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AGUS76 KRSA 201939

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

1240 PM PDT Wed Mar 20 2024



...A LOW PRESSURE SYSTEM WILL RETURN WET WEATHER TO THE REGION 

FRIDAY AND OVER THE WEEKEND...

...A SHORTWAVE INTO THE PACNW MONDAY TO BRING ADDITIONAL PRECIP 

CHANCES TO NRN CA/SRN OR...



.METEOROLOGICAL CONDITIONS (SHORT TERM: WED PM - SAT AM)...



High pressure remains overhead this afternoon with dry conditions 

across the region. A shortwave continues to approach the PacNW with 

two upper lows one well west of CA and the other offshore of BC. 

Forecast remains on track for the shortwave to move into the PacNW 

late this afternoon into the evening potentially dropping a few 

light showers over nw CA and srn OR. The two offshore lows will 

merge overnight and approach the region on Thursday as the next 

precip maker. The low will travel southward offshore of WA/OR 

sending a front towards CA early Friday. Initial showers still 

anticipated late Thursday night along the north coast spreading 

inland and to the south across CA the rest of the short term. Before 

Saturday, the low will shift its track back northward before the 

trough begins to head inland. The troughing and traveling cold front 

should spread precip into central CA as well late Friday. Models 

trended a bit wetter for the afternoon result in an increase in QPF 

for the short term by about 0.10-0.50". The afternoon update was a 

blend of WPC guidance and the previous forecast.  Highest precip 

amounts across the Sierra, Shasta, and over the Smith Basin/Kings 

Range area. QPF through 12z Sat: 0.75-2.50" Sierra, 1-2+" Shasta, 1-

2.50" north coast, 0.25-1" Bay Area/central coast, 0.10-1" down the 

valleys, and a few hundredths to a tenth of so just south of Point 

Conception. 



Freezing levels 6-8 kft across nrn CA through Thursday and 8+ kft 

elsewhere before the cold front lowers levels from nw to se into the 

weekend. By Saturday morning, freezing levels 3.5-4.5 kft north of I-

80 and 4.5-7 kft south to Point Conception.





.METEOROLOGICAL CONDITIONS (LONG TERM: SAT AM - TUE AM)...



Trof activity is forecast to continue into the long term forecast as 

a closed upper level low moves towards the Pacific Northwest over 

the weekend. Additional shortwave activity embedded within the base 

of the broad trof will produce shower activity over some portion of 

forecast region into early next week, though accumulations decrease 

as time progresses into the week. Majority of uncertainty pertains 

to exact timing and phase of the shortwave activity though all model 

guidance has some form of precipitation throughout the period. 



Afternoon forecasts followed guidance from WPC and increased amounts 

slight over the North Coast and Sierra (up to 0.25 inches). 





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







AS/CH



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