Area Forecast Discussion
Issued by NWS North Platte, NE
Issued by NWS North Platte, NE
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053 FXUS63 KLBF 172057 AFDLBF Area Forecast Discussion National Weather Service North Platte NE 357 PM CDT Mon Jun 17 2024 .KEY MESSAGES... - Thunderstorms this afternoon and into the overnight will lead to an increasing threat for severe weather, with very large hail, damaging wind, and isolated tornadoes. - The redevelopment of heavy rainfall this evening and overnight across north central Nebraska could lead to an increased threat of flooding where heavy rains fell last night. - ECMWF EFI values point to an unusually cool day relative to the M- Climate on Wednesday. There is nearly a 30% chance that high temperatures remain at or below 65F in North Platte. && .SHORT TERM /THROUGH TUESDAY/... Issued at 357 PM CDT Mon Jun 17 2024 Latest analysis from 20z shows that the warm front has been slow to lift north, this is due to abundant stratus remaining across the Sandhills and north central Nebraska. To the south, temperatures have warmed into the lower 90s across far southwest Nebraska, but still hang in the upper 70s and lower 80s along I80 in Lincoln County. Looking regionally, very little developed cumulus is noted, though there are signs of increased agitation across southeastern Colorado and High County of the central Rockies. Overnight there was an abundance of heavy precipitation across north central Nebraska with widespread reports of 3" or greater from eastern Cherry to Keya Paha County. The flood advisories that were out for much of the day have been allowed to expire. A special thanks to the NSSL group who gave us an early look at their 19z sounding. As expected with the delayed burnoff of the stratus, the capping inversion is quite strong near LBF. Uncertainty is the word of the day with the CAMs very bearish on the severe potential for later this afternoon and evening, though the environment would suggest otherwise. Looking aloft, southwesterly flow prevails, which is currently ushering increasing PVA as noted by the developing CU over SE Colorado. Cyclogenesis has ensued over the High Plains and subjectively now sits over far NE Colorado or south of KOGA, near Grant. Southeasterly flow at the surface has ushered TDs into the lower 70s as far north at KBBW and KLBF with mid 60s as far west as the Highway 61 corridor. The warm front is subjectively north of KLXN, but not as far as KBBW. Steep lapse rates along the front are contributing to nearly 4k MLCAPE where moisture is pooling just south of the boundary. HRRR soundings reveal an uncapped solution, but we know that is not the case, especially north where substantial CIN remains. That being said, we believe with the increasing upper level support, isolated to scattered severe storms will form eventually, which will be in the vicinity of the lifting warm front and sfc low. Once CI occurs, the environment will be very supportive of rotating updrafts, which given the current situation, the Sandhills looks prime, with the latest soundings indicating near pure streamwise vorticity in the lowest few KMs of the hodograph. This is due to a strengthening low level jet as evening progresses. With southwesterly flow in the mid levels, hodographs will be quite long which would point to all hazards with any supercell that develops, though south of the boundary, large hail/wind will be the primary concerns. As sunset occurs, increasing CIN would lead to elevated storms with the concern being hail, wind, and heavy rainfall. The storms should weaken as nightfall arrives, but if storms maintain into north central Nebraska and/or eastern Cherry County, will need to monitor for flooding as heavy rainfall occurred last night. Lastly, mechanical mixing will allow for gusts of 40-45 mph overnight south of the lifting front. A cold front slides across the area tonight and tomorrow, but remains a focus for storms Tuesday afternoon. At this point, most of the activity will be east of the forecast area, but locations along and east of a Frontier to Custer to Eastern Holt County could see additional storms. Otherwise temperatures will be cooler in a post frontal regime tomorrow afternoon with highs largely in the 70s. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Issued at 357 PM CDT Mon Jun 17 2024 A cold front is projected to be east of the area by the start of the forecast period, though additional showers and storms are possible as convection forms on a mid-level area of convergence. The area of concern would be from Hayes County northeast through Custer, Wheeler and eastern Holt Counties, though the heaviest QPF is expected to be just outside of the forecast area. A post frontal regime will usher in unseasonably cool temperatures mid-week. The latest guidance suggest widespread 60s to lower 70s across the entirety of the forecast area. Climatologically, highs on Wednesday will run some 10-20 degrees below normal. The threat for light showers continue, though continues to have highest chances to the east. Deeper low level moisture returns Wednesday night with easterly upslope flow projected. WAA spreading from the west may aid in the continuation of precipitation /thunderstorms/ well into Thursday morning. The return of southerly flow late week and early next weekend will keep the atmosphere unsettled with daily chances for QPF, though late Saturday into Sunday, coverage looks less promising. Severe weather, at least isolated coverage, would be possible as the the pattern switches from southwesterly to northwesterly aloft. Building heights from a central Rockies dome of high pressure and decreasing cloud coverage would allow a return to above normal temperatures early next week. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1232 PM CDT Mon Jun 17 2024 KLBF will shortly be on the warm side of a front lying east to west across the region, with clouds scattering out and CIGs trending towards VFR, continuing through much of the period. Expect KVTN will remain on the cool side of the front, keeping IFR CIGs over the terminal through this evening. Around 21Z, expect CIGs at KVTN will trend to MVFR or VFR. A highly conditional threat for thunderstorms is in place for later this afternoon through the evening. Exact timing/location of convective initiation remains uncertain, thus will leave out mention at both KLBF and KVTN. Future amendments and inclusion may be needed with subsequent TAF issuances. Winds have begun to amplify this afternoon and will become quite robust this evening with gusts 30 to 40kt, especially after 00Z. At the same time LLWS will increase considerably out of the south-southwest at 55 to 65kt and will continue through the 06 to 09Z timeframe. As the front transitions to a cold front, it will sweep from northwest to southeast, resulting in winds to veer towards the northwest around sunrise on Tuesday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Jacobs LONG TERM...Jacobs AVIATION...Viken