Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Eureka California
520 am PDT Monday Mar 10 2014
expect a few lingering showers this morning north of Mendocino
County in the wake of a cold front, otherwise clouds will give way
to sunshine this afternoon. The rest of the week will be dry, with
some frosty nights in the interior. Inland temperatures will
continue to warm through the weekend as high pressure dominates the
rain really hung on across the north coast as upper divergence
actually increased toward midnight with coupled upper jet streaks
passing through. This has quickly been replaced by subsidence aloft
as a drier but more unstable airmass pushes into northwest California this
morning. Brief window of marginally favorable lapse rates and
instability coupled with lingering moisture will last until 8 am or
so. This is allowing for some low-topped convective showers to
organize along the north coast and adjacent interior. After
middle-morning, shortwave trough will quickly move east out of the
area, with increasingly dry and stable air putting an end to shower
activity by this afternoon. Left isolated showers over the Siskiyous
this afternoon, but that would be more or less worst case scenario.
Skies will start off mostly cloudy early this morning but become
broken then begin clearing once the shortwave trough axis swings
through. Expect mostly sunny skies over Mendocino and along the
coast with just some leftover scattered cumulus or stratocu over the
Most rivers are nearing crest this morning while the larger Eel
River will continue to rise today. Smith and Klamath rivers came
within a few feet of action stage, while the Mad River is currently
within a foot. Opted to not issue any river statements as it looks
like the Mad River at Arcata will crest below 14.5 feet, below the
action stage of 15 feet.
Rest of forecast will be very quiet, with the main concerns turning
to temperatures, valley fog, and frost. Tuesday and Wednesday will
be the best chances for frost across the interior, and we went ahead
with a frost advisory for tonight in northern/central Mendocino where the
growing season has begun. Strong high pressure will be building over
the Pacific northwest into the Great Basin through Wednesday,
promoting offshore flow. This may keep easterly winds gusty through
the night tonight across the ridges, but with dry and stable air and
good radiational cooling conditions otherwise, expect valleys to
decouple. Tuesday night and Wednesday the winds will be less of an issue
as the gradient weakens, but this will be complicated by a warming
airmass...thus temperatures both nights should be about the
same...low to middle 30s for many interior valleys. With the offshore
flow at the coast, high temperatures may need to be bumped up higher than
guidance, potentially well into the 60s.
The rest of the forecast continues to look high and dry with high
pressure both at the surface and aloft dominating through the weekend.
Unfortunately for those hoping for more beneficial rains, the next
10 days does not look good, with guidance strongly supporting an
anomalously strong upper ridge building over California next
weekend. Expect sunshine and increasingly warm temperatures inland
through the week, possibly reaching into the low 80s in the interior
valleys this weekend. Aad
Aviation...IFR to MVFR conditions and light winds will continue at
kcec and kacv through this morning due to patchy fog reducing
visibilities and lower ceilings. VFR conditions will prevail this
afternoon as a frontal boundary moves farther to the east and
ceilings increase. Moderate northerly winds will prevail at kcec and
kacv this afternoon then light winds will prevail overnight tonight.
Conditions at kuki will vary today from VFR to IFR conditions as
showers move through the area at times reducing ceilings and/or
visibilities. Light winds to calm conditions will prevail at kuki
Marine...winds and seas have diminished as a high pressure ridge
begins to build across the region reducing the pressure gradient.
Northerly winds will prevail across the waters through the end of
this week. However winds will increase across the outer waters
tonight and Tuesday as a low pressure trough develops along the
coast increasing the pressure gradient offshore. Seas will remain
elevated this week as a long period westerly swell propagates
through the waters.
California...frost advisory from 1 am to 9 am PDT Tuesday caz076.
Northwest California coastal waters...
Small Craft Advisory until 5 am PDT Wednesday pzz475.
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