513
AGUS76 KRSA 211316
HMDRSA

Hydrometeorological Discussion
National Weather Service / California-Nevada RFC / Sacramento CA
615 AM PDT Tue Jul 21 2026

...BEST CHANCE FOR SHOWERS TODAY SIERRA CREST AND MUCH OF NV...
...TURNING DRIER AS THE WEEK PROGRESSES...

.METEOROLOGICAL CONDITIONS (TUE AM - MON AM)...

High pressure downstream of the area centered over Colorado...while
general troffing resides just off the west coast with a vertically
stacked low pressure system to the southwest of the SF Bay Area.
This has resulted in deep southerly flow across CA and NV...ushering
in ample amounts of lower latitude moisture. Looking at the 21/12Z
RAOBs across the region...PW values are all above the 1.00-inch mark
with the KOAK sounding showing an impressive 1.62-inches. Satellite
and radar imagery does show scattered cloud cover with weak returns
dotted across the area this morning. Overnight...best coverage of
precip was in a line from the area around Yosemite NP northward to
the Reno area. Automated precip gauges over the past 6-hours
indicates anywhere from a couple hundredths of an inch all the way
up to approx 0.33-inch.

Today looks to be the best of the forecast period for precip
production as models indicate afternoon showers and thunderstorms
developing along the length of the Sierra and points eastward across
the entire state of NV. The highest totals are looking to fall near
the crest of the central/southern Sierra and then across central NV
stretching up over the northeast portion of the state. This is also
where a Flood Watch is in effect today.

After today...Wednesday will be a transition day as the flow regime
does begin to shift to one that is drier from the southwest.
Moisture will erode from the west...leaving the highest PW values
across far eastern NV and southeastern CA by Thursday morning.
Precip will become less likely as the rest of the week progresses.

Freezing levels are currently running from 15000-feet to the west
and 16500-feet to the east. These may bump up slightly through the
period and take on a gradient that is more northwest to southeast by
the upcoming weekend.


Please Note: This product may NOT be routinely updated.
Please refer to the following product issued by the CNRFC
www.cnrfc.noaa.gov/Daily-Briefing for a graphical summary of
weather and hydrologic conditions.

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



DRK

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