Hydrometeorological Discussion
Issued by NWS California-Nevada RFC
Issued by NWS California-Nevada RFC
169 AGUS76 KRSA 181408 HMDRSA Hydrometeorological Discussion National Weather Service / California Nevada RFC / Sacramento CA 710 AM PDT Wed Sep 18 2024 ...CONTINUED COOLER TEMPERATURES WITH PRECIP AND ISOLATED THUNDERSTORMS POSSIBLE THE REST OF THE WEEK... ...DRY CONDITIONS RETURN BY THE WEEKEND WITH WARMING TEMPERATURES INTO THE COMING WEEK... .METEOROLOGICAL CONDITIONS (WED AM - TUE AM)... Between the previous low and the current one sitting just offshore of the northern CA coast, showers fell across the northern portion of the region yesterday dropping generally a few hundredths to a couple tenths of an inch over northern CA/NV. Isolated locations saw closer to 0.25-0.50". The low will continue to travel southward the rest of today with the core of the system just offshore. The center of the low is expected to pass the Bay Area this afternoon reaching the central coast by the evening. As it moves offshore, the low will generate some scattered showers and thunderstorms from the northern/central CA coast through to the Sierra and into NV. Current guidance has the low staying offshore longer than previous runs making for less precip over the region than prior forecasts. The exception is favorable orographics into the Sierra along with decent moisture (~1" PW) continue to increase QPF across that area (0.75- 1.25" for some locations). Both the GFS and the ECMWF have the low stalling when it reaches the Big Sur coast later today sitting in place until starting to move again Thursday afternoon-ish. The GFS has the low shifting south of Point Conception in the evening before moving inland through srn CA near San Diego early Friday. The ECMWF has it moving inland shortly after passing Point Conception but slowly enough that the two catch up position wise over soCal mid Friday morning. All this time scattered showers and thunderstorms will remain a possibility, though QPF amounts look generally low at 0.10" or less aside from thunderstorms and about 0.50-0.75" over the western Transverse Range. The low will then move through the southern tip of NV and start entering AZ by the early evening refocusing showers/thunderstorms over se CA and srn NV. In addition to precip, this system is also expected to bring widespread below normal temperatures through Friday by about 5 to 15 deg F. Behind the exiting low, a ridge of high pressure will build in over the eastern Pacific returning dry conditions to the region the rest of the forecast period along with warming temperatures. Expecting afternoon highs to rise to as much as 10 or so deg F above seasonal normals for parts of CA Sunday before becoming more widespread across the region Monday. 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. QPF graphics are available at www.cnrfc.noaa.gov/qpf.php AS $$