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AGUS76 KRSA 051459

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

700 AM PST Tue Mar 5 2024



...PRECIP FOCUSES MAINLY NORTH TODAY WITH SYSTEM ARRIVING ACROSS 

SOUTHERN CA TOMORROW...

...ANOTHER OPPORTUNITY FOR PRECIP ACROSS NORTHERN AREAS THIS 

WEEKEND...



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



Current setup shows broad upr troffing across the Pacific Northwest 

and northern Plains...extending from a circulation over southern 

Alberta...rotating through disturbances affecting the northern tier 

of the area. Off the CA coast is another s/wv trof between 140W and 

130W relatively slowly making its way toward the southeast. The 

focus for precip today will generally be from I-80 northward along a 

relatively stationary boundary close to the CA/OR border with the 

best totals from the Eel River basin northward along the coast...and 

then from the crest of the southern OR Cascades down through the 

Shasta Lake drainage and northern Sierra to about the Feather River 

basin. Totals in these areas should range from 0.75- to 1.50-inches 

with some localized amounts touching 2.00-inches. Freezing levels 

should range from 3500- to 5500-feet.



Into Wednesday...the broad upr troffing will continue over the 

Pacific Northwest stretching east over the northern Plains with a 

few more weak disturbances moving through the flow. The offshore 

s/wv trof will make its way to the vicinity of Point Conception 

Wednesday morning before crossing the coast between Los Angeles and 

San Diego counties. Models have ticked upward with expected precip 

amounts across coastal southern CA...spreading anywhere from 0.25- 

to 0.75-inch from the Santa Ynez mountains east across the rest of 

the transverse mountains...and then down toward the CA/MX border. 

Then back to the north closer to the stationary boundary across 

northern CA and northern NV...precip will generally be lighter in 

the range of a few hundredths of an inch locally to 0.50-inch across 

the wetter locations. Freezing levels across coastal southern CA 

will generally be from 5500- to 6500-feet...while to the north they 

will be from 3500- to 5500- feet.



As the s/wv trof moves across southern CA a positively tilted upr 

ridge will begin to nose its way from off the CA coast toward the 

Pacific Northwest with drier northerly flow developing across the 

Great Basin down toward southern CA. Some light precip may linger 

over the southern Sierra...coastal southern CA and eastern NV early 

in the period...but overall look for drying conditions as the day 

progresses. 





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



Dry conditions across the region to start Friday as ridging sets up 

over much of the western U.S. A trough will then approach from the 

west bringing showers to the north coast late Friday night as the 

trough arrives just offshore. The system will then move through nrn 

CA Saturday morning before entering NV in the late 

afternoon/evening. This will result in some precip across the 

northern portion of the region for Saturday. A surface/upper low 

will then approach from the Gulf of Alaska into Sunday. There are 

some timing differences between the GFS/ECMWF with the ECMWF 

bringing precip into the nrn CA coast Sunday morning while the GFS 

holds off until closer to the evening. Most of the GFS ensembles are 

overall on the slower side compared to the ECMWF, but a variety of 

arrival times are shown for the ECMWF members. Either way, expecting 

two rounds of precipitation in the extended from two separate 

systems. The first impacting the region on Saturday and the second 

Sunday into Monday.



The forecast was a combination of WPC guidance and the latest NBM. 

The highest precip amounts are expected along the north coast. QPF 

for the extended: 1-2.50" north coast, 0.50-1" Shasta, 0.25-0.50" 

northern Sierra, and a few hundredths to a couple tenths for the 

rest of nrn CA. Freezing levels lowering into Saturday with the 

first system to 4.5-7 kft north of I-80 and 7-9.5 kft to the south. 

Levels to lower further throughout Saturday reaching 3.5-5.5 kft 

north of I-80 in the evening. Freezing levels then generally 3.5-6.5 

kft north of I-80 the rest of the extended and 5.5-10 kft to the 

south.





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







Kozlowski/AS



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