textproduct: Eureka

KEY MESSAGES

- Showers and occasional thunderstorms continue late this afternoon and evening.

- Potential of thunderstorms increase (15-30% chance) across the interior, capable of produce dangerous lightning strikes, brief heavy downpours, small hail, and gusty, erratic winds.

- Drier with a gradual warming trend this weekend through early next week, with interior Minor HeatRisk potentially on Monday.

DISCUSSION

Isolated to scattered thunderstorms are forecast to developed on the back side of the closed low this afternoon. Cold air aloft and higher instability (MUCAPE value around 200-300 J/kg) will increase the chances (15-30%) of thunderstorms across the interior, with the highest chance in Trinity County. Occasional cloud-to- ground lightning, brief heavy downpours, small hail, and gusty, erratic winds will be possible.

A weak ridge builds in briefly on Friday, while the low exits the area shifting eastward. This will bring dry air across the area. However, some lingering moisture will yield in isolated mountain showers across the eastern portion of the area the on Friday. Although the chances of thundertorms are lower (less than 10%),a non-zero chances remains in place. High temperatures are expected to increase and become more seasonal for this time of the year.

Saturday, a weak disturbance will move across the area and trigger another chance of isolated mountain thunderstorm development over NE Trinity County in the afternoon. The NBM has a chance of thunderstorms up to 15% in Trinity County for Saturday afternoon. While most model soundings depict a well- defined cap that could inhibit convection over most of our CWA.

The 500 mb ridge appears to slowly build back Sunday through mid- next week, resulting in drier weather with a gradual warming trend. Minor HeatRisk will likely return on Monday, especially across the interior valleys. High uncertainties are for mid to late next week. Ensemble clusters suggest the ridge weakening and flattening by mid next week with a broad upper level trough developing over the Gulf of Alaska./ZVS

AVIATION

After a gusty northerlies passed through the area with lightning and thunder being observed near area terminals late Wednesday, lighter winds with a southerly bearing and obscurations with ceilings below 500ft will usher in Thursday morning. LIFR at KCEC could last through much of the day as southerly winds pick up to 10kts or more. KACV will have less of an LIFR period as GFS and NAM -MOS guidance have ceilings lifting up to 1100-1500 feet with winds out of the West-Northwest, turning more NW by Thursday evening. VFR is the prevailing condition at KUKI with light rain possible until 16-17z, if at all. /EYS

MARINE

North winds continue to weaken and pull further offshore throughout today. Steep seas will gradually diminish through today with a Small Craft Advisory still in effect for all zones into this afternoon. An unusually long period northwest swell will build up to around 7 feet today. Such a swell is unusual for May and will brining at least a moderate risk of sneaker waves to area beaches. Otherwise, Winds will be mostly calm by this afternoon along with falling short period seas. Moderate north winds will begin to return to all waters Friday and into the weekend. Some marginal gale conditions are possible by Saturday. /JHW

BEACH HAZARDS

The swell will peak today around 8 feet at 16 seconds. Though falling short period waves will somewhat mask the swell, there will be a moderate risk of sneaker waves on area beaches. The greatest risk will be in areas of mostly calm winds on beaches that are exposed to the northwest. /JHW

EKA WATCHES/WARNINGS/ADVISORIES

CA... Beach Hazards Statement through this evening for CAZ101-103- 104-109.

NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 6 PM PDT this evening for PZZ450- 455-470-475.