textproduct: Eureka

KEY MESSAGES

* Much cooler temperatures expected with inland highs in the upper 60s to middle 70s through the week.

* There is a slight chance of thunderstorms mainly in Trinity County Tuesday afternoon and evening.

* An early season storm is likely to bring widespread rain to the area Wednesday and Thursday.

SYNOPSIS

An upper level low will deepen will bring some light showers or drizzle tonight and Tuesday. There is slight chance for thunderstorms Tuesday and Tuesday night as this low moves overheard. An early season storm is expected to bring widespread wetting rain Wednesday afternoon through Thursday.

DISCUSSION

An upper level low approaching the area has deepened the marine layer and is keeping the interior temperatures cooler. The cooler air aloft has allowed the marine inversion to weaken and there could be some clearing this evening. Tonight and Tuesday as this low approaches the area and the marine clouds return, it may bring some drizzle to the coastal areas. Tuesday this low may bring some convective showers to the area. This convective nature may help the coastal areas to clear out in the afternoon or at least the low clouds. There is some instability over the interior in the models. This may need some clearing to be realized. The CAMS are showing some light convective showers over the portions of the area. The instability may be enough to produce some lightning, but confidence is low on this.

Once this first low moves through there may be a brief break in the weather early Wednesday. Another front is expected to move in on Wednesday starting in Del Norte county in the late morning and spreading south into the afternoon and evening. The heaviest rain is expected in Del Norte county with 1.5 to 2.5 inches currently expected. The highest amounts will be over the higher terrain. Farther south the amounts are expected to quickly diminish. A half to three quarters of an inch is expected around Humboldt Bay and the Eel river Delta. Northern Humboldt may see quarters of an inch to over 1.5 inches near the Del Norte county border. Northern Mendocino and Trinity county are expected to see 0.5 to 1 inch with southern Mendocino receiving less than a half inch and portions of Lake county may see less than a tenth of an inch. There is still the potential for some of Mendocino and Lake counties to receive little to no rain from this system.

Thursday and Friday an upper level low is expected to stall over the Pacific Northwest. This is expected to continue to bring cool and moist conditions, but rain is generally expected to be just a few showers around. For the weekend and into Monday there may be a gradual return of warmer and drier conditions. MKK

AVIATION

The marine layer has deepened and CIGS are generally MVFR along the coast. As the cooler air moves in aloft the marine inversion has been weakening. This is being shown with a more fractured look of the clouds off the coast. This may allow some clearing this evening. Tonight there may be some drizzle, but generally conditions are expected to remain IFR at least. Tuesday CIGS may lift to VFR by midday although there could be some convective showers around. This could bring some periods of lower conditions to UKI and other inland areas. MKK

MARINE

Winds have generally diminished across the area, however some local southerly winds have picked up to around 15 to 20 kt off the Del Norte coast. These are expected to diminish tonight and generally light southerly winds are expected on Tuesday. The waves are expected to be dominated by a small southerly wave at 14 seconds.

Tuesday night and Wednesday the southerly winds are expected to increase to around 20 to 25 kt in the northern waters and lighter farther south. This is due to an early season weather system moving through the area. Thursday winds are expected to remain light and southerly. Friday it looks like the winds will become northerly again and start to increase over the weekend. MKK

FIRE WEATHER

Late Tuesday afternoon and Tuesday night the upper low moves overhead bringing the potential thunderstorms. High- resolution models are supportive of isolated thunderstorms in Trinity County, with higher chances on the northern and eastern edges. Confidence is still low, at around 10-15%. These thunderstorms are likely to be a mix of wet and dry, but precipitation is expected to be little.

Wednesday afternoon and evening there is the potential for widespread wetting rain. Precipitation continues to trend wetter and farther south, with wetting rain now likely across NW California. Rainfall amounts close to two inches are possible in Del Norte and northern Humboldt counties. This will need to be watched if these amounts continue to be shown in the models for any potential impacts to recent burn scars. MKK/JB

EKA WATCHES/WARNINGS/ADVISORIES

CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... None.