Area Forecast Discussion
Issued by NWS Eureka, CA

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FXUS66 KEKA 272257
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
357 PM PDT Sat May 27 2017

.SYNOPSIS...
Temperatures will continue to warm over the next few days, with warm
temperatures likely across the interior, and seasonably warm
readings near the coast. Some coastal/river valley stratus will
develop during the late night/early morning hours through the
weekend. Isolated thunderstorms may develop across the interior
through much of the upcoming week, especially for Trinity County.

&&

.DISCUSSION...
.SHORT TERM...
(Tonight and Sunday)

Much like yesterday, stratus continues to hug much of the coast.
These clouds penetrated much farther inland along the river valleys
than earlier anticipated, and the grids were updated for tonight to
show a similar coverage given little change in the synoptic pattern.
Otherwise, look for seasonably mild temperatures to continue into
tonight

For Sunday, temperatures will warm into the 80s across much of the
interior, with a few locals hitting the lower 90s. The latest hi-res
models continue to show a few storms developing along an axis from
the Trinity Alps to the Yolla Bolly`s, and the previous forecast had
this well handled, so no areal changes to the POPs were made.

.LONG TERM...
(Sunday night through Saturday)

Convective potential continues to be the main challenge for the long
term portion of the forecast. Little change has been seen in the
model data, with the ECMWF and GFS converging on an open wave in the
base of a trough crossing the region on  Tuesday. Ahead of this
feature, several vort maxes will cross the region, providing bursts
of increased ascent. At the same time, the numerical guidance
continues to indicate isolated convection developing during the
afternoon hours Monday and possibly tuesday, along and east of the
coastal ridge. Instability won`t be too significant, but sufficient,
as sounds show MLCAPEs running in the 750 to 1500 J/kg range, with
lifted indices in the -3 to -6 range, and mid-level lapse rates
near 7 deg. C/km. This should be sufficient for storms to build as
convective temperatures are breached. Any storm that develops will
be slow-moving, with dangerous cloud to ground lightning, small
hail, damaging winds, and locally heavy rainfall being the main
concerns.

Temperatures will cool for the middle of the week as the trough axis
slides over the region, progressing to the east by the end of the
work week. Increasing subsidence and heights will lead to seasonably
warm and drier conditions. /PD

&&

.AVIATION...
A deep marine layer continued to plague coastal
areas with MVFR ceilings today. The depth of the layer should
gradually shrink tonight and Sunday as the air aloft warms up. As a
result, stratus should not push as far inland. Unfortunately,
coastal TAF sites will see lowering ceilings tonight through Sunday.
IFR to LIFR cigs are expected early Sunday morning at both KACV and
KCEC. Early morning fog with reduced vsbys will be possible as well.
Slight improvement is expected Sunday afternoon.

Stratus redeveloping at KUKI is not looking as favorable tonight as
the last couple of nights. Light northerly flow returning offshore
tonight will hinder low clouds from advancing northward from Sonoma
county. The guidance has been mixed and for now will push back the
timing of MVFR cigs at KUKI. MVFR cigs may need to be pushed backed
more or completely removed from the KUKI forecast in the 6z or 12z
issuance`s.

&&

.MARINE...
Light north winds will slowly return tonight through
Sunday, and then increase on Monday as high pressure rebuilds toward
the coast. Short period northerly seas will build early next week.
The highest wind waves will be offshore south of Cape Mendo. Light
northerly winds and uncomfortable seas will hold through mid week.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...None.
&&

$$

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