952
AGUS76 KRSA 031940
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
1240 PM PDT Thu Apr 3 2025

...SHOWERS DISSIPATING TONIGHT...
...SYSTEM IMPACTS AREAS NEAR AND NORTH OF I-80 SUN INTO MON...

.METEOROLOGICAL CONDITIONS (SHORT TERM: THU PM - SUN AM)...

Afternoon scattered showers have developed mainly across the Great
Basin with little so far across the Sierra...according to the latest
radar and satellite imagery. Still anticipating some shower activity
mainly near the Sierra crest from about I-80 southward and even
coastal locations of southern CA...dissipating around sunset.

Then for Friday into the beginning of the weekend...the broad upr
trof over the western US will finally begin to shift off toward the
east...being replaced by a narrow wavelength positively tilted upr
ridge. This will bring dry conditions to the region and warming
temperatures...especially the western half of the area that will
initially see the influence from the area of high pressure.


.METEOROLOGICAL CONDITIONS (LONG TERM: SUN AM - WED AM)...

Little change to the afternoon forecast (up to a few hundredths) for
Sunday into Tuesday with most of the precip Sunday into early
Monday.

A deepening trough and associated cold front approaches the Pac NW/
Nrn CA coast on Sunday and the short wave trough moves inland Sunday
night and through Nrn NV on Monday. PW plume about 1.3 inches aims
at the Nrn CA coast Sunday/Sunday night with PW around 1.1 inches
along the Nrn CA coast.  The models and ensemble still vary some
with the timing (12Z GFS still quicker than the 12Z EC) and details
for lower confidence in precip amounts and coverage areas for Sunday
into Monday.  The forecast uses a blend of the NBM and WPC mixed
with the previous forecast with mainly light precip along the NW
Coast Sunday morning then increasing and spreading south and east
over Srn OR and Nrn CA in the afternoon/night with precip possible
down to around the I-80 corridor Sunday night.  Precip amounts for
Sunday into Sunday night 1-2 inches over the Smith Basin and the
King Range and 0.25-0.75 inches for the Srn OR Cascades and Eel
Basin and around a half an inch or less for Shasta Basin and around
a third of an inch or less for the Nrn Sierra and Russian Basins and
generally around a tenth of an inch or less for the Sac Valley and
over Nrn NV. Lingering showers possible over Srn OR and Nrn CA and
Nrn NV into the day on Monday.  Precip amounts to around a quarter
of an inch for the Smith Basin and Srn OR Cascades and generally
around a tenth of an inch or less elsewhere over the north (mainly
along the coast and higher terrain) on Monday.

Another shortwave moves into the Pac NW/B.C. on Tuesday with nearly
zonal flow/weak ridging over the region.  Showers are possible over
the Smith Basin and Srn OR Cascades on Tuesday with amounts
generally around a tenth of an inch or less.

Max temperatures generally near normal to around 10 degrees above
normal over the region Sunday afternoon (except near normal to 10
degrees below normal along Nrn CA coast). Max temps lower to near
normal to up to 15 degrees below normal over Nrn CA and Srn OR on
Monday and generally near normal to around 10 degrees above normal
elsewhere. On Tuesday, high temperatures generally near normal to 15
degrees above normal, except up 12 degrees below normal along the NW
CA coast.  Overnight minimum temperatures generally near normal to
around 10 degrees above normal for most of CA and 5 to 15 degrees
above normal over SE CA and over NV.

Freezing levels generally around 9000-11,500 ft over the region on
Sunday morning then falling to around 4500-7000 ft over Srn OR and
Nrn CA and 8000-11,000 ft over Central CA and 11,000-12,000 ft over
Srn CA and around 7000-12,000 ft over NV (NW-SE) Monday morning.
Freezing levels rising to around 6000-10,000 ft over Nrn CA and
around 7500-12,000 ft over NV (N-S) by Tuesday morning and rise to
around 10,000-13,000 over the region Tuesday night as high pressure
builds over the region.



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



Kozlowski/Osborne

$$