textproduct: Eureka

KEY MESSAGES

* Light to moderate rain is expected this evening through Monday, mainly in Humboldt and Del Norte counties.

* Eastern Mendocino and Lake county Valleys are expected to see a near freezing or freezing temperatures again morning Monday.

* Minor coastal flooding expected Monday through Wednesday at high tide, mainly around Humboldt Bay.

SYNOPSIS

A weak front will bring some light to moderate rain to mainly Humboldt and Del Norte counties tonight and Monday. Farther south chilly temperatures are expected again in the eastern valleys of Mendocino and Lake counties. Cool and mainly dry weather is expected Tuesday and Wednesday with another chance for rain late Thursday and Friday.

DISCUSSION

Dry weather continues across the area today after a chilly start in many locations. The satellite shows the frontal boundary approaching the area this afternoon with high clouds spreading across the northern portion of the area. Rain is expected to start near or just after sunset in Crescent and spread south with some light rain making it to Eureka by around 10pm or so. It looks like there will be a quick band of rain that moves through in the a couple hours. Behind the main front showers are expected to linger into Monday. It is possible there will be a thunderstorm or two with these showers, but the instability looks pretty limited and what there is is at too low of a level to generate thunderstorms. So have removed them from the forecast. Rainfall amounts are expected to be the highest in Del Norte county with over 0.75 inches expected in the mountains. Rainfall is expected to be less than a quarter inch by the it makes it to Eureka and the King Range. Farther inland the Trinity river valley from Orleans to Hoopa and Willow Creek is expected to see less than a quarter inch. This is expected to quickly dissipate as it moves farther inland. Only a trace to a few hundredths is expected in Trinity, Mendocino and Lake counties although the northern mountains of these counties may see a bit more. The cloud cover and cool airmass associated with this trough and front is expected to keep highs in the 50s to low 60s.

Monday night into Tuesday the upper level trough remains in place, however most of the rain showers are expected to come to an end. Tuesday and Wednesday the upper level is expected to remain in place bringing a mix of sun and clouds. It is possible a few showers will develop in the afternoons if a shortwave happens to be moving around the trough. High temperatures are expected to remain in the upper 50s to low 60s both Tuesday and Wednesday. Some frost is possible in the valleys if any of them manage to remain clear overnight. Fog is likely in many of the areas closer to the coast.

Thursday through Saturday the upper level trough is expected to remain over the over the area. This is expected to keep temperatures cool, generally in the 50s to low 60s for the interior valleys. Some rain is expected but at this point the probabilities for a half inch in 48 hours remain less than 50 percent. The Atmospheric River Ensemble tools also hold off on any strong moisture plumes until the 3rd or 4th of November. MKK

AVIATION

An approaching frontal boundary is bring some high clouds to the area this afternoon, but generally VFR conditions persist. This evening the front is expected to bring a band of rain KCEC and then spread south to KACV a few hours later. As this band moves farther south and east it is expected to weaken and dissipate with KUKI remaining dry. It is possible KUKI may see some low clouds Monday by around midday or early afternoon. Behind the frontal band showers are expected. There is some instability, but it looks like it is only in the lower levels and not deep enough for thunder so have removed it from KCEC. These showers are expected to diminish on Monday, but the clouds may be slow to lift. The HREF shows the CIGS lifting by midday, but this it may be slower than this. MKK

MARINE

Light southerly winds are spreading south this afternoon ahead of a weak frontal boundary. Tonight a northwest well is also expected to build in. It is expected to build to be around 7 to 8 feet at 12 seconds by morning. Monday the winds are expected to gradually switch back to the north as an area of low pressure moves by to the north of the area. Monday night and Tuesday northerly winds are expected to increase again reaching 15 to 25 kt by Tuesday afternoon. These are expected to be strongest in the southern waters. North winds look to peak early on Wednesday before starting to diminish once again late in the week. MKK

COASTAL FLOODING

Water levels this morning only reached around 8.7 ft above MLLW at the North Spit. This fell below the 8.8 where flooding typically starts. This was with an anomaly of 1.1 to 1.2 feet above astronomical tides. The surge model shows a similar anomaly on Monday, although the southerly winds could increase this slightly. So with an astronomical high tide of 7.8 feet on Monday, expect water levels will reach 9.0 or 9.1 and cause some minor flooding. So have issued a coastal flood advisory.

Tuesday the winds start to turn back to the north. This may start to diminish the anomaly or keep it steady. This will be the highest astronomical tides, and highest chances for coastal flooding, are forecast to be on Tuesday and Wednesday of next week at 8.04 ft and 8.06 ft, respectively. This will likely bring at least minor coastal flooding and possibly moderate coastal flooding. This will mainly be around Humbodlt Bay with little expected outside the bay unless there are large waves. Arena Cove is also expected to see water level reach the highest astronomical tide levels. Waves are only expected to be around 6 to 7 feet at 11 seconds so am not expecting impacts on the Mendocino coast at this point, but this will need to be monitored. MKK