Area Forecast Discussion
Issued by NWS Goodland, KS
Issued by NWS Goodland, KS
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663 FXUS63 KGLD 211859 AFDGLD Area Forecast Discussion National Weather Service Goodland KS 1259 PM MDT Fri Jun 21 2024 .KEY MESSAGES... - Continued very windy today with 20%-30% chances for afternoon and evening thunderstorms, mainly along/north of I-70, some of which could become severe(Yuma/Dundy/Hitchcock counties). - Weekend looks to remain hot with highs in the 90s. Could be a few thunderstorms Sunday afternoon/evening. - Skeptical regarding how quickly the upper level ridge retrogrades west going into next week. Depending on where the ridge is will dictate where storms will move through. - If ridge is delayed, the arrival of the hottest temperatures will be delayed too. - Chances for storms each day next week. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 312 AM MDT Fri Jun 21 2024 Across the region this morning, skies are mainly clear, except for lingering clouds north from exiting precip, and some mid/high clouds over southern portions of the area. As of 100 AM MDT, temperatures are ranging in the 60s and 70s. With a surface low sitting off to the southwest of the CWA, and a front sitting over the extreme northern portion of the area, persistent southerly flow is occurring for most. Areas along/north of Highway 34 are seeing an easterly fetch in the vicinity of the boundary. Weather concerns for the short term period will focus on the hot conditions each day with above normal temperatures, strong southerly flow over the area today/tonight and the threat for showers and some thunderstorms(some may be strong to severe for portions of the area later today/this evening). Currently for today/tonight, the latest RAP40 500mb analysis and mid level water vapor imagery are showing a broad elongated ridge over a good portion of the eastern U.S. and with the western extent of this ridge extending into central/southern Plains, the Tri State area is seeing SW flow aloft. The aforementioned surface low sitting over eastern Colorado will shift eastward through the afternoon/evening hours, combining with a shortwave that works over the western/northern periphery of the upper ridge, and will trigger chances for convection with about 15-20% chance near I-70 and increasing to about 30-40% from Highway 36 and points north especially NW zones. The remnant front to the north will also aid in focusing convection as the entire complex lifts E/NE later this afternoon into the evening hours. SPC is carrying a Marginal Risk for severe storms for Yuma county in Colorado extending east into Dundy and Hitchcock counties in Nebraska. Best instability will be located closest to the front/low combo, but with daytime heating drying out lower levels ahead of expected activity later today, guidance is having inverted-v soundings around the 21z-03z timeframe, giving DCape values 1000-1400j/kg on top of PW values that increase form an inch in the west to around 1.5" in the east. While hail can`t be ruled out with any storms that do develop, wind could be the main threat along with locally heavy rainfall. Bulk of activity will clear the CWA by 06z Saturday per latest CAMs, with some scattered showers thereafter through 12z Saturday. Before seeing an increase in convection, the southerly gradient ahead of the low passage will afford the area gust potential into the 40-50 mph range by midday into the evening hours, tapering off from west to east as the flow shifts to the northwest. Guidance continues to shift the upper ridge westward into the upcoming weekend, allowing for SW flow aloft to become zonal both days. Dry conditions are expected to persist over the area Saturday, with a weak shortwave passage on Sunday. This system will track east over the northern extent of the ridge. 15-20% pops for isolated rw/trw over western areas during the day, tapering off over NW Kansas during the evening hours. Other than these storms chances, hot weather will persist area-wide. For temps, highs today will range in the lower to mid 90s. On Saturday, upper 80s to mid 90s are expected, and for Sunday, a range mainly in the upper 90s with a few spots around the 100F mark. Heat indices for the most part will range at or below forecasted highs, however, on Sunday a few spots east of Highway 25 will start to see readings approach the low 100s. Overnight lows tonight will range mainly in the 60s west of Highway 83. East of there, upper 60s through the mid 70s. Lower to mid 60s Saturday night will give way to mainly mid to upper 60s on Sunday night. Some locales across Graham and Norton counties will only drop to around 70F. && .LONG TERM /MONDAY THROUGH FRIDAY/... Issued at 1252 PM MDT Fri Jun 21 2024 This part of the forecast will be greatly influenced by the upper level ridge. Models have the ridge entrenched over the Southern Plains, centered over TX. With the ridge south of the forecast area, models have zonal flow over us. Within the zonal flow, upper level short wave troughs move overhead almost daily. This may lead to precipitation chances for us. However am skeptical of the ridge being centered over TX before next week starts. Models have been moving the ridge west too fast, which is to be expected when the ridge is a blocking high pressure. For this reason am doubtful the ridge will scoot west as quickly as currently forecast. A delay in the ridge moving west should cause the upper level flow over the forecast area to be more from the southwest than the west. This would influence where storms will track across the forecast area, and affect how hot the forecast area becomes. If the ridge does end up being slower to move west, the hot air under it will stay more to the east. Even though models have upper level short wave troughs moving through the flow over the forecast area, am thinking the storm coverage should be on the low side. This is more reflective of a summertime pattern in which storms are isolated to scattered at best. If the current forecast is on track, there may be a brief respite from heat midweek as a weak cold front moves through. However high temperatures rebound by the end of the workweek. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1117 AM MDT Fri Jun 21 2024 Generally VFR conditions will be observed at both KGLD and KMCK, but strong winds, made worse with storms this afternoon and evening, will make for some tricky conditions. Models are having a difficult time figuring out exactly what is going to happen over the next 8 hours, but we are currently expecting two waves of storms. The first will form around 21Z and move away from the TAF sites by 0Z. The second wave, the wave with higher confidence, will impact KGLD around 1Z and should stay south of KMCK. This second wave is expected to produce strong winds as it progresses eastward. If any of the stronger cells moves overhead of either TAF site, heavy rainfall will reduce visibility significantly. The heavy rain is the only concern for IMC throughout the period. Later in the period, winds will weaken and become northwesterly. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ SHORT TERM...JN LONG TERM...JTL AVIATION...CA