Hydrometeorological Discussion National Weather Service / California Nevada RFC / Sacramento CA 640 AM PDT Mon May 11 2026 ...HIGH PRESSURE RIDGE PEAKS TODAY INTO EARLY TUESDAY... ...LIGHT PRECIP NEAR THE CA/OR BORDER AND FAR NRN NV LATE TUE-WED... ...SEASONABLY WARM AND DRY INTO THE WEEKEND... .METEOROLOGICAL CONDITIONS (MON AM - SUN AM)... High pressure ridge is expected to settle and strengthen over the Four Corners region today and tomorrow...bringing dry conditions and increasing temperatures across CA and NV. Afternoon high temperature anomalies will peak anywhere from plus 10- to plus 25-degF over seasonal normals. However...this heat is expected to be short-lived as a s/wv trof currently approaching 140W off the Pacific Northwest and northern CA coast moves eastward will reach the west coast Tuesday afternoon or evening. This will displace the upr ridge farther downstream of the region with the potential for some light precip moving across areas near the CA/OR border and far northern NV later Tuesday through Wednesday. There are some model differences in terms of the trajectory and timing the system as it moves inland through the middle of the week...but overall are all showing this transition in the overall pattern. Total precip will generally range from 0.25- to 0.50-inch over the Smith River basin up to the crest of the southern OR Cascades...while elsewhere expect 0.10-inch or less. For the end of the week...Thursday will see weak upr ridging sliding across the region with some warming anticipated. Then for Friday into Saturday...a couple disturbances moving across the Pacific Northwest will lower heights across the region...but at this time any precip should remain north of the area. Freezing levels are currently ranging from 13000-feet northwest to 15500-feet close to the CA/MX border...currently very near the peak for this heat event. As the s/wv trof reaches the coast later tomorrow into Wednesday...look for freezing levels to drop with the most pronounced fall over northwest CA and the upper Klamath River basin...down to about 6500- to 9000-feet...while elsewhere will be from 10000- to 14500-feet from northwest to southeast. For later Wednesday into early Friday...a persistent pattern of 10000- to 14000-feet is anticipated before dropping again with the systems moving toward the Pacific Northwest with a sharp gradient of about 5000-feet far north to 14500-feet far south. 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. |