Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/29/20

Area Forecast Discussion
National Weather Service Denver/Boulder CO
821 PM MDT Thu May 28 2020 .UPDATE... Issued at 821 PM MDT Thu May 28 2020 Convection had a hard time firing off late this afternoon and evening because of the morning cool surge and warm air aloft. 00Z Denver sounding shows a strong cap in place near 690 mb. A few stronger storms were able to pop through in Park County/crest of the Palmer Divide with the higher terrain effectively minimizing the cap there. Farther north, a couple other showers and storms were still trying to drift off the higher terrain of the Front Range. We don`t think they`ll have much luck maintaining themselves due to the cap, but we`ll keep some low pops in for the rest of the evening based on latest radar/cloud trends. Forecast is on track. && .SHORT TERM...(This evening through Friday) Issued at 223 PM MDT Thu May 28 2020 An upper level ridge over the Desert Southwest today will slowly shift east over the next 24 hours and be centered over the Four Corners Friday afternoon. This will result in warmer temperatures across the area Friday with highs reaching the mid to upper 80s over northeast Colorado. With the ridge building over the region, warming aloft is occurring. This along with cooler surface temperatures behind this morning`s cold front is helping to stabilize the airmass. AMDAR Sounds show two caps to break. Best chance for thunderstorms this afternoon and evening will be over the higher terrain to the southwest of Denver. Across the Urban Corridor and eastern plains, just a slight chance thunderstorms survive moving off the higher terrain. The chance for storms ends by midnight as the airmass stabilizes. Expect more instability on Friday with MLCAPE around 500 J/kg. Scattered showers and storms are expected to form over the mountains and foothills early to mid afternoon and then spread eastward. The strongest storms will be capable of brief heavy rain, small hail, and wind gusts to 50 mph. .LONG TERM...(Friday night through Thursday) Issued at 223 PM MDT Thu May 28 2020 For Friday night into Saturday, there is a strong upper ridge in place over the four-corners region with a closed low sitting just off the CA coastline. This system will push inland and north into the Pacific northwest through Saturday with the upper jet staying north of the region. A 700 mb low will help to pull in increased moisture over the region with drier air in place to the west. PW values will increase to above 0.90 inches across most of the eastern plains Saturday with some models putting above an inch possible by late Saturday. Diurnal storms from Friday will come to an end during the evening hours with increasing CAA overnight with slightly cooler temperatures for Saturday. Convection will be stunted for most of the day given the slightly cooler and more stable conditions on the plains, especially with most of the lift further to the north. The lift of the day will most likely come from orographics with the mountains seeing some convection by the afternoon hours. Flow from the west will help to carry the storms off the mountains and over the plains during the evening hours where steering flow remains rather weak. This combined with the higher PW values mentioned earlier could lead to periods of heavy rain and minor flooding under the stronger storms. At this time models indicate elevated QPF values for the higher terrain areas especially Park county and eastward. Overall, look for a cooler and cloudier day with a chance of moderate to heavy rain into the evening hours. The northern Rockies will see another shortwave push on Sunday with a similar picture for Colorado with modest moisture creeping in under the upper level ridge. As the shortwave progresses eastward the drier air to the west will start to push into western Colorado by Sunday afternoon. There is enough CAPE and moisture around for diurnal storms by the afternoon hours east of the divide but with shear being on the weaker side storms will not be as strong with the main threats being gusty winds and lightning with heavy rain possible. For late Sunday and into the following week there is a large trough off the Pacific coast with a ridge stretching across the central and southern Rockies. Colorado will be on the edge of the drier air to the west ahead of the trough. Monday will see a chance of diurnal convection over the higher terrain with conditions at lower elevations staying mostly dry. Overall, the long term is looking warmer with increasing chances of convection by mid-week with moisture from the Gulf as well as the trough as it moves onshore over CA. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 821 PM MDT Thu May 28 2020 Isolated showers and storms are mainly south of the Denver area TAF sites, but still just a slight chance of a passing shower/storm til about 06Z. VFR conditions will prevail, but ILS landing conditions possible this evening due to lowering of the ceiling to around 5000-6000 feet. On Friday, scattered thunderstorms are expected to form over the higher terrain after 20Z and then spread eastward through the afternoon. Brief rain, gusty winds to 30 knots, and lightning expected from any storms, but coverage looks limited by warm air aloft. Main threat for the airports would be between 22Z and 03Z. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Barjenbruch SHORT TERM...Meier LONG TERM...Bowen AVIATION...Barjenbruch
