Area Forecast Discussion
Issued by NWS Goodland, KS
Issued by NWS Goodland, KS
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064 FXUS63 KGLD 181941 AFDGLD Area Forecast Discussion National Weather Service Goodland KS 141 PM MDT Sat May 18 2024 .KEY MESSAGES... - Active period begins this evening with showers and storms overnight; marginally severe hail is possible along with torrential rainfall. - The relative better potential for severe weather is Sunday and Monday. Very large hail and damaging winds are the primary hazards Sunday. - Cooler with frost concerns mid week. - Active weather may return next weekend (Memorial Day Weekend) && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 226 AM MDT Sat May 18 2024 Weak cold front and associated wind shift is moving into northern portions of the CWA currently. Some spotty virga or sprinkles may be possible post frontal for an hour or two. The cold front then looks to stall south of the area during the day time as a surface high then develops across eastern Nebraska. The surface high will then create a more easterly/upsloping component to the winds along for some moisture return. A disturbance then moves off of the Rockies during the mid to late afternoon time fram allowing for some showers and storms to move into the area from the Front Range and move to the northeast. The above mentioned stationary boundary then begins to creep ever so slowly back to the north overnight Saturday and early Sunday morning. The lift from the Rockies wave looks to interact with this boundary and form additional storms roughly along a Cheyenne Wells to Norton line. Last night the NAM was the most aggressive with showing a couple thousand joules over elevated MUCAPE; more guidance is starting to suggest this now as well which has increased my concern for some instances of severe hail around quarter size starting around 06Z through sunrise Sunday. Looking at forecasted 0-6 wind shear it appears that the strongest shear looks to be around initiation time near 06Z and then waning through sunrise. PWATS increase to around 1.25 inches overnight as well creating the potential for torrential rainfall. Still continue to think that any flooding potential will be low as these storms will moving fairly quickly but will need to keep an eye on back building and training storms as some guidance does suggest that rainfall may last through about 8am Sunday. Sunday, then continues to be the day of interest for the short term. Severe threat is looking a bit more promising than vs 24 hours ago. Last night there were some concerns about fog/stratus lingering across eastern portions of the area which would limit overall instability. While this does continue to remain a possibility, especially if morning convection does linger; most guidance has the temperatures rebounding. I did nudge down high temperatures across the northeast a few degrees if this scenario does pan out; but was not as aggressive as I would have been last night in this situation. As anticipated last night, the severe threat has shifted more westward as guidance has gotten on board with the western placement of the dryline which the NAM was suggesting. Discrete storms look to initiate along the dryline (roughly Highway 385) during the afternoon hours. I have fairly high confidence (70%) that these storms will remain discrete as a cap will be in place. Any storm that does manage to develop during this time will have the potential for very large hail, perhaps up to tennis ball size with MUCAPE around 2500-3000 j/kg, steep lapse rates and 0-6 shear around 40-45 knots. Once storms finally do initiate they are anticipated to grow upscale into more of a cluster posing more of a damaging wind and heavy threat; this currently favors locales east of Kansas Highway 25. Dependent on how much rainfall occurs Saturday night into Sunday morning, there may be more of an increased threat for flooding. Locales east of Highway 83 may be the relative more at risk as some portions of Gove County received 1-3 inches of rain earlier in the week. Storms look to move completely out of the area between 10p-1am CT across the east. Some additional storms may try to develop behind this cluster but currently think these should remain sub severe. Some near critical to locally critical fire weather concerns look to be present behind the dryline with RH values in the low to mid teens and gusts up to 25 mph especially from around the 22-00Z time when mixing should be strongest; mainly favoring Cheyenne county Colorado. Not planning and fire weather headlines this forecast package due to the anticipated limited spatial area and more marginal conditions. Upcoming shifts will need to keep an eye on this potential however. