Area Forecast Discussion
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
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010 FXUS65 KPUB 081721 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 1121 AM MDT Sat Jun 8 2024 .KEY MESSAGES... - Strong to severe thunderstorm activity is expected across most of the eastern plains today, with all hazard types on the table. - Thunderstorms, a few strong, possible Sunday and Monday across the mountains and adjacent plains with risks transitioning towards hail and heavy rainfall capable of producing localized flash flooding. && .SHORT TERM /THROUGH TONIGHT/... Issued at 343 AM MDT Sat Jun 8 2024 Today will be a more active weather day as energy translates through the mid-level flow. Along with moist post-frontal air, the large- scale ascent will allow for the formation of convective weather in our forecast area this afternoon. Post-frontal upslope will persist across the eastern plains starting this morning, pairing with that synoptic ascent to get us primed for precipitation formation. Looking at model variables in support of severe weather, there are a few differences but an overall consistent signal. CAPE will increase over the plains throughout the day, with the model spread typically between 500-1000 J/kg. Higher values will be possible near the border, with around 1200 J/kg in some of the high-res models. Looking at shear parameters, the model spreads are typically between 25-35 knots this afternoon. With many of the convective allowing models leaning towards the higher end of the CAPE estimates and modest wind shear at the low levels (0-6km), strong to severe storms and multiple severe hazards will be on the table this afternoon into evening. There are a few main areas of concern, the first being the northern half of our forecast area, east of the mountains. Better mid-level shear will be available just north of our area, and high-res model guidance has been consistently developing a line of thunderstorms off of the higher terrain that intensifies as it moves east. The southern extend of this line will reach down, depending on which model you look it, into Kiowa County and potentially into the Highway-50 corridor. For these areas, strong winds, heavy rain, some hail, and isolated tornadoes will all be possible, especially along the southern edge of that line. Meanwhile, largely south of Highway 50, more isolated convection will be possible, with a mix of severe hazards possible, though the magnitude of the severe impacts will decrease further south. Looking over the mountains, while convection will generally be much more scattered in nature today, cannot rule out flash flooding concerns over a burn scar or other vulnerable area, especially if several cells train over the same areas. Additionally, more discrete cells left behind the passing line of convection or influenced by outflow interactions could also result in lingering severe hazards late this evening and into tonight. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 343 AM MDT Sat Jun 8 2024 Day 2 post frontal upslope flow will be in place for Sunday with the morning starting out with areas of stratus banked up across the lower eastern slopes of the southeast mountains, southeast plains and southern slopes of the Palmer Divide. Flow aloft weakens some on Sunday which will decrease deep layer shears to around 20-25 kts by afternoon. However sustained dew points in the 50s pushed westward into the eastern slopes of the SE mts/Fremont county will provide the fuel for CAPEs up to 1500 J/kg based off HREF means. Weak energy propagating through the ridge aloft, along with surface based heating, will be sufficient to trigger scattered to numerous showers and thunderstorms across the mountains which will drift off into the adjacent I-25 corridor in the afternoon and plains through the evening. Some question exists as to amount of instability across the plains as soundings look pretty capped, especially the farther east you go. However with southerly upslope into the Palmer Divide, forcing may be enough for thunderstorms to maintain as they move eastward. Heavy rainfall and hail up to 1.25 inches look possible with any storms in and near the mountains and the Palmer and Raton ridges. Farther east, suspect risk will transition to smaller hail heavy rainfall as shear looks too weak for strong updraft maintenance. Will need to watch the southeast mountains, Pikes Peak region, and burn scars for potential flash flooding, especially as creeks and streams are still running near bank full in some locations due to snow melt. Any localized heavy rainfall could exacerbate conditions, though think this will stay localized and therefore may not require any flash flood watches. Forcing for nocturnal thunderstorm maintenance appears to stay to the south of the area overnight in better proximity to the frontal boundary, with most thunderstorms ending by midnight. Pacific energy lifting northward through the ridge across NM may spread some showers and thunderstorms into far southern plains overnight but CAPE doesn`t look all that substantial, so some lightning and rainfall will be the main risks. One more day for scattered to numerous showers and thunderstorms can be expected for Monday as the remnant Pacific energy cuts through the upper ridge and a northern stream system brushes by to the north. Overall, 0-6 km shears will be even weaker, so thunderstorms will be limited to locally heavy rainfall, small hail and gusty wind risks as they develop over the mountains early in the day and diminish as they move eastward into a more stable airmass across the plains. Monday looks to be the coolest day across the region. Upper ridging returns for mid week with thunderstorm chances decreasing and transitioning more towards higher based thunderstorms with a gusty wind potential. Temperatures will approach 100 again on the plains especially towards Thursday. Another Pacific system will approach CO on Friday. This will bring another uptick in showers and thunderstorms to the region and take the edge of max temperatures. Saturday returns to drier and warmer conditions as models are in better agreement with the upper system exiting to the east. -KT && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1121 AM MDT Sat Jun 8 2024 Outside of thunderstorm chances, VFR conditions are expected at all three TAF sites, KCOS, KPUB, and KALS, for the next 12 to 18 hours. Afternoon thunderstorm activity is expected over and near both KCOS and KPUB from 20Z until around 02Z today, with main concerns being gusty outflow winds in excess of 40kt, hail, and lightning. After 10Z tonight, MVFR and IFV ceilings are expected to develop at KCOS and KPUB, with conditions improving after 16Z tomorrow morning. && .HYDROLOGY... Issued at 343 AM MDT Sat Jun 8 2024 Rapid snow melt will continue across the mountains leading to elevated flows along the Arkansas River from Leadville to Canon City through Monday as well as on smaller creeks and streams in and near the mountains. Flows are expected to remain within banks for most locations along the Arkansas River but fast flows can still be dangerous. Slightly cooler temperatures may decrease the snow melt Sunday and Monday, however the potential for heavy rainfall will increase both days for the southeast mountains and adjacent plains. This could cause localized flash flooding and push flows above the projected bank full forecast for localized areas depending on where the rain falls. Latest projections place the heaviest rainfall across Teller, western El Paso and Fremont counties on Sunday though the flash flood risk still looks localized. Continue to monitor weather forecasts closely. && .PUB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...GARBEROGLIO LONG TERM...KT AVIATION...EHR HYDROLOGY...KT