Area Forecast Discussion
National Weather Service Louisville KY
836 PM EDT Thu May 28 2020 .Forecast Update... Issued at 835 PM EDT Thu May 28 2020 Widely scattered storms continue to move NNE this evening, mainly west of I-65. The upper low is positioned over eastern Arkansas and is forecast to pivot ENE over the Tennessee Valley tonight. The storms have exhibited strong updrafts, briefly, up to around 20 kft before struggling considerably. Lapse rates aloft remain very poor, so expect thunderstorms to diminish even more after sunset. Main change this evening was to boost PoPs back into the scattered range in southern KY through Midnight to account for a weakening area of showers and storms moving up from Middle TN. With the mid level wave rotating up to the KY/TN border by 12z, a rogue shower cannot be ruled out through late tonight, so did also extend slight chance PoPs by a couple hours. && .Short Term...(This evening through Friday) Issued at 253 PM EDT Thu May 28 2020 Visible satellite and regional radars are showing convection ongoing at this hour across portions of central Kentucky. Most activity at the time of writing this has struggled to maintain itself, largely due to warmer air in the low levels (~800mb via AMDAR soundings) and marginal mid-level lapse rates. As low level lapse rates continue to steepen this afternoon, we may see some of that warm air in the low levels erode and storms take on more strength given some marginal deep layer shear in place (25-30kts 0-6km bulk shear). Main threats with the isolated stronger storms will be gusty winds, perhaps getting up to marginally severe levels, and small hail. Coverage of storms should also increase by late afternoon, and then gradually taper down after sunset. A cold front will approach and move through the region tomorrow. A broken line of showers and storms are expected to develop ahead of the front, with the best coverage of precipitation during the afternoon hours. Deep layer shear will be rather weak so organized convection is not expected, but can`t rule out some gusty winds and small hail in the strongest storms. Localized flooding may become an issue if we have some training of storms. .Long Term...(Friday night through Thursday) Issued at 255 PM EDT Thu May 28 2020 Cold front pushes east during the start of the period across the Lake Cumberland region before moving along the the east coast of the CONUS by 12z Saturday. Canadian high pressure build in behind the front setting up a splendid weekend across the Ohio Valley. Cooler temperatures are expected with afternoon highs only in the 70s and overnight lows down in the 50s, lower dew points, and most importantly drier conditions for all of us needing to get yard work done. Sunday and Monday the surface high builds in over the Ohio Valley and continuing our nice weather to start the week. By Tuesday & Wednesday a broad upper level ridge builds over the central CONUS providing an active NW flow aloft with a storm track across the region, mostly to our north. Starting to see the chance of showers/storms move in by late Wednesday into Thursday as a front drops in across the Ohio Valley. Temperatures will return to the upper 80s to possibly near 90 for Wednesday and Thursday. && .Aviation...(00Z TAF Issuance) Issued at 747 PM EDT Thu May 28 2020 Isolated to to widely scattered storms continue across the region, with most likely impacts still possible at BWG/HNB for another few hours. Stayed a little more optimistic at SDF/LEX. Otherwise, expect VFR outside of any shower/storm with a steady S wind. After variable cloudiness and a steady SSW wind overnight, lower clouds and showers and storms to pick up again tomorrow ahead of an approaching cold front. Best chance for prevailing MVFR ceilings will be at HNB and BWG, with slightly lesser chances at SDF/LEX. Did mention a Sct020 layer due to low confidence in the MVFR eastward progression. Otherwise, any TAF site could be impacted by some showers/storms tomorrow, so tried to convey best timing with Prob30s for now. Cold front sweeps through late afternoon into the evening from W to E, veering winds to W and then NW and slowly drying out/VFR returning. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...EBW Short Term...DM Long Term...BTN Aviation...BJS