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AGUS76 KRSA 172026

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

130 PM PDT Sun Mar 17 2024



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

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

...PRECIP POSSIBLE OVER SRN OR AND NRN CA THURSDAY AND SPREADING 

SOUTH INTO CENTRAL CA AND NRN NV FRIDAY INTO SATURDAY...



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



Increased amounts a little over Srn CA for this afternoon and over 

San Bernardino County and South into Orange and western Riverside 

and San Diego Counties for Monday afternoon/evening and over NW CA 

for Thursday afternoon/evening. Decreased amounts a little around I-

80 and south into Central Ca on Friday night in the afternoon 

forecast.  



Pattern remains about the same with High pressure ridge over B.C. 

and Pac NW and into Nrn CA and Nrn NV with an upper low meandering 

around CA/NV/ AZ border today into Monday. The upper low has shifted 

a little farther east over Arizona with wrap around showers over Srn 

NV and SE Ca this morning then weakens and retreats back west 

towards CA/NV/AZ border on Monday. Scattered showers and isolated 

thunderstorms will continue to wrap around the low bringing some 

precip to the Srn Sierra and portions of Srn CA and Srn NV today and 

Monday along with cool temperatures. 12Z HREF shows a 10-30 % chance 

of half an inch or more in an hour on Monday afternoon/early 

evening, highest over San Bernardino and western Riverside into 

Orange and San Diego Counties.  Precipitation amounts will be 

variable with the convection but generally a hundredth or two to 

around a quarter of an inch will local amounts to around a half of 

an inch possible. Freezing levels around 7000 to 9000 ft today and 

rise to around 8000 ft and higher Monday. High pressure over the 

north will continue to bring warm and dry conditions to the northern 

portion of the region into Monday. 



The pattern starts to shift Tuesday into Wednesday as a low pressure 

system approaches the B.C./WA coast and high pressure shifts south 

over the region and low moves off to the east into AZ/NM. A few 

showers possible in the Shasta Basin and along the Sierra and mainly 

over the higher terrain of Srn Ca and Srn NV on Tuesday and 

Wednesday. High pressure weakens and shifts east with a trough/lows 

deepening over the Eastern Pacific on Thursday and approaching the 

west coast Friday. This will bring a chance of precipitation to Srn 

OR and Nrn CA on Thursday. Precip may begin over NW CA Thursday 

afternoon and spread south and east into Central CA and Nrn NV 

Friday. Variability among models and ensemble members in the details 

of the strength and track and timing of the low leading to lower 

confidence in timing and precip amounts and coverage. 12Z GFS faster 

and farther north and stronger with low than 06Z and a little closer 

in timing to the EC and Canadian. 



Freezing levels around 8000 ft and higher Tuesday and dropping to 

around 6500-8000 ft over Srn OR and Nrn CA on Thursday night and 

down to around 4000-6000ft over Srn OR and Nrn CA and around 6000-

8000ft over Central CA Friday night. Max temps drop to near to 

several degrees below normal over Nrn Ca and along the CA coast and 

near to around 10 degrees above normal over SJ Valley and into SE CA 

and over NV on Thursday and Friday. 



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







Osborne



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