Area Forecast Discussion
Issued by NWS Eureka, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
FXUS66 KEKA 211045

National Weather Service Eureka CA
345 AM PDT Sat Oct 21 2017

.SYNOPSIS...A warm front will prolong wet weather for northwest
California today and Sunday. The best chances for additional
rainfall will be to the north near the Oregon border. Then strong
high pressure will bring hot and dry weather across the interior
for early next week.


.DISCUSSION...Moist, onshore flow will bring more wet weather to the
region today and Sunday. This warm frontal system will bring a light
yet persistent rain to mainly Humboldt and Del Norte counties today
and then primarily to Del Norte on Sunday as the warm front lifts to
the north. Del Norte could observe as much as an additional 1.5
inches by the end of the weekend with Humboldt forecast to get 0.10
to 0.50 inches. Rain across Trinity and Mendocino counties looks
less likely but a few hundredths is certainly possible. Daytime and
evening temperatures will gradually increase as 500mb heights rise
and 850 mb temperatures increase with warm air advection. As a
result, snow levels will be quite high around 10,000 feet.

Looking into next week, confidence tools suggest anomalously strong
ridging will develop across the north eastern Pacific Ocean. This
will bring abrupt warming and plummeting afternoon humidity for
Monday and Tuesday. MOS guidance suggests interior areas, especially
Mendocino County, will see temperatures reach the 80s and 90s. This
would be nearly 30 degrees warmer than temperatures expected for
today. During this period a thermal trough is forecast to position
over the coast brining enhanced northeasterly winds across most of
the forecast area. Mendocino County could see some breezy
conditions on ridgetops, however, the strongest 925mb winds look
to be farther south across Lake, Napa, and Sonoma counties early
Monday and Tuesday mornings.

Then 500 mb heights will begin to fall later next week as an inside
slider tracks down the ridge over the Pacific Northwest. This
will bring decreasing inland temperatures through the end of the
week. Little to no precipitation is anticipated with this dry
system. /KML


.AVIATION...A warm front has been generating breezy southerly winds
and occasional light rain at KCEC. The light rain should should spread
southward to KACV by daybreak, however southerly winds will remain
lighter. Ceilings and vsbys should fall at the coastal terminals
after southerly winds die down tonight. VFR conditions with high
and mid clouds will prevail at KUKI today.


.MARINE...A west-northwest swell will continue to subside through
Sunday. Seas will remain high enough (10ft and higher) through Sunday
to warrant an advisory. A warm front will generate brisk southerly
winds and steep southerly waves north of Cape Mendo today. Winds will
fall below advisory or warning levels on Sunday. Brisk northerly
winds and short period northerly wind waves will return early next week.
Another long period (but smaller) WNW swell will start to build to
formidable levels on Monday. The beach hazard threat will once again
be on the rise as the swell builds to 6 ft at 17 seconds on Monday.


CA...Frost Advisory until 8 AM PDT this morning for CAZ110-111.

NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 5 AM PDT Monday for PZZ450-455-470-



Visit us at

Follow us on Facebook and Twitter at:

For forecast zone information
see the forecast zone map online: is the U.S. government's official web portal to all federal, state and local government web resources and services.