Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Eureka California
931 PM PST Wednesday Nov 25 2015
Synopsis...dry weather and cold overnight temperatures will
continue through this weekend.
Update...temperatures trends indicate that lows will likely fall
into the upper 20s in portions of the Mendocino coast zone. So
the freeze warning has been upgraded to a hard freeze warning at
this time. Otherwise the forecast remains on track and the
previous discussion is below.
Previous discussion......issued at 318 PM PST...
Short term (today through Saturday night)...cold temperatures
and dry conditions will persist across the region through this
weekend. Overnight lows will range from the 20's to 30's across
most areas the next few nights. Freeze warning is in effect from
midnight tonight through 8 am PST Thursday for the Mendocino coast
zone 002. A hard freeze warning is in effect for the Redwood
coast zone 001 from midnight tonight through 8 am PST Thursday
morning. Afternoon temperatures will only warm to the 40s and 50s
through this weekend for most areas. Dry conditions and mostly
clear to partly cloudy skies will continue across the region
through Saturday. Light to moderate winds will continue across
the area the next few days. However winds will become moderate and
gusty across ridge tops the next few days.
Long term (sunday through wednesday)...Sunday continues look dry
as a low pressure system over the Great Basin edges eastward and a
ridge aloft build across northwest cal. The overall weather picture going
into early to middle next week (mon through wed) is still a bit unclear
due to the differences between the GFS and European model (ecmwf). The GFS and European model (ecmwf)
continue to be way out of agreement on how quickly to breakdown the
Rex block. On the one hand we have the European model (ecmwf) which insists on
maintaining the blocked flow pattern over the West Coast through
Wednesday. If the European model (ecmwf) is correct we will not see any rain for the
next 7 days. This seems highly unlikely. At the other end of the
spectrum is the GFS which indicates a warming and moistening trend
Monday through Wednesday as westerly-southwesterly flow aloft busts through
The Block. The Canadian model was similar to the GFS with
bringing the first bout on rain onshore Monday followed by a second
episode Tuesday into Wednesday. The GFS ensemble mean and various members
have been supportive of the operational GFS runs as well. Thus
will lean toward the GFS/Gem/gefs mean and indicate a
warming/moistening trend along with periodic bouts of light to
Aviation...a cold and drier air mass will settle over northwest
California tonight and hold through Thursday. Light to moderate offshore
wind flow tonight/early Thursday will probably produce blustery NE-east
conditions over the higher elevations and exposed ridges. Some
patches of fog and low clouds may still form in the interior valleys
as winds go light or calm tonight...however kacv and kcec will
remain VFR. Even Ukiah which saw fog this morning should remain VFR
as the air mass dries out.
Marine...strong northerly winds will gradually diminish tonight as
an offshore flow pressure pattern develops over the coastal waters.
Northeast and easterly winds should remain fairly light Thursday through
Sat though a few gusts around 25 knots will be possible in the early
morning hours as a cold and dry air mass seeps into the interior of
northern California. Enp and nwps continue to indicate a northwest swell
entering the waters Thursday and Friday...with fairly small significant wave
heights. Another storm will approach late on Sunday. GFS continues
to indicate the potential for strong southeast winds along with steep short
period southerly waves on Monday. The timing and exact magnitude of the
southeast wind is still uncertain.
hard freeze warning until 8 am PST Thursday for caz001-002.
Northwest California coastal waters...
Small Craft Advisory until 3 am PST Thursday for pzz455.
Small Craft Advisory until 3 am PST Thursday for pzz450.
Small Craft Advisory until 9 am PST Thursday for pzz470-475.
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