Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
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878 FXUS64 KJAN 290356 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 1056 PM CDT Sun Apr 28 2024 ...New MESOSCALE UPDATE... .MESOSCALE UPDATE... Issued at 1056 PM CDT Sun Apr 28 2024 Rest of tonight... Ongoing MCS is somewhat waning as it moves into the area, with the forward propagation component of this MCS more focused towards central-eastern AR. A tornado watch was issued for southeast AR, northeast LA & extreme northwest MS & continues through 2AM. GOES-East infrared imagery & regional radar mosaic indicate somewhat warming cloud tops aloft & convection somewhat waning in radar presentation on the leading edge of this MCS. More vigorous deep convection/intense cloud tops over southern portions of the ArkLaTex. Evening synoptic analysis remains across the Carolinas to Appalachians while subtropical sfc high remains right off the Atlantic seaboard. 1005mb sfc low is moving into the Mid West. As the trough swings east-northeast, strong southern stream shortwave, indicated by stout drying over the southern Plains, will continue to eject to the east overnight through the morning hours. This will provide the impetus for more convective development, especially in the areas along the ArkLaTex & expected to slide to the east-southeast a MCS. For areas south of the ongoing complex & cold pool moving into northeast LA & southeast AR, low-level jet around 30-40kts, low-level instability & somewhat favorably aligned low-level flow for organized MCS to remain likely into the overnight hours. SPC earlier added an "Enhanced" for areas west of the MS River & kept it confined to this zone, with the most likely area of seeing the higher wind probs of up to 70mph along & south of the I-20 corridor from Rustin, LA to Natchez, MS area through the overnight hours. Main hazards remain damaging winds 60-70mph, with best chances west of MS River, spinup tornadoes & large hail in any deeper core that could develop. Timing has been tricky, as guidance earlier indicated some of this convection could precede a later MCS, but have now congealed into one definitive MCS propagating southeast, with the southern half along & south of I-20 corridor becoming the most concerning. Main updates were to add the "Enhanced" to the HWO graphics for west of the MS River, tweak an earlier start timing for the western timing slot & speed up timing slightly along & east of the I-55 corridor. Heavy rain looks to be confined for the southwestern half of the area, with most confident area along & southwest of a line from Bolivar to Lincoln county in MS. No other major changes were needed. Updates are out. /DC/ && .DISCUSSION... Issued at 253 PM CDT Sun Apr 28 2024 As anticipated, weaker inhibition today is allowing for warm advection showers to develop and spread north across the forecast area today. Isolated thunderstorms are embedded with this activity as well, but deep layer shear is not favorable for organized updrafts. Expect quick moving, and short-lived storms where they do develop. Regional radar mosaic showed the remnants of last night`s convective line were all but washed out across North Texas into Arkansas, but an organized cluster of storms has re-fired east of Waco and Killeen in Texas this afternoon. High res guidance has struggled with how to transition from last night to today`s activity, but but they all generally get to the point of one or more MCS segments drifting east through Louisiana and Arkansas toward Mississippi late tonight. 06Z and 12Z HRRR were previous fast outliers, but 18Z run has come into a little closer agreement with consensus of HREF members regarding timing. Southerly low-level jet winds and greatest instability located to the south of any MCS activity will favor southward propagating MCS activity by morning (or at least most intense MCS activity farther south along any broken line). Forecast MLCAPE values over 1000 J/kg seem to favor MCS trajectory to be along or southwest of a diagonal line roughly from Ruston, LA down Natchez, MS or so. Depending on timing and placement of overnight storms, the potential for severe storms could extend farther east to around the Interstate 55 corridor. Bowing segments along any line could lead to increased potential for damaging wind gusts and possible spinup tornadoes. The Slight Risk for severe storms was expanded to account for this wind and isolated tornado potential - including southeast Arkansas, northeast and central Louisiana, and far southwestern Mississippi. The Marginal Risk area extends south through Mississippi generally along Interstate 55. In addition to any severe threat, heavy rainfall could cause localized flash flooding concerns. End timing is a little uncertain, but an organized line will probably clear out earlier in the day than anything disorganized. /NF/ Monday Night through Sunday: A fairly progressive split flow regime sets up over the CONUS through the rest of next week, driving a few potential periods of showers and thunderstorms as shortwave troughs moving east and interact with spring-like humid and unstable air masses across the South. Nothing at this point looks to fully scour out the decent moisture in the region, and PWAT values over 1.3 inches should support air mass thunderstorms on any given day. When not raining, afternoon high temperatures should push the upper 80s/lower 90s range. Glimpses of summertime are coming into view. /NF/ && .AVIATION... (00Z TAFS) Issued at 826 PM CDT Sun Apr 28 2024 Southeasterly sfc winds will continue through early evening. MVFR stratus should develop at all TAF sites, with onset between 29/04-7Z & earlier onset at southern-central TAF sites. TSRA ongoing across northern LA into southwestern AR will propagate northeastward, with more SHRA & TSRA expected overnight. Some gusts in these storms could bring 40-50kts at times & variable ceilings/vsby. Expect a gradual decrease in coverage from west-east overnight & some improvement to VFR flight categories in spots. SHRA & TSRA will decrease from west-east into the morning hours, mainly after 29/15-20Z. /DC/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 69 78 63 83 / 10 80 60 20 Meridian 64 81 63 84 / 0 70 80 30 Vicksburg 67 77 63 84 / 40 90 40 20 Hattiesburg 67 81 64 84 / 10 70 70 40 Natchez 67 76 63 85 / 40 90 40 30 Greenville 69 75 63 82 / 60 90 40 10 Greenwood 68 76 63 83 / 20 90 60 10 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ DC/NF/DC