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AGUS76 KRSA 101451

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

750 AM PDT Sun Mar 10 2024



...A PAIR OF TROUGHS TO BRING PRECIPITATION TO NRN/CNTRL CA AND 

NRN NV THRU TUES...

...BUILDING HIGH PRESSURE TO RETURN DRY CONDITIONS TO THE REGION MID-

WEEK THRU THE REST OF THE PERIOD...



.METEOROLOGICAL CONDITIONS (SUN AM - SAT AM)...



Radar imagery capturing showers along the north coast and over srn 

OR as a front sits stretched along the PacNW coast out to sea just 

offshore of nrn CA. An upper trough is also situated along the west 

coast. The front will slowly move inland the rest of this morning 

through nrn CA weakening as it does so. This will spread precip 

across the north coast and inland to I-5. This afternoon, the upper 

trough will split with the northern half moving inland around WA/OR 

and the southern half digging just offshore of the nrn CA coast. 

This part of the trough will progress eastward across the state late 

this afternoon through this evening passing into NV early Monday 

morning and exiting the area in the afternoon. This will allow 

showers to spread further across nrn CA and southward into the Bay 

Area/central coast.



Behind this system another surface/upper low will move into the Gulf 

of Alaska sending additional precipitation towards nrn CA. Showers 

expected to reach the north coast Monday afternoon spreading inland 

across nrn CA the rest of the day as the core of the low travels 

south offshore of BC. The trough will then progress inland across 

the region the rest of Tuesday keeping showers going across nrn 

CA/NV. There is some disagreement regarding the depth of the trough 

between the GFS/ECMWF. The ECMWF has a deeper trough thereby taking 

precip further to the south into central CA compared to the GFS. By 

Tuesday evening, the ECMWF has the axis of the trough stretched all 

the way through srn NV into se CA and western AZ while the GFS shows 

a shallower system mostly contained north and east of the CA/NV 

border. 



Both models then realign into Wednesday showing a strong ridge of 

high pressure building over the eastern Pacific and expanding into 

the west coast as the previous trough digs into ID, NV, and the Four 

Corners. The result will be drying conditions over CA and some 

lingering showers over eastern NV for Wednesday. The trough will 

then form itself into an upper low for Thursday continuing to shift 

to the south encompassing parts of srn CA and NV. The ECMWF Thursday 

has the core of the low centered over soCal while the GFS has it 

further eastward over AZ. Both models keep the low rotating in 

roughly the same places the rest of the period. This is causing the 

ECMWF to predict scattered showers across srn CA the rest of the 

week while the GFS is dry. The low will also moderate 

temperatures/freezing levels across NV and srn CA in the later part 

of the week with warming expected elsewhere.



The majority of the precipitation expected this week will be today 

through Tuesday afternoon with drying conditions thereafter aside 

from some lingering light showers. Best precip will be north of I-

80, particularly along the nrn CA coast over the Smith Basin and 

Kings Range as well as Shasta. Total QPF through Tuesday: 1-2.50" 

nrn CA coast Sonoma northward (2.50-4" Smith Basin/Kings Range), 1-

2.50" Shasta, 1-2" northern Sierra, 0.25-0.75" central Sierra, 0.10-

0.75" Bay Area, and a few hundredths to 0.50" or so down the valleys.



Freezing levels 3.5-6.5 kft north of I-80 and 6.5-10.5 kft to the 

south the rest of the weekend. Lower freezing levels expected to 

spread further to the south into early Monday at 3.5-5 kft north of 

I-80 and 4.5-8 kft to Point Conception. After Monday, generally at 

3.5-6.5 kft again north of I-80 for the rest of the precip events. 

Building high pressure will raise freezing levels along the coast up 

to 8.5-11 kft by Wednesday afternoon. The presence of the low inland 

will keep levels down to 4-7 kft across NV and 4.5-7.5 kft over 

eastern CA through Thursday morning before higher levels spread the 

rest of the day. By Friday morning, most areas north of I-80 in CA 

forecast at above 10 kft while locations near the NV border are 

closer to 7-9 kft and NV/se CA sits at 5-7 kft. High pressure will 

keep spreading higher freezing levels (8.5-11 kft) across the region 

into Saturday while the upper low keeps seCA and srn NV closer to 7-

8 kft.





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







AS



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