Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
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039 FXUS64 KJAN 291454 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 954 AM CDT Sat Jun 29 2024 ...New MESOSCALE UPDATE... .MESOSCALE UPDATE... Issued at 946 AM CDT Sat Jun 29 2024 Several updates were made to the forecast to better reflect current conditions and expectations. Isentropic ascent beneath building ridging aloft has lead to isolated to scattered showers and cloudcover holding on longer than expected. This has introduced some uncertainty regarding the temperature forecast. Current thinking is greater low level moisture and cloudcover will keep temperatures lower than anticipated southeast of the Natchez Trace. As such, ticked down temps in this area a few degrees. Conditions will continue to be monitored and the forecast will adjusted accordingly. In addition to the lower than expected temps, the dewpoints are holding higher. Regardless, it is going to be quite a muggy afternoon. Have also opted to cut back on PoPs to better reflect a more isolated to scattered nature. Further north, little changes were made. GLH already has a heat index of 105, and clearing is visible on satellite in this area. This area should feel more influence of the ridge, which should act to suppress cloudcover as opposed to areas further south and east. Thinking it will still be quite a hot day in the Delta./SAS/ && .DISCUSSION... Issued at 420 AM CDT Sat Jun 29 2024 Today and Tonight: Dangerous heat conditions will continue to be the primary hazard in the short term period as early morning global guidance continues to show upper ridging building over the southeast CONUS. Southwesterly low level flow will continue across the forecast area today. This will allow for dewpoints to hold in the upper 70s across our CWA, with a few spots across the Delta seeing dewpoints in the 80s. This combination will yield heat indices well into the 105-115 F deg range areawide. For this reason, an excessive heat warning remains in effect from 10 am this morning to 8 pm Sunday evening, including the Delta, southeast Arkansas, and northeast Louisiana. Elsewhere, a heat advisory remains in effect mainly for areas along and east of the I-55 corridor. Later in the afternoon, it is possible that some of the counties currently under heat advisory could see slightly higher dewpoints. If this trend holds, it is possible that several counties could see an upgrade to excessive heat warning. Rain chances will be fairly low across northwest portions of our area with the best rain chances (between 60- 70%) across the Pine Belt. No changes were made to the heat graphic for today and we maintained a "Significant" heat risk for areas where the excessive heat warning remains in effect. Rain chances will begin to diminish heading into the evening hours. Nighttime temperatures will drop into the mid to upper 70s across the area providing very little relief heading into the overnight period. /CR/ Sunday through Friday: Heat is still going to be the main message for the week ahead. As the subtropical ridge moves east over the Gulf Coast region through the week, subsidence below the core of the ridge will limit rain chances and support mostly above normal temperatures. This isn`t to say rain is impossible, but just that rain chances increase more around the periphery of the ridge. A "cold front" moving south into the area Sunday night into Monday will arrive in advance of the ridge`s passage, with the week`s best areawide chances for showers and thunderstorms Sunday afternoon. Temps on Monday will even be knocked down a few degrees north of Interstate 20, but as the front washes out temps should quickly rebound for the rest of the week. Daily rain chances will be focused in the afternoon with peak heating and mainly in the south and southeast with possible sea breeze activity and better moisture availability. Flow trajectories around the high will bring drier air generally from the east through most of the period. Guidance looks to be trending a little drier for Thursday July 4th, though a slight chance to chance for showers and storms cannot be ruled out at this time. Friday into the weekend, the ridge shifting farther east will allow for troughing to more influence the central and southern US. Another cold front moving into the region will likely bring another focus for rain during the weekend. Will continue to evaluate Heat products for this Sunday, but current forecast temp/dew point values yield similar values for current Advisory/Warning configuration. Monday`s heat will be mainly in the southern half of the area, and an extension of the Heat Advisory is possible for those areas. Headlines likely to continue into the Independence Day holiday as well if trends continue as they are. /NF/ && .AVIATION... (12Z TAFS) Issued at 621 AM CDT Sat Jun 29 2024 A mixture of VFR/MVFR ceilings are occurring across central MS to start off the TAF period. Rain chances will start to increase across portions of southeast MS starting around 12Z Saturday. A few southern TAF sites (HEZ and PIB) will see ceilings drop to MVFR/IFR conditions through 13Z Saturday. SHRA and TSRA will become widespread by 18Z Saturday with MVFR ceilings prevailing across central MS through 00Z Sunday. Rain chances will start to diminish by 01Z Sunday. By 02Z Sunday, ceilings will begin to improve to VFR conditions. VFR ceilings will prevail through 08Z Sunday. Areas along and south of the Hwy 84 corridor will see ceilings drop to MVFR/IFR ceilings starting around 09Z Sunday. /CR/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 92 76 93 76 / 40 20 60 20 Meridian 90 74 95 73 / 50 20 80 20 Vicksburg 95 77 95 76 / 30 20 40 20 Hattiesburg 89 76 95 77 / 50 30 80 20 Natchez 94 75 93 76 / 30 20 40 20 Greenville 97 79 96 76 / 10 20 50 20 Greenwood 96 77 96 73 / 20 20 60 20 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...Excessive Heat Warning until 8 PM CDT Sunday for MSZ018-019- 025>027-034>036-040>042-047-053-059-060. Heat Advisory until 8 PM CDT Sunday for MSZ028>033-037>039- 043>046-048>052-054>058-061>066-072>074. LA...Excessive Heat Warning until 8 PM CDT Sunday for LAZ007>009-015- 016-023>026. AR...Excessive Heat Warning until 8 PM CDT Sunday for ARZ074-075. && $$ CR/NF/CR