textproduct: Eureka

SYNOPSIS

Hot temperatures return to much of the interior Sunday. Monsoonal moisture will bring cloud cover and moisture Monday and Tuesday. Isolated thunderstorms or showers are possible early next week in the interior.

DISCUSSION

An upper level trough off the Pacific Northwest is sliding eastward while an upper level ridge over the Southwest US continues to expand westward. Monsoonal moisture from the south has started to stream over the area, bringing a few high clouds. Additional moisture streams over the area tonight into Sunday. A few virga showers are possible for the eastern and southern portions of the area, but there is low confidence in anything reaching the ground. Monday and Tuesday, additional moisture streams over the area. Instability is meager, but could bring a few isolated thunderstorms to the interior areas, with the highest chances in the Yolla Bollys and the Trinity Alps. The RRFS is showing some convection continuing overnight Monday, but confidence remains low on any thunder at this time. Instability does increase Tuesday, though moisture starts to move eastward. Currently models do show just enough moisture remaining by Tuesday afternoon, bringing a 10- 20% chance for thunderstorms mainly in Trinity County.

High temperatures are forecast to remain in the 90s for most interior valleys with the warmest areas exceeding 100 this weekend. Additional cloud cover early next week may nudge these forecasted temperatures down a few degrees. HeatRisk remains minor to locally moderate. Coastal areas remain in the high 50s to mid 60s with stratus forming overnight and partially clearing by the afternoon.

Drier air returns mid this week as the Pacific Northwest trough moves southwestward. A deeper marine layer will likely bring interior temperatures down by a few degrees, while bringing more widespread, and possibly persistent, coastal stratus. JB

AVIATION...(18Z TAFs)

Stratus has lifted and scatter from the coastal areas and VFR conditions are likely across the area this afternoon and early evening. Stratus may make a return to the coastal areas this evening and overnight, but confidence is lower than previous days. CEC has around a 45% chance to see stratus, while ACV has a 60% chance. Should stratus develop, LIFR to IFR ceilings are expected. Any stratus will lift and scatter by late morning Sunday. Interior areas are likely to remain VFR for the next 24 hours. JB

MARINE

Northerly winds increase again this evening and overnight with localized gale force gusts likely in the lee of Cape Mendocino. Outside of this, sustained winds of 15-25 kts are likely for the outer waters. Nearshore winds will be much lighter at 10-20 kts, but could still be breezy in the afternoon. Northerly winds ease somewhat Monday into Tuesday, but will remain strong in the lee of Cape Mendocino. Strong winds and steep seas return mid to late next week. Seas will be dominated by wind waves with only small mid to long period southerly swells. Steep wind waves may propagate to the inner waters even as winds remain milder. JB

FIRE WEATHER

Monsoonal moisture has arrived to the area and will peak Monday and Tuesday. There is high uncertainty if this will lead to thunderstorms as instability is low, but with warm and dry low levels, any thunder is likely to be dry. The RRFS is showing some potential for convection Monday night into Tuesday morning, starting from the south in the evening and moving northward. Other models show this feature, but instability is much weaker. The highest chances for thunderstorms remains on Tuesday afternoon with 10-20% chances in Trinity County and into the Yolla Bollys. This may still nudge westward and southward, but is highly dependent on how far east the moisture nudges. Some models do show moisture completely to the east of the area, still, so confidence generally remains low. JB

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 PM PDT Sunday for PZZ455.

Small Craft Advisory from 1 AM Sunday to 9 AM PDT Monday for PZZ470.

Small Craft Advisory until 3 AM PDT Tuesday for PZZ475.