Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Eureka California
440 am PST Friday Dec 26 2014
Synopsis...cooler and drier conditions will persist through the
weekend as high pressure delivers brisk and dry northerly flow to
the region. Even colder air is in store for early next week.
Discussion...an upper trough continues to move away from the area
over the east rockies. High pressure over the east Pacific will amplify
into early next week. This will allow cool north flow to continue to
pour into the area.
A freeze warning continues this morning for the north coast interior
zone with a frost advisory for the Redwood and Mendocino coastal
zones. The freeze in the north coast interior zone will likely end the
late growing season there...so will hold off on issuing products
for the cold weather tonight. Another frost advisory will probably be
necessary for the coastal zones.
A reinforcing cold front will approach the area on sun preceded
by a few showers over the north. The upper ridge over the east Pacific will
really amplify during this time with a clear shot of cold air down
the West Coast from northwest Canada. Latest model runs are keeping a
deep trough from central Canada to Nevada...perhaps with a cut off low
developing over S Nevada by the middle of the coming week. If this
develops...a ridge will build north of the upper low. However...the
coldest weather of this Young winter is expected on Tuesday and Wednesday
mornings. Freezing temperatures may still make it to the coast...
although there are indications that a rather tight gradient may
develop between an inverted surface coastal trough and high pressure
NE of the area. If this develops...the combination of more low-
level mixing and some downsloping may modify the cold air mass...
particularly along the coast. /Sec
Aviation...high pressure overhead will help make for good aviation
conditions today with the exception of patchy fog that developed
across some interior valleys last night. Expect patchy valley fog to
burn off by late morning. Otherwise VFR prevails with patchy valley
fog possible again tonight. \Kml
Marine...a weakening ridge of high pressure will gradually allow
winds to decrease across the coastal waters into the weekend. Low
end small craft winds can be observed mostly across the outer waters
this afternoon as the thermal trough slides offshore. I allowed the
Gale Warning to expire this morning and put an advisory in its place
for the southern outer waters through late tonight. Additionally I
hoisted an advisory for the northern outer waters starting this
afternoon. Wind gusts up to 30 knots can be observed beyond 10 nautical
Gentle to fresh winds will persist through the weekend before
an approaching low pressure system increases northerlies on Monday.
There are some differences between the GFS and European model (ecmwf) regarding the
timing of this system thus the European model (ecmwf) hangs on to strong winds longer
than the GFS. Will have to wait for models to fall into better
agreement before determining whether any products will be needed
early next week. Otherwise a new swell train arriving tonight will
help maintain the sea state near 7 feet into the weekend. \Kml
California...frost advisory until 8 am this morning for caz001-002.
Freeze warning until 8 am this morning for caz003.
Northwest California coastal waters...
Small Craft Advisory from 3 PM this afternoon to 3 am Sat
Small Craft Advisory until 3 am Sat for pzz475.
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