383
AGUS76 KRSA 132105
HMDRSA

Hydrometeorological Discussion
National Weather Service / California Nevada RFC / Sacramento CA
105 PM PST Fri Feb 13 2026

...QUIET REST OF FRIDAY...
...PATTERN SHIFT TO COOLER AND WETTER LATE SATURDAY INTO NEXT WEEK...

.METEOROLOGICAL CONDITIONS (SHORT TERM: FRI PM - MON AM)...

Transitory upr ridge is currently overhead as the elongated system
from yesterday is now moving through the 4-Corners region with the
majority of the shower activity across the lower Colorado River
basin. Otherwise...expect mainly dry conditions to wrap up the work
week.

The weekend is still looking to be the transition to a wetter and
cooler pattern as the initial disturbance moving from the Gulf of
Alaska diving toward the south-southeast and slows its forward
progress when reaching the coastal waters west of CA. This slowing
has resulted in a delay in precip reaching coastal areas and then
spreading inland...but models (sans the NAM) are starting to get a
bit better handle on keeping much of Saturday dry except for some
light shower activity across southwest OR and northwest CA ahead of
the main precip band. Then into Sunday...precip increases along
coastal sections primarily between Cape Mendocino and Point
Conception before shifting inland across the Sierra...best northern
and central sections. This is all as a second disturbance drops
south along the west coast and kicks this initial system within 130W
and angles it toward the CA coast.

Freezing levels will drop through the event...starting out Saturday
evening between 5500- and 7000-feet across northern CA and 6500- to
9000-feet over central CA. Then through Sunday as the cooler airmass
begins making its way over the region these will reach down to 4000-
to 5500-feet across northern CA and 5000- to 7000-feet for central
CA.


.METEOROLOGICAL CONDITIONS (LONG TERM: MON AM - THU AM)...

Monday morning, the surface low offshore will begin to push inland
as the upper trough is nudged southeastward towards the CA coast by
the next low dropping in from the Gulf of Alaska. This will spread
precip inland and across central/southern coastal areas. There are
some timing and positional differences between the GFS/ECMWF for
Monday morning with the GFS more quickly progressing precip across
the Transverse Range while the ECMWF is a bit slower. By the late
afternoon, troughing from the next upper low will merge with the
current system leaving CA/NV under a broad troughing pattern. This
will allow showers to persist across the region with the coastal
mountains and Sierra receiving the bulk of the precip. The offshore
low will continue to descend offshore of the PacNW on Tuesday while
the broader pattern shifts eastward. Expect continued precip
throughout the day Tuesday, particularly along the central/srn CA
coastal mountains and over the Sierra due to terrain effects.
Wednesday, the system will push inland across CA and into NV with
precip diminishing from west to east as it does so.

There is uncertainty in the precip for next week, mainly as some
slight timing and positional differences on the placement/path of
the low exist. There is decent confidence that the central coast
mountains, Transverse Range, and Sierra will see the highest totals.
Ensembles are divided now mainly on how much precip will fall along
the coast north of the Golden Gate inland into Shasta. These
disagreements are not slanted towards any one parent model, as in
each QPF cluster is not dominated by one set of members. There is
just a decent spread of values. 24 hour QPF spreads at Arcata for
Tuesday/Wednesday are about 1.50".

The official forecast mainly went with the NBM, but blended in
either the EC based west WRF or the GFS based west WRF over parts of
the Transverse Range/srn Sierra depending on which was closer timing
wise to the NBM. This was done in order to get in a little terrain
enhancement that the broader models will not yet capture. QPF 12z
Mon-12z Thurs: 3-7.50" Transverse/Sierra, 2.50-6" central coast
mountains, 2-3.50" Shasta, 1.50-3" CA coastal areas and down the
valleys.

Freezing levels starting out 4-7 kft across the Sierra Monday
morning lowering into Tuesday down to 3-5 kft. The entire region by
that point should be below 7 kft. Lower freezing levels will push
further to the south into Wednesday down to 2.5-3.5 kft north of I-
80 and 3-4.5 kft from I-80 to the southern Sierra. Most of the
region, north of San Diego, should remain below 5.5 kft through the
period.


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



DRK/AS

$$