205 FXUS64 KJAN 181130 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 630 AM CDT Sun Aug 18 2019 .UPDATE... Updated for 12Z aviation discussion && .AVIATION... 12Z TAF discussion: VFR conditions are expected to prevail at all TAF sites through the period, however some patchy BR is causing localized reductions in visbility early this morning. Otherwise, expect isolated to scattered SHRA and TSRA around the region after 18Z. Brief reductions in visibility could accompany any heavier showers or storms before dissipating this evening. /NF/EC/ && .DISCUSSION... Today and Tonight: The chance for showers and thunderstorms will return to most of our forecast area today, all except for the Golden Triangle area where drier air (PWAT less than 1.7 inches) should limit precip chances. Otherwise, expect returning moisture from the south to permit summertime air mass thunderstorms to develop with daytime heating. Meager mid-level lapse rates and meager downdraft instability should limit strong microburst potential today, but the stronger storms could produce locally heavy downpours and gusty winds. The returning humidity will also result in heat index values a little warmer than yesterday if showers can hold off into the afternoon, but with convection expected to develop around Noon, the chance to reach heat advisory criteria (105 heat index) will be limited by increasing cloud cover and possible rain cooled outflow. Monday through Saturday: A strong subtropical ridge axis extending from west to east across much of the southern CONUS will continue to maintain a hot and humid airmass over the ArkLaMiss region. Indications are that the heat will peak during the Mon-Wed time frame when H850 temperatures are forecast to be around 20 C over the Delta region into north central MS. So will continue the limited (yellow) heat threat in the HWO as currently depicted, and it is possible that the threat may need to be raised to elevated (orange) over portions of this area as we get closer in time. In terms of thunderstorm potential, weak shortwave trough energy over the NE Gulf of Mexico should be drawn westward along the Gulf Coast, and this will help enhance diurnal convective precipitation over mainly southeast portions of the ArkLaMiss region through the long range forecast. Global ensembles suggest that more distinct upper troughing and increased moisture transport over the region this weekend could support locally heavy rainfall as we go later into the week and weekend. /EC/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 92 75 93 74 / 39 17 48 13 Meridian 96 74 95 72 / 15 13 44 17 Vicksburg 92 75 95 75 / 36 14 41 13 Hattiesburg 92 74 92 72 / 47 21 69 22 Natchez 91 75 92 74 / 44 16 57 16 Greenville 92 75 93 74 / 32 14 33 6 Greenwood 93 75 93 74 / 27 12 35 9 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$