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CNRFC Hydrometeorological Discussion

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Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
815 AM PDT Thu May 12 2022

...ONE MORE DAY OF WIDESPREAD BELOW NORMAL TEMPERATURES TODAY WITH 
LIGHT PRECIP NEAR THE CA/OR BORDER AND ALONG THE NORTH COAST THROUGH 
EARLY SATURDAY...

...TEMPERATURES WILL RISE LATE THIS WEEK BECOMING ABOVE NORMAL FOR 
MOST AREAS OVER THE WEEKEND BEFORE TROUGHING GRADUALLY LOWERS 
TEMPERATURES CLOSER TO NORMAL EARLY NEXT WEEK...

.METEOROLOGICAL CONDITIONS (THU AM - WED AM)...

The upper trough that brought yesterday's showers and cooler 
temperatures has exited off to the east. High pressure is building 
over the area in its wake as another system approaches the PacNW. 
Temperatures will remain below normal today by about 5-15 degrees 
before increasing tomorrow and over the weekend to above normal. 
Showers are expected to reach the north coast this morning and 
continue into early Friday as the surface front and upper trough 
move inland. Another surface low and upper shortwave will approach 
on Friday bringing the next round of precip to the north coast and 
CA/OR border. Between lingering showers from today's system and pre-
frontal showers from tomorrow's, expect light precip to continue for 
most of Friday. The surface low will take a more northward 
trajectory along the PacNW coast and towards BC Saturday morning. 
This will pull precip north of the CA/OR border by Saturday 
afternoon with showers tapering off throughout the morning. The 
majority of the precip over the next 6 days will take place during 
the short term period. Highest totals remain over the Smith Basin 
and the crest of the Cascades at about 0.80-1.50". Lesser amounts 
forecast gradually southward with little to no precip south of Cape 
Mendocino.

High pressure will then build over the region the rest of Saturday 
as the next shortwave moves through the Gulf of Alaska towards BC 
early Sunday. The trajectory of this system will confine any precip 
well to our north with generally dry conditions expected for the 
rest of the weekend. By Sunday evening, a broader surface/upper low 
will have formed in the Gulf of Alaska with troughing beginning to 
take over the west coast while the ridge shifts eastward. This will 
begin to allow for cooling from nw to se back to near normal 
temperatures early to mid next week as the trough expands. Surface 
high pressure west of CA will prevent any of the trough's associated 
surface systems from reaching the northern border. Therefore, dry 
conditions are forecast throughout the extended.

Lower freezing levels over nw CA today of 4-6 kft with progressively 
higher freezing levels to the south. Freezing levels will gradually 
rise from s to n the rest of the week with lower levels becoming 
confined along the CA/OR border and 9-13 kft south of I-80 by this 
evening. This upward trend will continue into the weekend with 
levels along the CA/OR border up to 8.5-10 kft by early Saturday and 
12-14.5 kft south of I-80.