Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 212309

National Weather Service Eureka CA
409 PM PDT Thu Sep 21 2017

.SYNOPSIS...Frost will be possible across interior valleys
overnight tonight, but a steady warming trend is expected tomorrow
through early next week. Aside from perhaps a few showers near the
coast tonight, precipitation will be minimal for the foreseeable


.DISCUSSION...While cool conditions will persist through tomorrow,
a gradual warming trend will take place beginning Saturday and
continuing through early next week. Shower activity today has
remained across the waters thanks to largely northerly steering
flow, although there remains a slight chance for a shower or two
to clip the Redwood Coast late this afternoon and evening,
particularly near Cape Mendocino. Otherwise, precipitation has
ended for the foreseeable future as the upper level trough drifts
farther and farther from the region. Frost will again be a concern
across interior valleys, particularly Trinity and northern
mendocino counties. Temperatures may actually be colder than they
were the night before in many of these valleys, as the airmass
will be drier and cloud cover not as extensive. A few isolated
pockets may even dip slightly below freezing, but this is not
expected to be widespread enough to warrant a freeze warning.

Building high pressure aloft will cause temperatures to steadily
rise tomorrow through early next week, and by Monday afternoon
highs are likely to exceed 90 degrees in many interior valleys.
This period of above normal temperatures will likely continue
through at least Wednesday, but should begin a slight downward
trend towards the latter half of the week as the upper ridge
begins to break down. Precipitation will be hard to come by for
the foreseeable future. /BRC


.AVIATION...No major aviation concerns expected during the 24
hour TAF period as post frontal weather conditions will result in
generally widespread VFR Cigs. Cool air advection mixing and a
weak offshore flow will suppress widespread stratus formation at
the coast overnight and morning. However, early morning local
(shallow) fog development is possible. As far as the remainder of
the day goes, mid afternoon Vis Sat Pict show lots of mid-high
cloud advection into Northwest California. Also a few local small
BLDUPS due to residual moisture, and afternoon heating may be
enough for an isolated shower to move over the coastal Taf
stations (Cec & ACV) and possibly coastal hills. An isolated
shower may also develop over a few interior locations. The
exception with the VFR cigs will be brief MVFR cigs associated
with any afternoon showers. /TA


.MARINE...The northwesterly will subside through the next several
days. High pressure will bring increasing northerly winds over
our waters which will in turn generate some steep wind waves this
weekend. Small craft advisories will likely be hoisted for the
outer water zones over the next 24 hours for the increasing winds
as gusts will peak around 20-25 knots out past 10 nautical miles.
Winds then increase for all of the waters by Sunday and continue
into early next week with near gale force gusts possible for the
outer waters.

Tuesday into Wednesday a shortwave will approach the area and this
is expected to break up the pressure gradient and diminish the winds
and seas. Models are in general agreement on this, although the
ECMWF is a bit slower than the GFS. Generally sided with the ECMWF
and a slower solution. MKK/KAR


.FIRE WEATHER...Cool and humid conditions will continue through
tomorrow, but a steady warming and drying trend is expected
Saturday through early next week. Temperatures will reach near
normal values by Saturday, and are expected to be well above
normal Monday through Wednesday. In addition to the warming
temperatures, humidity will also steadily drop, both during the
afternoon and overnight periods...particularly at high elevation.
the period of greatest concern will be Monday and Tuesday, as
nocturnal northeasterly winds will increase markedly in addition
to the well above normal temperatures. This will be most
concerning in our southern areas like Mendocino and Lake counties
where winds will be strongest and fuels the driest. /BRC


CA...Frost Advisory from 1 AM to 8 AM PDT Friday for CAZ107-108-110-



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