National Weather Service Forecast Discussion |
Thornton Weather Forecast Today's Forecast Story |
965 FXUS65 KBOU 312054 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 254 PM MDT Sun May 31 2026 .KEY MESSAGES... - A chance for strong thunderstorms returns for Monday and Tuesday afternoons, with locally heavy rain possible. - Trending warmer and drier by the end of the week. && .DISCUSSION /Through Sunday/... Issued at 247 PM MDT Sun May 31 2026 It is a sunny afternoon for most of Colorado today, with near- seasonable temperatures ranging from the low 60s over the mountains to the low 80s at low elevations. Satellite imagery shows increasing cloud cover over the high terrain, but most areas should remain dry with only a small chance (15%) for a light shower over the highest mountain peaks and western slopes. The latest SPC convective outlook for tomorrow has placed a slight (2/5 level) risk over the NE Colorado plains extending west into Weld County and DIA, and a marginal (1/5 level) risk over the foothills. East to southeast flow at the low levels will advect dewpoints in the 40s-50s into the east Colorado plains and Denver metro area by the early afternoon hours. High-res ensemble guidance suggests precipitable water (PW) values in the 90th percentile of climatology will be in place Monday afternoon through Tuesday evening, with values over the easternmost counties of our CWA exceeding 1.0 in. PW values at times. A decent amount of shear (40- 50 kt bulk shear), curved hodographs, 0-3km SHR ~100 m^2/s^2, and upslope enhancement will provide an environment that will be conducive to a few strong supercells that will be able to produce large hail and strong winds. From a thermodynamic perspective, CAPE will extend vertically into the hail growth zone, and steep mid- level lapse rates >7.0 C/km will also be present. There is also a small (30% chance) probability that showers and thunderstorms could linger into the late evening or early morning hours of Tuesday, aided by strong low-level moisture advection. The convective environment for Tuesday afternoon will be very similar to Monday`s setup. The primary difference in Tuesday`s setup will be weaker shear, which will limit the potential for a more discrete storm mode. Monday evening`s convection will also pose additional challenges for convective initiation on Tuesday given the increased chance for low stratus or fog in the morning, and a more capped environment to begin with. However, high-res model guidance suggests CAPE values exceeding 1500-2000 J/kg and 700-500mb lapse rates greater than 8.5 C/km, which would support another afternoon of severe hail potential if any CIN is overcome. Looking ahead, daily chances for afternoon showers and weak thunderstorms will persist through next Sunday. Upper level flow remains weak and there is no strong signal for synoptic forcing. Long-range ensembles suggest ridging setting up over the central U.S. Plains by Tuesday afternoon, and a return to zonal flow to start the weekend. Temperatures will generally trend above normal, with 90-degree afternoon highs becoming increasingly likely for Saturday and Sunday over the Denver area. && .AVIATION /18Z TAFS through 18Z Monday/... Issued at 1143 AM MDT Sun May 31 2026 VFR to prevail through the TAF period. West winds with gusts to 25 knots are just northwest of DEN and north of BJC. Through 20-21Z, these gustier winds will be possible. Winds are then expected to turn north and then northeast 22-24Z. Northeast winds will then prevail through the evening and possibly overnight due to a weak cold front moving through. Mid level clouds will increase behind the front after 06Z with a few showers possible northeast of DEN early Monday morning. Winds turn to the southeast Monday morning advecting moisture into the area. This will lead to a chance for thunderstorms after 21Z Monday. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...AA AVIATION...12