Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Eureka California
338 am PDT Friday Mar 14 2014
Synopsis...a weak frontal boundary will bring increased cloud
cover and some light rain or drizzle to northwest California today. Building
high pressure will result in warm and dry weather over the
Discussion...water vapor shows a shortwave trough and dissipating
frontal boundary approaching the coast this morning. This has
spread high clouds across much of the area. There are also some
low clouds along the coast. With the main forcing well to the
north...this system only is expected to bring some very light rain
or drizzle to the coast this morning.
This afternoon expect skies will clear fairly quickly as high
pressure builds back in over the area. Tonight this may allow some
areas to see frost in interior areas. A frost advisory may be
needed in interior Mendocino County where the growing season has
begun. Will hold off on issuing it for now due to uncertainty on
how quickly clouds will clear. At the coast it looks like winds
will become very light and the NAM is indicating a return of
coastal clouds. Am skeptical that we will see any due to the
subsidence of the front moving inland so will leave them out.
Dropped temperatures to around 40 along the coast as the clear
skies will allow for better radiational cooling. There is the
potential for frost at the coast as well...but for now it looks
like there will be too much moisture around to allow temperatures
to fall that low. Dewpoints will need to be watched.
With high pressure overhead expect Saturday will be mostly sunny
across the area. After a chilly start to the day temperatures will
warm nicely in the afternoon. Highs will be in the 70s to near 80
in inland areas. The coast will stay cooler this time
around...around 60...due to the onshore flow. Sunday will be
nearly a Carbon copy of Saturday...although the coast may see a
few more clouds.
Sunday night models have finally come into better agreement on a
shortwave bringing some light rain to areas north of Cape Mendocino.
The best forcing remains north of the area...but rainfall amounts
of up to a half inch are possible in the favored areas of del
Norte County. Little to no rain looks to make it south of Cape
Mendocino. Snows levels look to remain fairly high with this
Monday kept a slight chance of rain in the forecast to account for
shifts in timing...but at this point the models show the ridge
building back into the area and Monday looks to be a fairly dry
day with clearing skies.
Tuesday is expected to be another dry day with the ridge overhead.
Wednesday through Friday the pattern looks to start to get a bit
wetter. At this point the details remain fuzzy with little
continuity between models or run to run. The European model (ecmwf) brings a
shortwave onshore on Wednesday...while the GFS splits the flow and
creates a cut off low that meanders off the coast and finally
brings some precipitation onshore Friday. The Gem is similar to the
European model (ecmwf)...but slower. For now have favored a blend of the European model (ecmwf)/Gem
solution and went with probability of precipitation near climatology. Mkk
Aviation...9z satellite imagery shows low clouds along the coast
and some higher clouds inland. Most of the coast is experiencing
MVFR/IFR. Expect these conditions to continue early this morning and
to gradually improve to VFR by this afternoon. Inland, some patchy
valley clouds/fog may reduce conditions this morning. These
conditions should improve to VFR late this morning into this
Marine...no changes made to the forecast. Several swell trains will
enter the area through the forecast period, with the largest expected
to arrive late this weekend. This will build seas into next week.
Generally light winds are expected until Monday when northerlies once
again increase due to a tightening pressure gradient between high
pressure to the northwest and an inland trough.
Northwest California coastal waters...none.
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