Area Forecast Discussion
Issued by NWS Goodland, KS
Issued by NWS Goodland, KS
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950 FXUS63 KGLD 201855 AFDGLD Area Forecast Discussion National Weather Service Goodland KS 1255 PM MDT Fri Sep 20 2024 .KEY MESSAGES... - Briefly critical fire weather conditions are possible today in eastern Colorado. - Showers and thunderstorms will develop over majority of the Tri-State area this weekend. Severe weather does not look likely, but there is a slight concern for flooding. - Low temperatures in the mid to upper 30s are forecast for eastern Colorado by Monday morning. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 323 AM MDT Fri Sep 20 2024 This morning, a high pressure system over Texas is extending a ridge over the Great Plains and Midwest. This will create mostly clear skies for majority of the day, allowing temperatures to warm into the low 90s. Winds will be south- southwesterly throughout the day. In the far western CWA, around the Joes to Flagler, CO area, the winds are expected to mix out surface moisture and drop RH values to around 15% for a couple hours. The winds will have picked up at this time and gusts around 25-30 kts are expected, briefly leading to localized critical fire weather conditions. For more information, see the fire weather section below. Starting around 19-21Z this afternoon, a shortwave is forecast to fire off some storms south of the CWA. Majority of this precipitation will occur outside of the Goodland CWA, however, Gove, Wichita, and Greeley counties could (~15% chance) see some light showers late this afternoon. There is a low (~15%) chance that lingering showers or sprinkles could last through the night in the far eastern CWA. The best chance for showers over there would be after 6Z Saturday. Looking at isentropics, there is a well define moisture boundary at 315K around the 19-23Z timeframe near the Tri-State border. This feature could set off an isolated storm or two this afternoon, but confidence is only around 10-15% this will occur. Overnight tonight, the pattern gets a bit more interesting as the 850mb LLJ will kick up to around 30 kts, moving Gulf moisture into the area. A shortwave ridge will move back over the area, clearing out the skies by morning. A low pressure system near the Four Corners will be moving northeast to stir up the atmosphere throughout the day Saturday. Lows look to drop into the low 50s in the northwestern CWA where the winds will be weaker and skies will be clear, but in the southeast, mid 60s are forecast where the cloud cover will linger most of the night. Saturday morning, the aforementioned low will be crossing over the Rockies, but will extend a shortwave trough over the southern CWA to cause some warm-front type showers. This shortwave will push out the ridge from overnight, allowing clouds to form across a large portion of the CWA. The shortwave will also cause a broad cold front to move in from the northwest, shifting winds as it move in. The new northerly winds and additional cloud cover look to bisect the area, causing a fairly strong thermal gradient to setup. In the northwestern CWA, temperatures will be capped in the lower to mid 70s, but southeast of the front, mid 80s are forecast. Around 21Z Saturday, 500mb vorticity increases and begins moving northward, indicating a start to the widespread forcing. This forcing will cause showers and storms to form across majority of the area with the precipitation lasting until Sunday morning. Severe weather does not look likely (<5% chance) due to a lack of instability, but deep shear and strong forcing could cause a storm to over preform. Saturday night, the low will move over the CWA causing widespread precipitation. For more information about the rain, see the hydrologic discussion below. Overnight lows will drop into the 40s. Sunday morning and into the mid-day, the low will be moving out of the area to the east-northeast. The following pressure rises will cause the rain to cease in the west around 15Z with lingering showers in the east likely until around 18-21Z. Northerly winds and clouds will keep temperatures capped to the 50s for the area. The skies are expected to clear in the evening, allowing efficient overnight cooling. && .LONG TERM /MONDAY THROUGH FRIDAY/... Issued at 1255 PM MDT Fri Sep 20 2024 The latest extended guidance from the GFS/ECMWF do start off the period on Monday consistent showing a 500mb shortwave trough sliding southeast through the central Rockies. The models then do break off as to the evolution of the system