Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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102 FXUS65 KBOU 010529 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1129 PM MDT Fri May 31 2024 .KEY MESSAGES... - Chance of more storms through tonight, a few could be severe with the greatest threat over the Palmer Divide into East Central Colorado. - Severe storm threat over eastern plains on Saturday. - Low 90s possible for highs over the plains on Sunday. && .UPDATE... Issued at 846 PM MDT Fri May 31 2024 Current radar shows the cluster of strong to severe thunderstorms pushing south and east across southern Lincoln County. Large hail and wind will be the primary threats. Made minor updates to the precipitation probabilities otherwise no changes needed to the current forecast. && .SHORT TERM /Through Saturday/... Issued at 233 PM MDT Fri May 31 2024 Surface observations show a convergence line extending from the Palmer Divide east-northeast across Washington County. Expect storms to form along the boundary later this afternoon. With ML CAPE of 1000-1500 J/kg and 0-6km Bulk Shear around 40 knots, supercell thunderstorms with large hail and strong winds will be possible. For the Front Range Urban Corridor, soundings show the airmass should stay capped through most of the afternoon. Better chance for storms will be this evening, if temperatures can warm into the lower to mid 70s, which will help break the cap. Also, if a strong outflow boundary from convection off to the east is thrown westward, it could kickoff convection as well. Another possible source of lift for storms will be the right entrance of a speed max moving across northern Colorado and southern Wyoming. If storms develop they could become severe as well with ML CAPE climbing to 1000-1500 J/kg. Models generally agree storms form along the boundary to the southeast of Denver. For the rest of the area, not much model agreement if and where storms will form late this afternoon through tonight, so forecast confidence is low. For Saturday, another round of afternoon/evening thunderstorms is expected. Mostly clear skies will prevail Saturday morning, allowing temperatures to warm into the lower 80s by early afternoon. A wave embedded in the westerly flow aloft should kick off weak showers and thunderstorms over the high country by early afternoon. This activity will progress eastward through the day. A dry line/surface trough sets up over eastern Colorado, roughly from Fort Morgan to Limon. Strong to severe storms are expected along and east of the dry line with ML CAPE up to 2000 J/kg and good shear. Large hail and damaging winds will be possible with severe thunderstorms. && .LONG TERM /Saturday night through Friday/... Issued at 301 PM MDT Fri May 31 2024 Models have zonal flow aloft over the CWA Saturday night with flat upper ridging Sunday. There will be weak northwesterly flow aloft Sunday night into Monday night. There is weak upward synoptic scale energy late Saturday night through Sunday night and again Monday night. The low level winds look to be normal diurnal patterns through the period. Moisture-wise, is is pretty dry, with he best precipitable water values and dew point readings over the far eastern border areas. It seems the models are not quite as dry as they were previously, especially for Monday. CAPE-wise, there is still some over the far eastern plains Sunday evening early. On Monday, the best CAPE is over the far eastern border late in the day. Will leave the limited pops in for the eastern plains Saturday evening, and again for the northern and eastern border areas late day Sunday. Monday looks pretty dry with just isolated storms for the high mountains for now. Temperatures look to heat up pretty good for Sunday and Monday, with Sunday`s highs 3-6 C warmer than Saturday`s highs. Monday highs are close to Sunday`s. Denver could see it`s first 90 F degree reading on Sunday. For that later days, Tuesday through Friday, upper ridging seems to dominate the weather for the CWA. Pops will be sparse, with the best chances in the high country. Temperatures look to stay above seasonal normals. && .AVIATION /06Z TAFS through 06Z Sunday/... Issued at 1123 PM MDT Fri May 31 2024 Believe potential for any low clouds tonight is rather low considering favored southwest drainage flow through early morning and lack of observed precipitation Friday in the Denver metro, so have removed any mention of this from the TAF. VFR conditions should prevail for all terminals through the TAF period. Winds will become light and variable after ~15Z Sat, with generally east/southeast flow favored later in the day. However, wind direction is the most uncertain variable for Saturday and will likely be driven by thunderstorm outflows in the afternoon. Primary window for any convective activity in the vicinity of the Denver metro is 20-02Z. Dry low levels should lead to relatively high bases at/above 080-090, so leaning towards mostly isolated high-based showers/virga for I-15 corridor, with stronger storms more favored for areas to the east of KDEN. Expect return to south/southwest drainage flow Saturday evening. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Mensch SHORT TERM...Meier LONG TERM....RJK AVIATION...Rodriguez