Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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783 FXUS65 KBOU 251035 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 435 AM MDT Sat May 25 2024 .KEY MESSAGES... - Seasonal temperatures through this weekend with isolated to scattered mainly afternoon thunderstorms. Storms will be most numerous in the mountains on Saturday afternoon. - Elevated fire weather conditions across parts of the plains Sunday, but green fuels will limit the fire danger. - Warm through the coming week. There will be limited late day thunderstorm activity on Tuesday with better coverage Wednesday through Friday. && .SHORT TERM /Through tonight/... Issued at 419 AM MDT Sat May 25 2024 GOES-16 water vapor imagery currently shows the next approaching trough making its way into Nevada late on this Friday night. It is expected to shift eastward and through the Great Basin Saturday morning increasing west/southwest flow aloft and bringing Pacific moisture into Colorado. Broad scale ascent from this passing disturbance mixed with orographics will bring rain and snow showers to the mountains today with increasing chances likely around noon. Ensemble means show CAPE values increase through the day reaching upwards of 500 J/kg across portions of the mountains and northern plains, which would support a slight chance for some storms to develop. Most of the activity for the mountains looks to be focused around the Park and northern Front Range mountains where chances for rain/snow showers will linger through Sunday morning. A few inches of snow may accumulate at the higher elevations mainly above 10,000 feet. The best chance for thunderstorms looks to be Sedgwick and Phillips Counties as CAPE values increase to the 750 - 1000 J/kg range in the afternoon. Max temperatures for today are likely to be widespread 70s for the plains, 60s for the foothills, and 50s for the mountains. As the trough axis shifts east overnight tonight, a more westerly flow aloft will return. Cross sections indicate a mountain wave signature developing early Sunday morning that could mean some enhanced downslope winds for the lee side of the Front Range Mountains and Cheyenne Ridge. There is a roughly 60% chance that these could gust up to 45 mph. && .LONG TERM /Sunday through Friday/... Issued at 419 AM MDT Sat May 25 2024 Subsidence and drying with a little warm advection aloft will move in behind the shortwave on Sunday. The little bit of wave amplification should fade by afternoon, though it will remain windy across the foothills and plains, with some decrease in the blocked area around Denver. There may be a few showers left in the early part of the morning along the northern border and mountain ridges, but then this should get squashed by the subsidence. Winds aloft will gradually decrease through Monday, and we should have a pretty quiet day with lighter diurnal winds east of the mountains. There may be enough moisture for some weak convection late in the day from the central mountains drifting east in the evening, but this will likely just be capped cumulus with perhaps a few sprinkles. The ridge axis will be over us on Tuesday, leading to light southwest flow Wednesday and then a gradual increase in the flow through the end of the week as a trough develops west and northwest of us. There`s pretty good agreement on holding this back through Thursday, then stronger flow and probably some QG lift and a frontal passage by Friday. The air aloft should remain dry through Thursday, and this pattern probably favors a dry line somewhere over the eastern part of the plains or near the eastern border. There will be sustained southeast low level winds so moisture should increase enough for some thunderstorms, but how much we get over the foothills and adjacent plains is in doubt, as is potential capping of the moisture over the east. Can`t really argue with the NBM PoPs too much, but the severe threat should start as pretty low in the middle of the week without much shear and relatively warm temperatures aloft. There could be better moisture by Thursday but it might be a dry line day. Then the usual post frontal questions for Friday. It`s likely a more active day with some QG forcing, and shear will be greater, but it may also be too cool for much CAPE. The solutions with a weaker front are probably more favorable for stronger storms. && .AVIATION /06Z TAFS through 06Z Sunday/... Issued at 1157 PM MDT Fri May 24 2024 Winds have gone more easterly than anticipated at DEN tonight, we are expecting a more southerly component to return in the next few hours. Early tomorrow afternoon (~19Z), southwest winds are likely with gusts up to 30 mph, then after roughly 21Z some passing showers are likely over all airports. These are expected to be high based showers that could produce some gusty and erratic outflows up to 40 mph. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Bonner LONG TERM...Gimmestad AVIATION...Bonner