Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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365 FXUS65 KBOU 151539 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 939 AM MDT Wed May 15 2024 .KEY MESSAGES... - Cooler today, with some scattered afternoon/evening showers and thunderstorms. - Warmer and generally drier starting Thursday, with lesser but at least isolated daily afternoon showers/thunderstorm coverage, highest for the mountains. - A return to more active weather early next week with a better chance for afternoon and evening showers and storms. && .UPDATE... Issued at 939 AM MDT Wed May 15 2024 Upper level trough axis and jet streak are producing showers over far northeast Colorado at this time. The lift and showers will shift east of the state by this afternoon. Subsidence behind the trough is expected to limit showers and storms over the northeast plains this afternoon. The trends with the 12Z models has been for fewer showers and storms over much of northeast Colorado, but more so for the northeast plains. Northeast low level flow will enhance lift in and near the foothills today. Plenty of moisture around this morning as well with dew points in the 40s. The upslope flow and moisture combined with modest instability (500 J/kg) still should produce scattered showers and thunderstorms this afternoon and into early evening along the Front Range and Palmer Divide. && .SHORT TERM /Through tonight/... Issued at 140 AM MDT Wed May 15 2024 The region will be under the influence of upper-level troughing today, with cooler temperatures as a result. Highs will be close to 10 degrees below yesterday`s values for the lower elevations, and around 5 degrees cooler in the high country. There will be a few showers around extending along the northern tier of our forecast area this morning, including both the mountains and plains. Instability will be tapered today, but still sufficient for isolated to scattered thunderstorms in the afternoon, most numerous after 2 PM. Any thunderstorms today should remain sub- severe, but may produce brief heavy rain and small hail. Later this evening, a weak front associated with a secondary fast-moving wave carrying a more southward trajectory will advect slightly deeper moisture into the area, and inject more northerly/northeasterly near-surface winds into the plains and urban corridor. This will provide for a slight increase in precipitation coverage for southwestern portions of our forecast area, where shallow upslope flow will favor some local enhancement (mostly the southern foothills/Palmer Divide and adjacent parts of the Denver metro, and also Park County). Under generally stable conditions it would largely come in the form of more stratiform rain and some high elevation snow above ~9,500 ft. Precipitation intensities shouldn`t be too high with this second wave but a few tenths of an inch look likely for a few locations when all is said and done, especially closer to the foothills. Precipitation will taper off for most areas by midnight though a few lingering showers will be possible overnight across southern Park, Jefferson and Douglas Counties. && .LONG TERM /Thursday through Tuesday/... Issued at 140 AM MDT Wed May 15 2024 A departing trough along with convergent flow aloft will lead to strong subsidence across norther Colorado on Thursday. The vast majority of our forecast area will remain dry although a few showers and weak storms could form over the higher terrain south of I-70. Highs will warm to the 70s across the plains in what will be a gorgeous weather day. Zonal flow aloft will develop on Friday and Saturday as an upper level ridge will influence the weather in Colorado. Subsident flow along with downslope winds will lead to warm conditions. Highs will warm well into the 80s across the plains on Friday with a cold front early Saturday morning keeping highs slightly cooler on Saturday. On Sunday, a return of downslope flow will result in highs well above normal. The warm, dry, and breezy conditions Friday through Sunday will create elevated fire weather conditions across portions of the plains. The only area that may near Red Flag Warning criteria is just south of the Cheyenne Ridge as winds will be strongest there. A trough will move over the western US during next work week and will stall out. There will be southwesterly flow aloft with numerous shortwave troughs that move across Colorado throughout the week. These troughs will provide forcing for storms to form most afternoons. Models do not show much moisture return to eastern Colorado during the week but if moisture is better than forecast, there will likely be severe thunderstorms. && .AVIATION /12Z TAFS through 12Z Thursday/... Issued at 528 AM MDT Wed May 15 2024 Seeing some partial scattering at mid-level on satellite imagery on the back end of current deck of BKN mid-level clouds. Forecast leans towards increased scattering later this morning before coverage increases again in the afternoon with cumulus buildups as isolated to scattered thunderstorms develop. This convection should hold off until 20Z at least, possibly closer to 21Z, and convective bases will likely be lower than previous days, around 040 or 050. Light drainage or variable winds early this morning will transition to NNE or NE flow past sunrise, strengthening some through the morning. By Wed evening (00-02Z), thunderstorms should become less numerous with a modest and temporary reduction in cloud cover, along with a counter-clockwise rotation in winds back to light west or southwest winds for the remainder of the evening and overnight period. More stratiform rain showers should then begin to fill in through the evening, most persistent across the foothills and southwest metro, but likely impacting all Denver area terminals at times for most of the evening with a return to lower CIG heights in the 015-025 range. Some potential for minor vis restrictions of 5-6SM in BR dependent on extent of evening precipitation and exact cloud bases. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Meier SHORT TERM...Rodriguez LONG TERM...Danielson AVIATION...Rodriguez