Area Forecast Discussion
Issued by NWS North Platte, NE
Issued by NWS North Platte, NE
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853 FXUS63 KLBF 060909 AFDLBF Area Forecast Discussion National Weather Service North Platte NE 409 AM CDT Thu Jun 6 2024 .KEY MESSAGES... - Dry conditions persist again today, with temperatures slightly cooler than yesterday with the area behind a cool front. - Scattered thunderstorms are expected to form along a frontal boundary Friday afternoon, with a threat for large hail and damaging winds. Though the threat appears low, a tornado cannot be ruled out as well. - Additional thunderstorm chances will persist into the weekend and early next week, though the threat for any severe weather is uncertain. - Increasing temperatures are expected for the middle of next week and beyond, with widespread 90s and increased heat concerns possible. && .SHORT TERM /THROUGH FRIDAY NIGHT/... Issued at 407 AM CDT Thu Jun 6 2024 For today and tonight, the area will remain under the influence of an upper ridge, centered over the southwestern CONUS. Height rises and increasing subsidence aloft should keep skies clear again today across the area. Today has the markings aloft of another very warm day (H5 heights ~90th percentile climo), though the area will remain post-frontal this afternoon with a backdoor cool front draped across northeast CO into northern KS and southeast NE. Weak cold advection behind this boundary will keep highs in the low to middle 80s this afternoon, as much as ~5 degrees cooler than yesterday. By this evening, a surface high will begin to migrate eastward across western Nebraska, dropping into eastern KS/western MO by late tonight. As this surface ridging exits the area, southerly flow will quickly redevelop across the area in its wake. Increasing warm advection overnight will keep lows more mild tonight, in the middle to upper 50s across southwest Nebraska. The southerly flow continues into tomorrow, with increasing lee cyclogenesis noted across the high terrain to the west into tomorrow afternoon. During the morning hours tomorrow, a warm front is expected to lift through the area, with a threat for scattered showers and thunderstorms primarily north of HWY 2. These showers and thunderstorms are expected to exit the area through late tomorrow morning and pose little to no severe threat. By tomorrow afternoon, a surface low will slide into northern Nebraska and will need to be monitored for redevelopment of convection. Though subtle differences remain in guidance solutions with respect to precise placement, the majority show the same basic evolution. This evolution drapes a warm front across the northern Sandhills by mid-afternoon, with a triple point somewhere in the vicinity of HWY 27/HWY 61 across the western Sandhills. A surface trough then extends southward from the surface low through southern Panhandle and into northeast Colorado. In the warm sector across much of southwest and central Nebraska, continued southerly flow will advect richer boundary layer moisture into the area through the afternoon, with dewpoints expected to climb into the upper 50s to low 60s. Aloft, a subtle shortwave trough will progress around the northern periphery of the upper ridge axis, crossing southwest NE/northeast CO during the late afternoon. This will both augment the mid-level wind fields (lengthening hodographs) and steepen lapse rates aloft. This will both increase deep layer shear (to ~40-45kts) and instability, with more bullish solutions suggesting MLCAPE values >2500 J/kg. As convergence increases along the aforementioned surface boundaries (especially near/ahead of the surface triple point), at least scattered convective initiation is anticipated by mid/late afternoon. Winds fields support an initial supercellular storm mode, albeit somewhat high based given large T/Td spreads and resultant high LCLs. This could lead to some propensity for storms to become more outflow dominant, though confidence in this is low initially. The exception to this would be in vicinity of the surface warm front, where moisture pooling could lead to more favorable T/Td spreads and lower LCLs locally. Additionally, backed east- southeast surface flow could lead to a narrow corridor of increased tornado potential, and the positioning of this boundary will need to be monitored closely. The main hazards for much of the area looks to be large hail initially, with ample instability below 0C, straight and long hodographs in the mid- levels, and somewhat favorable mid-level storm relative winds to limit updraft seeding. The longevity of the hail threat will be determined on how quickly storms can form cold pools, where after damaging winds will become more common. Forecast soundings show good inverted-v thermodynamic profiles, suggesting ample sub-cloud layer evaporation and more than adequate DCAPE for strong outflow winds. At least some threat for significant damaging winds would exist should cold pool formation occur through late afternoon. Storm scale interactions will likely drive the corridor of greatest damaging wind threat, and this will remain low confidence until tomorrow afternoon more than likely. That said, a growing number of high-res guidance solutions suggest this threat would be maximized across central Nebraska as storms initiating along the triple point and warm front grow upscale and drop southeast. Storms will quickly exit the area through sunset, ending the threat for severe weather locally. Lows tomorrow night fall into the 50s again in the post-frontal airmass. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 407 AM CDT Thu Jun 6 2024 The area will remain post-frontal Saturday, with the threat for strong to severe storms largely remaining off to the south. Still, some threat for showers and thunderstorms could exist Saturday afternoon as post-frontal low level upslope flow could lead to thunderstorms off the high terrain. Near daily thunderstorm chances will then continue through the weekend and into early next week. Placement of mesoscale boundaries and associated instability will drive the degree of threat each day, and confidence remains low for this reason in severe weather. BY midweek, upper ridging will begin to amplify across the southern Plains, leading to much warmer temperatures and a lesser threat for thunderstorms locally. In fact, widespread highs in the 90s look to enter the forecast for Wednesday, and persist towards the end of next week. This could also lead to the first round of heat concerns this season, and will need to be monitored closely for potential impacts. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1212 AM CDT Thu Jun 6 2024 VFR conditions will prevail across western and north central Nebraska overnight through Thursday evening. Winds are expected to remain northwesterly at 10KT or less overnight into Thursday morning. After 17Z, northwest winds will be strongest across north central Nebraska along and east of a line roughly from KVTN to KBBW, near 31014G22KT. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Brown LONG TERM...Brown AVIATION...Roberg