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AGUS76 KRSA 282004

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

100 PM PDT Thu Mar 28 2024



...LINGERING SHOWERS AND ISOLATED TSTORMS TODAY AS A COLD FRONT 

CONTINUES TO MOVE THROUGH CA/NV...

...A LARGE SURFACE/UPPER LOW WILL TRAVEL ALONG THE COAST FRIDAY INTO 

THE WEEKEND BRINGING WIDESPREAD PRECIP AND ISOLATED TSTORMS...



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



Radar imagery continues to show scattered showers across the region 

this afternoon along with some thunderstorms as a cold front passes 

through soCal/NV and troughing takes over the west coast. The 

surface/upper low continue to inch closer to the coast as well while 

the next system develops offshore. Another 0.25-0.75" has fallen 

over the Sierra the past 6 hours with 0.10-0.50" along the north 

coast and through to Shasta. Forecast overall remains on track for a 

surface/upper low to approach the CA coast tonight arriving Friday 

morning. The system will draw in some moisture from the southwest 

funneling into soCal as the low travels south along the coast into 

the weekend. This is expected to produce widespread precipitation 

and isolated thunderstorms Friday/Saturday with the heaviest amounts 

along the central/srn coastal CA mountains, across coastal soCal, 

and over the Sierra. A secondary low is still expected to develop 

over NV/UT late Saturday into Sunday producing additional precip 

over NV.



There haven't been many changes in the 12z model runs compared to 

this morning aside from some subtle shifts in timing/positioning of 

the low. QPF change from this morning over the three day period has 

generally between 0.10-0.50" up or down depending on location. 

Exceptions have been 0.50-1" increase along the Big Sur coastal 

mountains. Ensemble spread is just as wide across coastal soCal as 

this morning with 24 hr QPF ending Sunday morning at San Diego 

ranging between <0.50" to over 3" between the GFS and ECMWF. 



The official forecast was a blend of the latest WPC guidance and the 

12z GFS/ECMWF along with the previous forecast. QPF through 12z Sun: 

1-2.50" CA coast from Sonoma to San Diego, 2-4" Transverse Range, 2-

4.50" central coast mountains, 1.50-3" Sierra, 0.50-1.50" most of 

the rest of nrn CA, 0.25-1" down the valleys, and 0.10-0.50" for 

ne/se CA.



Freezing levels 3.5-5 kft north of I-80 and 4-11 kft to the south 

today with lower freezing levels spreading across the region into 

Friday. Mid Friday morning, expecting freezing levels 3.5-6.5 kft 

north of Point Conception and 5.5-10.5 kft to the south. Most of the 

region will be below 6 kft by Saturday morning with the entire 

region down to 4.5-6.5 kft at the end of the period as the low takes 

over.





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



Minor changes to the afternoon forecast issuance after incorporating 

the latest WPC QPF and NBM as two areas of low pressure move out of 

the area...one over northeast NV and the other crossing the CA/MX 

border area. These two features will be the focal points of the 

precip on Sunday before tapering off. Coastal southern CA and 

northern NV near the I-80 corridor will see the best precip with 

0.25- to 0.75-inch. Freezing levels will range from 4000- to about 

6000-feet from north to south. After the upr trof moves a bit more 

inland...an upr ridge building over the eastern Pacific will nudge 

across the Pacific Northwest and northern CA...which will generate 

dry north to northeast flow aloft. Freezing levels will bump up to 

10000- to 12000-feet. 







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







AS/Kozlowski



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