Area Forecast Discussion
Issued by NWS North Platte, NE
Issued by NWS North Platte, NE
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344 FXUS63 KLBF 190533 AFDLBF Area Forecast Discussion National Weather Service North Platte NE 1233 AM CDT Thu Sep 19 2024 .KEY MESSAGES... - Critical fire weather conditions continue this evening across northwest Nebraska, where a Red Flag Warning remains in effect. Dry and windy conditions across western and northwestern Nebraska on Friday may introduce another chance of elevated to near critical fire weather concerns. - A cooler, wet weekend is expected as a slow moving upper level system brings potential for a steady rainfall this weekend. - Cooler temperatures Sunday and early next week, with highs generally at or below seasonal averages. && .SYNOPSIS... Issued at 332 PM CDT Wed Sep 18 2024 Upper level analysis and water vapor satellite imagery place an upper level low over the Montana-North Dakota border, with another upper level low off the central California coast. At the surface, an occluding low pressure system is located over eastern Montana, with a cold front extending through the Dakotas into southwest Nebraska.A secondary low is located over southwest Nebraska, with another cold front through the Oklahoma and Texas Panhandles. On satellite, cumulus clouds are observed along and east of a line from roughly Hayes Center to North Platte to O`Neill. Some additional high clouds are observed over the Nebraska Panhandle and the Pine Ridge. && .SHORT TERM /THROUGH FRIDAY/... Issued at 332 PM CDT Wed Sep 18 2024 Dry, mild, and windy conditions continue across northwest Nebraska through the evening hours, keeping the Red Flag Warning is place through 9 PM CDT/8 PM MDT. Overnight humidity recovers to around 50 to 60 percent near the Pine Ridge, but most helpful will be the calming of the surface winds. As the boundary layer decouples later this evening, surface winds should calm to around 10 mph, which will ease fire weather concerns for the night. The cold front will continue to slowly track east throughout the night, with temperatures behind the front expected to drop into the 50s overnight. Ahead of the front, overnight lows in the lower 60s are expected. Similar to last night, there may be the potential for some patchy fog in the early morning hours in the vicinity of the front, where moisture is likely to be higher. Forecast soundings would suggest the possibility, though at this time, it appears to be generally light in coverage and duration. Probabilistic guidance suggests at most a 30 percent chance for visibility restrictions less than half a mile, and mostly east of the forecast area. With this in mind, will leave fog out of the overnight forecast for now, but will need to be monitored if conditions become more favorable. By tomorrow, the front should be out of the area, with temperatures ranging from the upper 70s to mid 80s across the region. Some stronger winds across South Dakota may get as far south as the Sandhills, though the strongest gusts are expected mostly along the stateline. Current thinking is that wind gusts will remain at or slightly below 25 miles per hour tomorrow afternoon. The current upper level trough should continue tracking north and east, with a slight ridge developing for Thursday. Aside from the winds across northern Nebraska, tomorrow should be a fairly pleasant day. Skies should remain mostly clear through the evening and overnight, with low dropping into the upper 40s to mid 50s. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 332 PM CDT Wed Sep 18 2024 The slight upper level ridge continues to build on Friday, ahead of an aggressive upper level low across the Four Corners region. The main concern on Friday is the return of elevated to near critical fire weather conditions, mostly across northwest Nebraska. Under the upper level ridging, temperatures are expected to climb into the mid to upper 80s, with potential 90s across portions of northern Nebraska. Dry conditions are expected, mostly along the Pine Ridge and into portions of western Cherry County. Forecast soundings suggest an environment favorable for mixing of upper level winds to the surface, mainly across southwest Nebraska, the Panhandle, and the Sandhills. Current thinking is wind gusts during the afternoon hours could reach 25 to 30 miles per hour, so will be closely monitoring the conditions heading into Friday. By Saturday afternoon, the upper level ridging is displaced to the east, with the upper level low moving across Colorado. The pattern will set upper level divergence across the region, and a surface low is expected