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CNRFC Hydrometeorological Discussion

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Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
725 AM PDT Thu May 13 2021

...COOL SYSTEM DROPPING SOUTHEAST ACROSS THE REGION THIS WEEKEND...

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

Relatively flat anti-cyclonic flow across the region this morning 
with a couple upstream disturbances to the northwest of the region 
expected to phase and form an upr low over the next 24 to 48 hours. 
The first is located west of the Oregon coast located along 135W 
while the next is a bit farther north and west...near 52N/145W. This 
upr low is expected to bring a change in the pattern with cooler 
temperatures and scattered precip as it drifts southeast across CA 
this upcoming weekend before finally shifting off toward the east 
near Las Vegas late Sunday or early Monday.

At this time...best opportunity for precip looks to be near the 
CA/OR border region and then down the Cascades/Sierra and points 
east over the northern two-thirds of NV...which will be more in the 
front-right quadrant of the upr low as it moves across the area. 
Localized totals from 0.25- to 0.50-inch are possible. Also...models 
are depicting some light precip across coastal southern CA from 
about LA county down to the CA/MX border. This all looks to be from 
a deepening marine layer.

Into next week...west-southwest flow aloft will be the rule on 
Tuesday into Wednesday as a deep upr trof approaching the BC and 
Pacific Northwest coast. Some light precip is possible over northern 
and eastern NV.