Hydrometeorological Discussion National Weather Service / California Nevada RFC / Sacramento CA 830 AM PDT Thu Sep 28 2023 ...SHOWERS OVER SRN OR AND NRN AND CENTRAL CA AND NV FRIDAY THEN OVER MOST OF THE REGION ON SATURDAY AND MAINLY OVER AREAS OF CENTRAL AND SRN CA AND DOWN ALONG THE SIERRA AND EAST OVER NEVADA SUNDAY THEN MAINLY CENTRAL AND ERN NV MONDAY AS A LOW/TROUGH AFFECTS THE REGION... ...COOLER OVER THE WEEKEND WITH MAX TEMPS DROPPING BELOW NORMAL BY 10-20 DEG F OVER MOST OF THE REGION AND OVER NEVADA ON MONDAY... .METEOROLOGICAL CONDITIONS (THU AM - WED AM)... Trough over the Western U.S. with dry conditions over the region today. A disturbance approaches the ORCA border tonight and deepens the trough over the region on Friday into Saturday with a closed low forming Saturday night into Sunday shifting to the east on Monday as high pressure builds into the region from the Eastern Pacific. Precipitation may start as early as Thursday night over NW CA coast (around Cape Mendocino north) and along the Srn Or Cascades. Showers spread south and east over Srn Or, Nrn CA and NV Friday afternoon into night and spreading south and east into Central CA and along Srn CA coast and mountains and over NV on Saturday. Isolated thunderstorms are also possible. Showers mainly along the Sierra and east over Nevada with few showers possible over Central CA and along the SRN CA coast and mtns on Sunday and decreasing and mainly over Central and Eastern NV on Monday. Freezing levels dropping to around 7000 ft near the ORCA border and around 8000-9000 ft for the Sierra Saturday and around 7000-8000 ft for the NE Plateau and Nrn Sierra and into Wrn NV Sunday. Highest precipitation amounts generally expected along NW CA coast and Shasta Basin and along the Sierra and over higher terrain of NV with 0.5-1.5 inches. The trough will also bring cooler temperatures with max temperatures generally dropping to 10 to 25 degrees below normal and min temps near normal to 10 degrees below normal over the weekend. Nevada and Srn CA will still be around 10 to 20 degrees below normal on Monday but Nrn and Central CA will warm up to near normal to 10 degrees below normal as high pressure builds in. Dry and warmer conditions are expected on Tuesday with ridge of high pressure over the west coast. Please Note: This product may NOT be routinely updated Friday through Sunday between Jun 1 and Oct 1. Please refer to www.cnrfc.noaa.gov/dailyBriefing.php for a graphical summary of weather and hydrologic conditions. |