017 FXUS64 KLUB 060555 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 1255 AM CDT Mon May 6 2019 .AVIATION... Thunderstorms slowly departing to the east about 80-100 miles east-southeast of KLBB and south of KCDS and will not threaten TAF sites overnight. Lower atmosphere remains disrupted from the earlier storms while a low level jet was trying to establish with southerly low level flow returning. Cloud tops still obscuring our ability to peer into the lower atmosphere but can see indications of low cloud deck gradually forming across the southern Texas Panhandle and this should spread more south as the night progresses though short term solutions not consistent with indicating this. So, aviation forecast is forced to use more conjecture than normal with pattern seemingly favoring development of IFR conditions later in the night, then lifting once more to an MVFR or slightly higher layer mid to late this morning. Thunder development later today will be more favored at KPVW and possibly KCDS than KLBB given expected height rises aloft, but confidence in including or excluding mention is not particularly high. Leaving thunder mention out later in the forecast, for now. RMcQueen && .PREV DISCUSSION... /issued 703 PM CDT Sun May 5 2019/ AVIATION... All the focus was in the near-term. Additional convective development could still flirt with KLBB and KPVW the next hour or two, but the primary storm focus was shifting to the south and east of the terminals. The activity in the south-central Texas Panhandle could affect KCDS over the next 1-3 hours and have included a TEMPO group to address this. Otherwise, the moist atmosphere will remain in place and we could see a repeat of low stratus and fog late tonight/Monday morning. NWP is not as insistent on a repeat of sub-VFR conditions, but given a similar environment, think odds are pretty good and have included it in the TAFs. After that, attention will turn to our next chance of robust convection Monday afternoon/evening. That will be addressed in future forecasts. PREV DISCUSSION... /issued 228 PM CDT Sun May 5 2019/ DISCUSSION... Severe storms are once again in the hopper for later this afternoon and evening, but compared to yesterday's event the setup today involves a much broader and stronger area of both CAPE and wind shear. Observations at 2 PM showed a thermal low near western Cochran County coincident with an axis of strong heating and superadiabatic 0-3 km lapse rates. This has already yielded a pocket of towering cumulus along a N-S dryline and should become the primary focus for storm initiation in the coming hour(s) as vertical mixing remains maximized in this vicinity. Aside from the dryline poised just east of TX and NM border, a residual boundary of weakly convergent flow was aligned roughly along Highway 84 and this could serve as a railway for a few supercells to anchor to later today. Otherwise, the environment is more unstable than yesterday with SBCAPEs already over 3000 J/kg spanning much of the Caprock. Around 35 to 40 knots of 0-6 km bulk shear will again prove more than sufficient for supercell modes, likely more robust and longer lasting than yesterday's abbreviated supercells. A few tornadoes are again possible mainly near the aforementioned NW-SE boundary and also as 0-1 km shear improves this evening with a 30-40 knot southeasterly LLJ. We expect scattered supercells (some splitting given largely straight line hodographs) to transition off the Caprock by early evening under mostly zonal flow and perhaps grow upscale into small lines at times provided outflows can consolidate. Following another round of overnight and early morning stratus over much of the region, the dryline on Monday is progged to be more diffuse locally underneath shortwave ridging, rising height fields, and more importantly less veered surface flow to its west. Complete with 700 mb temps warming a few degrees, this setup could prove more hostile for deep convection. However, this forecaster and many of my colleagues have lived here long enough to know that you should rarely dismiss the dryline in such marginal setups. Stronger heating will likely breed some attempts at moist convection which could easily skyrocket into isolated supercells given still favorable thermodynamic and kinematic profiles. The HREF and TTU WRF appear quite optimistic in this scenario and the subsequent upscale growth of storms in the evening, but we're a bit skeptical of this broad coverage of storms given no discernible background triggers within weak anticyclonic flow aloft. As such, we'll keep PoPs tomorrow afternoon just at slight chance in expectation of spottier storms. Tuesday still has the makings of a potentially significant severe event anywhere from the TX South Plains north to southwest KS as a dryline sharpens considerably in response to deeper SW flow ahead of a robust upper trough. The usual concern in these situations is antecedent convection and its effects on boundaries which is at odds among some models. Concern is that the NAM may very well be correct with its accelerated cold front into the Panhandle Mon night via convective outflows. The blended models still account for this time at this time, so we've left this scenario intact which favors a synoptic front or merely outflow boundary in our northern zones Tue afternoon. The intersection of these boundaries and the dryline would be the main focus for significant severe storms, but nearly the whole length of the dryline appears fair game for storms especially by the evening as the peak height falls and a Pacific front arrive. A quick inspection of the broader environmental data says some significant tornadoes could be in the offing anywhere east of the dryline Tue afternoon and evening which will obviously bear watch in later forecasts. Storms should quickly clear the region by daybreak Wed ahead of breezy west winds and deepening subsidence aloft. Thereafter, a modified Canadian front sweeps south Wed night ahead of a slow moving low in the Desert SW that should not impact the region until next weekend at the earliest. GFS and ECMWF favor a lead trough ejecting from this low o/a Friday which could easily spur rounds of elevated showers atop the cool dome. High temps may need to be curbed considerably Friday and Saturday. Additional precip seems plausible Sun into Mon as the aforementioned low finally lifts across Texas and much closer to our domain than prior models and ensembles suggested. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 99/99/05