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Area forecast discussion 
National Weather Service Eureka California
453 am PDT Thursday Jul 30 2015

Synopsis...hot temperatures will continue across Trinity County
today as the remainder of northwest California begins a cooling trend. A
few thunderstorms are possible across the Trinity County mountains
on Friday.

&&

Discussion...another hot day is expected across Trinity County with
temperatures creeping another degree or two higher than Wednesday. Heights
continue to build over Trinity County with 925mb temperatures around 35c.
Elsewhere, temperatures will fall by a few degrees. Morning satellite shows
low clouds along the mendo and so hum coast as part of a stratus
surge from the south. The nose of the status has pushed as far north
as the Klamath, but remains well off the coast due to weak offshore
flow. Low clouds are not expected to push into the del norte or
northern Humboldt coast, but instead dissipate with daytime heating.
There remains the chance for clouds to curl in this morning to the
Humboldt Bay region. While in the forecast, I am not totally sold on
this solution and the forecast will need to be updated if the clouds
fail to arrive. Afternoon onshore flow should keep the temperatures capped
today in the upper 60s to middle 70s along the coast. Today will be the
last day of warming.

The upper ridge that has brought the heat will shift east slightly
tonight as an upper low off the central California coast takes
shape. This set up is entraining subtropical which is beginning to
make its way toward northwest cal today. This shift in pattern will allow
for daytime highs to cool due to lowering heights and increasing
cloud cover, bringing more seasonable temperatures for the weekend.
That said, the upper low will help to provide a focus for convective
development. Models are showing sufficient ingredients for
thunderstorms, but The Fly in the ointment is the cloud cover.
There is a hint in cross sectional model data that there may be a
weak middle level cap. This could inhibit substantial thunderstorm
development. We'll have to wait and see how the dynamics pan out
once the low shapes up and we see where it sets up.

Beyond the weekend, the cooling trend will continue as a broad
upper trough slowly transits the region. Bfg

&&

Aviation...while fog/stratus continues to slowly creep northward
along the coast...thus far it appears that light offshore flow has
prevented it from moving onshore. There remains a small
possibility that as southerly winds round Cape Mendocino and turn
onshore this morning that some of these clouds could move into acv
for a couple of hours before mixing erodes them. Thus...will
represent this possibility with a scattered mention through the early
afternoon. Light southerly flow along the immediate coast may be
just enough to see the return of low ceilings at coastal sites during
the evening...but uncertainty is high and model guidance continues
to handle this situation poorly. VFR conditions will continue at
inland sites for the next 24 hours. /Brc

&&

Marine...winds and seas continue to settle down as we head into
the early morning hours...and as a result all advisory headlines
have been allowed to expire. Seas remain somewhat elevated at area
buoys with sig wave heights of around 5 to 6 feet...the vast
majority of which is made up of a combination of lingering fresh
northwesterly swell and a moderate long period southwesterly
swell. Some south and southwestesterly facing beaches and harbors
will likely feel the presence of this swell...but major impacts
are not expected. By this afternoon...multiple model guidance
solutions indicate that light to moderate southerlies along the
Mendocino coast will accelerate and round Cape Mendocino...and
localized wind speeds of 15 to 20 knots will be possible near the
cape as this occurs. This could also result in the development of
some choppy southerly wind waves in these areas...resulting in
mixed but not particularly heavy seas. This pattern is expected to
persist through the early part of next week...with moderate north
northeasterly breezes well offshore...and fluctuating light to
moderate southerlies in the near shore waters...and seas generally
between 3 to 6 feet. /Brc

&&

Fire weather...we continue to watch for the potential of
thunderstorms across the mountains of Trinity and far NE Mendocino
County on Friday. Some models are very aggressive while other are
much more reserved. I am not totally sold on strong or widespread
thunderstorms, so have kept any mention at a slight chance and
over the mountains. Bfg

&&

Eka watches/warnings/advisories...
California...none.
Northwest California coastal waters...none.
&&

$$

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