textproduct: Eureka

SYNOPSIS

A short break in the rain is forecast Monday before the next round of heavy rain and strong wind returns Monday night through Tuesday night. Another brief break is expected Wednesday with more strong winds, heavy rain and now lower snow levels expected Wednesday night and Thursday. Drier weather is finally possible Friday.

DISCUSSION

The heavier rain has moved out of the area, but moist southwest flow continues to bring some light rain showers to the area, especially in Mendocino and Lake counties. Monday generally dry weather is expected. Skies are expected to remain cloudy and there certainly may be some light showers across the area, especially in Del Norte county and Lake county.

Monday night the next weather system is expected to start bringing rain and wind to the area. This is expected to start in Mendocino county move north to Humboldt county overnight. Rainfall amounts are now expected to be around 2 to 4 inches south of Del Norte county. Del Norte county is only expected to see 1 to 2 inches. The IVT from the GFS and ECMWF ensembles back this up with a brief spike up 700 kg/m/s from Cape Mendocino and south. However this could shift northwards again. This is a fairly small system and fast moving system. This produces a high potential of forecast bust with significantly more rain or less rain. The 75th and 25th percentile from the NBM shows a wide range of rainfall possibilities so this will need to be monitored and a flood watch will likely be needed. See hydrology section for more details. Snow levels are expected to be around 3500 to 4000 feet when the precip starts, but are expected to rise rapidly. Confidence is low on exactly how quickly this will take place.

This system also is expected to see high winds. The deterministic models are showing a very strong area of low pressure moving onto the Humboldt coast. The 06Z NAM and the 00Z GFS now both keeps the low just off the coast and rapidly deepen it to around 986 MB. The NAM shows 80 KT at 850 mb just off Cape Mendocino. The GFS is similar, but slightly lower. Either of these solutions would bring winds over 70 mph to the ridges. The NBM is showing a 40 to 70 percent of max 24 hour wind gusts over 60 mph on the ridges and coastal headlands. So have issued a high wind watch in Mendocino and Lake counties to highlight these winds. This may need to be expanded farther north into Humbodlt and Del Norte counties.

This is expected to move out of the area early on Wednesday and this may provide a small break in the rain. This will be shortlived with potential for another system to move into the area Wednesday late in the afternoon or evening. This system looks be a large low pressure that becomes a cutoff low. Strong winds are expected again with with several areas of strong area of low pressure rotating around each other off coast. This low may be slightly farther off the coast, but may still bring some strong winds to the area. This will need to be monitored as it gets closer. Current forecast is showing another 2 to 4 inches south of Hwy 36 with less rain farther north. Snow levels are expected to be around 4000 to 5000 feet during the heaviest precip. Thursday afternoon this low moves closer and may bring some thunderstorms and possibly small hail.

Friday the upper level low gradually starts to pull out of the and there may be some lingering showers. This could bring some lower snow levels. Saturday it looks like high pressure starts to build into the area finally ushering in a break in the weather. MKK

AVIATION...(06z TAFs)

Rain continues after several hours of inundation. Flight categories at KCEC have improved as of 05z with rain easing for a few hours Monday before the next deluge, Tuesday evening. This is more likely for the terminals south of Del Norte as heavier rains are predicted from the SW. KACV could see a few hours of LIFR/IFR overnight with reduced visibility and ceilings below 500ft but recover with MVFR by Monday morning, 14-15z. KUKI will have improvements by the afternoon Monday, expect ongoing reduced conditions fluctuating between IFR/LIFR as the AR diminishes later in the day than the other terminals. /EYS

MARINE

West to southwest winds are forecast to remain gentle to moderate tonight through Monday. Another low pressure system may generate gale force winds south of Cape Mendocino late Tuesday. A powerful storm will bring another threat for gales Wednesday through Thursday. Considerable uncertainty with timing, location and magnitude of winds with each of these storms. Westerly swell from 6 to 7 feet at 10 seconds is expected to gradually diminish tonight through Monday. Short period seas forecast to build with storm. Larger swell is expected to build toward the end of this week.

HYDROLOGY

The rivers are generally receding this morning with the exception of the Eel River at Scotia and Fernbridge. These are expected to crest this morning and gradually diminish through the day.

The next rounds of rain are likely to produce flooding impacts again across the area. While most ensemble members show the heaviest rain heading to Mendocino and Lake Counties again, significant rain is still likely for the entire area. Small stream, creeks, and main stem rivers are all likely to see impacts again. It is also possible the focus of the heavier rainfall will shift north again. Currently the Russian River at Hopland the Navarro river at Navarro are expected to reach flood stage again. The Eel river and the Mad river are expected to be close to flood stage, but not expected to exceed it at this time. This will need to be monitored closely.

The final system in these series is not expected to have as much rain with with, but with this rain coming only 12 to 18 hours after the previous this has the potential to bring more serious flooding.

EKA WATCHES/WARNINGS/ADVISORIES

CA... Flood Watch until 4 AM PST early this morning for CAZ108.

Flood Watch until 9 AM PST this morning for CAZ109>115.

High Wind Watch from Tuesday evening through late Tuesday night for CAZ109>115.

NORTHWEST CALIFORNIA COASTAL WATERS... Gale Watch from Tuesday evening through late Tuesday night for PZZ455-475.

NORTHWEST CALIFORNIA COASTAL WATERS... None.