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CNRFC Hydrometeorological Discussion

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Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
800 AM PDT Sun May 15 2022

...ABOVE NORMAL TEMPERATURES TODAY AND FOR MANY AREAS INTO MID WEEK 
GRADUALLY TRANSITIONING TO BELOW NORMAL AT THE END OF THE WEEK...
...DRY CONDITIONS TO GENERALLY PREVAIL THROUGH THE PERIOD ASIDE FROM 
POTENTIAL LIGHT PRECIP OVER NORTHERN AREAS TODAY/TOMORROW AND 
WEDNESDAY/THURSDAY AS WELL AS OVER EASTERN NV TUESDAY...

.METEOROLOGICAL CONDITIONS (SUN AM - SAT AM)...

An upper ridge is currently over the region with surface high 
pressure offshore of CA. This will keep temperatures above normal 
today for most locations by about 5-15 degrees. A weak surface low 
is offshore of the PacNW this morning with an embedded shortwave 
inside of a larger upper trough/low stemming from the Gulf of 
Alaska. A cold front also sits offshore stretching southward from 
the PacNW and southwestward out into the Pacific. The surface system 
and shortwave will take a more northward turn into this afternoon 
towards BC and make its way inland into the evening. The more 
northward track of this system will keep the majority of the 
precipitation well to our north. There is a chance that some light 
showers will reach the CA/OR border and the north coast, but this 
would likely only be a few hundredths of an inch between today and 
Monday. 

As this next systems moves eastward, it will displace the upper 
ridge further inland later today and tomorrow. This will allow for 
some cooling along the coast and Central Valley to below/near normal 
on Monday with areas to the south and east remaining above normal 
due to lingering influences of the exiting ridge. Another weak 
embedded shortwave will move over central/southern CA on Tuesday 
potentially dropping some light precip over eastern NV. A 
surface/upper low will still remain over the Gulf of Alaska. In-
spite of the upper troughing pattern, temperatures look to rise 
again for most areas Tuesday/Wednesday back up to about 5-10 degrees 
above normal as surface high pressure strengthens west of CA and 
shifts closer to the coast. 

Things look drier for Wednesday/Thursday than they did the past 
couple of days. The surface/upper low over the gulf will begin to 
move towards the PacNW later Wednesday and into Thursday. Models now 
show the upper low/trough moving inland further to the north than 
before and not extending over the region to the same degree. Some 
light showers will reach the north coast and CA/OR border Wednesday/ 
Thursday, but it now looks like it will generally be less than a 
tenth of an inch. The system will begin to cool temperatures from n 
to s with areas north of I-80 below normal for Thursday. The trough 
will move through northern NV Friday morning and take over much of 
the Central U.S. by the evening. This will spread below normal 
temperatures across most of the region Friday. Aside from those 
light showers Wednesday/Thursday over northern areas, conditions are 
expected to be dry for the extended.

Higher freezing levels today into mid-week at 10-14.5+ kft from 
north to south. Levels will begin to lower along the CA/OR border 
into Thursday down to 4-7 kft by the early morning. Lower levels 
will spread into northern NV with northern areas around 4-7 kft by 
early Friday. Freezing levels will then begin to rise up to 8-10 kft 
over northern NV and ne CA before the end of the forecast period.