textproduct: Eureka

SYNOPSIS

Shower activity and the chance for thunderstorms today through Thursday. Isolated to scattered thunderstorms across the interior on Thursday. Breezy NW winds over the interior ridges and channeled terrain into Wednedsay, shifting to the coast Wednesday afternoon. Drier with a gradual warming trend this weekend through early next week.

KEY MESSAGES

- Showers and thunderstorms over the interior through Thursday.

- Enhanced northwest winds with gusts from 25 to 35 mph across the exposed ridges and channeled terrain Today into Wednesday, shifting to the coastal headlands Wednesday afternoon. - Isolated to scattered thunderstorms (15-30% chance) across the interior on Thursday, capable of produce dangarous lightning strikes, brief heavy downpours, and gusty, erratic winds.

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

DISCUSSION

A closed low is already center over Northeastern California continue to track southward, bringing cooler temperatures and showers activity across the area. Isolated mountain thunderstorms are possible (10-20% chance) late this afternoon and evening over the interior Del Norte, interior Humboldt, northeastern Mendocino, Lake and Trinity counties. In addition, an enhanced in the northwest winds is expecetd across the interior exposed ridges and channeled terrain this evening into Wednesday, with gusts from 25 to 40 mph possible. Then shifting along the coast on Wednesday, with north- northwest gusts of 25 to 35 mph over the coastal and exposed ridges.

Cool and unsettle weather pattern is expected to continue through Thursday as the low settle over California, before weakens and shift eastward into the Great Basin. PWAT values increase up to 1.0 inches on Wednesday and Thursday, with PWAT anomaly generally about 150-200% above-normal across the area. Instaibility diminish across the area on Wednesday; however, some shallow instability with a cold air aloft will be capable of produce moderate showers bands rotaring around the low and moving toward the coast. There remain a slight chance (10-15%) of thunderstorms for Trinity County on Wednesday afternoon and evening, with a non-zero probability elsewhere. On Thursday, the back side of the closed low will promote an increasing chance of convective showers and thunderstorms. There is a 15-30% chance of thunderstorms across the interior on Thursday, with the highest chance in Trinity County.

A weak ridging builds in briefly on Friday, while the low exits the area shifting to the east to northeast. This will bring dry air across the area. However, some lingering moisture will yield in isolated mountain showers and thunderstorm is the Trinity Horn on Friday. High temperatures are expected to increase and become more seasonably for this time of the year. A shortwave trough may bring an increasing cloudiness and some isolated mountain showers and thunderstorms again to Trinity County on Saturday.

The 500 mb ridge appears to slowly build back Sunday through early next next week, resulting in a drier weather with a gradual warming trend. Minor HeatRisk will likely resturns on Monday, especially across the interior valleys. /ZVS

AVIATION

Showers passing the area brought intermittent IFR conditions this morning, but lingering instability combined with northwest winds have helped scatter out ceilings and create mostly VFR conditions all across the area this afternoon. There is a 60% chance of some shallow mist and broken ceilings briefly generating MVFR to IFR conditions overnight along the coast, but skies will most likely quickly scatter back to VFR during the day on Wednesday. /JHW

MARINE

Steep, mid to short period seas up to 14 feet continue to dominate the sea state in all waters this afternoon. Moderate north winds have built in the outer waters and will push closer to shore overnight into Wednesday. Marginal gale conditions will build first in the southern outer waters early Wednesday morning with brief bu stronger gale conditions transitioning into the northern outer waters Wednesday afternoon. Near gale force gusts will push into the inner waters throughout the day. Seas will remain steep and hazardous throughout the day.

Winds will weaken and pull further offshore on Thursday. Just as short period seas begin to fall, however, a unusually long period northwest swell will build up to around 7 feet. 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 Thursday afternoon alongside falling short period seas. Moderate north winds will begin to return to all waters Friday and into the weekend. /JHW

FIRE WEATHER

Breezy NW winds with gusts from 25 to 35 mph is expected to continue this evening and into Wednesday over the exposed ridges and channeled terrain across the interior. Daytime relative humidity values are in the upper 30s to mid 40s percent in Trinity and Lake counties, with highest amounts up to 80 percent for the coastal counties. Enhanced fire weather threat exists for zones 418 and 421 due to gusts up to 40 mph and low daytime RH values around 35 percent and overnight recovery values around 70 percent. Winds are the expected to diminish throughout the day on Wednesday for the interior, before shift to the coastal headlands Wednesday afternoon. /ZVS

BEACH HAZARDS

Surf is currently elevated thanks to mid period seas up to around 14 feet. These shorter period seas and winds will calm Wednesday evening into Thursday. At the same time, an unusually long period northwest swell will build Wednesday evening and through the day on Thursday. The forerunners of this swell will begin to build in at just couple feet around 24 seconds. The swell will peak Thursday 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... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 AM PDT Thursday for PZZ450-455.

Small Craft Advisory until 3 PM PDT Wednesday for PZZ470.

Gale Warning from 3 PM to 11 PM PDT Wednesday for PZZ470.

Small Craft Advisory until 3 AM PDT Wednesday for PZZ475.

Gale Warning from 3 AM to noon PDT Wednesday for PZZ475.