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AGUS76 KRSA 081511

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

710 AM PST Fri Mar 8 2024



...DRY CONDITIONS ACROSS THE REGION TODAY...

...A SERIES OF SYSTEMS WILL BRING PRECIP TO THE NRN HALF OF THE 

REGION THIS WEEKEND THROUGH EARLY NEXT WEEK...



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



Dry conditions across the region today as a positively tilted upper 

ridge sits over the west coast. The ridge will gradually shift 

inland the rest of today and tonight being displaced by an 

approaching upper trough. The trough will arrive offshore of the 

PacNW and nrn CA by early Saturday morning bringing showers to the 

north coast. The system will then head inland the rest of Saturday 

lifting to the northeast and weakening in the late afternoon. This 

will result in some showers across nrn CA and srn OR Saturday. As 

the Saturday trough lifts out of the area, a surface/upper low will 

drop in from the Gulf of Alaska arriving offshore of the PacNW/BC 

early Sunday morning. This system will send more moderate to locally 

heavy precip to the north coast Sunday morning. The low is forecast 

to then open into a trough stretching from BC through nrn CA before 

traveling inland across the region Sunday afternoon and overnight.



There is still some model disagreement on the Sunday system on how 

far along the north coast higher QPF will spread, but the ensemble 

spread is lower than for previous systems at about 1-1.50" with more 

ensemble members on the same page on the area seeing at least an 

inch inch and a half for Sunday. Highest precip amounts through 12z 

Monday forecast for the north coast at about 2-4" (locally higher 

for isolated spots). QPF for the rest of the area: 1-2" Shasta, 0.50-

1.50" northern Sierra and rest of the nrn CA coast, 0.10-0.75" 

central Sierra/Bay Area, and a few hundredths to 0.50" or so down 

the valleys. Majority of the precipitation for these events expected 

north of I-80.



Freezing levels lowering into Saturday morning down to 4-7 kft north 

of I-80 dropping further into the afternoon to 3-6.5 kft. Levels 

will fluctuate the rest of the weekend but remain generally around 

those heights until spreading further to the south into early Monday 

at 3-4.5 kft north of I-80 and 4.5-6 kft to Point Conception.





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



The s/wv trof primarily affecting the area on Sunday will be moving 

downstream of the area...crossing the NV/UT border early in the 

period. At the same time...the next s/wv trof making its way across 

the northern Pacific will be making its way toward the Pacific 

Northwest and northern CA with an area of elevated moisture pooling 

around 130W to the west of the CA coast with PW values peaking just 

above 1.00-inch. Look for precip to increase across the upper 

Klamath River basin and northern CA throughout Monday with the best 

totals falling after sunset as the best moisture intersects the 

northern CA coast down to the SF Bay Area and the s/wv trof moves 

within 130W. Into Tuesday the moisture will have been shunted south 

of the area...while the s/wv trof elongates as it moves inland and 

begins to show signs of splitting. Precip will push across northern 

NV and down across portions of central CA from a Big Sur coast to 

Kings Canyon/Sequoia NP. Precip will begin to taper off on Wednesday 

as the s/wv trof moves downstream of the area across the Rockies 

with the southern extent of the system beginning to form a cutoff 

low near the 4-Corners region. Back over the eastern Pacific...a 

strong area of high pressure will pump up and situated itself 

primarily along 130W...helping to form a fairly amplified patters 

over the central/eastern Pacific and the western US.



Freezing levels with the precip moving through will be from about 

4500- to 5500-feet north near the CA/OR border and far northern NV 

and about 6000- to 7000-feet along I-80. After this system moves out 

and the pattern becomes a bit more amplified...freezing levels will 

become oriented more east-to-west from 3000- to 5000-feet over NV to 

approx 10000-feet along the CA coast.





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







AS/Kozlowski



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