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AGUS76 KRSA 081417
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
615 AM PST Wed Jan 8 2025

...MAINLY DRY CONDITIONS UNDER NORTHERLY FLOW ALOFT...
...WEAK SYSTEMS TO BRING LIGHT PRECIP FAR NORTHERN AREAS FRI/SUN...

.METEOROLOGICAL CONDITIONS (SHORT TERM: WED AM - SAT AM)...

Low pressure over northwest Mexico and an upr ridge centered to the
west of Point Conception near 33N/135W has generated dry northerly
flow across CA and NV this morning with PW values running less than
0.50-inch for most locations. A weak s/wv trof is moving up and over
the upr ridge...crossing the coast near southern BC. Overall...the
pattern will be slow to evolve...as the s/wv trof to the north
eventually dives southward on the downstream side of the upr ridge
past the 4-Corners on Thursday region before reaching north-central
Mexico early on Friday and phasing with the slow moving system
currently over northwest Mexico. Also on Friday...another s/wv trof
will make its way across the BC and Pacific Northwest coast that is
expected to drag the southern extent of the cold front along the
CA/OR border region and far northern NV. This will generate some
scattered light precip for these areas with amounts generally
remaining near or less than 0.10-inch. Otherwise...the region will
continue to experience dry northerly flow with no precip expected
into the early part of the weekend.

Freezing levels this morning show a sharp gradient from east-to-west
across the region with approx 4500- to 6000-feet for areas near the
UT/NV border and down to the CA/AZ border...while coastal locations
of northern/central CA range from 10000- to 12000-feet...while
coastal southern CA ranges from about 7000-feet near San Diego to
9000-feet near Point Conception. These will bump up a bit into early
Friday ahead of the s/wv trof moving toward BC and the Pacific
Northwest as the upr ridge shifts closer to the region...generally
ranging from 8500- to 13000-feet...lowest northwest and highest
southwest. Finally into early Saturday...as the s/wv trof
passes...the freezing levels will fall over northeast areas from
3500- to 5500-feet and then 12500-feet or so across coastal southern
CA.


.METEOROLOGICAL CONDITIONS (LONG TERM: SAT AM - TUE AM)...

Strong high pressure will remain over the eastern Pacific into the
weekend as a trough moves through NV. Models have little moisture at
this point with maybe a couple showers dropping a few hundredths of
an inch over ne NV. Sunday, another shortwave looks to drop in from
the PacNW through NV and into soCal by Monday morning, expanding as
it does so to encompass much of the region. Unfortunately, this will
be another dry system maybe generating a light shower or two over ne
NV with the rest of the region dry under broader offshore flow.
Bottom line, no widespread precip in sight with CPC outlooks
continuing to show below normal precipitation for the region through
mid to late month.

The weekend troughs will keep lower freezing levels over ne CA and
NV at 4-7 kft expanding across the Sierra by Sunday evening with
levels 7-10 kft to the west. Higher freezing levels (9-10.5 kft)
will fill back in from nw to se into Tuesday.


QPF graphics are available at www.cnrfc.noaa.gov/qpf.php



Kozlowski/AS

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