Scientific Forecaster Discussion
fxus66 keka 262206
Area forecast discussion
National Weather Service Eureka California
306 PM PDT Mon Jun 26 2017
Synopsis...isolated thunderstorms over the interior through this
evening, then once again tomorrow afternoon. After that, returning
to typical Summer pattern of mostly dry conditions. Warm
temperatures will return to inland areas by Wednesday and persist
through the weekend. Marine stratus continuing along the coast
during the overnight hours through rest of this week.
Discussion...overnight last night, convection was impacting del
norte and Trinity counties. Around 50 strikes were detected by the
lightning network in del Norte County, which was fairly impressive.
Small hail were also reported in Trinity County. These convections
dissipated late overnight.
We started this morning with widespread marine stratus. By this
afternoon, the marine stratus is braking up pretty good, especially
from Eureka Point south. Do expect the marine stratus to persist
north of Humboldt Bay through tonight. For areas south of Humboldt
Bay, there is a break in the sky cover. Do expect some afternoon sun
before the marine stratus creeps back in this evening.
Over the inland area, cumulus and weak convection is trying to
develop as a weak mid-level disturbance is making landfall over SW
Oregon coast. For this afternoon, there will be up to 1500 j/kg of
MUCAPE with Li as low as -3c. However, proximity sounding shows that
there is a conditional stable layer in the lower part of the
atmosphere. Air parcel will have to overcome that before it can get
to the level of free convection. Think that the threat of
thunderstorm is very marginal for this afternoon into this evening.
However, it cannot be ruled out at this time. Thus, have included
eastern del norte and northern Trinity County in the isolated
On Tuesday afternoon, another weak upper level disturbance will
try to make its way across northwest California. This feature will
trigger isolated thunderstorms over the interior, similar to the
area being affected today.
Starting on Wednesday, looks like the ridge of high pressure will
finally establish itself over east Pacific Ocean, and this will
bring in the typical Summer weather pattern to northwest California.
Temperatures inland will warm up to the 90s, while coastal areas
will remain in the 60s. Marine stratus will be impacting the coastal
area during the overnight hours through this week.
Marine...light winds and low seas will continue into tonight into
Tuesday morning. However, this will change by Tuesday afternoon. We
will return to a strong northerly wind regime as the east Pacific
high re-establishes itself. With tight northerly pressure gradient,
the strong northerly wind regime will persist through most of the
week. Gale force wind gusts will be likely starting middle of the
Forecast is still on track. Little changes were made to the previous
forecast package. GFS is used to update the forecast package.
Aviation...a deep marine layer continued today, stretching
extensively into the coastal river valleys. Although the marine
layer is quite prevalent, brief periods of sunshine was occurring
along portions of the north coast by mid-afternoon. The stratus
deck has been enhanced by mid- level troughing...with the layer
penetrating inland as far as uki. Previous discussion: "stubborn
clouds should stick around through most of the day. IFR to LIFR
conditions will return to the coast tonight but troughing aloft
will help keep the marine layer deep and thus visibility should
remain higher". Model guidances generally agree that marine clouds
will spill over into the coastal valleys again Tuesday, thus
allowing for some morning clouds...including uki. However, overall
cloudiness may not be quite as extensive as this morning. Ta
Northwest California coastal waters...Small Craft Advisory from 9 PM Tuesday to 3 am PDT Friday for
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