341 FXUS64 KJAN 132037 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 337 PM CDT Mon Sep 13 2021 .DISCUSSION... Tonight into Tuesday: Our overall driving pattern will continue to transition as more influence from TS Nicholas erodes the ridging to our E and deeper moisture takes shape through advection processes. We're currently seeing some Iso/Sct shower activity and look for this to dissipate in the 6-8pm time window with little or generally light precip for much of the night period. Look for clouds to thicken and increase overnight as peripheral affects of TS Nicholas spread over the region. Due to thicker clouds, MinT tonight should hold a tad warmer with more widespread lower 70s. On Tue, more peripheral things from Nicholas will occur with precip spreading more over the SW and S half of the forecast area during the afternoon hours. Clouds will again increase and be thicker resulting in lower MaxT values across the region. In general, high rain rates look to remain out of our area by tomorrow afternoon, thus any accumulations leading to a flooding threat will have better chances in the periods after Tue afternoon. /CME/ Tomorrow night through Monday: The forecast period starts off tomorrow night with a northern stream shortwave trough swinging through the Upper Mississippi Valley while Tropical Storm Nicholas moves inland over eastern Texas. Nicholas will miss the trough connection to the north as the system remains stuck in a weak flow regime beneath flat upper ridging. Nicholas remains a tricky system to forecast with confidence dropping off beyond the first several days of the period. The system has continued to feel the effects of southwesterly shear and low-level dry air, which has caused the center to relocate northeast several times. This continues to plague the track and timing forecast with guidance still displaying a range of possible solutions. The overall consensus, however, is that Nicholas will weaken into a tropical depression and eventually into a post-tropical remnant low as it lifts northeast and east through Louisiana and into southwest Mississippi Tuesday night through Wednesday night. This is in line with the GFS/ICON/HREF solutions while the ECMWF solution remains a much slower outlier with regards to timing. As the remnants of Nicholas progress inland, it will become increasingly disjointed as the low-level center gets left behind and the mid- and upper-level center lifts northeast across the area. This will further complicate the forecast as the upper forcing may become the primary mechanism for focusing heavy rainfall while a dry slot wraps around the lagging low-level center. Guidance remains split into two camps with placement of rainfall; the first camp with the greatest support favors along and south of I-20 for the heaviest rainfall of 3-6", while the second camp with less support paints a heavy rain axis along the Natchez Trace corridor. Ultimately, placement of heaviest rainfall will hinge on how the remnant low evolves, so will keep the forecast in line with WPC guidance for now, which favors the first scenario along and south of I-20. The limited threat for flooding in the HWO/graphics has been expanded to include this area where 3-6" of rain may lead to flash flooding. An elevated threat area and flash flood watch may eventually be needed for portions of the area as forecast confidence increases. A humid tropical airmass will remain in place across the region following Nichola's departure/dissipation. This will keep at least scattered to numerous showers and thunderstorms around late week through the weekend. Temperatures will start off mild with copious amounts of cloud cover and precipitation holding afternoon highs to the mid to upper 70s on Wednesday with a slow warming trend back into the 80s by late week. Mid to upper 80s will be possible by the weekend with a few readings near the 90 degree mark over the Delta if enough breaks in the cloud cover are realized. /TW/ && .AVIATION... 18Z TAF discussion: Mostly quiet TAF period for the rest of today into much of tonight. After 09-11z, there will be increasing probability of some MVFR conditions developing around PIB/HBG then potentially HKS/JAN/MEI after 12z. This is shown in the latest TAF issuance. As for precip, most confidence in precip coverage will be increasing over the S and central areas around midday and then into the afternoon. Look for the next TAF cycle to capture that. /CME/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 72 81 70 77 / 33 78 93 93 Meridian 71 81 68 76 / 33 61 84 93 Vicksburg 73 81 72 78 / 34 82 93 93 Hattiesburg 72 81 70 81 / 26 80 84 93 Natchez 72 79 70 79 / 39 92 93 93 Greenville 72 83 70 78 / 16 57 86 93 Greenwood 72 83 70 79 / 18 52 87 93 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ TW/CME