622 FXUS64 KSHV 201203 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 703 AM CDT Thu Jun 20 2019 .AVIATION... For the 20/12Z TAF period, some patchy low stratus will continue to affect some sites through mid to late morning before this low cloud cover lifts into a cu field by this afternoon. Some mid and high clouds will also be passing through our terminal airspace as these lingering convective debris clouds gradually exit with the departing upper level trough. Any intermittent IFR/MVFR cigs this morning will become VFR closer to midday as they scatter out with the cu field gradually dissipating by early evening. Expect clear to mostly clear skies through much of the evening and overnight, but low clouds are expected to return toward daybreak with MVFR cigs likely at most sites near the end of the period. Southerly winds will prevail from around 6-12 kts throughout much of the period. /19/ && .PREV DISCUSSION... /issued 431 AM CDT Thu Jun 20 2019/ SHORT TERM.../Today through Friday/ The early morning MCS continues to quickly shift E of the region this morning while weakening, as dry slotting has spread E beneath the shortwave trough over Ern AR/Ern LA. The morning mesoscale analysis indicates that a residual cold pool has pushed SSE into Deep E TX into Cntrl LA, with 2-3 mb/3 hr pressure rises over Ncntrl LA suggesting that this bndry will continue to spill SE a little more away from the region before becoming stationary. However, the lack of pressure rises over Deep E TX suggests that the bndry has stalled, with a discernible instability gradient noted over Cntrl and SE TX where MLCapes still range from near to in excess of 2000 J/Kg. In fact, a small cluster of strong to svr convection has recently developed near and just SE of ACT, where moisture convergence has increased near the far Wrn periphery of the sfc bndry. While the short term global models have failed to pick up on this convection, the CAMs have to some extent and suggest the convection continuing to build SE this morning near this bndry/instability gradient, even as SE winds return to Deep E TX to help nudge what's left of the bndry Nwd. Thus, have inserted slight chance pops this morning for portions of Deep E TX, while also maintaining isolated pops this morning for the far Ern zones of Ncntrl LA to account for any isolated convection that may linger to start the period. The cold pool leftover from the overnight MCS should gradually modify today as SSW low level winds return, although strong insolation should result in max temps near or slightly warmer than what was observed Wednesday. Based on the fact that enough mixing occurred in wake of Wednesday morning's cold pool erosion over the region, have tried to tailor dewpoints today to something similar, resulting in heat indices just shy of Heat Advisory criteria across portions of E TX. However, with 09Z dewpoints in the mid and upper 70s this morning over the coastal bend of SE TX and much of Srn LA, these higher dewpoints should quickly expand Nwd later today and especially this evening, with enough of a pressure gradient resulting in enough wind and low stratus development to keep min temps from falling much (if not at all) into the mid 70s. The short term progs continue to suggest ridging aloft will begin to build and expand N tonight across LA/AR into the Lower MS Valley, with the ridge slowly shifting E into the SE CONUS Friday. As a result, enough of a deep Srly flow on the backside of the ridge may result in isolated seabreeze convection developing and shifting N into portions of Lower E TX/Ncntrl LA during the afternoon, as suggested by the CAMS as well as the 00Z ECMWF and GFS. Thus, have expanded slight chance pops a bit for these areas just S of the I-20 corridor. With the ridge building N over the region tonight through Friday, and given the fact that min temps will be on the warmer side, have trended max temps Friday into the mid 90s for much of the area, with limited mixing given the deeper Srly low level flow resulting in heat indices near the Heat Advisory criteria across portions of E TX. Thus, later forecasts will take into account observations and model trends for the potential need of an Advisory for portions of these areas Friday. 15 LONG TERM.../Friday Night through Wednesday Night/ The upper ridge axis will continue to shift farther eastward into the SE CONUS to begin the period. Meanwhile, the next major upper level trough will be shifting out of the Rockies into the Southern Plains to start the weekend. As a result, SW flow aloft will return across our region with a slight chance of showers and thunderstorms on Saturday afternoon mainly over our western zones. Otherwise, the main weather story will be the intense heat and humidity which may warrant heat advisory conditions over parts of the region through the first half of the weekend. By Sunday, the upper trough will shift a bit farther east into the Plains with increasing large scale ascent spreading farther across our region. As the trough begins to accelerate SE late Sunday into Monday, expect showers and thunderstorms to become more widespread with some strong storms possible through the afternoon on Monday. Although the trough will eventually shift eastward by Monday night into Tuesday, rain chances will continue to linger through mid week as an upper level ridge will slowly retrograde westward across the Gulf of Mexico and build to our SW over northern Mexico and western Texas. This will allow for a return to NW flow aloft over our area, favoring better rain chances with disturbances riding around the periphery of the upper ridge. Temperatures will generally run near or just slightly below normal during this more unsettled period from late in the weekend through early to mid week. /19/ && .PRELIMINARY POINT TEMPS/POPS... SHV 93 77 94 77 / 10 10 10 0 MLU 92 76 94 77 / 20 10 10 0 DEQ 90 74 92 75 / 10 10 0 0 TXK 91 76 93 76 / 10 10 0 0 ELD 91 75 93 76 / 10 10 10 0 TYR 93 77 94 77 / 10 10 10 0 GGG 92 77 94 77 / 10 10 10 0 LFK 94 77 94 77 / 20 10 20 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 19/15