CNRFC Hydrometeorological Discussion
Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
130 PM PST Thu Feb 6 2025
...A SYSTEM MOVES THROUGH TODAY INTO FRIDAY BRINGING PRECIP TO MOST
OF THE REGION....
...MAINLY DRY OVER THE WEEKEND INTO MONDAY EXCEPT LIGHT PRECIP
POSSIBLE OVER NW CA AND SRN OR CASCADES THEN MORE WIDESPREAD PRECIP
POSSIBLE MID-WEEK NEXT WEEK...
.METEOROLOGICAL CONDITIONS (SHORT TERM: THU PM - SUN AM)...
Increased amounts (up to 0.25 inches) in the Nrn and Central Sierra
and along the transverse range for this evening and about a tenth of
an inch or less for San Gabriel and San Bernardino into San Diego
Mtns Friday morning. Decreased amounts a little for Friday during
the day.
An upper level low/shortwave trough positively tilted off the Pac NW
coast and a sfc low approaching the Central CA moves onshore this
afternoon/evening and the upper level shortwave trough moving
through the region tonight into Friday. PW plume about 1.05 inches
from around Pt Arena to the Bay area around to Point Conception to
around LA County and inland this afternoon then focused on the Srn
CA coast tonight into Friday morning and dropping south into Mexico
in the afternoon. This is bring precipitation to Srn OR and most of
CA (except SE) and much of NV into tonight with showers tapering off
during the day of Friday as the shortwave trough moves off to the
east. Isolated thunderstorms possible over Nrn CA and along the
Sierra today. Precipitation totals for today into tonight generally
around 1.5-3.5 inches for the Sierra and Central CA coast and 1-2.5
inches for the transverse mtns and 0.5-2 inches along Nrn CA coast
and Shasta Basin and 0.5-1.5 inches for the Sac Valley and generally
a half an inch or less over Nevada and SJ valley. Precipitation
amounts for Friday generally nothing up to a half an inch except
locally up to an inch possible over the San Gabriel and San
Bernardino Mtns and in the Srn Sierra on Friday. Freezing levels
around 3000-4000 ft near the ORCA border and 6000-7500ft over the
Nrn and Central Sierra and 7500-8500ft for the Srn Sierra and 6000-
9500 ft over NV and 8000-12000 ft over Srn CA this afternoon.
Freezing levels drop Friday morning to around 2000-4000 ft over Nrn
CA and around 4000-7000 ft over Srn Sierra and around 7000-12000 ft
over Srn CA and around 5000-9000ft (NW-SE) over NV.
Another weak shortwave trough moves into the Pac NW and brushes Nrn
CA on Saturday. Not much moisture with this system with PW less than
half an inch. A chance of light precipitation to NW CA and the Srn
OR Cascades on Saturday with amounts generally a tenth of an inch or
less on Saturday. Freezing levels around 2000-3000 ft near the ORCA
border on Saturday.
.METEOROLOGICAL CONDITIONS (LONG TERM: SUN AM - WED AM)...
A weak disturbance will be exiting the area from southern CA toward
AZ to start the weekend with a west-to-east aligned s/wv trof
dropping south from western Canada toward the Pacific Northwest on
the downstream side of a narrow wavelength upr ridge situated along
140W. Model spread is a bit tighter this morning as compared to
yesterday with the general pattern of dropping the s/wv trof across
the region on Sunday into Monday. The GFS has trended closer to what
the EC and CMC was previously showing...which has increased
confidence in widespread light to locally moderate precip. Best
totals look to fall along the length of the Sierra and the coastal
mountains of southern CA from Point Conception to the CA/MX border
(0.50- to 1.00-inch). Also...given the trajectory of this
system...this will usher in a cooler airmass across the region.
Freezing levels early Saturday will start from near 2500-feet north
and east to 9000- to 10000-feet south and west. By Monday...as the
cold air settles in across the area...freezing levels will bottom
out from near sea-level north to 4000-feet far south.
|