National Weather Service Forecast Discussion |
Thornton Weather Forecast Today's Forecast Story |
356 FXUS65 KBOU 192320 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 420 PM MST Wed Nov 19 2025 .KEY MESSAGES... - Accumulating snow is likely (70-80%) across the Front Range mountains and foothills. Generally 1-6" of snow is expected with the highest amounts in the Front Range Mountains. Only a slight chance (20%) of snow for the Denver metro and plains. The northern plains and Palmer Divide have a 40% chance of seeing snow with minimal snow amounts expected. - The plains will see widespread rainfall late Thursday through early Friday. Amounts over an inch of rain are possible mainly from Limon to Sterling and nearby areas. - Another rain event is possible late Sunday across the plains. Light snow is likely in the mountains and foothills. - Turning cooler around Thanksgiving with the potential for a couple very light snowfall events during the latter half of Thanksgiving week. && .DISCUSSION /Through Wednesday/... Issued at 250 PM MST Wed Nov 19 2025 It`s hard to believe it`s the week before Thanksgiving and we will be talking about two rain events for the Denver metro. But it`s been a warm month that`s running 8.5 F above normal in Denver. A trough that will bring precipitation to our area on Thursday is currently over the California/Arizona border. There are plenty of thunderstorms in Arizona which is indicative of the moisture in the area. This trough will weaken, become more negatively tilted, and will end up in eastern Colorado by Friday morning. A wave of precipitation is expected to form over southeast Colorado Thursday morning and will become more widespread and intense as it moves northward into our forecast area. A deformation zone on the northwest side of the trough will help to keep the precipitation going in northeast Colorado through Thursday night and into Friday. The difficulty will be determining how much precipitation will fall and where the heaviest amounts will be. Models like the NAM and HRRR have consistently been forecasting significant precipitation for November standards. Each model has a wide swath of rainfall around 1.5" across the plains. Meanwhile, the ECMWF has been consistent with showing about a quarter inch of rainfall in the Denver metro and around a half inch of rain across the plains. The forecast was trended towards the ECMWF for QPF amounts and the PoPs were increased across our CWA since the likelihood of precipitation is increasing. While the QPF was trended towards the ECMWF, the higher forecast QPF amounts are certainly possible given the ample moisture arriving in our area with 40+ F dew points expected. The other forecast uncertainty in this event will be precipitation type and snow level. As previously mentioned, dew points in the low 40s will advect over the eastern plains and this will mean precipitation will likely (80% chance) fall as all rain. However, if precipitation amounts are more intense that expected, areas near the Cheyenne Ridge and Palmer Divide could receive some light snowfall late Thursday night. Across the higher terrain, the snow level will be around 7,000-7,500 feet. The Front Range Mountains and higher Foothills will see 1-6" of snow. If the higher end precipitation values occur, snowfall amounts could reach up to 10" especially in Rocky Mountain National Park. Brief ridging will move over Colorado late Friday into Saturday. Friday night through Sunday morning will be dry with slightly above normal temperatures. The model trend has been very consistently moving a cut-off trough over the Desert Southwest farther north on Sunday. The majority of models take the center of the 500 mb trough into southeast Colorado. This will bring a chance of precipitation to our forecast area. The latest NBM doesn`t have this new data in it so PoPs were increased on Sunday night to include a 30-40% chance of precipitation across most of our area. This system will be similar in regard to precipitation type as the first one. Rain is likely across the plains and light snow is possible in the mountains. A period of ridging will move over Colorado on Monday and into Tuesday with dry weather and normal temperatures expected. A trough will bring cooler temperatures by Thanksgiving with below normal temperatures expected. There will be multiple chances of very light snowfall during the latter half of next week. && .AVIATION /00Z TAFS through 00Z Friday/... Issued at 417 PM MST Wed Nov 19 2025 Light east winds will become more SE by 01z and then to drainage by 05z. For Thu, light WSW winds in the morning will become easterly by 21z or so. VFR conditions will be in place thru 18z Thu but expect ceilings to gradually lower to aroun 5000 ft by 22z with a slight chance of a rain showers. After 00Z rain chances will increase with ceilings lowering to MVFR. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Danielson AVIATION...RPK