Weather Service Report

FXUS66 KEKA 192128

National Weather Service Eureka CA
228 PM PDT Mon Mar 19 2018

.SYNOPSIS...Another rainy period setting up for NW CA beginning
late Tuesday. A brief break on Thursday followed by periods of 
widespread moderate rain Friday and Saturday. 


.DISCUSSION...Dry weather will continue tonight before another
inclement weather pattern returns during the latter part of 
tomorrow lasting through much of the rest of the week. There was 
some consideration of adding another frost advisory over the Mendo
interior for tonight but a little airmass warming combined with 
some mid to high cloud cover associated with the approaching storm
system should keep most areas frost free thus decided to hold 
off. As mentioned above...the next weather maker will approach 
from the southwest on tomorrow and then stall offshore. Moist 
southwesterly flow intersecting the coastal ranges will result in 
light to moderate rain mainly in the afternoon for most 
areas...but some areas may see some light rain or sprinkles 
earlier in the day. The offshore storm will be slow to progress 
eastward Tue Night through Wed and expect additional waves of rain
with mild conditions and relatively high snow levels. Models were
in good agreement with driving the cold front across the forecast
area Wed night into early Thu morning. A brief break in the 
precipitation will occur the 2nd half of Thursday but another band
of rain and snow follows that up on Friday with lowering snow 
levels, low top convection and bouts of rain and snow showers are 
expected Thu through Sat as a cold upper trough develops offshore 
the Pac NW. The threat for winter weather and snow over the 
mountain passes will increase late Fri and Sat as snow levels fall
to near 3000 ft and possibly lower. Next break in the weather 
looks to occur on Sunday.


.AVIATION...High pressure allowed for mostly SKC and unlimited VIS across 
local airfields/airports through afternoon. However, a few local 
interior valleys were the exception...especially UKI's airport. UKI 
reported IFR conditions during the latter half of the morning. 
Through the 00Z TAF period: first high clouds...then lowering clouds 
overnight/morning as a Western Pacific low pressure system 
approaches from the southwest. Models seem to be in agreement that 
rain will began in Mendocino...then spread northward. Models do show 
some conflict in timing. However, most agree that rain will begin in 
Southern Mendocino by late Tuesday morning. /TA


.MARINE...Low winds and seas will continue into tonight before an 
approaching storm system causes conditions to deteriorate over the 
next several days. Southeast winds will begin to increase Tuesday 
afternoon, first across the southern waters and then the northern 
waters by Wednesday morning. Models have backed off on the strength 
of winds for Wednesday with gusts around 25 kt looking more likely 
than gale force gusts. This will be followed by a period of 
westerlies and another round of increasing south winds for Friday. 
Steep waves will build with increasing winds this week but a fresh, 
westerly swell will elevate the sea state near 12 to 15 feet late in 
the work week. /KML




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