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AGUS76 KRSA 191946

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

1245 PM PDT Tue Mar 19 2024



...CHANCES OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS 

INTO THE EVENING MAINLY OVER SRN SIERRA AND SRN CA/NV...

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

WEEKEND...



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



Forecast remains on track this afternoon with no changes from this 

morning. An upper low continues to drift into AZ while high pressure 

sits across the rest of the western U.S. This will allow for some 

slight chances of scattered showers and isolated thunderstorms over 

parts of srn CA/NV and the srn Sierra into this evening. So far 

convection today has remained confined east of the forecast area. A 

small upper low also approaches from the backside of the ridge 

headed towards the PacNW. The low will open into a shortwave Weds am 

just before arriving offshore of OR/WA and moving inland in the 

afternoon/evening. This system may result in some light showers 

along the north coast and near the OR border. The next surface/upper 

low will approach from the Gulf of Alaska on Thursday remaining 

offshore the rest of the near term. Some initial showers are 

expected along the nrn CA coast and through to Shasta late Thursday 

night into Friday morning. There is still some uncertainty regarding 

the timing, but the det GFS/ECMWF keep the more moderate precip band 

associated with the low offshore before Friday morning. The official 

forecast is the combination of the updated WPC guidance the 12z 

GFS/ECMWF and previous forecast. This amounts to roughly 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)...



Models still indicating a shift toward cooler and wetter for the end 

of the week into early next week as the upr ridge currently overhead 

shifts off toward the east across the interior...and is replaced by 

a slow moving upr trof over the northeast Pacific that eventually 

shifts across the west coast before exiting the area to the east on 

Sunday. Best precip still appears to be focused on coastal areas 

from the Russian River basin northward and then inland over the 

southern OR Cascades down across the Shasta Lake drainage and Sierra 

down to the Merced River basin with 1.00- to 2.50-inches (highest 

north of I-80). Amounts really trail off across the central CA coast 

with scattered amounts reaching southern CA and past the Sierra 

crest over northern NV. Freezing levels start Friday in the range of 

6000-feet northwest...8500-feet along I-80...and close to 10000-feet 

at the CA/MX border. These bottom out as the core of the upr trof 

moves across the area later Saturday into early Sunday from 3500-

feet northwest...4000- to 4500-feet along I-80...and 5000- to 6000-

feet for southern CA and southern NV. After this system exits the 

area...an upr ridge will build over the eastern Pacific pretty much 

along 145 W with northwesterly flow across the west coast on Monday. 

Afternoon forecast issuance basically took the previous forecast and 

blended in the latest NBM and WPC QPF...which overall didn't result 

in any dramatic changes.





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







AS/Kozlowski



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