729 FXUS65 KPUB 262136 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 336 PM MDT Fri Aug 26 2022 .SHORT TERM...(This evening through Saturday) Issued at 336 PM MDT Fri Aug 26 2022 ...Widely scattered to numerous thunderstorms expected across southeast Colorado this afternoon and evening with some flash flooding possible for burn scar and urbanized areas... Key messages: 1) Scattered to numerous PM thunderstorms will develop over the higher terrain later today, and then move over into the I-25 corridor during the late afternoon and eastern plains by later in the evening. 2) Flash flooding will be possible with some of the stronger storms if they get hung up on the mountains, especially for the burn scar areas. A slight risk of flash flooding will also be possible for urbanized areas. 3) There is a slight risk of a stronger or possibly severe thunderstorm over the southeastern plains by late afternoon and into the evening. Main threat will be strong and gusty outflow winds to 50 mph or greater, and hail up to 1 inch in diameter. Detailed discussion: Currently... A minor shortwave at the 700-500 mb level is currently transitioning over the region and this has provided thunderstorm development to be more widespread over all areas of the CWA. A developing lee side surface low over the northern I-25 corridor will continue to move eastward and enhance convection development over the eastern plains by later this evening. Deep mixing has been evident across the southeastern plains this afternoon, with locations such as Springfield reporting gusty winds out of the southerly direction above 30 mph this afternoon. This is evident that the trough is beginning to enhance the low level jet ahead of it and bringing up higher dewpoints into the 60s over the central and eastern plains. SPC mesoanalysis shows the best mid level convergence currently over the I-25 corridor and there are currently developing showers and thunderstorms that will continue to move northeastward. The high MLCAPE over the southern San Luis Valley and over the Raton Mesa. This is proving to be the best location at the moment for convective development, and possibly a stronger storm or two over this area for the next 4 to 5 hours. Higher dewpoints are remaining in place over the central plains for the most part, east of La Junta, whereas locations further west are beginning to mix out now. Given the current trends, the best area for a stronger storm could be over the Raton Mesa and Eastern Las Animas and Baca counties later this evening. Some stronger or possibly even an isolated severe storm may still occur along the mid level convergence axis as it moves out over into the central and eastern plains later this evening. If a stronger or severe storm is to occur, the main threat with a well pronounced inverted-v profile showing up in the soundings will be strong and gusty outflow winds to 50 mph or greater, and perhaps some hail up to an inch in diameter. The other concern that will continue to be the possibility of flash flooding over the burn scar areas, if a stronger storm gets hung up on the mountains. The good news thus far is that it appears that storms are moving relatively quickly and hopefully this will not allow for storms to become stalled out. Tonight... Any remaining showers and thunderstorms this evening will likely continue past midnight for areas of the eastern plains. The latest CAMs reflect most of the stronger convection to be out of the CWA by roughly 10 PM, with perhaps just some residual showers and isolated thunderstorms continuing over the eastern plains up until around midnight or shortly after. Otherwise there will just be some mid level clouds remaining in place while the lower levels continue to dry out. Behind the trough, temperatures will cool into the 50s for most areas of the plains and perhaps only some low 60s over the far southeastern plains, and into the 30s and 40s for the higher terrain. Tomorrow... As the shortwave continues to progress eastward, there will be high pressure building in with subsidence over the region. This will allow for only some of the recycled moisture in the mid levels to cause thunderstorms to develop due to orographic lifting over the mountains and be mostly isolated in nature. The greatest CAPE of around 900 J/kg will be located over the San Juan Mountains, where there will be highest probability of thunderstorms to form given these values. A few storms could also develop over the northern Continental Divide and eastern mountains, which could then move over into the adjacent mountain valleys and plains with a southeasterly storm motion driven by a northwesterly flow in the mid to upper levels. Due to there being a sufficient amount of capping over the plains, if storms do make it over into the I-25 corridor, they will likely weaken and dissipate rather quickly. Otherwise, mostly clear skies and slightly warmer and drier conditions will exist elsewhere across the CWA. Temperatures will be slightly warmer and expected to reach into the upper 80s and mid 90s across the plains, and generally in the upper 70s to low 80s for the upper Arkansas River Valley and San Luis Valley, and 50s to 60s for high country. -Stewe .LONG TERM...(Saturday night through Friday) Issued at 336 PM MDT Fri Aug 26 2022 Saturday night-Sunday night...Latest models are fairly consistent with shortwave ridging in place across the region on Saturday giving way to increasing westerly flow through the day Sunday, as a stronger system remains progged to translate across the Northern Rockies and into the Northern High Plains through Sunday night. Scattered showers and isolated storms over and near the higher terrain Saturday evening gives way to clearing skies through the late evening. While models continue to indicate weak uvv associated with the passing Northern Rockies wave on Sunday, they also indicate drier air within the westerly flow aloft moving into the region, with dew points dropping into the 30s and 40s areawide. With that said, can't rule out isolated to scattered afternoon and evening showers over and near the higher terrain on Sunday, though these storms will be higher based, supporting gusty outflow winds and less measurable rainfall. As for temperatures, with the westerly flow aloft, at or above normal high temperatures look to continue, with highs in the 80s to mid 90s across the plains, and with mainly 60s and 70s across the higher terrain. With the drier air moving into the region, overnight lows could cool into the mid 30s to mid 40s across the the higher terrain, with lows mainly in the 50s across the plains. Monday-Tuesday...Models continue to indicate upper level ridging building across the Great Basin and into the Rockies into the middle of next week, though continue to indicate enough moisture in place to support isolated to scattered diurnal convection over and near the higher terrain through the period, with temperatures remaining near to slightly above seasonal norms. Wednesday-Friday...While there remain some differences, models do indicate the upper ridge flattening across the Rockies through the end of the work week, with short wave energy translating across the Northern Tier and into the Northern High Plains. These systems will bring in slightly cooler air, especially for the plains, with continued chances for daily showers and storms over and near the higher terrain. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 336 PM MDT Fri Aug 26 2022 VFR conditions are expected to prevail for all TAF sites (KALS, KCOS, and KPUB) throughout the forecast period. SHRA and TSRA are expected to be in and around the vicinity of all stations later in the afternoon and evening today. If SHRA/TSRA does develop, it could temporarily reduce CIGs and VIS to MVFR/IFR criteria for KALS. It could also result in periodic windshifts and increased wind speeds at for all terminals. Winds will switch later in the day with a passing trough from a S-SE'ly direction to a NW-N'ly direction for all stations. The shift looks to occur around 00Z for KALS and KCOS, and 02Z for KPUB. Keep in mind that developing convection in and around the vicinity of all stations could help to expedite the timing of the windshift to occur. SHRA/TSRA should end by later this evening at all stations with only mid level broken coverage expected to remain in place throughout the remainder of the forecast period. Diurnal winds will become established by tomorrow morning and there will be a very low chance of SHRA/TSRA to be in or near of the vicinity of KALS or KCOS towards the end of the forecast period by tomorrow afternoon/evening. -Stewey && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...STEWARD LONG TERM...MW AVIATION...STEWARD