052 FXUS64 KLUB 092314 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 614 PM CDT Tue Oct 9 2018 .AVIATION... Challenge with this forecast will be the risk of MVFR this evening as the post frontal stratus attempts to make its way southward. At some point this evening, we should see erosion of the stratus from SE to NW becoming VFR. && .PREV DISCUSSION... /issued 346 PM CDT Tue Oct 9 2018/ DISCUSSION... The upper level trough continues to slide off to the northeast across the Texas Panhandle with a trailing surface cold front making very slow progress to the south. The front was generally along Highway 114 into Lubbock and then curving north towards Childress. Still seeing isolated showers and storms developing along and behind the boundary but these will gradually weaken with the loss of daytime heating and as the lift from the trough continues to push off to the northeast. Light showers may last through midnight before the trough axis pushes east of the forecast area early Wednesday morning but amounts are expected to remain low at only a few hundredths of an inch. Wednesday will remain dry but cool thanks to the remnant surface moisture from rainfall across the area and as generally zonal flow aloft develops. Zonal flow will gradually transition to southwesterly flow aloft which will help to deepen a lee surface trough near the Texas/New Mexico state line. Enough convergence may develop in the trough axis to generate isolated to scattered showers and storms late in the afternoon but the coverage remains uncertain. At the same time, Hurricane Sergio will push into the Baja and start making progress towards the forecast area. Another item that will be occurring is a shortwave swinging out across the Northern Plains which will help push a weak front towards the region Friday. This front will stall out in the northern part of the forecast area into the southern Texas Panhandle Friday afternoon which could focus storms across the northern part of the area. The biggest forecast issue will be the timing on the remnants of Sergio pushing over the region which will bring quite a bit of moisture into the region and lift to help generate precipitation. The GFS has this arriving Saturday morning while the ECMWF holds off until later in the day and further south across central Texas. With the old frontal boundary nearby, influx of deep tropical moisture, and lift from the remnants of Sergio, conditions will be favorable for widespread precipitation. Some of this will be locally heavy at times as well as precipitable water values climb above normal and could approach 2 inches across the Rolling Plains. The only good news is that this window will be fairly narrow during the day Saturday with precipitation decreasing afterwards for a brief windows Saturday night into Sunday morning. Did not go as high as the 100% PoPs that the model blend put in the forecast but did keep them in the upper 80% range as coverage should be fairly high. However, coverage could be much lower if the ECMWF solution verifies and keeps the heaviest precipitation south of the forecast area. On the heels of that, a stronger cold front will push across the region during the day Sunday which will help generate another round of precipitation. Amounts should be lighter as the deeper moisture shifts east and there is little in the way of upper-level support for widespread precipitation. However, convergence along the front at is races south should be strong enough to generate precipitation. Temperatures Sunday afternoon will be 10-15 degrees cooler than Saturday and highs may struggle to climb out of the mid 40s across the northern South Plains. Models had morning low temperatures on Monday below freezing for Parmer, Castro, Swisher, into Briscoe counties but this may hard to realize if there is widespread precipitation over the weekend. Bumped temps up 2-3 degrees which will keep all but the far northwestern part of Parmer county above freezing. Again, it will be fairly close so we will have to monitor heading through the week. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 14/14/26