Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 222054

National Weather Service Eureka CA
154 PM PDT Thu Mar 22 2018

.SYNOPSIS...Winter Storm Warning tonight through Friday, another
winter weather system on Saturday. Dry weather returns next week.


.DISCUSSION...Through this morning, a heavy rain band associated
with the weather front moved across the area. Most areas saw 1 to
2 inches of rain, with less inland and further south. During the
day today, we had strong cold and dry advection over the area.
Skies cleared and snow level dropped to 2000 feet. However, the
dry break won`t last too long. The next area of precipitation will
move into Del Norte County tonight, and spread into the rest of
the area by early Friday morning.

Snow level will be around 1500 feet overnight tonight, then rising
to around 2500 to 3000 feet during the day on Friday, then
dropping back down to 1500 feet Friday night. For locations above
3000 feet, this is almost like a classic textbook example for
snowfall. However, the difficulty in this forecast will be how
much snow will fall at around 2000 to 3000 feet. Models are
forecasting periods of heavy precipitation hitting the area. With
cold air aloft, the heavy precipitation can drag down the colder
air to lower part of the atmosphere. Snow level will fluctuate
between 2000 to 3000 feet, with lower snow level in locations that
see heavy precipitation rate. During periods of heavy snowfall, do
expect snowfall rate to exceed 1 inch per hour at times. This will
significantly lower visibilities, making travel hazardous. Winter
Storm Warning is in effect from tonight through Friday night for
elevation above 2000 feet. The thinking is still about 6 inches at
elevation above 2000 feet, with 12 inches above 3000 feet. This
system will wind down Friday night.

However, there may not even be anytime for breather. The next
batch of precipitation will move into NW California Saturday
morning, and continue through Saturday night. Something to keep
in mind with the Saturday storm system. Snow level will be around
1500 to 2000 feet. Some models are now showing this event will be
a longer duration event. Also, with strong upper level dynamics,
the rising motion (omega) will be stronger. Snowfall rate can be
as high as 1 inch per hour in ares of heavier snow showers. Stay
tune for future updates with the Saturday storm system, as it has
potential to produce advisory level or higher impact winter

If you are living along the coastal area, Saturday will also be an
active day for you. Factors are pointing to favorable conditions
for small hail. 500 mb temperature are expected to be around -35C,
well below the -30C criteria. There will be warm air advection at
around 850 to 700mb. The lapse rate at 700 mb will be steeper than
7C/km, with temperature at 700 mb below -12C. There will be more
than 200 J/kg most unstable CAPE. 850 mb temperature will be
around -4 C, which is slightly colder than the -1 C criteria. But
overall, conditions are favorable for small hail to take place on
Saturday afternoon and evening. Small hail can make roads very
slick, so travel can be hazardous due to slippery road conditions.

Sunday will be the day of transition. Showers will be ending, and
skies will clear, with offshore flow developing. Do expect Sunday
night to be a cold one, with frosty conditions developing in
interior areas. /RCL


A high pressure system, moving in from the west, parks itself
next to us starting on Monday. This will help drop chances of
precipitation, keeping us dry throughout all of next week with a
nice addition of clear skies. Next week is looking to be quite a
pleasant work week for the North Coast. The high starts to move
south next Thursday but clear and dry conditions will continue for
Friday. /SL/RCL


.MARINE...Brief west-northwesterly winds today will become
southerly this evening as the next system brings near gale force
gusts to the waters through Friday. Strong southerlies will return
to the waters on Saturday as the final front in this storm system.
Then building high pressure will causes increasing north winds in
the middle of next week. The wind-driven wave environment will be
steep and chaotic over the next few days with the constantly change
wind field. Nevertheless, expect steep building waves with each
frontal passage on Friday and again on Saturday. Otherwise a large
northwesterly swell system will keep seas elevated through the
weekend. Expect 12 to 14 foot seas to develop by Friday. Although
there will be very brief periods lowering winds and seas, we opted
to issue small craft advisories at least through Sunday morning.


.AVIATION...Mostly cloudy skies continued across NW California today following
the passage of a robust cold front in the morning. By noonday,
coastal air terminals were reporting VFR conditions, although
occasional CIGS near 3000 feet were hovering near CEC. Cigs became
VFR shortly after 12 noon at UKI. Satellite and Composite Radar at
noon also indicated showers generally east of the region. For the
00z TAF through 24 hours (Fri aftn): another weather system will
approach the North Coast Friday. Increasing clouds, showers and
"ramping up" southerly winds will precede the system starting
overnight. Models indicate LLWS, mainly at the coastal terminals
beginning in the early morning. /TA


CA...Winter Storm Warning from 11 PM this evening to 11 PM PDT Friday
     for CAZ102-105>108-111.

NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 2 PM PDT this afternoon for PZZ455-

     Small Craft Advisory until 9 AM PDT this morning for PZZ450.

     Small Craft Advisory until 11 AM PDT this morning for PZZ470.



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