Area Forecast Discussion
Issued by NWS Reno, NV
Issued by NWS Reno, NV
379 FXUS65 KREV 230843 AFDREV Area Forecast Discussion National Weather Service Reno NV 143 AM PDT Mon Sep 23 2024 .SYNOPSIS... * A dry and mild pattern is expected this week with light winds through tomorrow. * Increased southwest winds are likely Wednesday with areas of elevated to localized critical fire weather concerns across northeast CA and northwest NV. * Temperatures will remain around 3-7 degrees above season averages this week with the warmest days forecasted tomorrow and on Wednesday. && .DISCUSSION... The latest RAP analysis of the upper air pattern shows a generally north-northwesterly upper air flow over the CWA being under the forward portion of a Pacific Northwestern upper air ridge while a localized upper level low resides off the coast of central CA this morning. Current satellite imagery and surface observations report generally light winds across the region with some high clouds moving into northern portions of area from OR this morning. Going through the rest of today and into tomorrow, model guidance shows the upper air ridge progressing eastward over the western CONUS while the aforementioned low off the CA coast stays in place. With this setup aloft, dry conditions are expected to continue along with lighter winds across the CWA. Daytime temperatures look to be slightly warmer today compared to yesterday with the warming trend expecting to continue into tomorrow as above average temperatures are in the forecast with valley portions of the CWA potentially seeing Tuesday afternoon highs in the middle to upper 80s. By late Tuesday, forecast guidance depicts the upper air low opening off into a trough causing a southwesterly flow over the CWA on Wednesday. As a result of this pattern development above, a pretty good pressure gradient looks to develop at the surface across the CWA ahead of a cold front in the Pacific Northwest. While the precipitation chances look to stay in OR and WA on Wednesday, the forecast looks to call for increased surface winds out of the southwest compared to those earlier in the week particularly in portions of the CWA closer to the OR border. When looking at latest NBM wind gust probabilities: Lassen, eastern Modoc, and northern Washoe Counties see around a 40-60% chance of gusts of 30 mph or greater during the Wednesday afternoon hours. With relative humidity values in the middle to upper teens in the forecast, these areas may see elevated to near critical fire weather conditions during Wednesday afternoon as a result. As localized critical fire weather conditions may seem possible for a few hours, will continue to monitor this going forward in upcoming forecasts. While Wednesday`s daytime highs across the CWA appear to be similar to those on Tuesday, cooler lows are in the forecast for Wednesday night/early Thursday morning with western NV ranging between the middle 40s and middle 50s while the higher Sierra elevations look to range between the lower 30s and the middle 40s. For the rest of the week and going into the weekend, ensemble guidance currently shows a mostly zonal flow over the CWA following the trough`s departure on early Thursday. While daytime temperatures expect to cool by few degrees on Thursday afternoon, regional temperatures on Friday and Saturday do look rebound back to around those expected on Tuesday and Wednesday. Dry conditions also are in the forecast for the area for the remainder of the week. Over the weekend, ensemble forecasts do show a weak upper level low developing off the coast of CA once again on Saturday which may interrupt the zonal flow aloft. Will continue to monitor this going forward, but there are some early indications of area temperatures starting a slight cooling trend coming out of the weekend. -078 && .AVIATION... VFR conditions are expected at all REV TAF sites going through today with very low (>5%) chances for precipitation across the entire region. A few high level clouds may develop during this morning over areas closer to the OR border before skies look to clear up during the afternoon hours. A few high clouds may develop briefly in the late afternoon and early evening hours in western NV, but they look to diminish going into the overnight hours. Winds across the area are forecast to be generally on the lighter side today as well as Tuesday. The area forecast then calls for an increase in winds out of the southwest on Wednesday with portions of the OR closest to the OR border possibly seeing gusts up to around 25-35 kts during the afternoon hours. -078 && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$