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AGUS76 KRSA 191413

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

715 AM PDT Tue Mar 19 2024



...UPPER LOW WILL BRING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS 

MAINLY OVER SRN SIERRA AND SRN CA AND SRN NV...

...PRECIP SPREADS OVER THE REGION FOR THE END OF THE WEEK INTO THE 

WEEKEND...



.METEOROLOGICAL CONDITIONS (SHORT TERM: TUE AM - FRI AM)...



An upper ridge is currently stretched across the PacNW and through 

to central CA/NV as an upper low sits across the CA/AZ border. The 

low will shift eastward into AZ the rest of today while high 

pressure remains over the rest of the region and an upper low 

approaches the PacNW. The presence of the CA/AZ low will allow for 

another day of scattered showers and potential thunderstorms over 

parts of srn CA and the southern Sierra. This will diminish into 

tonight as influence from the low wanes and high pressure takes 

over. The next system will approach the PacNW into Wednesday as a 

low that will open into a shortwave early Wednesday morning. Models 

have the system traveling northward but sending some light precip 

towards the north coast later Weds into early Thursday. Just behind 

the shortwave, a larger surface/upper low will move into the Gulf of 

Alaska heading eastward towards the PacNW and nrn CA the rest of the 

near term. Some initial showers may reach the north coast late 

Thursday night, but the bulk of any precip will arrive after the end 

of the near term. The official forecast went mainly with the morning 

WPC guidance which has maybe 0.10" or so along the north coast and 

over Shasta with generally less elsewhere except under thunderstorms.

Freezing levels generally above 8 kft except down to 6-8 kft for 

parts of nrn CA.





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



A pattern shift will be underway for the end of the week as the 

persistent upr ridge along the western US will shift inland...while 

a deep upr trof over the northeast Pacific makes its way toward the 

west coast and spreads unsettled conditions over the area. 

Initially...there will be a narrow plume of moisture entrained ahead 

of the cold front with PW values peaking out near 1.00-inch with 

approx 0.50- to 0.75-inch PW intersecting the coast and advecting 

inland. Then as this moisture gets shunted south of the area...the 

broad cyclonic flow will set up along the west coast on Saturday 

with the upr trof axis overhead. Then finally on Sunday...the slow 

moving system will push inland and east of the area as an offshore 

upr ridge builds near 30N/145W. A moisture plume moving up and over 

this feature will make its way toward the west coast for another 

round of mainly light precip later Sunday into Monday. Best totals 

through the weekend will range from 1.00- to 2.50-inches for the 

north coast and then inland for the southern OR Cascades down 

through the Shasta Lake drainage to the northern/central Sierra. 

Amounts then taper off farther south and farther inland. 

Overall...models are in reasonable agreement with the evolution of 

the pattern. Freezing levels will start Friday from 6000-feet 

northwest to 8000- to 9000-feet along I-80...and 10000-feet or so 

near the CA/MX border. These will bottom out later Saturday as the 

upr trof moves inland..ranging from 3500-feet northwest to 4500-feet 

along I-80...and 5000- to 6500-feet for southern CA and southern NV. 





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







AS/Kozlowski



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