Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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611 FXUS65 KBOU 061101 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 501 AM MDT Sat Jul 6 2024 .KEY MESSAGES... - Near average temperatures on Saturday before a dip on Sunday. - Cooler temperatures and scattered storms are possible early Sunday morning until late afternoon across the region. - Lower thunderstorm chances and warmer next week. && .SHORT TERM /Through tonight/... Issued at 445 AM MDT Sat Jul 6 2024 Water vapor imagery reveals dry west-northwesterly flow over Colorado with a shortwave trough over the North Dakota/South Dakota border and another near Glacier National Park. Our forecast area will be under mostly zonal and dry flow today before the trough near Glacier NP arrives late tonight. Plenty of sunshine and downslope winds will result in high temperatures returning to the 90s across the urban corridor. Models had been forecasting a dryline to set up on the eastern edge of our CWA but the latest runs push this dryline farther east. That should keep the primary area of severe weather well to the east of our CWA. However, in Logan, Phillips, and Sedgwick Counties, there will be enough lingering moisture and elevated instability this evening that a strong to severe storm or two could form. The primary threats would be hail and strong wind gusts from these storms. A few light showers and perhaps a thunderstorm or two may form over the higher terrain and the northern plains south of the Cheyenne Ridge this afternoon. Showers and storms may increase in coverage this evening as QG ascent ahead of the trough arrives. A cold front/outflow boundary will move through our forecast area after midnight tonight. This will decrease temperatures and may initiate a few showers and storms. Gusty winds up to 35 mph can be expected with this front. && .LONG TERM /Sunday through Friday/... Issued at 445 AM MDT Sat Jul 6 2024 The shortwave trough now exiting Alberta will move across northeast Colorado early Sunday. Most of the QG forcing should be in the morning, but there`s a little cooling aloft which will likely combine with weak low level upslope to keep showers and thunderstorms going into the afternoon. The focus may initially be over the northeast plains, then shift to upslope driven showers by afternoon. There may be up to 1000 J/kg of CAPE briefly in the middle of the day, but with the cloud cover and wind structure the severe threat looks low. There could be a bit of a focus for convective development around the Cameron Peak burn area, though moisture availability is limited with precipitable water likely 0.5 to 0.75 inch and cells should be moving at least 10 mph. So there is a threat of heavy rain, but the flood threat should be limited. Previous forecast of scattered to likely PoPs during the day, decreasing from north to south overnight still looks good along with highs mostly in the 70s. On Monday, drier air is drifting in from the northwest along with a little subsidence/warming aloft. There`s probably still enough low level moisture for some diurnal showers/storms but they should be weak, and maybe confined to the east slopes of the Front Range and adjacent plains. Cell motions may be weak, but with low CAPES and less available moisture, we don`t think there`s much of a flood threat. Tuesday looks similar, with temperatures warming but still some low level moisture around. The upper level ridge over the western U.S. will slowly nudge eastward later this week into the weekend. This will bring a warming trend. Low level winds will be southeasterly, keeping some foothills convergence and low level moisture, so there will likely still be a little thunderstorm activity mainly over and near the foothills. The more aggressive scenarios with the eastward spread of the ridge could result in very limited thunderstorm activity by Friday along with near record temperatures (101 Friday and 100 Saturday and Sunday in Denver). Northwest flow over the ridge may delay this a little longer or keep us slightly cooler, but we`ll be on the edge of pretty hot air centered over the Great Basin. && .AVIATION /06Z TAFS through 06Z Sunday/... Issued at 1155 PM MDT Fri Jul 5 2024 There will be drainage winds and clear skies through the rest of the night. Winds will shift to the northwest during the morning hours tomorrow and could briefly gust up to 20 knots. By the afternoon, wind direction will be hard to forecast but a northerly component is expected. An outflow boundary from storms to the east may move through the terminals in the evening with gusts up to 25 knots out of the east. On Saturday night, there will be a shortwave trough that moves through the area. It may initially bring light showers with minimal impacts before midnight. After around 10Z, there could be thunderstorms that develop which could lower ceilings to around 3 kft and reduce visibility. Sunday morning will likely have stratus that impacts the terminals. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Danielson LONG TERM...Gimmestad AVIATION...Danielson