Area Forecast Discussion
Issued by NWS Eureka, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
FXUS66 KEKA 251206

National Weather Service Eureka CA
450 AM PDT Tue Jul 25 2017

An upper-level low will continue to bring a chance of thunderstorms
to portions of northwestern California through Wednesday. For the
remainder of the week, high pressure will regain control of our
weather, bringing dry weather and warming temperature for the
interior. Closer to the coast, look for seasonal temperatures to
prevail with low clouds and patchy fog developing each night,
lasting into the morning.


(Today through Wednesday evening)

An upper-level low was located over Fort Bragg this morning. This
system is forecast to wobble across the southwestern portion of
Mendocino County through the day, before lifting northeast towards
Redding overnight and into tomorrow. Although thunderstorms have not
developed as much as previously thought, today does look to have the
best potential compared to the previous two days. Spoke of energy
(vort maxes) rotating around the low will provide bursts of lift
through the day. This, combined with increasing moisture values
being pulled north through the Sacramento Valley and into our area
should prove beneficial for at least isolated thunderstorm
development, mainly north and east of a eureka to Yolla Bolly
mountains line. Not much has changed in the sounding data across the
region, as they continue to show afternoon SBAPEs ranging from 500
to 2000 J/kg, with steep mid-level lapse rates above 8 deg. C/km and
various other indices indicative of potential convection. However,
a warm stable layer below 8000 to 10,000 feet continues to be seen
as well, which could inhibit thunderstorm development to some
extent. Should a storm form, dangerous cloud to ground lightning,
gusty outflow winds, and small hail will be the main storm concerns.
These storms look to be of the wetter variety compared to what we
expected the past few days.

As the disturbance aloft moves to our east tomorrow, additional
pieces of energy rotating around the low may spawn a couple of
storms again, mainly east of a Hoopa to Yolla Bolly mountains line.
A similar storm environment will be in place, with the storm
concerns identical to today. Otherwise, look for low clouds and
patchy fog to form tonight near the coast. Overall, temperatures
will be near seasonal values.

(Thursday through Monday)

Warming interior temperatures any drying conditions will be the
theme for the second half of the week. The latest numerical runs
continue to re-build the upper-level high, with heights aloft
climbing towards 598dkm. A similar response is seen in 850mb
temperatures. Thus, look for afternoon high temperatures to increase
a few degrees each day through the weekend for the interior, with
seasonal to perhaps slightly above values seen during the daytime
hours near the coast. /PD


The morning TAF issuance will continue to reflect
persistence at CEC and ACV, with IFR ceilings Tuesday morning
expected to briefly clear during the afternoon, followed by the
redevelopment of coastal stratus tonight leading to a repeat of IFR
ceilings. In addition, hi-res model guidance indicates isolated
thunderstorms may spread westward across the Del Norte and NRN
Humboldt coast. Meanwhile, UKI has maintained dewpoints in the low
50s during the past 24 hours, which indicates the presence of deeper
boundary layer moisture that may be favorable for the development of
low clouds this morning, and again late tonight. Latest satellite
imagery doesn`t indicate cloud development yet, but will continue to
hint at this potential in the UKI TAF.


The surface pressure gradient is forecast to weaken in the
vicinity of the coast today, which will support decreasing northerly
winds...though still strong enough for small craft conditions over
the NRN outer waters. Elsewhere, small craft waves and wind speeds
are expected to diminish over the SRN outer and NRN inner waters by
this afternoon. Small craft conditions are then forecast to
redevelop during the second half of the week across much of the
coastal waters.


The main concern lies with our thunderstorm potential over the next
couple of days. Dangerous cloud to ground lightning and erratic wind
patterns near thunderstorms will be the main fire weather concern.
The good news is moisture will continue to increase through
Wednesday. For the remainder of the week, dry conditions are
expected for all of our neck of the woods with increasing afternoon
highs and lower relative minimum humidities expected. /PD


AM PDT this morning for PZZ450.

     Small Craft Advisory until 5 PM PDT Thursday for PZZ470.

     Small Craft Advisory until 5 PM PDT this afternoon for PZZ475.



Visit us at

Follow us on Facebook and Twitter at:

For forecast zone information
see the forecast zone map online: is the U.S. government's official web portal to all federal, state and local government web resources and services.