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AGUS76 KRSA 191429

HMDRSA



Hydrometeorological Discussion

National Weather Service / California Nevada RFC / Sacramento CA

730 AM PDT Fri Apr 19 2024



...WARM AND GENERALLY DRY INTO MONDAY ASIDE FROM ISOLATED 

SHOWERS/TSTORMS FOR THE CNTRL/SRN SIERRA THIS AFTN/EVE...

...CHANCE OF PRECIP MID TO LATE WEEK AS A LOW APPROACHES THE CA 

COAST...



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



Generally dry conditions across the region today as a ridge passes 

across the west coast. An embedded shortwave moving through soCal 

later today may result in some isolated showers/thunderstorms over 

the central/southern Sierra in the afternoon/evening. Dry conditions 

will persist into the weekend as the area remains under high 

pressure. A surface low and upper trough will approach the PacNW 

Saturday from the Gulf of Alaska before moving through WA in the 

afternoon/evening. A few stray showers may reach the CA border, but 

otherwise precip is forecast to remain far to the north. Behind that 

low, high pressure will move into the eastern Pacific centered west 

of the PacNW for Sunday. This will keep the area dry the rest of the 

weekend and through Monday.



Uncertainty grows as we get deeper into next week due to model 

differences. The GFS/ECMWF generally agree that two lows will 

approach on Tuesday, one offshore of BC coming from the Gulf of 

Alaska and another approaching from west of CA. The models have 

these systems in different positions relative to each other as well 

as differences in timing. The ECMWF has the northern low reaching 

the BC coast Tuesday afternoon while the GFS has the same low just a 

bit further offshore and closer to WA/OR. In spite of these 

differences, both models are predicting some light showers across 

nrn CA/NV for Tuesday. The other difference comes with the low west 

of CA. Both models have the low shifting to the south towards soCal 

on Tuesday, but the GFS speeds up the systems arrival across coastal 

soCal to mid Weds morning while the ECMWF still has it much further 

out to sea. In fact, the ECMWF does not have the low arriving until 

Thursday morning while the GFS already carries the now open trough 

into AZ with another system dropping in from the nw. The CMC is on 

the slower side as well more in line with the ECMWF, but still with 

some differences. Looking at the ensembles, timing varies from 

Tuesday to Thursday on the arrival of precip from the southern most 

low. Either way, this system is not expected to produce significant 

amounts of precipitation. Will keep an eye on the models over the 

weekend and hopefully they will come into better agreement.



As for temperatures, expecting afternoon highs to be 5-15 deg F 

above normal away from the coast through Monday. Temperatures will 

then lower from west to east early to mid week as the low 

approaches. Timing of the cool down will depend on when the low 

arrives, but when it does expecting afternoon highs down to 5-10 deg 

F below normal for most of CA. Freezing levels 8-12 kft N to S 

through Sat am rising to 8.5-13 kft Sat afternoon with higher 

freezing levels spreading northward throughout the rest of the 

weekend. Freezing levels to then lower mid week down to 7-10.5 kft 

then 6-10 kft depending again on the timing of the next low.





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







AS



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