Area Forecast Discussion
Issued by NWS Eureka, CA
FXUS66 KEKA 302210
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
310 PM PDT Sun Apr 30 2017
.SYNOPSIS...Generally mild and dry conditions are forecast to
prevail across the region through Wednesday. Thereafter, cooler
temperatures and increasing rain chances are possible during the
latter portions of the upcoming week.
.DISCUSSION...The weak frontal boundary is currently over the
area, but the only impact has been some coastal stratus. This will
continue to move through the area this afternoon and evening.
Stratus will diminish later tonight skies will mainly clear out.
Northerly winds will persist along the coast and over the ridges,
but the interior valleys will likely decouple later tonight. This
will bring the potential for frost in the Trinity county valleys.
For now will hold off on issuing a frost advisory for Hayfork, but
it is possible they will see some frost. Monday afternoon another
weak wave moving over the top of the ridge will bring some high
and mid level clouds to the area. This will also diminish the
winds along the coast a bit. There may be a few showers in Del
Norte county, but they should be pretty light. The NAM is the only
model with any precip at all.
Tuesday and Wednesday the ridge moves overhead. This is expected
to bring offshore flow and mostly sunny skies across the area.
Temperatures will warm into the low 60s on the coast and to around
90 in the inland valleys. Offshore flow weakens Wednesday morning
as the ridge starts to progress east. Models do show an increase
of SFC RH around Humboldt Bay Tuesday evening, but confidence is
low on this.
Thursday the ECMWF and the GFS shows an upper level approach the
area. The GFS is showing quite a few showers over the inland areas
while the ECMWF is slower and only has a few showers over Trinity
county. The 12Z GFS and ECMWF both keep the area in a cooler
pattern for Friday and Saturday with the potential for a few
showers. Sunday the GFS builds the ridge back in rapidly warming
temperatures and bringing strong gusty winds to the coast. The
ECMWF is slower and keeps the low in the area on Sunday. For now
will generally take an average of the two solutions, but lean
slightly toward the GFS due to the fact that a ridge is more
climatologically likely. MKK
.AVIATION...Northerly winds will increase again this afternoon
behind the frontal boundary. Skies are expected to clear this
evening, but low clouds may return on the northern Humboldt and
southern Mendocino coasts later tonight. Del Norte county looks to
have enough offshore flow to stay mainly clear tonight. Inland
areas are expected to be clear. Monday winds will be lighter along
the coast north of Cape Mendocino, but remain elevated on the
Mendocino coast and there may some gusty winds in the interior
valleys in the afternoon. MKK
.MARINE...Northerly winds are continuing increase this afternoon
behind the weak frontal boundary that moved through. These are
expected to peak late this evening with near gale force gusts over
the southern outer waters. Steep short period waves will increase
as well, peaking around 8 feet at 7 seconds. The small craft
advisories look to be on track.
Northerly winds will ease north of the Cape on Monday as another
front approaches the West coast and disrupts the offshore ridge.
South of Cape Mendo, north winds will remain in the 15 to 25kt
range to warrant an advisory through mid week. Thursday models
show another system moving through the area, but they are
struggling with the strength and timing of this system. Friday
into the weekend the models really start to struggle with the
evolution of the upper level low moving across the area. The
ECMWF is much slower and has much lighter winds over the waters.
THe GFS quickly builds the ridge back in pushing the low off to
the southeast. This brings gale force winds to the waters and is
currently the forecast. Confidence is lower than normal for this
time period. MKK
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory from 2 PM this afternoon to 5 AM PDT
Monday for PZZ455-470.
Small Craft Advisory until 5 AM PDT Wednesday for PZZ475.
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