Area Forecast Discussion
Issued by NWS Eureka, CA
FXUS66 KEKA 201122
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
322 AM PST Mon Feb 20 2017
.SYNOPSIS...Wet week ahead with no real drying in sight. Light to
moderate rain showers will continue through today. The rainfall
rate will increase tonight, with moderate steady rain continuing
through midday Tuesday. Expect windy conditions this morning and
then once again tonight as a pair of low pressure systems pass by
to our NW. Rain showers will linger from late Tuesday through the
end of the work week. We will have a cooling trend later this
week, with lowering snow level to around 2500 feet at times.
.DISCUSSION...Southerly winds have been increasing early this
morning as a surface low moves northeastward toward the Oregon
coast just off Crescent City. The HRRR continues to indicate
925MB winds ramping up to 50 to 55 kt just offshore of Crescent
City before sunrise. The surface low generating these winds is
expected to pass NW into the Oregon coast rapidly this morning so
have continued the wind advisory through 8 am as previously
forecast. Once the surface low passes to the NW of KCEC winds will
drop off some along the northern CA coast. SW winds will likely
continue to be gusty across Del Norte county through mid morning.
The next storm will develop quickly Monday afternoon and another
round of strong and gusty southerly winds are expected Monday
evening and again overnight. It is interesting to note that the
strongest winds with this second storm will be from the west. With
greater instability and the potential for thunderstorms, gusts to
50 to 60 mph will definitely be possible as cooler air aloft
The low pressure system bringing the SW-ly flow will enhance the
onshore upslope flow bringing continued showers through the day.
The main axis of heavy rain will focus towards the SF Bay Area.
Models are now indicating NW CA will get moderate rain from
Monday afternoon through Tuesday morning as the next disturbance
moves toward the coast bringing deeper moisture north with it.
Rain will be heavy at times especially south of Cape Mendocino.
Rainfall rates of about 0.5 to 0.75 inches every 6 hours. Expect
storm total precipitation around 2 to 4 inches, with higher
amounts over upslope terrain locations.
Winds will increase rapidly ahead of the next 2 surface lows and
attendant frontal systems. The first increase is occurring this
morning. A Wind Advisory continues as mentioned above for this
event, with the focus of the winds over the higher elevations of
Humboldt and Del Norte counties. The next wind event is expected
late Monday afternoon through Monday night. The models have been
varying quite a bit with this system, but the latest indications
are that the associated winds will be a bit stronger and more
widespread than the first event and from the west. As a result,
have continued the High Wind Watch for most areas that was issued
earlier. It appears the strongest winds will reach farther
inland. As mentioned, the stability with this second system is
much lower and as we had some isolated strikes overnight near our
southern border have added slight chance of thunderstorms over the
marine and for most areas inland. The only exception is the
higher inland mountains.
Precipitation will taper off on Tuesday, as the storm track shifts
north of the area. However, showers will still linger over NW
California. NW California will be on the back side of the upper
level trough, under NW-ly flow. However, there will be impulses
moving across the area from the NW at regular interval, which will
keep the showery weather over NW California. With the NW-ly upper
level flow, colder air will move into the area, dropping the snow
levels as low as 2500 feet at times. /mkn
.AVIATION...VFR to MVFR conditions and moderate to moderate and gusty winds will
continue at KCEC, KACV and KUKI through the early afternoon. The lower conditions
will be due to reduced ceilings and at times reduced visibilities as showers move
across the region at times this morning. The winds will be moderate this afternoon
and evening at KCEC, KACV and KUKI. VFR to MVFR conditions will prevail at KCEC,
KACV and KUKI overnight tonight and early Tuesday with gusty winds occurring. The
lower conditions will be due to reduced ceilings and visibilities as showers move
through the area. The showers and gusty winds will be due to the passage of a
cold front early Tuesday.
.MARINE...The winds and seas have increased across the waters as an offshore
low pressure system moves northeastward toward the Oregon coast. As the low
pressure system moves northeastward into Oregon the winds and seas will diminish
slightly this afternoon and evening. Another low pressure system will move into
Oregon overnight and early Tuesday morning. An associated cold front will move
across the waters early Tuesday morning. Therefore the winds and seas will
increase overnight tonight. A gale warning is in effect across the northern waters
through noon today and across the southern waters through early this morning.
A gale warning is likely across all the waters from early Tuesday morning through
late Tuesday morning as the cold front moves across the waters increasing the
winds. The winds and seas will diminish across all the waters Tuesday afternoon
and Tuesday night in the wake of the cold front.
HYDROLOGY...A Flood Watch for the Navarro River at Navarro has
continued this morning. The Eel River at Fernbridge and the
Klamath River at Klamath are forecast to rise above monitor stage
on Tuesday. The forecast for the Russian River at Hopland is being
watched closely and we may need to issue a Flood Advisory for
this location. /mkn
CA...Flood Watch from this afternoon through Tuesday afternoon for
High Wind Watch from this afternoon through late tonight for
Wind Advisory until 8 AM PST this morning for CAZ101>106.
NORTHWEST CALIFORNIA COASTAL WATERS...Gale Watch from late tonight through Tuesday morning for PZZ450-
Small Craft Advisory until 3 AM PST early this morning for
Gale Warning until noon PST today for PZZ450-470.
Gale Warning until 9 AM PST this morning for PZZ455-475.
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