Area Forecast Discussion
Issued by NWS Eureka, CA
FXUS66 KEKA 262236
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
336 PM PDT Sun Mar 26 2017
.SYNOPSIS...A front will slowly exit Northwest California this
afternoon producing scattered showers this afternoon. A trough in
the cooler air will generate additional showers tonight through
Monday morning. High pressure will build Monday afternoon and
maintain dry weather through Tuesday.
.DISCUSSION...The cold front which brought rain earlier today
and continues to supply some gusty winds is slowly migrating
eastward. Although the heaviest rain is behind us the air column
will start to cool down significantly behind the front tonight
while a secondary vort max is still expected to move over the
region later tonight into Monday morning and sparking up
additional shower activity. Mid level lapse rates will steepen in
response to strong 500mb cooling, however temperatures through the
entire column will cool as well and snow levels are expected to
fall to around 3kft by daybreak Monday. Freezing levels will be
low enough to consider small hail. Instability parameters (lifted
indices and CAPE) as well as mid level lapse rates are very
unfavorable for hail production. Shallow convection may still
generate a mix of rain and hail as a mid level trough line swings
across the area early Monday morning. The best location looks to
be across Del Norte and far northern Humboldt counties. Confidence
is by no means high due to the lack of instability and available
buoyant energy to sustain updrafts. After this short-wave
impulse moves across the area Monday morning, upper level ridging
will build over the area and squash any showers that try to sprout
up with daytime heating. An offshore wind flow pattern will
develop Monday night resulting in dry and stable weather
conditions through Tue. The latest GFS and ECMWF remain consistent
with bringing another front toward the coast Tue night. There
were still some variations between the two models on how fast the
rain will arrive and how long it will last. The models differed
also on the southern extent of the rain. It is not going to be a
major dumping, however, Del Norte and Humboldt counties will
probably receive some light rain. After that Upper level ridging
will return by Fri and provide for 2 to 3 days of dry weather.
The ECMWF and GFS hint at a weak front riding over the ridge
toward the latter portion of next weekend that may generate some
light rain, primarily along the coast and over Del Norte county. A
spring like weather pattern is starting to take shape with
surface northerlies dominating offshore. DJB/JT
.AVIATION...For most of today, lingering showers were impacting all
terminals. Do expect the showers to continue through the evening.
For Ukiah, the showers will diminsh overnight. While for Arcata and
Crescent City airports, do expect the rain showers to continue
overnight into tomorrow morning. These showers will bring in lower
flight categories at times, down to MVFR. There will also be some
gusty south winds through early this evening, before diminishing
tonight. Behind the weather front, winds will turn northerly and
northwesterly for all terminals tomorrow during the day. /RCL
.MARINE...Fairly active pattern for the next few days. Moderately
steep seas and gusty winds this evening. Winds and seas will subside
overnight tonight. A noticeable swell will be moving into the area
starting on Monday night and will persist through most of the
Gusty south winds today as a weather front pushed through the area.
Area buoys saw wind gusts to 35 kt. Do expect the winds to subside
this evening as the weather front push inland. The winds should then
turn northwesterly at around 10 to 15 kt with occasional higher
Seas-wise, we are still dealing with agitated seas this afternoon.
With short period waves of 9 to 10 feet at around 8 seconds. Do
expect the moderatly steep seas should gradually subside this
evening. Thus, have extended the small craft advisory for the NW
California waters through this evening.
With a northwesterly flow, we will have a fresh northwesterly swell
approaching NW California coast by tomorrow afternoon. The swell
will then remain in the area through most of the work week.
Minimal changes to the previous forecast package were made, as the
forecast is still on track from the previous version.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 9 PM PDT this evening for PZZ450-455-
Small Craft Advisory until 9 PM PDT this evening for PZZ470.
Gale Warning until 3 PM PDT this afternoon for PZZ470.
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