Scientific Forecaster Discussion
Area forecast discussion...updated aviation
National Weather Service Eureka California
914 am PDT Friday Jul 25 2014
Synopsis...high pressure building over California will result in
dry conditions and above normal daytime temperatures across
northwest California through the weekend.
Short term...(thru mon) building high pressure will allow northwest
California to continue to warm under generally sunny skies. Some low
clouds and patchy fog have formed overnight over the Eel River Delta
and around Humboldt Bay...but generally the clear skies should
850 mb temperatures will warm to near or above 25c across the
interior allowing afternoon high temperatures to warm into the upper
90s or over 100 degrees f by Saturday. Temperatures are currently
not anticipated to approach records...though they will be several
degrees above normal. Besides a few morning clouds at the
coast...generally sunny skies will allow temperatures to climb into
the upper 60s and possibly low 70s at the coast.
As the upper ridge and high pressure system builds over the area...a
weak cut off low off the California coast will gradually drift
north toward northwest California. The low will degrade into a
shortwave trough and move over northwest California Sunday
afternoon riding over the west side of the upper ridge. Surface
moisture return will be too slow to couple with the shortwave
passage and a middle to upper level stable layer will keep a
convective cap in place through at least midday Monday...not
allowing thunderstorms to form Sunday afternoon. Thus the
forecast has been kept dry through the weekend. Mkn
Long term...(late Monday-fri) models continue to indicate weak
instability over northeastern and eastern Trinity County on Monday
afternoon and Tuesday. Moisture continues to look limited with the
stable layer near 500mb weakening by Monday afternoon and Tuesday. Models
continue to show weak disturbances rotating northward around the
west side of the ridge on these days. The timing and strength of
these waves remains uncertain. Have continued the existing forecast
of increased precipitation chances as well as thunderstorm coverage around The Horn
of Trinity Monday and Tuesday. Wednesday and Thursday convection chances remain
uncertain at this time. Otherwise seasonably mostly clear and warm
conditions in the interior with some increase in stratus and fog
along the coast late in the period.
Aviation...low clouds/fog formed around Humboldt Bay and the Eel
River valley this morning producing IFR to LIFR conditions at kacv
and kfot. VFR conditions were found elsewhere except for some fu in
the lower Trinity River valley due to the sugarbowl fire between
Willow Creek and Hoopa. Expect conditions to gradually improve to
VFR across the area today with moderate to gusty northwest winds
along the coast into the evening. Conditions should deteriorate to
IFR along the coast during the late evening and overnight with VFR
across the interior. Stp
Marine...a strengthening high pressure ridge across the
northeastern Pacific interacting with an inland thermal low has
tightened the pressure gradient over the coastal waters increasing
the winds and steep seas. Gale conditions will continue over the
outer waters through Saturday evening. Small craft advisories will
continue across the near shore waters through Saturday morning.
Winds and seas will gradually diminish late this weekend and early
Northwest California coastal waters...
Small Craft Advisory until 5 am PDT Saturday pzz450-455.
Gale Warning until 11 PM PDT Saturday pzz470.
Gale Warning until 11 PM PDT Saturday pzz475.
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