581 FXUS64 KLCH 170414 AFDLCH Area Forecast Discussion National Weather Service Lake Charles LA 1114 PM CDT Thu May 16 2019 .DISCUSSION... For the 17/06Z TAF Issuance. && .AVIATION... Upper air sounding from this evening shows a relative dry air mass in the mid and upper levels with upper level ridging blocking any cloudiness from reaching the forecast area tonight leaving clear skies. This along with light and variable winds will make for mainly VFR conditions. Some patchy fog will be possible during the overnight toward sunrise, and will place a tempo group from 17/10-13Z at KAEX/KLFT/KARA for MVFR visibilities. On Friday, southerly winds will increase as low pressure moves into the Plains. This will help increase low level moisture, so a little more daytime heating cloudiness, especially at KBPT/KLCH. However, conditions are expected to remain VFR. Rua && .PREV DISCUSSION... /issued 914 PM CDT Thu May 16 2019/ UPDATE...The previous forecast remains on target this evening so no changes are needed at this time. PREV DISCUSSION... /issued 406 PM CDT Thu May 16 2019/ DISCUSSION... Short Term [Tonight and Friday] Visible satellite imagery shows scattered cumulus humilis across the CWA this afternoon. A few localized pockets of more robust cumulus have been noted along the Sabine River and there has even been a failed attempt or two at the initiation of deep convection. This indicates that there is a small chance ( < 10% ) of an isolated thunderstorm developing across Tyler, northern Jasper, and northern Newton counties over the next 1-3 hours. However, the most likely scenario is that surface thermals and cloud cover will diminish with the loss of insolation as sunset approaches. Therefore, the short term "silent" PoPs through tonight were left as is. The 1018 hPa surface high pressure currently centered over the northern is forecast to begin shifting eastward on Friday. Southeasterly flow along the western periphery of the high pressure will advect greater deep layer moisture into the region. This will result in higher chances ( around 20% ) for afternoon showers and thunderstorms on Friday. The greatest potential for thunderstorms will be across southeast Texas where more significantdeep layer moisture will be in place. Long Term [Saturday through Wednesday] During the long term period, a series of shortwave troughs are forecast to be rotating through a mean longwave trough centered along the western portions of the CONUS. Return flow will result in a conditionally unstable atmosphere developing across the Southern Plains. Global models point continue to project a robust N-S oriented band of convection developing across Central TX during Saturday afternoon. The line convection is then expected to progress east-southeastward Saturday afternoon and move through the region late Saturday evening through Sunday morning. Ahead of the line, an increasingly favorable synoptic environment for ascent and increasing deep layer moisture will allow for convection to develop along sea breeze from Saturday morning through the afternoon hours. A combination of moderate conditional instability and moderate deep layer shear over the CWA will result in an environment supportive of organized convection from Saturday through Sunday. Currently, the Storm Prediction Center has an Enhanced Risk just to the northwest of the CWA. The entire CWA to the west of US 165 is highlighted in a Slight Risk of severe thunderstorms and areas to the east are highlighted in a Marginal Risk of severe weather. There is some question as to what types of convective modes will be likely over the CWA as the surface trough moves through and this will have a great influence on the potential weather hazards. Continue to monitor the forecast on Friday and Saturday for further refinements as the event gets closer. Early next week another shortwave trough is forecast to dig into the Southern Plains resulting in another round of convection. There is still some uncertainty as to whether this round of convection will even be able to develop far enough south to impact the area. Therefore, 20% to 40% PoPs remain in the forecast from Tuesday afternoon through Tuesday night. The series of digging shortwave troughs will contribute to height increases and a ridge developing over the northern Gulf Coast during the later half of the week. This will likely result in warmer and drier conditions after Wednesday. MARINE... Light to modest east to southeast winds will continue tonight before becoming southeasterly on Friday as high pressure shifts to the east. The increasing pressure gradient between the high pressure and an approaching surface trough will result in the onshore flow strengthening to 15-20 knots on Saturday. Small craft exercise caution or small craft advisory headlines may be needed from Saturday through Sunday morning. Showers and thunderstorms will be likely from Saturday through Sunday as a surface trough moves across the coastal waters. The surface pressure gradient is forecast to increase over the coastal waters again late Monday through Wednesday. Another round of small craft exercise caution or small craft advisory headlines may be needed during this timeframe. && .PRELIMINARY POINT TEMPS/POPS... AEX 63 87 66 85 / 0 10 0 50 LCH 66 85 71 85 / 0 10 10 30 LFT 66 87 70 87 / 0 0 0 30 BPT 68 83 72 84 / 0 20 10 30 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$ AVIATION...07