Area Forecast Discussion
Issued by NWS Eureka, CA
FXUS66 KEKA 252315
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
415 PM PDT MON JUL 25 2016
.SYNOPSIS...Strong high pressure will bring a significant warming
trend through mid-week with triple digit temperatures across
portions of the interior. Coastal areas will continue to see a
mix of clouds and sun as the marine layer fluctuates in depth.
.DISCUSSION...Low clouds over the coastal waters were much more
expansive this morning on the heals of a departing weak upper
trough. In addition, the marine layer was deeper, allowing more
clouds up the inland river valleys. Clouds still eventually eroded
over the interior, and peeks of sun have been occurring along the
coast. However, clouds appear to be redeveloping along the Redwood
Coast per latest visible satellite imagery. Due to the strong N
flow, downsloping has produced a fairly pronounced clear area
downstream from SW OR as well as S of Cape Mendocino. Max
temperatures across the interior are probably going to be down a
degree or two over yesterday due to the slightly lower thicknesses.
Temperatures along the Pacific Coast are running in the lower to
mid 60s with the coolest readings in the cloudier areas.
High pressure aloft will continue to gradually build over the
desert SW over the next few days, with high temperatures at many
interior locations exceeding 100 degrees. A few high valley spots
may see readings reach 110 by mid to late in the coming week with
500 MB heights building to near 597 dam as close as the NV/UT
Rain chances will be low to nonexistent this week. Have some
isolated PoPs over the N interior on Saturday afternoon.
Instability parameters still look iffy, with CIN values in excess
of 100 J/kg. There may be enough forcing from a weak upper trough
to get some shower development, but still not anticipating much
threat of thunder. Moisture will be limited. /SEC
.AVIATION...Ceilings currently remain around 500 feet at KCEC.
However, the latest visible satellite loop suggest we should
become VFR in the next hour or so. At KACV, scattered clouds are
in the area but we expect to remain VFR through mid-evening.
Overnight, ceilings will drop back into the 300 to 800 foot range
at both of these terminals. Farther south at KUKI, VFR conditions
with light winds will prevail. /PD
.MARINE...Not too much has changed with the marine forecast for
the next several days. Current observations show seas holding
around 8 feet with periods of 6 to 8 seconds. For the outer
waters, waves should increase into the 10 to 12 feet range during
the next 24 hours, with similar wave periods expected. This will
put us in the Hazardous Seas Warning criteria. Winds will also
increase with them expected to reach Gale criteria (sustain or
frequent gusts to 34 knots or more) in the next 24 to 36 hours.
Since we already have Gale Warnings in effect through Wednesday
morning, will leave the current headlines in place (versus going
from Hazardous Seas to Gales in the headlines, which could add
confusion to the forecast).
Closer to shore for the waters within 10 nautical miles, the Small
Craft Advisories in place through Wednesday morning look good, as
waves heights and periods currently observed (6 to 8 feet at ~8
seconds) will persist through the headline period.
It should be noted that today`s long range model runs have stepped
up the forecast wind speeds for Thursday through the weekend.
Although some change to what type of headline may be needed for this
time period, some type of warning/advisory will likely be issued
during the next day or two. We decided to wait another forecast
cycle or two to see if the increased wind speed trend in the latest
data continues, which will allow us to better determine the warning
type/temporal period. /PD
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory until 2 PM Wednesday for PZZ450-455.
Gale Warning until 3 AM Wednesday for PZZ470-475.
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