202 FXUS64 KLUB 210527 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 1227 AM CDT Tue May 21 2019 .AVIATION... Sharp apparent Pacific frontal boundary shoving strongly east of KLBB and KPVW with very strong northwest winds behind impacting mainly KLBB. Solutions indicate these winds will diminish within about 3-5 hours. At KCDS, thunderstorms have recently redeveloped in advance of the approaching boundary while some amount of the cooler saturated surface airmass that has blanketed much of the Panhandle also has seeped in. This forecast will indicate temporary thunder and light fog early this morning at KCDS until passage of the boundary around 10Z or 11Z. RADAR also has been showing what appears to be a possible second surface boundary crossing southern New Mexico that may initiate stronger winds during the daytime Tuesday. Solutions have ramped wind speeds for Tuesday quite a bit above earlier guidance. We have added a mention of blowing dust to KLBB as well for Tuesday. But airmass will be dry with VFR conditions otherwise expected. RMcQueen && .PREV DISCUSSION... /issued 1035 PM CDT Mon May 20 2019/ UPDATE... A new tornado watch was issued by SPC to replace the one that expired at 10 PM. This one will focus on the southeastern counties where an area of discreet supercells is training northeastward and downstream from a line segment of storms that extends north from Midland. Meanwhile, thunderstorm chances look less further north. Will watch as the Pacific front which is along a Plains to Hart line at 1030 PM moves into better low level moisture toward I-27. However, the more extensive activity from Midland through Aspermont toward Wichita Falls, may cut off the better, richer inflow to what, if anything, might develop in the vicinity of Lubbock or further north. As a result have pared back precipitation chances and cancelled the northern half of the Flood Watch. The southern part of the Flood Watch still looks good with this training of supercells in a SW-NE orientation and have extended its duration to 09Z to match the new tornado watch. PREV DISCUSSION... /issued 749 PM CDT Mon May 20 2019/ UPDATE... The previous Tornado Watch 197 is extended two hours until 10 pm and maintained as a PDS. Solutions are unclear where the approaching Pacific cold front will lead to thunderstorms, could be western South Plains or could skip into eastern South Plains and Rolling Plains. So, with this uncertainty the watch is extended with no change. RMcQueen PREV DISCUSSION... /issued 638 PM CDT Mon May 20 2019/ AVIATION... Current thunderstorm activity nearest KCDS and will continue in the vicinity at least the next two hours. Back west, activity has ended, but we are watching an approaching Pacific cold front boundary moving out of eastern New Mexico that is expected to move through KLBB and KPVW near 04Z and KCDS around 06z-07z. This will be accompanied by increasing lift and moisture remains in the vicinity, so have adjusted thunder chances to time with arrival and passage of this cold front. Forecast will continue to indicate temporary MVFR conditions but brief IFR also are possible. Remember the area remains in a highly unusual High Risk of severe thunderstorms with tornado and very large hail threats. Pilots are advised to follow RADAR trends closely. Behind the cold front, drier westerly flow will spread in with expected around 20 knots of flow. RMcQueen PREV DISCUSSION... /issued 156 PM CDT Mon May 20 2019/ DISCUSSION... The main focus of today's forecast will be the not-so-secret severe threat. Skies have already begun to thin out with a cumulus field forming from southeast to northwest. This will allow the build up of additional CAPE in which MLCAPE is already sitting at over 3000 J/kg. At the same time the dryline is just now approaching the TX/NM state line at a slower/later pace than previously shown by short- term models. This would hint at storms developing further west (west of Lubbock) than current models are indicating (along/east of the I27/US87 corridor). The one thing that could hinder westward development would be mixing occurring across our western zones. Right now at most this would hinder the extent of the significant tornado threat, however it would not make it null. There are also indications of convection trying to develop along the dryline with light reflectivities showing up near Olton and Anton. Any storm that develops will have a high probability of becoming severe. Very steep lapse rates with 0-6km shear in excess of 50 knots will support the potential for very large hail over 3-4 inches. 12Z soundings at MAF and AMA revealed 0-1km SRH of 295 to 341 m2/s2 respectively. Current analysis shows that SRH has decreased somewhat due to surface winds becoming more southerly, but this does little to deter the threat for tornadoes. SRH remains higher across the Rolling Plains and eastern Texas Panhandle where the greatest tornado threat exists. With abundant shear, helicity, and low LCLs some tornadoes will have the potential to be violent. Tomorrow the surface low will pull eastward across KS allowing for a fairly windy day with near to above advisory level winds across much of the FA especially across our northwestern zones. We could see additional bouts of showers and thunderstorms by late week into early weekend as another upper low digs into the Four Corners region. && .LUB WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch until 4 AM CDT early this morning for TXZ036>038-042>044. && $$ 99/99/05