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AGUS76 KRSA 111940

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

1240 PM PDT Thu Apr 11 2024



...TRANSITION TO COOLER AND UNSETTLED FOR THIS WEEKEND...



.METEOROLOGICAL CONDITIONS (SHORT TERM: THU PM - SUN AM)...



Primarily clear skies and warm temperatures are the rule this 

afternoon as high pressure slides across the area today. At the same 

time...a polar upr low is beginning to drop south-southeast from the 

Gulf of Alaska...now crossing 50N on its way toward the CA coast for 

this upcoming weekend. Models in reasonable agreement showing the 

primary circulation reaching down near 30N just outside of 130W by 

Friday morning at 12Z...while the frontal boundary lurks just 

offshore of the north coast. Then through Friday...the upr low will 

make its way to just west of the SF Bay Area with the best precip 

along coastal areas of northern and central CA...before spreading 

inland and farther south on Saturday. Changes to the afternoon were 

slightly higher in areas near the CA/OR border and then down the 

coast through central CA (plus 0.10- to 0.25-inch). Then amounts 

were slightly decreased for the southern Sierra (minus up to about 

0.10-inch).



Freezing levels are peaking today and will decrease through the 

weekend as the cooler airmass moves overhead...from about 9500- to 

12500-feet now to about 3500- to 5000-feet for northern/central CA 

and 5000- to 10000-feet for NV and southern CA.





.METEOROLOGICAL CONDITIONS (LONG TERM: SUN AM - WED AM)...



With continued spread in the overall details, guidance continues to 

disagree on the exact placement and location of precipitation on 

Sunday into Monday morning as the deep upper low begins to shift 

inland. EC forecasts point to a wetter solution over northern 

California whereas the GFS is slightly wetter over the southern 

Sierra and Transverse range of central/southern California. 

Afternoon QPF primarily followed WPC while working in some of the 

GFS and EC early on Monday to extend shower activity as the low 

trajects inland. Amounts slightly increased over northern 

California/Nevada (<0.10 inches) and the southern Sierra (up to 0.15 

inches). Forecasts will continue to update as guidance hones in on 

the details of the pinwheeling low as it moves inland. Ridging will 

become the main story next week as it builds in behind the upper 

low, resulting in a return to warmer and drier conditions. 



Freezing levels over northern California will begin the period below 

4,000 feet under the upper low before rising across the region to 

above 5,000 feet across the north and 12,000 feet across the south. 







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







Kozlowski/CH



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