somewhere along the Colorado/Nebraska/Kansas borders. The stage will be set for a potential long duration rain event across southwest into western and north central Nebraska this weekend. At this time, the severe threat appears fairly low, with the potential for some embedded thunderstorms. However, the pattern is more reminiscent of a winter system, that may provide mostly rain showers and wetting precipitation across the region. Notable, the ECMWF Extreme Forecast Index and Shift of Tails highlights most of western and southwest Nebraska as an area supportive of anomalously high QPF this weekend. At this time, areas further south appear more favorable. However, there is a slight spread of solutions in the GEFS Spaghetti plots for the track of the upper level system. A more northern track could potentially favor bringing precipitation a bit further north. This is also potentially supported in the ECMWF EFI and SoT, with little to no EFI, but a SoT marker across northern Nebraska, meaning there is a chance for anomalously high precipitation, though confidence is low. While confidence in the placement of rain this weekend is somewhat lower, the system does bring with it a pattern change lasting until at least mid week. Temperatures remain near seasonal to slightly below seasonal starting Sunday and lasting through at least mid week. For reference, seasonal temperatures next week are typically around 76 to 78 degrees. With this pattern shift, we could be seeing temperatures maxing out in the 60s to mid 70s early next week. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1232 AM CDT Thu Sep 19 2024 VFR conditions are expected outside of patchy low-level fog across central Nebraska which may encroach upon LBF for a few hours early in the period. Currently, southerly flow is noted ahead of a surging frontal boundary that is fairly pronounced on radar. Current location as of 19/0530z is an ANW to TIF to OGA line. This feature is quickly shifting southeast and timing of this into LBF is around 19/08-09z. Ahead of this, visibilities are already dropping modestly but the arrival of this boundary will lead to a wind shift to the west-northwest and drier low-level air and the expected end to any fog threat. Additional concern with this boundary is the threat for isolated to widespread convection across north central Nebraska. This should remain east of Valentine which is already post-frontal but uncertainty with southward extent and whether impacts are felt at LBF remains medium at best. For now, will omit mention and monitor going forward. Outside of some patchy cloud cover early this morning, skies will remain clear with even the most aggressive NWP guidance suggesting the same. Increased high- level clouds will approach from the south near the end of the period but arrival may fall just beyond the valid period. && .FIRE WEATHER... Issued at 332 PM CDT Wed Sep 18 2024 Dry, mild, and windy conditions will continue across northwest Nebraska through the evening hours, keeping the Red Flag Warning in effect through this evening. Relatively poor overnight moisture recovery is expected, with humidity bouncing back to around 65 percent across the Pine Ridge tonight. What will help limit the fire weather conditions overnight is the boundary layer decoupling, which will slow wind speeds overnight to around 10 miles per hour. This will also prompt a slight wind shift from southwesterly to mostly westerly winds tonight. Tomorrow, afternoon humidity is expected around 25 to 30 percent across most of the region, with a limited area of higher winds across portions of northern Nebraska. However, wind gusts are mostly expected to remain at or just below 25 miles per hour. The next concern for fire weather conditions is Friday afternoon, where afternoon humidity is expected to drop to the 15 to 20 percent range across the Pine Ridge and portions of north central Nebraska. Higher wind gusts up to 30 miles per hour are possible across the Panhandle and Sandhills, so will be monitoring conditions of Friday quite closely. Beyond Friday, a system moving through this weekend may bring some wide spread and possibly long duration rain across most of western and north central Nebraska. At this time, heavier rainfall totals are more likely across southwest Nebraska, but will continue to track this system as it gets closer. Additionally, temperatures are expected to trend to near seasonal to slightly cooler than seasonal temperatures starting Sunday lasting through at least mid week. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Richie SHORT TERM...Richie LONG TERM...Richie AVIATION...NMJ FIRE WEATHER...Richie