Area Forecast Discussion
Issued by NWS Jackson, MS
Issued by NWS Jackson, MS
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
433 FXUS64 KJAN 081738 AAC AFDJAN Area Forecast Discussion...UPDATED National Weather Service Jackson MS 1238 PM CDT Wed May 8 2024 ...New AVIATION... .MESOSCALE UPDATE... Issued at 944 AM CDT Wed May 8 2024 We`re off to another mostly cloudy and muggy start this morning, with lower stratus clouds slowly beginning to erode/lift. The 12z KJAN RAOB revealed stout capping in the 750-850 mb layer. Generally speaking, this cap is expected to remain through today limited precip potential, but some guidance solutions do suggest a few updrafts may be able to break through more toward this afternoon and mainly north of I-20. If any cells do develop and can persist, they will have access to an unstable environment with somewhat strong deep shear and steep mid level lapse rates, so we can`t rule out an isolated severe storm during the afternoon hours. Damaging wind gusts and large hail would be the primary concerns. However, the greater potential for severe weather as currently outlooked is for later tonight with any development outside of our region that moves into the area during the overnight hours. PoPs for today were adjusted to add isolated showers and storms over a larger area. Otherwise, no notable tweaks will be made at this time. /DL/ && .DISCUSSION... Issued at 501 AM CDT Wed May 8 2024 Today through tonight: After a hot day in which temperatures are expected to reach ~90 F over much of the forecast area, we should see the threat for severe weather increase late tonight. Subsidence associated with anticyclonic flow aloft will maintain a capping inversion over the forecast area today, and this will help keep thunderstorm chances to a minimum through this evening in spite of the hot and humid surface conditions. While isolated discrete storms could manage to develop during peak heating near the Highway 82 corridor, where ML CAPE will likely exceed 3000 j/kg, the threat for any organized storms will remain well north of the area until the cold front and associated convective system begin to shift southward late tonight. The combination of very unstable air and moderately strong deep layer shear will help to maintain a potential MCS as it shifts south, but the persistent ridge over the forecast area will tend to deflect greater forcing and slow the system progression down while veering the lower level flow. So will maintain the slight/marginal risks over northwest portions of the area and continue to emphasize damaging straight line/hail potential over tornado threats. The overall severe weather threat should be diminished as we approach daybreak Thursday morning. /EC/ Thursday through Thursday Night: A more significant severe weather threat may evolve late afternoon into the overnight. Most models indicate shortwave energy digging southward from the upper midwest will help to flatten the ridge and allow the cold front to shift closer to the I-20 corridor by late in the day. During the day, steep lapse rates and strong heating will make for a very unstable airmass with ML CAPE approaching 4000 j/kg, but the lack of forcing combined with a capping inversion will keep the potential for deep convection relatively low. The potential for strong to severe storms will begin to pick up during the evening (starting a little after 5pm) as greater ascent in the mid levels interacts with the stalled frontal boundary. This is when forecast confidence diminishes due to increased spread in the guidance concerning the convective evolution. While storms will likely develop well to the west over eastern TX initially, determining how they organize and where they go from there is a challenge. It appears the most probable scenario will follow that of the consistent GFS, which indicates the potential for an intense linear convective moving west to east across our forecast area with damaging wind gusts up to 70 mph and hail up to golf ball size being the primary concerns with these storms. The ceiling is relatively high concerning the potential severity of the late Thursday/Thu night convective system given the extreme thermodynamic parameters combined with strong deep layer shear, but in terms of probability, there is a good bit of spread still among the guidance in the placement/timing, and will maintain a slight risk in the outlook for now. As the event gets closer in time and guidance hopefully come into more agreement, then an increase in risk level will be likely for portions of the forecast area, especially for locations along/south of the I-20 corridor. In addition to the severe potential, there may be some potential for multiple storms to move across the area and produce locally heavy rainfall at times which could lead to minor runoff issues in poor drainage areas. We will continue to monitor trends associated with this system and will provide updates as they become available. Friday through Tuesday: Any thunderstorm chances will come to an end Friday as the frontal boundary surges further south out of our forecast area. Heading into the weekend, a 1020mb sfc high will develop in the ArkLaTex region before slowly pushing east towards our CWA. This will allow for quiet weather to settle across the south with cooler-than-normal temperatures expected. Rain chances will return to the area on Monday and Monday as future guidance hints at another low pressure pressure system developing across the Central Plains. /CR/EC/ && .AVIATION... (18Z TAFS) Issued at 1238 PM CDT Wed May 8 2024 MVFR stratus still linger at a few sites early this afternoon, but ceilings should return to VFR within the next hour or two at most sites. MVFR to locally IFR stratus will return again, spreading northward overnight and continuing into much of Thursday morning. Southerly winds will be gusty at times today, with gusts to around 25 kt possible. Isolated TS cannot be ruled out this afternoon, but most areas will remain dry. Later tonight into early Thursday morning, SHRA and TS are possible across northern portions of the area including GLH/GWO/GTR, but the greatest chances will be north of these locations. If TS does occur, wind gusts to 50 kt are possible. /DL/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 72 88 65 80 / 30 40 60 10 Meridian 71 89 64 82 / 30 50 60 10 Vicksburg 72 89 65 81 / 30 20 60 0 Hattiesburg 73 91 68 84 / 20 30 60 20 Natchez 72 91 64 81 / 20 20 60 10 Greenville 72 87 64 78 / 60 30 40 0 Greenwood 71 87 63 78 / 70 40 40 0 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ /