Area Forecast Discussion
Issued by NWS Goodland, KS
Issued by NWS Goodland, KS
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312 FXUS63 KGLD 291905 AFDGLD Area Forecast Discussion National Weather Service Goodland KS 105 PM MDT Wed May 29 2024 .KEY MESSAGES... - Chance for severe weather and flooding throughout the week. Confidence in specific hazards change each day, but a very active pattern is expected. - Potential for critical fire weather conditions Sunday and into early next week. High temperatures could also climb into the 90`s. && .SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 358 AM MDT Wed May 29 2024 Light south/southeasterly winds this morning along with ample moisture left from the storms yesterday will make a favorable environment for patchy to locally dense fog to form across most of the CWA this morning. This fog is expected to lift by the mid- morning. SPC has continues the Slight risk for severe thunderstorms on Wednesday and Thursday. Through Saturday, there is concern of flooding across the CWA. The Hydrology section below will go into more detail about this risk. Today, the upper-level ridge axis looks to be moving over the CWA and will exit to the east throughout the evening and overnight hours. A 250 mb trough will be moving in from the northwestern CONUS and push the ridge on to the east. A 500 mb shortwave expected to form around 21-0Z this afternoon, move east over the CWA, and continue impacting the CWA until about 12Z Thursday. Around mid-day today. a high pressure system over the Gulf of Mexico will extend a ridge up into the easter Great Plains, leading to a persistent LLJ that will move additional moisture into the mid-CONUS. These features will fuel the storms during the short-term. The Slight risk for severe weather is focused over eastern Colorado and adjacent counties to the east. The main threats with these storms will be 1- 1.5 inch hail and wind gusts near 60 MPH. A brief tornado cannot be ruled out early in the event, mainly in the southwestern CWA. As the evening progresses into the night, the severe potential will drop significantly, but showers and storms are expected to continue into the eastern portions of the CWA into Thursday morning. CAMs are generally in agreement with the timing and storm mode with convection later today. Storms look to form around the Palmer Divide around 21Z and by 0Z the storms will be at our western borders. Initially, storms will develop as individual cells along the north/south oriented dry line. By 0Z, the cells will have grow more numerous into a long line of storms, potentially reaching all the way into Canada. Soon after, the line will break up and clusters of cells will move across the region. CAMs are suggesting we will have two clusters moving through the CWA. One will move to the east- northeast from Yuma county while the other will move east-southeast and remain generally south of I-70. Confidence in these exact locations is only about 50% as the CAMs have been struggling with the past few events. Thursday, the upper-level trough works farther to the east, as does the ridge. The LLJ looks to remain consistent until Thursday night, mainly due to the 850 mb ridge either strengthening or splitting off and becoming it`s own high pressure system near the Great Lakes region. Thursday night, an 850 mb lee low is expected to move to the south of the CWA around 6-12Z Friday. While this will disrupt the LLJ moving moisture directly into the for the remainder of the period, the low will cause wrap around moisture to move into the area. This moist conveyor belt will keep PWATS in the 1-1.3+ inch range through the period. Thursday is looking to have the highest PWATS, ranging from 1.15-1.4 inches, EBWD shear around 25-35 kts, and the 0C line being around 14,000 feet. These parameters suggest storms that form will produce heavy rain and potentially severe weather. Instability in the environment could easily turn heavy rain storms into large hail storms. MUCAPE from the RAP and NAM is around 3,000 J/kg. The most likely hazards Thursday will be heavy rain leading to flooding, hail, and strong winds, in that order. Temperatures will be in the mid 70s to low 80s today while tomorrow will be a bit cooler, with majority of the CWA remaining in the 70s. Low temperatures will remain fairly warm Wednesday night through Saturday night due to generally southerly winds and cloud cover, and will remain in the 50s to low 60s Wednesday night with Thursday night seeing upper 40s and mid 50s. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... Issued at 100 PM MDT Wed May 29 2024 Shortwave trough comes through the zonal flow on Sunday with convective initiation in the afternoon along a lee trough or dry line draped over western portions of the forecast area. Deep layer shear is forecast to be weaker than it has been, around 20-25 kts, suggesting more of a pulse storm mode. Nonetheless, should see a low end risk for severe storms as they move east Sunday evening. For areas west of the dry line Sunday afternoon, near critical to critical fire weather conditions will be possible due to low humidity, though wind appears to be lacking at this point. For early next week, a ridge over the southern plains is forecast to gradually build northward. If the ridge axis is over the Rockies as forecast, then the central plains will be transitioning to a northwest flow aloft. The door will still be open for disturbances coming over the ridge axis, especially eastern areas, though as you get into Colorado the ridge might start to suppress convection. Another impact of the building ridge will be lighter flow aloft, with deep layer shear generally in the 20-30 kt range each day. This would tend to somewhat limit storm organization and severe risk. However, instability does not look like it will be lacking with moderate instability forecast just about every afternoon in some part of the forecast area. So, daily thunderstorms chances appear to continue but with some decrease in storm intensity and severe risk. Temperatures will be above normal with proximity to the upper ridge. Highs will be in the 80s and 90s and lows in the 50s and 60s. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1115 AM MDT Wed May 29 2024 KGLD...VFR conditions are expected from taf issuance through 01z then again after about 16z. Southerly winds gusting to 35kts are expected from taf issuance through 01z. From 01z-07z, the terminal could be impacted from showers and thunderstorms with gusty winds, perhaps some hail and locally heavy rainfall that could produce sub VFR visibilities. From 08z-16z, southerly winds gusting to around 20kts will subside while slowly veering to the southwest. Stratus and fog are anticipated, producing sub VFR conditions. After 17z, VFR conditions return with winds from the north around 10kts. KMCK...VFR conditions are expected from taf issuance through at least 09z. Southeast winds gusting to 30kts are expected from taf issuance through 02z, decreasing to around 10kts through 08z. There is a chance for showers and thunderstorms to impact the terminal from 03z-08z. After 09z, stratus and fog will develop, creating sub VFR cigs/vis with winds from the southeast under 10kts. && .HYDROLOGY... Issued at 358 AM MDT Wed May 29 2024 Highly efficient moisture return has already began and will continue into the end of the workweek with aid from the 850 mb LLJ. This moist conveyor belt will cause PWATS to increase above 1 inch starting Wednesday and potentially remain that way until Sunday. The highest values will be in the eastern CWA, but the majority of the Tri-State area will have a good chance (70%+) at seeing PWATS above 1 inch. Throughout this active pattern, a high melting layer is also expected, generally 11,000-15,000 feet agl. Tuesday evening saw 2-3+ inches of rain in Cheyenne county Colorado, and a few other locations in eastern Colorado. This rain did not cause any flooding, but it will make it easier for flooding to occur over the next few days. Locations that received heavy rainfall are not fully primed for flooding (SAC-SMA soil saturation is around 30- 45% in these area), but will become susceptible to flooding sooner than normal. Based on what the CAMs are showing, the southern cluster of storms would be a slower mover and larger in size, meaning based on its projected path (south of I-70 across the CWA) and potential for heavy rainfall, it will need to be watched closely for flash flooding. Thursday is currently the best day for training storms to create heavy rainfall that could lead to rate-driven flash flooding and duration-driven areal flooding. Friday and Saturday are also at risk for flooding potential due to a combination of efficient rain producing storms and potentially multiple days of heavy rain saturating the soil. Current confidence in localized flooding occurring through Saturday is around 25-45%. Confidence in widespread flooding is about 20%. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ SHORT TERM...CA LONG TERM...024 AVIATION...99 HYDROLOGY...CA