighttime RH only around 50 percent. ERC has rapidly increased across the board with most RAWS likely to reach near the the percentile by midweek, even close to shore. That said, the general lack of wind will continue to suppress the risk of any fast moving fires. Hot and dry conditions will weaken by midweek.

Long term models show a weak trough crossing the area late in the week. Such a pattern could produce thunderstorms. Most models, however, currently show moisture profiles insufficient to really drive convection. Current thunder chances are less than 10 percents with the highest chances in NE Trinity County. That said, any showers that do form over high terrain are most likely to be dry given the setup and preceding conditions. JHW

COASTAL FLOODING

High astronomical tides are predicted through Tuesday June 16 for Northwest California with the highest tide just before midnight each evening. High tides peaked around 9 feet on Saturday night. Weakened north winds and higher astronomical tide will likely push the tide even slightly higher Sunday night near 9.1 feet. High tides will cause minor coastal flooding round Humboldt Bay, including King Salmon and low- lying roads near Arcata Bottoms. /JHW

EKA WATCHES/WARNINGS/ADVISORIES

CA... Heat Advisory until 10 PM PDT Tuesday for CAZ102-105-108- 111-116-117.

Coastal Flood Advisory until 1 AM PDT Monday for CAZ103.

Heat Advisory from 11 AM Monday to 10 PM PDT Tuesday for CAZ114.

NORTHWEST CALIFORNIA COASTAL WATERS... Coastal Flood Advisory until 1 AM PDT Monday for PZZ415.

Small Craft Advisory from 3 PM Tuesday to 3 AM PDT Wednesday for PZZ450.

Small Craft Advisory from 9 PM Monday to 8 AM PDT Tuesday for PZZ470.

Gale Watch from Tuesday morning through late Tuesday night for PZZ470.

Small Craft Advisory from 3 AM Tuesday to 3 AM PDT Wednesday for PZZ475.