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Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
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538 FXUS64 KJAN 140239 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 939 PM CDT Sat Jul 13 2024 ...New MESOSCALE UPDATE... .MESOSCALE UPDATE... Issued at 939 PM CDT Sat Jul 13 2024 Rest of tonight... Convection is mostly winding down this evening, with only some scattered showers lingering. Evening regional upper air soundings indicate deeper moisture return across the area, keeping nearly 1.75 to 2 inch precipitable water (PWs) across the Gulf Coast Region. Water vapor/RAP analysis are similar to yesterday evening: stagnant Atlantic subtropical ridge & nearly 600DM ridge parked over the Four Corners, while sfc high persists over the Gulf Coast. Boundary layer & deep moisture remain elevated, keeping dewpoints up & seasonably warm lows in the low-mid 70s. Mid-level cloudiness will persist overnight, with some patchy fog possible south of Interstate 20, especially in areas that received rain today. Updates are out. /DC/ && .DISCUSSION... Issued at 311 PM CDT Sat Jul 13 2024 Today through Next Saturday: Looking at how today`s weather has trended, two features are worth noting. First is the areas of convection over Southeast Texas and southwestern Louisiana this afternoon. This activity is within a plume of 2.0 inch PWAT air and beneath the right entrance region of the jet stream associated with an upper-level trough in the region. Increased lift and saturation in that area is generating a fair amount of convection and spreading the cirrus blowoff clouds over Northeast Louisiana. This has helped to shade the western half of our area so far this afternoon and limit max temps by a few degrees. Meanwhile, eastern Mississippi zones are sufficiently warming into the mid and upper 90s as advertised. The other feature of note is the sprawling surface high over the Southeast U.S. and the drier air it is helping to mix down over northern portions of our area this afternoon. Dew points even south of Interstate 20 have mixed out into the lower 70s today. The resulting drier conditions have limited expected heat index values today, with only the Pine Belt retaining the peak heat and humidity for strict Heat Advisory criteria. Areas through the I-20 corridor in Mississippi are still near 105, so will keep current advisory in effect, but portions of Northeast Louisiana and northwest Mississippi were removed from today`s advisory. The NAM and GFS explicitly show some sort of mid- level low or MCV feature evolving from the TX/LA convection this evening and drifting northeast with the flow, and this seems like a reasonable possibility given the jet dynamics and vorticity in the base of the upper-level trough. Such a feature will continue at least slight chance POPs into the evening, increase cloud cover for tomorrow, and bring possible earlier start to rain chances tomorrow. Either way, guidance pegs higher cloud cover and resulting lower temps in the western zones again tomorrow. Have left the Heat Advisory unchanged for tomorrow at this time, but current projections have peak heat index values only near or exceeding 105 degrees in Southeast Mississippi. Will let the next forecast shift evaluate trends into the evening. The upper-level trough axis never truly clears out of the central Gulf Coast region through the end of this week, so afternoon convection and increased cloud cover will continue to challenge peak heating potential. If convection should hold off any afternoon, there is the potential for dangerous heat to be a concern . Will continue to advertise the Elevated risk out through the middle of this week. A shortwave rounding the base of the trough will usher a cold front into the region around Thursday time frame, which should limit any further heat potential and also will focus rain chances again in our area. /NF/ && .AVIATION... (00Z TAFS) Issued at 730 PM CDT Sat Jul 13 2024 SCT-BKN cloud deck remains in VFR range but will persist the next several hours. Slow-moving SHRA & TSRA remain possible south of I-20, mainly near southeast TAF sites, PIB & HBG, through 14/02Z Sunday. Some patchy fog/BR can`t be ruled out near PIB & psbl at HBG just prior to daybreak 14/09-11Z Sunday. Low probs of light SHRA & isolated TSRA are again psbl Sunday at central-southern sites of JAN, HKS, MEI, HEZ, with more confidence of SHRA & TSRA at HBG & PIB, mainly late Sunday aftn between 14/19-23Z. Light westerly winds, less than 10mph, are expected through the next 24 hours. /DC/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 75 95 75 95 / 10 50 30 60 Meridian 74 98 74 96 / 10 50 30 60 Vicksburg 74 94 75 95 / 20 40 20 40 Hattiesburg 75 97 76 95 / 30 70 20 70 Natchez 73 93 75 93 / 30 50 10 40 Greenville 75 94 75 95 / 10 30 10 20 Greenwood 75 96 75 95 / 10 30 10 30 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...Heat Advisory from 10 AM to 7 PM CDT Sunday for MSZ040-041- 047>049-053>057-059>066-072>074. LA...Heat Advisory from 10 AM to 7 PM CDT Sunday for LAZ007>009-015- 016-023>026. AR...None. && $$ DC/NF/DC