Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/28/20

Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
1018 PM CDT Tue Oct 27 2020 .UPDATE... Mixture of freezing rain and sleet have been the dominate modes within the band of heavier convective precipitation stretching across the center of the FA. We could still see a little snow in this general corridor before the precipitation shifts east, but the wintry mix is eating into the potential snow totals across the central South Plains, including in Lubbock. Hence, we have reduced the forecast snow totals here, while maintaining 4 to 6 inches of snow across the far southwest Texas Panhandle and northwest South Plains, where they will receive their best shot of snow through the early morning hours. We did also expand the thunder mention in the grids given the observed trends with the activity this evening. The winter weather headlines remain unchanged. && .PREV DISCUSSION... /issued 643 PM CDT Tue Oct 27 2020/ AVIATION... IFR conditions will persist for the majority of the upcoming TAF period as a winter storm affects the region. Light freezing drizzle will continue for much of the evening prior to the next round of heavier precipitation later this evening into Wednesday morning. Mostly freezing rain can be expected at KCDS while a freezing rain/sleet/snow mix is expected at KLBB and KPVW. By daybreak the majority of the heavier precipitation should be east of all the terminals however light precipitation may linger through mid to late morning as the upper level low moves through the region. There is some potential for heavier wintry precipitation to stick around for northern locations from roughly CDS to near PVW late tomorrow morning into the afternoon however confidence is not high on this scenario. Aircraft icing will remain possible through this TAF period as cloud depths remain around 8,000 feet. By tomorrow afternoon ceilings at the area terminals may begin to gradually improve into the MVFR range. /WCI PREV DISCUSSION... /issued 257 PM CDT Tue Oct 27 2020/ SHORT TERM... The upper low was located over southwestern New Mexico and is slowly moving towards the southeast. Water vapor imagery indicates that a jet max may be rotating around the western periphery of this low. This feature will be important to watch over the next 18 hours as it may lead to a slightly farther south track to the upper level low which the GFS has indicated with the latest run. A few brief sleet and freezing rain showers continue to move towards the northeast this afternoon as weak lift remains across the forecast area. However, this lift should wane later this afternoon leading to a lull in the showery winter precipitation. Even with the lull in heavier precipitation light freezing drizzle will continue through the evening. The next area of large scale lift is across east central NM and this will swing over the forecast area late this evening. As this feature moves across the forecast area mid level cooling and moistening will occur which will help erode the warm nose currently residing around 750-650mb. The 18z sounding from Amarillo indicates that this warm nose has been eroded already while the Midland sounding has only eroded slightly. This will allow for a sharp gradient in precipitation type across the forecast area which will transition eastward through the night. Still expecting mostly freezing rain for locations off of the caprock with a mix of freezing rain, sleet, and snow in the central South Plains with mostly snow in the extreme southwestern Texas Panhandle. Lubbock continues to reside on the gradient of where the heaviest icing will occur to the east and the heaviest snowfall will occur to the northwest. Therefore, exact amounts for the city of Lubbock can differ drastically depending on how quickly the warm nose aloft is/is not eroded. Based on current guidance a switch over to snow in Lubbock should occur around midnight tonight with snow lingering through the morning on Wednesday. Farther east across the Caprock this elevated warm nose should never fully erode therefore a mix of freezing rain and perhaps eventually some sleet should occur through the night. There are some indications that elevated instability will be present with this area of lift so also included a mention for a slight chance of thunderstorms overnight. Any location that sees this convection could see snow/ice totals rapidly increase. Depending on the exact track of the upper level low an area of wrap around moisture will move across the area on Wednesday. Some guidance has this area moving as far south as a Lubbock to Guthrie line, while most guidance keeps it across the southern Texas Panhandle. As mentioned above, depending on if the jet energy can force the upper level low a bit farther south than previous guidance indicates, additional light to moderate wintry precipitation may continue through late Wednesday morning. If the low tracks farther north this activity should come to an end by daybreak Wednesday for most locations within our forecast area except for the southern Texas Panhandle. Most locations except for the southwest Texas Panhandle should warm above freezing by Wednesday afternoon which may help to improve road conditions across the region. /WCI LONG TERM... By 00Z Thursday, we may finally see which solution ended up handling this system most effectively. The GFS remains the more southerly track though some 30-60 NM further north than we saw yesterday whilst the NAM/ECM produces a wobble briefly into the SWRN Panhandle before continuing eastward along the Red River Valley. Still, how the system pans out for Wednesday night will depend on the track of the low. The low should exit the region on Thursday leaving us in a period of NW flow aloft which will become zonal as a trough translates across the northern half of the plains late Friday into Saturday. Flow will return to northwesterly in the wake of the Friday system becoming increasingly southwesterly into the middle of next week. Ongoing precipitation should be tapering Wednesday evening (if any is left at all). Temperatures across the Rolling Plains are progged to be just above freezing during the afternoon though some uncertainty exists as the cloud cover could limit diurnal heating. Again, depending on the dynamical cooling associated with the eventual track of the ejecting low, things could change. Would be hard pressed, with the persistent overcast, and continued northerly fetch to see temperatures rise too far above freezing. As such, the precipitation phase and southerly extent for Wednesday evening remains a bit unclear at this point. Given the uncertainty, will continue with a rain/snow mix up across the southern Panhandle and northern Rolling Plains. Once the precipitation finishes late Wednesday, we`ll see a return to mostly clear skies through next week. A dry front will help cool things off for Sunday after peaking near 70 on Saturday. Generally speaking, high temperatures will edge to slightly above average for Saturday and beyond. && .LUB WATCHES/WARNINGS/ADVISORIES... Ice Storm Warning until 1 PM CDT Wednesday for TXZ026-031-032- 037-038-043-044. Winter Storm Warning until 1 PM CDT Wednesday for TXZ021>025- 027>030-033>036-039>042. && $$ 23/99