902 FXUS64 KLUB 171944 AAA AFDLUB Area Forecast Discussion...UPDATED National Weather Service Lubbock TX 144 PM CST Fri Jan 17 2020 .UPDATE... One final update this afternoon to account for current observations and recent/expected trends. Specifically, have trimmed low shower chances to the far southeast zones before 21Z, and removed them completely after 3 pm. Cloud cover is finally giving way to sunshine across the western South Plains, and temperatures should be able to recover well into the 50s (even a few lower 60s) across much of the Caprock late this afternoon. However, the window for insolation across the eastern zones before sunset will be slim, at best, and thus have dropped forecast highs down several degrees there. Otherwise, only minor adjustments made to the remaining grids through this evening. && .PREV DISCUSSION... /issued 1155 AM CST Fri Jan 17 2020/ AVIATION... Low clouds and BR have been holding firm at the terminals late this morning, resulting in LIFR at KLBB and KPVW and MVFR at KCDS. A return of drier downsloping winds will eventually bring VFR conditions back to the terminals, though somewhat delayed from earlier thinking. Currently we have VFR returning to all terminals by 21Z, though the exact onset could vary either side of this by 1-2 hours. There is enough residual low-level moisture to provide a risk of stratus/fog redevelopment at any/all of the terminals this evening; however, winds will be veering westerly, then northerly behind our next FROPA, and this will tend to mitigate the threat of sub-VFR conditions developing tonight. Also, a modest LLJ could introduce periods of LLWS, but at this point it looks marginal and has been excluded from the TAFs. PREV DISCUSSION... /issued 825 AM CST Fri Jan 17 2020/ UPDATE... We have extended the Winter Weather Advisory (WWA) until 9 am for our far eastern column of counties. The bulk of the precipitation will be shifting east of this area soon, and we don't anticipate extending the WWA further. Plus, temperatures have been moderating too and even slightly above the freezing mark across the southern Rolling Plains, so conditions will gradually improve as this slow warming trend continues. No other adjustments were made to the forecast at this time. PREV DISCUSSION... /issued 613 AM CST Fri Jan 17 2020/ UPDATE... Quick update just sent out to remove Winter Weather Advisory from the Caprock, extend until 8 am for the Rolling Plains, and adjust timing of PoPs to bring precipitation to an end faster by about 3 hours from west to east. Current trends show band of precipitation has shifted east of the Caprock and temperatures continue to slowly warm. Calls to parts of the Rolling Plains have yielded reports of ice in some areas and intensity of current band may still yield pockets of icing even with temperatures at 32 to 33 degrees. Although the trough axis remains west of the area, water vapor loop shows the leading edge of the strong lift looks to have shifted east with the current band with little enhancement further west. There could still be a stray shower until the dry air reaches the forecast area late this morning but amounts should be very light. Jordan PREV DISCUSSION... /issued 404 AM CST Fri Jan 17 2020/ DISCUSSION... Band of rain and freezing rain was located along the edge of the Caprock and will continue to shift east through the morning. Also have seen a few lightning flashes on GLM, LMA, and ground- based networks so have included mention of isolated thunder through mid- morning. This band will be the last hurrah for precipitation as the main trough continues to push east out of the Great Basin and across the forecast area through the day. There could be additional light showers before the trough axis moves overhead but regional radar loop shows a lack of precipitation on the western side of the moisture plume. Last aircraft that provided AMDAR data into KLBB Int'l Airport at 0518 UTC showed -2.7C/27F at roughly 2400 ft and surface temperatures have remained within a degree or two over the past several hours near freezing so any precipitation may still occasionally be a mix of freezing rain and rain through mid-morning. By this point, temperatures are forecast to climb above freezing...across the South Plains as skies start to clear and the Rolling Plains as warm advection increases ahead of the trough axis. Should finally see a transition to all liquid by mid-day as the precipitation band shifts east of the region. This means that the Winter Weather Advisory will be allowed to expire on-time at 6 am. Quite possible that rain may end faster than what is in the first 12 hours of the forecast if the trough starts to speed up a bit faster than models forecast. Regardless, precipitation will have shifted east of the region by sunset with skies continuing to clear into tonight. A weak cold front will follow behind the departing trough and will push south of the forecast area before sunrise Saturday. Quiet weather will continue through the weekend into the first part of next week as a shortwave trough moves over the area Monday night into Tuesday morning. Increasing subtropical moisture aloft and weak low-level moisture advection will take place Tuesday morning as well ahead of a shortwave trough that will rapidly push east Tuesday afternoon. Models continue to generate precipitation by Tuesday afternoon although coverage and intensity remains uncertain due to differences in timing with the trough. The ECMWF lingers precipitation into Wednesday morning while the GFS has precipitation east of the forecast area by sunrise. Temperatures will once again be tricky as model blends have lows at or below freezing in parts of the forecast area which would mean mixed precipitation potential. However, warm advection and cloud cover may help to hold temperatures just above freezing so will keep precipitation all liquid for now. On the heels of this trough will be another system that will move near or across the region during the day Thursday. The GFS continues to dig a strong closed low into the Central Plains while the ECMWF is weaker and further south with a smaller closed low moving just south of the forecast area. GFS solution would mean the potential for a breezy to windy day Thursday and potential for light wrap-around precipitation while the ECMWF would favor a better chance of mixed precipitation and winds nowhere near as strong as the GFS. Opted to go with the NBM for now until details with this system become clearer over the next several days. Last two days of the forecast for this cycle remain uncertain as the ECMWF has yet another trough moving towards the region Friday into Saturday that could bring light precipitation with the GFS bringing shortwave ridging overhead. Only similarities for the extended are highs remaining in the low to mid 50s to near 60 and lows at or just under freezing. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 23/14