242 FXUS65 KBOU 011822 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1222 PM MDT Thu Jun 1 2023 .UPDATE... Issued at 1030 AM MDT Thu Jun 1 2023 There has been a good deal of cloud cover this morning and a few showers have been observed as well. This is keeping temperatures down a bit below model consensus. As a result, the instability will be on the lower side today despite good moisture in place. This will likely keep storms below severe thresholds although a storm or two could produce severe winds. This will also keep storms in the burn areas slightly weaker than expected which could limit the flash flood threat. The HREF models are largely underwhelmed by today's conditions and they don't have many strong updrafts or max wind speeds forecast. This seems reasonable and the forecast grids for PoPs and QPF were largely left the same. && .SHORT TERM...(Today and tonight) Issued at 413 AM MDT Thu Jun 1 2023 Models have a good handle on the big picture, but seem to be lacking with the strength of the lift rotating from the OK/TX panhandles across eastern Colorado today. There are hints of this area of lift drifting northward, but it doesn't produce much precipitation in the models and it looks like there should be more given that we already have some isolated showers out ahead of the lift. We bumped up PoPs a bit especially this morning, and lowered temperatures a couple of degrees. Cell motions still look decent and with a rather cloudy airmass keeping temperatures down, convection mostly won't be that strong. CAPEs should be mostly 500-1000 J/kg, maybe up to 1500 J/kg out on the plains if there's sun, but there might not be. So the only burn area flood concern is if there's training along a foothills convergence line. This is possible, especially at the start of diurnal convection in the early afternoon if that's how today plays out. Severe threat looks low as there's not much shear and less CAPE than yesterday. .LONG TERM...(Friday through Wednesday) Issued at 413 AM MDT Thu Jun 1 2023 Early in the period, there will be a negatively tilted, messy trough over the western states. This trough will weaken as a large ridge builds to our northeast, centered over south-central Canada and the Dakotas, then models have a closed low moving in over the Desert Southwest early next week. Models still develop that MCS to our south on Friday night, at the leading edge of a shortwave coming up out of the Desert Southwest. While there are notable differences in the development and progression of the system and its features, there is a good chance that does wrap back around the wave to keep widespread showers going across northeast Colorado all Saturday, and moderate to heavy rainfall is possible. There looks to be great moisture throughout the period streaming constantly from the Gulf of Mexico. Friday might be the driest day and still has near normal precipitable water; otherwise, values look to be often 150 to 200 of normal across all northeast Colorado. Surface dewpoints will persistently be in the 40s and 50s across the plains and 30s and 40s across the high country, and 6 to 9 g/kg low to mid level specific humidity. All the moisture and associated cloudiness should also limit instability, however. Lapse rates look modest at best most places most of the time. Expect showers to develop each afternoon, with some thunder, though the primary hazards will generally be hydrologic rather than severe due to a general lack of shear. There should be enough most days to support multi-cell storms but not many supercells. A few storms may produce marginally severe hazards, particularly farther east and northeast over the plains where there will tend to be better heat and instability. Forecast soundings exhibit long, skinny CAPE profiles and warm rain processes will likely dominate, and there is certainty a marginal risk of flooding, but for now the flow looks strong enough to keep storms moving. It doesn't seem likely that widespread flooding will be a significant threat without training. There will at least a limited threat of burn area flash flooding each day, and often an elevated threat to the Cameron Peak burn area due to its location relative to the Continental Divide. Due to the unusual flow aloft, shower and thunderstorm motions will tend to be southerly, and sometimes with an easterly component - which is downright rare for us. The cooling trend will continue through Saturday, and high temperatures will be down to the 60s across the plains, and mostly 40s and 50s across the high country. Then there should b a gradual warming trend for the rest of the period, back to near normal temperatures by Tuesday or Wednesday. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 1215 AM MDT Thu Jun 1 2023 Thunderstorms are forming over the foothills this early afternoon and will move towards the terminals in the next couple of hours. These storms will bring gusty winds possibly as high as 35 knots. This could impact arrival rates as ceilings could drop to around 6,000 ft or lower. The best chance for storms is around 20Z at BJC and APA and at 21Z at DEN. There may be a second round of showers and storms in the early evening around 00-02Z but these would be weaker. Overnight tonight, winds will become very weak. There is a slight chance that fog develops at DEN but it is a low enough chance to not include it in the TAF. Tomorrow, showers and storms will likely form in the afternoon again. Strong wind gusts would be the primary hazard. && .HYDROLOGY... Issued at 413 AM MDT Thu Jun 1 2023 Storms are expected to be weaker today and they will still be moving. There's still enough moisture for some of the storms to produce a period of heavy rain. There is a chance of upslope winds focusing storms in the same area for a few hours this afternoon on the east slopes of the Front Range. For this reason, we'll maintain an elevated risk of burn area flooding for the Cameron Peak burn area, with a limited risk elsewhere. There looks to be great moisture throughout the rest of the period, but a general lack of instability and shear. Forecast soundings exhibit long, skinny CAPE profiles and warm rain processes will likely dominate, and there is certainty a marginal risk of flooding, but for now the flow looks strong enough to keep storms moving. It doesn't seem likely that widespread flooding will be a significant threat without training. There will at least a limited threat of burn area flash flooding each day, and often an elevated threat to the Cameron Peak burn area. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Danielson SHORT TERM...Gimmestad LONG TERM...EJD AVIATION...Danielson HYDROLOGY...EJD/Gimmestad