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Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
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185 FXUS64 KJAN 180916 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 416 AM CDT Thu Jul 18 2024 ...New DISCUSSION... .DISCUSSION... Issued at 414 AM CDT Thu Jul 18 2024 Today and tonight... This morning, an upper trough will continue to dig into our CWA, bringing deep moisture into the region along a frontal boundary progged to hang up across central MS later this afternoon. Early morning radar imagery depicts precipitation diminishing across the northern portions of our area, but is expected to be short lived as we inch closer to daybreak. Isolated showers and some storms are present across the I-20 corridor, but is expected to remain isolated for the next few hours. By the early afternoon hours, showers and storms will increase from the S/SW and become scattered to numerous across the region as boundary brings a moist airmass into the area. Ahead of rain potential, heat indices are expected to increase to or near 105 degrees across portions of central and southeast MS. A Heat Advisory is in effect from 10am - 7pm to account for areas that may not see widespread precipitation until later in the afternoon. By this evening into the overnight, showers and storms are expected to continue across the CWA. Some guidance suggests slow moving/training storms across western portions of the CWA, but confidence is low for any widespread flash flooding issues. Some locally heavy rainfall and intense rainfall rates could create isolated flooding for these areas. For now, flood products will not be advertised, but the low end threat seems to remain in guidance. Cloud cover will increase overnight with lows in the upper 60s to low 70s. /AJ/ Late week through mid next week (Friday-next Wednesday)... The synoptic pattern will consist of persistent longwave troughing over the MS River Valley up through the Great Lakes, with more perturbed/jet energy focused across the northern portions of the nation into eastern Canada. The Gulf Coast will remain in perturbed southwesterly flow late this week all the way through the middle of next week. This is mainly driven by two features: deep ridge axis over the Four Corners & gradually building northward into the northern Rockies to west-northwestern Canada & southwestern Atlantic subtropical ridging extending into the FL Peninsula to southeast Gulf of Mexico. This is will keep a Rex Block type pattern with nearly 600DM 500mb ridge across the Four Corners to Intermountain West & broad troughing east of the Rockies through the MS River Valley into the Great Lakes to northeast. There will be a series of perturbations that will dive southeast through the period, with the first shortwave moving through tomorrow into Saturday, with some drier building in the wake in the Delta this weekend. This will aid in the highest coverage this weekend of scattered to numerous showers & storms along & southeast of the Natchez Trace corridor, while more scattered to the northwest. With light upwind propagation vectors, soupy tropical airmass of > 2inch precipitable water (PWs) & support from the HREF, there are localized prob match mean / maximum of the ensemble envelope that could support some 2-4", with localized 4-6" rainfall amounts. HREF prob match mean indicate 30% probs of >3 inches, which is usually a solid indicator of flash flooding potential. However, this remains low confidence in narrowing a corridor & also don`t feel the need to broad brush an areawide "Limited" in the HWO. The most likely area would be along the I-55 corridor to the southwest, southeast of the ArkLaMiss Delta, towards the I-20 corridor west of Vicksburg. WPC currently has "Marginal" advertised Friday & shifting southeast through the weekend. If an areal focus can be narrowed down, we will likely need to advertise some focused area in the HWO. Holding off for now. Temperatures will be seasonably cool Friday in the low-mid 80s before moderating into the upper 80s into the weekend, with seasonable lows in the upper 60s-low 70s through the weekend. Heat stress will be held in check through the weekend. Some patchy fog is possible as well through the weekend, especially in areas that receive sufficient rainfall. While some strong storms can`t be ruled out, severe convection is not anticipated at this time through the weekend. The first round of convection will be focused southeast of the Natchez Trace along the stationary frontal boundary, which is progged to lift back northward into early next week. This will be in response to a stronger shortwave diving into the Great Lakes early- middle of next week, with the trough axis deepening across the ArkLaTex into the Mid-Upper MS Valley. This will help drive deeper moisture back to the northwest, lifting scattered to numerous rain & storm chances northwest across the area, with the highest remaining southeast of the Natchez Trace corridor. This wet, rainy & stagnant pattern will keep highs slightly below seasonable values in the mid- upper 80s, with seasonable lows in the upper 60s-low 70s. This pattern will keep needed relief from any heat stress concerns through the middle of next week. With soupy, tropical airmass remaining in the area, lapse rates will remain poor, so poorly organized convection will be the case through the middle of next week. /DC/ && .AVIATION... (06Z TAFS) Issued at 1254 AM CDT Thu Jul 18 2024 SHRA/TSRA is expected to briefly diminish across GWO/GLH/GTR through 10Z, but toggle between MVFR/VFR cigs. MVFR/IFR conditions are expected to prevail across the sites by 18Z as a second round of TSRS/SHRA moves into the region as a boundary hangs up and precipitation becomes more widespread through 03Z. /AJ/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 91 71 84 70 / 80 80 80 60 Meridian 94 70 85 69 / 90 70 90 70 Vicksburg 89 71 84 70 / 70 80 70 40 Hattiesburg 94 73 88 73 / 80 80 100 70 Natchez 89 71 84 70 / 90 80 80 50 Greenville 85 70 83 68 / 60 60 40 20 Greenwood 89 70 84 69 / 70 70 50 30 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...Heat Advisory from 10 AM this morning to 7 PM CDT this evening for MSZ054-055-059>066-072>074. LA...None. AR...None. && $$ AJ/DC/AJ