as it slides to our S/SW. The GFS carries the system through the Kansas area as an open wave Monday night into Tuesday morning, followed by amplified ridging coming eastward through the Rockies. This will provide the CWA with mainly dry conditions for most of Tuesday onward. The current ECMWF however allows the shortwave to move slower into Tuesday, forming a cutoff low over northern Texas then lifting northeast towards the southern Kansas border late in the week. The latest NBM guidance does take into account both models initially as the trough approaches the CO/KS border Monday night with a 15-30% chance for precip. Highest pops closest to the Colorado tapering off into the central CWA. It does look like the consensus is for the cutoff system to occur then slide south of the CWA Tue-Tue night, keeping a 15-20% chance over S/SW zones into Tuesday night. This does follow previous runs yesterday at this time, so will stick with this consistency for now. The bulk of the QPF will stay south of the area closest to the formed cutoff low. Late Thursday into Friday as the system lifts northeast, the northern periphery of the system could bring enough moisture into eastern zones that could trigger a few rw/trw(15-20%). For temps, upper 60s to lower 70s expected for highs Monday and Tuesday due to expected clouds/rain, will give way to mid 70s Wednesday, trending warmer to the upper 70s and lower 80s for most for next Thursday and Friday as the aforementioned upper ridge works east off the Rockies and southerly surface flow persists area-wide these days. Lows in the 40s Monday night will trend warmer as well with upper 40s west into the mid 50s east for the end of next week. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1104 AM MDT Fri Sep 20 2024 For KGLD & KMCK... VFR conditions are forecast through the period. There is a less than 10% chance of storms this afternoon and evening with the forecast keeping storms well southeast of the airports. The low level jet is forecast to develop tonight across the area around 03Z and persist until around 12-15Z when a front passes through the area. Winds will then shift from out of the south, to out of the north and strengthen to 20-25 kts with gusts to 35 kts. A few sprinkles may occur at the very end of the period. && .FIRE WEATHER... Issued at 323 AM MDT Fri Sep 20 2024 This afternoon, in western Kit Carson and Yuma counties, southwesterly winds are expected to pick up. Sustained winds around 15-20 kts with gusts up to 25-30 kts are expected. These winds will work to mix in drier air, lowering RH values into the mid teens across eastern Colorado. In the area mentioned above, local RH values around 14% are expected for an hour or two. Widespread, long duration critical fire weather conditions are not expected. If the winds over perform and extremely dry air mixes down to the surface, we could see some locations meet Red Flag criteria. Confidence in the current forecast is moderate, around 60-70%, meaning there is about a 30% chance three hours of critical fire weather conditions could occur in the far western CWA. && .HYDROLOGY... Issued at 323 AM MDT Fri Sep 20 2024 An efficient 850mb LLJ is expected to set up around 21Z Friday-0Z Saturday and continue until Sunday morning/mid-day. This LLJ will provide a moist conveyor belt from the Gulf of Mexico into the High Plains. As mentioned above, an organized low pressure system will move into the region Saturday, creating a moderately strong forcing mechanism to start precipitation. Precipitation looks to start in the eastern CWA early Saturday morning, intensifying Saturday afternoon, and begin weakening Sunday morning/mid-day before moving out of the area by Sunday evening. Between 21Z Saturday and 18Z Sunday, nearly the entire Tri-State area will see at least a few tenths of rain with the potential (~25%) of seeing 1.25+ inches in that timeframe. If the higher amounts do occur, especially in the eastern CWA, there will be increased flooding concerns. Concerns for flash flooding are low (<10%) with the potential for areal or river flooding being slightly higher at around 20%. Throughout the entire event, locations along and southeast of a line from Wallace, KS to Norton, KS can expect to see 0.9-1.6 inches of rain, with pockets of 3+ inches being possible. Locations west and north of that line will receive less precipitation, likely around 0.4-1 inch of rain, with some pockets up to 1.75 inches. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ SHORT TERM...CA LONG TERM...JN AVIATION...KAK FIRE WEATHER...CA HYDROLOGY...CA