Hydrometeorological Discussion National Weather Service / California Nevada RFC / Sacramento CA 635 AM PDT Wed May 20 2026 ...WARMING TREND THE REST OF THE WEEK AS HIGH PRESSURE PUSHES TOWARDS THE WEST COAST... ...AFTERNOON SHOWERS OVER THE CREST OF THE SIERRA THURS-SUN, POSSIBLE LIGHT SHOWERS OVER THE N COAST & CA/OR BORDER INTO TUES AM... .METEOROLOGICAL CONDITIONS (WED AM - TUE AM)... Troughing remains over the interior of the western US as an upper ridge pushes closer to the west coast from offshore. This will keep temperatures below normal over NV and above normal for most of CA today. The rest of the week, the ridge will shove that troughing further inland while creeping closer to the coast resulting in a warming trend. Models do have a disorganized low forming west of Baja towards the end of the week, but 500mb heights are still relatively high and will not act to mitigate this warming outside of far southern CA. Temperature anomalies are expected at +5 to +15 deg F away from the coast. These warmer temperatures look to stick around through the rest of the current forecast window. Potential for some cooling looking out into the extended as some models/ensembles have a stronger upper low descending in from the PacNW early to mid next week. Timing is still a source of uncertainty, the det GFS/ECMWF bring in some light showers over the north coast towards the end of the period. The official forecast only has a few hundredths of an inch or so. Models continue to show some convective scattered showers (and maybe a thunderstorm) developing over the crest of the Sierra in the afternoons tomorrow onwards. Low confidence again with the ECMWF still having the most buy in. Any amounts look relatively light at this point. Freezing levels today back up above 10.5 kft and up to 12.5 kft rising throughout the rest of the week up to 12-13.5 kft by weeks end. Potential for levels to lower by quite a bit over nrn CA into Tuesday, but this will depend on the timing of that low mentioned above. Official forecast for now has freezing levels 6.5-9 kft north of Shasta by 12z Tues. Please Note: This product may NOT be routinely updated. Please refer to the following product issued by the CNRFC www.cnrfc.noaa.gov/Daily-Briefing for a graphical summary of weather and hydrologic conditions. |