Area Forecast Discussion
Issued by NWS North Platte, NE
Issued by NWS North Platte, NE
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119 FXUS63 KLBF 060539 AFDLBF Area Forecast Discussion National Weather Service North Platte NE 1239 AM CDT Mon May 6 2024 .KEY MESSAGES... - A strong storm system crosses the area Monday, bringing a threat for strong winds and strong to severe thunderstorms. - The greatest risk for severe weather Monday will reside generally east of Highway 83 during the mid to late afternoon hours ahead of a fast moving frontal boundary. - Strong winds and low humidity values are anticipated across western Nebraska Monday afternoon, leading to at least elevated fire weather concerns. - Monday`s storm system lingers over the Plains through much of the upcoming workweek, keeping winds elevated and near daily precipitation chances. && .SHORT TERM /THROUGH TUESDAY/... Issued at 347 PM CDT Sun May 5 2024 The primarily concern for the short term will revolve around a strong storm system, progged to impact the area tonight and tomorrow. Currently, the aforementioned upper low is centered over northern Nevada, with broad southwesterly flow in advance of this wave aloft, entering the Plains. At the surface, broad cyclogenesis has begun across portions of the Rockies, with an increasing pressure gradient noted across western Nebraska. Flow from the southeast has increased in response to the deepening surface pressure, and is leading to increasing low level moisture advection. Dewpoints have increased into the upper 40s across southwest Nebraska this afternoon amid gusty southeast winds. For tonight, expect the increased southeast winds to persist, as a strong low level jet develops across much of the Plains. Forecast soundings suggest limited to no boundary layer decoupling overnight, and even strengthening winds as the strong flow aloft is mechanically mixed downward. Will have to watch for the potential for high wind gusts (60+ mph) near the Pine Ridge at higher elevation, though confidence in this is low for now. The boundary layer remaining mixed will also promote mild overnight lows, in the low to middle 50s across the area. Closer to sunrise tomorrow morning, the increasing warm advection will lead to lowering cloud decks, and a period of drizzle through late tomorrow morning. As we head into the early afternoon, a pacific front will begin to push quickly into the area from west to east, reaching the HWY 83 corridor around Noon. Ahead of this boundary, upper 50 to potentially near 60 degree dewpoints will stream northward into the area, with a narrow corridor of instability developing near the HWY 183 corridor. This (HWY 183) is where convective initiation is anticipated by 1-3pm CDT. That said, questions remain regarding the degree of destabilization that can occur with northward extent, though guidance continues to suggest at least some MLCAPE for convection to work with ahead of the advancing Pacific front. As the upper low continues to deepen aloft, it begins to take a negative tilt and mid-level becomes largely meridional with height. Shear vectors show near boundary parallel storm motions, suggesting quick upscale growth when combined with increasing forcing for ascent with the approaching wave. This points towards a line of thunderstorms initiating near HWY 183 mid-afternoon, quickly moving east by late afternoon. The primary hazard with this looks to be damaging wind gusts, though some hail risk will exist with initial discrete updrafts. Any QLCS tornado threat would be tied to low- level thermodynamics, and meager low-level lapse rates could be in place due to persistent stratus. Will have to monitor for any clearing closely, and better low-level thermodynamic profiles could support at least a brief window for an isolated QLCS tornado threat. Behind the Pacific front and exiting convection, strong west winds are anticipated amid clearing skies and quickly warming temperatures. This, combined with increasing dry air advection, should lead to quickly falling relative humidity values by late afternoon. The combination of the strong west winds and low humidity will lead to at least an elevated fire threat, with the caveat of this being maximized in areas where green up is most delayed. Will also have to watch for the potential for another period of high wind as diurnal mixing leads to good momentum transfer. That said, confidence remains higher further north in South Dakota in closer proximity to the surface low center. North of the tongue of dry low-level air, scattered wraparound precipitation is possible near and just after sunset, though should end prior to midnight as the upper low begins to pull away to the north. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Issued at 347 PM CDT Sun May 5 2024 The upper low that impacts the area Monday is anticipated to continue to influence weather locally through much of the workweek, as it remains anchored over the northern Plains. This looks to keep winds elevated each day, as additional frontal boundaries pass through the area this week. Precipitation chances exist nearly each day as well, though confidence in placement and amounts from any one day remains lowered for now. Highs remain nearly average, generally in the 60s each day this week. As we head towards the weekend, upper level ridging will begin to amplify across the Pacific Northwest, with northwest flow developing aloft across the Plains. As the ridge begins to slide eastwards, this could bring a brief lull to the active pattern. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1238 AM CDT Mon May 6 2024 Deep moisture surging north into and through wrn/ncntl Nebraska this morning is the basis for expected MVFR/IFR/local LIFR ceilings developing mainly along and east of highway 61. A strong Pacific cold front across WY will move east through Nebraska today with flight conditions improving to VFR from west to east. It is worthing noting, scattered showers/isolated thunderstorms are possible behind the front and the best chance for this will be across nrn Nebraska. Aviators will encounter strong south winds 17025G40KT ahead of the front. Scattered showers and thunderstorms are also possible ahead of the front this afternoon. Flight conditions will improve this evening with MVFR ceilings and isolated SHRA north of highway 2 and VFR to the south. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Brown LONG TERM...Brown AVIATION...CDC