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AGUS76 KRSA 061539
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
830 AM PDT Sun Apr 6 2025

...PRECIP AROUND I-80 AND NORTH INTO MONDAY...
...CHANCE OF PRECIP OVER NW CA AND THE WEST SLOPE OF THE SRN OR
CASCADES ON TUESDAY AND THURSDAY...

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

A shortwave trough and associated cold front approach the Pac NW and
Nrn CA coast during the day today and weakening front and associated
shortwave trough move through later Sunday afternoon into Monday.
This system taps into some moisture with a PW plume about 1.1 inches
along the Pac NW coast and NW CA coast this morning. The moisture
plume drops south along the Nrn CA coast during the day today to
around the Bay Area tonight and erodes off the Central CA coast on
Monday. Precip has started along the NW CA coast and into the Srn OR
Cascades this morning (less than a tenth of an inch so far) and will
increase and spread south and east through Nrn CA during the day
into tonight. Precip will spread down to around the I-80 corridor
later tonight into Monday. Forecast precip amounts into tonight are
1.5-3 inches over the Smith Basin and 1.5-2.5 inches over the King
Range and 0.5-1 inches for the Srn OR Cascades and Shasta Basin and
0.25-0.75 inches for the Eel Basin and Feather Basin and around a
third of an inch or less for the Yuba to America Basins and Russian
Basins and generally around a tenth of an inch or less for the Sac
Valley. Another disturbance moves into the Pac NW Monday brushing
Nrn CA and another one moves in farther north in the Pac NW/ B.C. on
Tuesday. Showers possible over Srn OR and Nrn CA, especially over
the higher terrain and along the coast, during the day Monday then
tapering off Monday night. Precipitation amounts 0.25-0.75 inches
for the Smith Basin and Srn OR Cascades and Shasta Basin and Nrn
Sierra and elsewhere generally a tenth of an inch to nothing over
the Sac Valley and far Nrn NV. Precip is mainly confined to the
Smith Basin and Srn OR Cascades  and possibly the Shasta Basin on
Tuesday with amount generally around a quarter of an inch or less.

Ridging over the region on Wednesday for dry conditions in between
systems.  An upper/low level low approaches the Pac NW/B.C. on
Thursday for a chance of precipitation over NW CA and the west slope
of the Srn OR Cascades.  Precip amounts for Thursday into Thursday
night generally less than a quarter of an inch for the Smith Basin
and less than a tenth for the Srn OR Cascades. Friday looks dry for
now with a weak shortwave moving into the Pac NW later Friday.

Maximum temperatures generally near normal to around 12 degrees
above normal this afternoon and cool to below normal up to 15
degrees over Srn OR and Nrn CA and near normal to around 10 degrees
above normal elsewhere on Monday afternoon and near normal to around
10 degrees below normal over Srn OR and Nrn CA and near normal up to
10 degrees above normal Tuesday afternoon. Max temperatures warm to
around 5 to 20 degrees above normal (except near normal along the
Nrn CA coast) on Wednesday. Temperatures near normal to around 15
degrees above normal over nrn CA and around 5 to around 20 degrees
above normal elsewhere Thursday afternoon and cool to near normal to
10 degrees below normal along the Nrn CA coast Friday afternoon and
near normal to up to 20 degrees above normal elsewhere. Low
temperatures generally above normal up to 15 degrees Monday morning
dropping to near normal to around 10 degrees above normal for most
of CA and around 5 to 15 degrees above normal for SE CA and NV
Tuesday morning and Wednesday morning. For Thursday and Friday
mornings, low temperatures generally 5 to 20 degrees above normal.

Freezing levels around 9000-11,500 ft over the region this morning
drop to around 5000-8000 ft over Nrn CA Monday morning and fluctuate
around 9000-12,500 over Central and Srn CA and 8000-11,500 ft over
NV. Freezing levels around 4000-9000 ft over Nrn CA and 9000-12,000
ft over Central CA and 12,000-13,000 ft over Srn CA and around 7000-
12,500 ft over NV (N-S) Tuesday morning then rising to around 8000-
14,000ft over the region (N-S) Wednesday morning then fall to around
7000-10,000 ft over Nrn CA and fluctuate around 11,000-14,000 ft
over Central CA and Srn CA and around 10,000-13,000 ft over NV (N-S)
Friday morning then dropping to around 4500-7500 ft near the ORCA
border and around 8000-14,000 ft elsewhere Friday night.

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



Osborne

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