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 140 PM MDT Sat May 18 2024 The latest from the GFS/ECMWF continues to show potential for rainfall/storms to impact mainly the northern portion of the CWA from late Monday on into the end of next week. With a blocking upper ridge over the eastern portion of the country through the midweek timeframe, a strong trough will swing east out of the north central Rockies late Monday, making a slow trek eastward due to the blocking effects of the eastern ridge. This system will eventually lift northeast along the western periphery of the block. This will be followed by a second shortwave taking a similar track although a bit more easterly as guidance breaks down the ridge for the latter portion of the week. Another amplified ridge build into the Plains region for Thursday, shifting east to end the week. This will be ahead of an elongated trough stretching through the northern/central Rockies. At the surface, low pressure sets up across southern Kansas late Monday into Tuesday, lifting northeast with an associated front. The position/track of this low will allow for a moist, easterly upslope flow from the surface to 850mb and eventually going northerly by Tuesday as the low lifts east. A similar setup will occur late Tuesday into Wednesday for the second system, although a bit further south based on both the GFS/ECMWF. High pressure traverses the CWA Thursday/Thursday night, with southerly flow setting up increased warmth/moisture ahead of the end-of-week upper system. A surface low does work off the Front Range in tandem with the upper system. As a result, the main wx concerns are going to focus on the potential for showers and storms. QPF/track through midweek puts the best chances for rain north of the Interstate, especially along/north of Highway 36. For Fri/Sat, the coverage is ahead of the low/front that moves off the Front Range, but for areas closest to the surface low. The chances for storms will be focus mainly for the Mon-Tue timeframe with the passage of the aforementioned shortwaves. The end of week system does differ with timing/placement of storms/QPF, but these could be problematic. Decent instability along with increasing PW values from west to east on Mon-Tue, will afford the potential for strong to severe storms, especially Monday. SPC currently has a Marginal risk for most locales east of the Colorado border. The surface low passages to the south will bring in PW values of an inch plus, especially east of Highway 83 which is closest to the surface trough/front that extends into central Kansas. So, besides a hail/wind threat, heavy rainfall/flooding potential will also be high. Monday looks to be the main focus, with WPC having a Marginal risk area out for locales north of highway 36 Mon night-Tue. Please refer to the Hydro section below for more details. The passage of the second system Tuesday night into Wednesday will bring about some cooler/colder air into western locales. Areas in Colorado could see some frost potential, but will be highly dependent on the extent of clearing from the exiting system. Right now, western portions of Kit Carson/Cheyenne counties are most prone. For temps, with a cold front settling through the region during the first portion of next week, looking for a downtrend in daytime highs before rebounding for the latter portion of the week. On Monday, mid 70s north through the mid 80s south are expected. A wide range for Tuesday with mainly 60s north of the Interstate and 70s south will give way to lower and mid 70s area-wide for Wednesday. 80s Thursday drops to the mid 70s through the lower 80s to end off the week. Lows during this time will mainly range from the mid 40s west through the lower and mid 50s east. Tuesday night will be the coldest, with lower to mid 40s east of the Colorado border, with upper 30s to around 40F for northeast Colorado. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 451 AM MDT Sat May 18 2024 VFR conditions are currently ongoing at each of the terminals and are forecasted to continue for the majority of the 12Z TAF period. Some Alto Cumulus clouds are in the vicinity of each terminal as weak front has passed through the area, but are forecasted to dissipate throughout the morning. A period of breezy winds gusting around 25 knots looks to occur at each terminal around 14Z and ending before 18Z. Winds will then slowly become more easterly throughout the day as a surface high develops in Nebraska. This will increase moisture and also increase the potential for showers and storms for each terminal throughout the night. Confidence is also increasing in a period of stratus behind the exiting showers and storms towards the end of the period so have introduced IFR ceilings at KGLD and MVFR conditions as rainfall should be ongoing at KMCK. Also wouldn`t be surprised if IFR or lower conditions occur at KMCK just after this TAF period, will pass along to the next shift to look for this potential. && .HYDROLOGY... Issued at 226 AM MDT Sat May 18 2024 Some potential does exist for torrential rainfall and isolated flash flooding starting Saturday night/Sunday morning into early portions of the new work week. The majority of the area, especially western and southern portions have seen a lack of rainfall in recent weeks and worsening drought conditions. Overall main concern for any hydro issues lies to the east of Highway 83 in Kansas where portions of Gove county for example received 1-3 inches of rainfall earlier in the week. PWATS will rapidly increase tonight around 1.25 inches and remain above 1 inch for the duration of the weekend. Overall widespread flooding potential is relatively low as overall systems should be fairly quick moving with fast Corfidi Vectors. The overall main concern for any hydro related issues lies in multiple rounds of heavy rainfall and any potential training locales. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ SHORT TERM...Trigg LONG TERM...JN AVIATION...BV HYDROLOGY...Trigg