Area Forecast Discussion
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
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003 FXUS65 KPUB 071000 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 400 AM MDT Fri Jun 7 2024 .KEY MESSAGES... - Scattered showers and thunderstorms today with hot temperatures across the area. - Severe thunderstorm risk increases for Saturday across the southeast plains with large hail, damaging winds and even an isolated tornado possible. - Strong to marginal severe thunderstorm risk pulls westward across the southeast mountains and adjacent plains on Sunday with hail and heavy rainfall the primary risks. - One more active day for thunderstorms across the mountains and adjacent plains Monday then another drying and warming trend returns through late week. && .SHORT TERM /THROUGH SATURDAY/... Issued at 348 AM MDT Fri Jun 7 2024 The upper ridge overhead will flatten somewhat today, leaving flow aloft largely west-northwesterly. Surface flow will remain westerly across the higher terrain, while southerly flow out east turns more zonal throughout the day and into the afternoon hours. Our main forecast challenge for today will be the extent of showers and thunderstorms that form across the area as some embedded energy in the flow translates overhead. Current short-term model guidance shows scattered convection popping up across our area this afternoon, initially over the higher terrain before quickly moving east later in the day. Main areas of initiation will be the Central Mountains, Palmer Divide, and Raton Mesa. Impact concerns will be limited by lacking moisture at the surface with plenty of low-level mixing. Models only show a few hundred J/kg of CAPE over and near the I-25 corridor, and while these values do increase out east, greatly varied in magnitude depending on which model you look at, any storms that manage to intensify in this better air will move into Kansas quickly. Additionally, forecast soundings show low humidity at the surface, so storms today will likely be high-based and fairly short-lived, with the main impact being gusty outflow winds. If storms do manage to get some residence time in the more unstable air closer to our eastern border, we could also see some hail production. Our other main forecast concern for today will be above average temperatures across the area. Forecasted highs for today for the plains reach the high-90s with a few locations in the triple digits. Meanwhile, even the high valleys will see high-80s. Some model guidance shows temperatures a few degrees higher, especially around the I-25 corridor. Will have to monitor for heat-related impacts should these conditions persist over the next few days. Later tonight, a weak front will move its way in across the plains, though overnight temperatures should stay relatively warm. However, the influx of moisture and post-frontal upslope could set us up for a more active weekend. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 348 AM MDT Fri Jun 7 2024 Still looks like a favorable set up for severe thunderstorms on Saturday across the I-25 corridor and southeast plains. Active west to northwesterly flow aloft continues into Saturday with another shortwave moving through the flow in the afternoon. Cold front will drop through the southeast plains early Saturday morning with low level flow becoming easterly by afternoon, advecting 50s to lower 60 dew points westward towards the mountains. Timing looks a little slower with the moisture advection which would impact CAPE values along the I-25 corridor. Latest HREF means show mid to upper 40 dew points along the I-25 corridor around 21z as convection rolls off the mountains. However, some CAMs models bring lower to mid 50s into the I-25 corridor with low 60s across the far eastern plains by the same time. This could mean CAPE values along the I-25 corridor ranging from near 1000 J/kg on the drier side of the spectrum to over 2000 J/kg on the higher side. CAPE increases with eastward extent across the plains with 2000-2500 J/kg near the eastern border. Easterly flow beneath west northwest flow aloft will provide ample deep layer shear (40 kts) for supercell development and 00z HREF updraft helicity swaths maximize along and north of highway 50. Overall, still looks like a few severe thunderstorms are likely across the southeast plains Saturday afternoon and evening. Best instability will be east of the I-25 corridor and this is also where soundings show some enhanced curvature in the low levels where easterly surface winds maximize. Can`t rule out an isolated tornado or two. Thunderstorms will congeal into an MCS as it moves southeastward into KS overnight, however westward propagating outflow will spread stratus westward across the southeast plains along with the potential for some isolated thunderstorms into the overnight hours if any brief enhanced outflow can make use of the terrain to break the cap. Overall pops should be tailing down towards morning. Plenty of low level moisture will be in place across the region on Sunday for a repeat thunderstorm day, this time focused across across the southeast mountains where best moisture and heating will be coincide to trigger afternoon thunderstorms. CAPE values up to 1500 J/kg look probable along and west of the I-25 corridor. Deep layer shears look a little weaker as the ridge aloft expands slightly northward. Still looks like sufficient CAPE and marginal shear for a few severe thunderstorms over and near the mountains. Question will be how far east the severe risk will extend as model soundings show a stout cap across the eastern plains. Surface heating will be the primary driver of how much CAPE will be present east of the mountains. Have leaned towards the NAM12 for these details and decreased pops out east slightly where cap is likely to maintain. One or two thunderstorm clusters will spread southeastward off the mountains into the evening and overnight hours though think the main MCS will develop farther south along the frontal boundary across TX/OK. Will maintain some scattered to likely pops into the evening hours across the plains for now given uncertainties. Will also have to consider burn scar flash flooding potential this day as this may be the first round of heavier rain of the season for those areas. Our older burn scars have become more resilient and storm motions and potential for hail may help mitigate this risk some. But it will still require attention and monitoring. Urban areas may be at risk as well depending on clearing and available instability as storms push off the mountains. Otherwise, a couple days of below normal temperatures expected, with coolest readings on Sunday, even across our western mountains as moisture works westward into our high valleys and afternoon thunderstorms mitigate peak heating. Better forcing will move in for Monday in NW flow aloft for another round of afternoon and evening thunderstorms. Dew points begin to drop off and focus for afternoon thunderstorms will remain across the mountains/adjacent plains. Deep layer shears weaken a tad but could be sufficient for a strong storm or two into the evening hours. Otherwise, plains dry out as dew points fall off and temperatures remain below normal with highs in the 70s across our lower elevations. Upper ridge builds in for Tuesday through late week which will bring another drying and warming trend. Sufficient moisture will be present for daily afternoon and evening thunderstorms over and near the mountains but storms will become high based gusty wind makers, and less efficient at producing rainfall. Eventually a Pacific system moves through the Desert Southwest bringing return southerly flow, greater moisture and perhaps an uptick in thunderstorms by Friday into next weekend. There is quite a bit of variability in timing of this system so will maintain the isolated to scattered pops for now from model blends. -KT && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 348 AM MDT Fri Jun 7 2024 VFR conditions are expected at KALS, KCOS, and KPUB through 24 hours. Breezy southwest winds will set in across the area this afternoon, with increasing chances for storms at KCOS and KPUB. The best chances of storms impacting a TAF site will be at KCOS, starting around 20Z and lasting into the evening. Passing storms are expected to produce gusty outflow winds today, which could result in short-term shifts in wind direction at KCOS and KPUB after 20Z. Conditions will be closely monitored for changes. && .HYDROLOGY... Issued at 348 PM MDT Fri Jun 7 2024 Rapid snow melt will continue across the mountains leading to elevated flows along the Arkansas River from Leadville to Canon City through the weekend as well as on smaller creeks and streams in and near the mountains. Flows are expected to remain within banks along the Arkansas River but fast flows can still be dangerous. Slightly cooler temperatures may decrease the snow melt this weekend into early next week, however the potential for heavy rainfall will increase Saturday through Monday for the southeast mountains and 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. Confidence in this scenario unfolding is low for the major river stems for now. Continue to monitor weather forecasts closely. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...GARBEROGLIO LONG TERM...KT AVIATION...GARBEROGLIO HYDROLOGY...MOZLEY