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AGUS76 KRSA 041438

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

740 AM PDT Sat May 4 2024



...WIDESPREAD PRECIP ACROSS THE REGION TODAY WITH ISOLATED T-STORMS 

OVER NRN CA THIS AFTN/EVE AS A LOW MOVES THROUGH NRN CA AND A COLD 

FRONT/MOISTURE PLUME TRAVEL THRU CENTRAL/SRN CA...

...LIGHT SHOWERS ALONG THE NRN REGIONAL BORDER MON BEFORE DRYING AND 

WARMING KICK OFF THE REST OF THE WEEK...



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



An upper low is on the approach currently west of OR as a cold front 

and moisture plume traverse CA. TPW satellite has the moisture plume 

surrounding the Bay Area as radar imagery shows widespread precip 

across much of CA north of I-80 and currently spreading across the 

bays. Precip overnight came in a bit heavier than models initially 

predicted with observations over the past 12 hrs along the north 

coast reporting anywhere from 1.50" to over 3". Amounts then taper 

off to the south and east down to 0.10-0.25". 



The front and moisture plume will continue to sweep through the 

region this morning reaching Point Conception in the afternoon and 

moving through soCal overnight. Meanwhile, the upper low offshore 

will head inland through nrn CA this afternoon before moving into NV 

this evening/overnight. As the low moves through nrn CA, chances of 

isolated thunderstorms for the afternoon and evening. Heaviest 

period of precip will be mainly through this morning as the front 

and moisture plume separate further from the parent low the rest of 

the weekend. Scattered showers will persist this afternoon and 

tonight diminishing across CA on Sunday as the front/moisture plume 

exit to the south and the low progresses further eastward through 

NV. The low is then expected to start to enter UT/ID in the late 

afternoon/evening Sunday. The exiting low and a weak disturbance 

moving through the PacNW will keep light scattered showers possible 

along the CA/OR border and over ne NV into Monday morning. 

Today/tomorrow contain the bulk of the QPF for the next 6 days with 

highest amounts expected along the central coast and across the 

Sierra. QPF 18z today to 12z Mon: 1-2.50" across the Sierra, 0.25-

0.75" along the north coast, 0.10" to <1" Bay Area/Central 

Coast/valleys, and a few hundredths to 0.25" along coastal soCal 

(0.50-1" for some of the mountains).



This system will also act to cool temperatures and lower freezing 

levels across the region this weekend. Afternoon highs for today are 

looking 10-20+ deg F below normal for most of CA with still near to 

above normal conditions across se CA and eastern NV. Lower 

temperatures will spread into Sunday with most of the region 10-20+ 

deg F below seasonal normals through Monday. Freezing levels 

lowering from nw to se today starting at 3-6.5 kft north of I-80 

this morning before lower levels spread across much of the state to 

2.5-5.5 kft north of Point Conception by Sunday morning. As the low 

exits, freezing levels will rebound up to 4-8 kft north of I-80 and 

7-13 kft to the south early Monday.



Some brief transitional ridging then on Monday ahead of a shortwave 

approaching OR. Troughing will dig through the PacNW throughout 

Monday scraping the northern CA/NV borders resulting in shower 

chances for those areas through Tuesday morning. Models also have 

the back edge of the trough dipping across NV generating some light 

showers further across the state Tuesday morning. At this time, the 

low that is currently offshore will have strengthened and joined the 

system that moved through the PacNW over the central US while high 

pressure builds over the eastern Pacific. This pattern of high 

pressure offshore of the west coast and low pressure over the 

central U.S. will persist the rest of the period with troughing 

occasionally retrograding back into NV and pushing high pressure to 

the west. This will keep dry conditions in place and temperatures 

for much of interior CA and NV below normal while parts of northern 

and coastal CA see above normal temperatures. 





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







AS



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