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Displaying AFOS PIL: AFDLUB Received: 2018-10-11 23:22 UTC
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335 FXUS64 KLUB 112322 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 622 PM CDT Thu Oct 11 2018 .AVIATION... Areas of rain showers and drizzle may periodically affect each terminal through the overnight hours. Current data suggest that IFR conditions should hold off until near sunrise Friday morning. That said, the risk of going IFR later this evening is perhaps about 30%. Extra fuel and alternates seem to be a great idea this evening. && .PREV DISCUSSION... /issued 402 PM CDT Thu Oct 11 2018/ DISCUSSION... Low clouds have hung around for much of the day across all but the Rolling Plains. This has held highs in the mid 50s across most of the South Plains with mid 60s across the Rolling Plains. Low clouds have also killed off any chances for thunderstorms along the TX/NM state line but we could still see occasional showers and drizzle heading into tonight into tomorrow morning. There will be a short lull in precipitation Friday afternoon before rain chances start to increase late Friday with the approach of the remnants of Sergio. Models continue to have slightly different tracks with the GFS taking the heaviest precipitation north; the ECMWF NAM and CMC all carry the heaviest precipitation south. However, the trend from the 00Z runs of tracks converging close to the forecast area does continue so we should see the bulk of the moisture and lift move near the area providing another round of good precipitation chances and locally heavy rainfall. The bulk of the precipitation will shift east of the forecast area by Saturday night which then turns attention to the first part of next week, which is also where the "fun" begins in the forecast process. A strong cold front will dive south through the weekend arriving into the northern part of the forecast area by late Sunday morning. A quick check of the source region for this front indicates the air will come from the Northwest Territories and Nunavut region where temperatures were generally in the low 20s. Although this isn't too terribly cold, both the GFS and ECMWF keep a continued meridional flow through the first part of next week which will allow a continued flow of cold air into the region. As the front pushes through the area, lift along and behind the front along with a weak shortwave should help to increase rain chances although much of the deep moisture will have shifted east of the area by that time. Cloud cover and the strong north wind will make it feel rather chilly on Sunday. By far the biggest concern will be whether we will see a first freeze for parts of the area Monday morning with the trend in all the operational runs and ensembles continuing to drop temperatures 3-5 degrees each run. Extremely high standard deviations in the ensemble runs show that there continues to be a lot of uncertainty on how cold we will be Monday morning but the northwestern South Plains generally north and west of a Tulia to Morton line may see temperatures in the 29-32 degree range by Monday morning. Precipitation chances will also linger into Monday morning so there will be a potential for a mix of snow and rain across this area and possibly some snowfall up around Rhea, Bovina, and Friona but we do not expect any accumulations at this time. Clouds will remain over the area through the day Monday which is one reason highs will struggle to make it out of the low 40s across the area. This will also set up the potential for a more widespread freeze and potential hard freeze Tuesday morning. Confidence is very low on how things will unfold for Tuesday morning because both models show we keep southwesterly flow above a dry boundary layer. This typically pulls in moisture from the Pacific resulting in mid to high level clouds that would blanket the area and keep radiational cooling from occurring. The flip side is that even with the cloud cover, both the ECMWF and GFS show that 850 hPa temps will be at or below freezing indicating a pretty cold airmass over the area. Finally, the ECMWF shows the surface ridge setting in over the region Tuesday morning with dry advection all day; two of the three things needed for excellent radiational cooling and colder temperatures. Operational model blends were coming in colder than what the published forecast has but even going towards the warmer guidance values would have the freezing line as far south and east as Childress to Tahoka. This is a pretty big change from previous runs and we will need to watch closely heading through the weekend to see how the models handle this airmass which historically has been poorly with the first "major" cold front of the season. Beyond Tuesday, a gradual warmup is expected but with highs still 10-15 degrees below normal through Friday. This is likely due to continued southwesterly flow over the region due to a persistent western U.S. trough keeping mid-level moisture and associated cloud cover over the region. We will also see rain chances return by Wednesday as a series of shortwaves move over the region providing weak lift and moisture for rain. Too early to pinpoint what days will be favored and much of the focus for this forecast was for precipitation this weekend and cold weather early next week. Jordan && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 99/99/26